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1. Extreme temperature events monitored by Raman lidar: Consistency and complementarity with spaceborne observations and modelling

Author

Alexandre Baron, Patrick Chazette, and Julien Totems

Subjects
comparison, ERA5, IASI, IFS, observational requirements, rotational Raman, Meteorology. Climatology, QC851-999
Abstract

Abstract Two extreme temperature events (ETEs), both triggered by atmospheric blocking situations, were monitored by a pure rotational Raman lidar 20 km south of Paris. The first ETE lasted 6 days in late February 2018 with the onset of a cold wave surging from Siberia, and the second was a short heatwave that occurred at the end of July 2020. After calibration using simultaneous radiosoundings, lidar vertical profiles of temperature are derived with an uncertainty of less than 1 °C within both the planetary boundary layer and the lower/middle free troposphere (~3/6 km above ground level [a.g.l.] for day/night), with a final vertical resolution of 50 m and a temporal resolution of 30 min. Such capabilities fulfil the observational requirements of the World Meteorological Organisation and contribute to fill a gap left behind by current operational instruments, which struggle to follow the diurnal cycle of the planetary boundary layer due to insufficient spatial and temporal resolutions in the low troposphere. These case studies allow to assess how such weather events are represented by numerical weather prediction modelling and whether they can be correctly observed by the Infrared Atmospheric Sounding Interferometer (IASI) spaceborne mission. Our results demonstrate that during these events both ECMWF reanalyses and forecasts are in overall very good accordance with lidar observations (correlation >0.9 in average). Still, they show warm biases (~1°C–2°C) compared with the lidar and improvable temperature field representation in the boundary layer. The radiances measured by IASI, assimilated in the operational model, do not capture temperature profiles adequately below ~2–3 km a.g.l., mainly due to the altitude location of its weighting functions. The bias computed against the lidar reaches 2°C during the heatwave and 4°C during the cold wave case in the first 2 km of the atmosphere, beyond expected errors found in the literature.

Published
2022
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2. Lidar Profiling of Aerosol Vertical Distribution in the Urbanized French Alpine Valley of Annecy and Impact of a Saharan Dust Transport Event

Author

Patrick Chazette and Julien Totems

Subjects
aerosol, lidar, atmosphere, structure, valley, lake, Science
Abstract

The vertical aerosol layering of the troposphere is poorly documented in mountainous regions, particularly in the Alpine valleys, which are influenced by valley and mountain winds. To improve our knowledge of particulate matter trapped in the Annecy valley, synergetic measurements performed by a ground-based meteorological Raman lidar and a Rayleigh-Mie lidar aboard an ultralight aircraft were implemented as part of the Lacustrine-Water vApor Isotope inVentory Experiment (L-WAIVE) over Lake Annecy. These observations were complemented by satellite observations and Lagrangian modeling. The vertical profiles of aerosol optical properties (e.g., aerosol extinction coefficient (AEC), lidar ratio (LR), particle linear depolarization ratio (PDR)) are derived from lidar measurements at 355 nm during the period between 13 and 22 June 2019. The background aerosol content with an aerosol optical thickness (AOT) of 0.10 ± 0.05, corresponding to local–regional conditions influenced by anthropogenic pollution, has been characterized over the entirety of Lake Annecy thanks to the mobile ultralight payload. The aerosol optical properties are shown to be particularly variable over time in the atmospheric column, with mean LRs (PDRs) varying between 40 ± 8 and 115 ± 15 sr (2 ± 1 and 35 ± 2%). Those conditions can be disturbed by air masses that have recirculated over the valley, as well as by contributions from neighboring valleys. We have observed an important disruption in the atmospheric aerosol profiles by the arrival of an exceptionally dry air mass (RH ~ 30%), containing aerosols identified as coming from the Great Western Erg (AOT ~ 0.5, LR = 65 ± 10 sr, PDR = 20–35%) in the Sahara. These desert dust particles are shown to influence the entire atmospheric column in the Annecy valley. Such an experimental approach, coupling upward and downward lidar and spaceborne observation/Lagrangian modelling, was shown to be of significant interest for the long-term monitoring of the evolution of aerosol loads over deep valleys. It allows a better understanding of the influence of dust storms in the presence of severe convective weather processes.

Published
2023
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3. End-to-End Simulation for a Forest-Dedicated Full-Waveform Lidar Onboard a Satellite Initialized from Airborne Ultraviolet Lidar Experiments

Author

Xiaoxia Shang and Patrick Chazette

Subjects
link budget, spaceborne, canopy, lidar, simulation, Science
Abstract

In order to study forests at the global scale, a detailed link budget for a lidar system onboard satellite is presented. It is based on an original approach coupling airborne lidar observations and an end-to-end simulator. The simulator is initialized by airborne lidar measurements performed over temperate and tropical forests on the French territory, representing a wide range of forests ecosystems. Considering two complementary wavelengths of 355 and 1064 nm, the end-to-end simulator computes the performance of spaceborne lidar systems for different orbits. The analysis is based on forest structural (tree top height, quadratic mean canopy height) and optical (forest optical thickness) parameters. Although an ultraviolet lidar appears to be a good candidate for airborne measurements, our results show that the limited energy is not favorable for spaceborne missions with such a wavelength. A near infrared wavelength at 1064 nm is preferable, requiring ~100 mJ laser emitted energy, which is in agreement with current and future spaceborne missions involving a lidar. We find that the signal-to-noise ratio at the ground level to extract both the structural and optical parameters of forests must be larger than 10. Hence, considering the presence of clouds and aerosols in the atmosphere and assuming a stationary forest, a good detection probability of 99% can be reached when 4 or 5 satellite revisits are considered for a lidar system onboard the ISS or ICESat, respectively. This concerns ~90% of forest covers observed from the lidar, which have an optical thickness less than 3.

Published
2015
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4. Observing the Forest Canopy with a New Ultra-Violet Compact Airborne Lidar

Author

Dominique Guyon, Denis Loustau, Pascal Genau, Sylvie Durrieu, Joseph Sanak, Pierre H. Flamant, Tristan Allouis, Patrick Chazette, Juan Cuesta, and Cyrille Flamant

Subjects
vegetation active remote sensing, laser, canopy lidar, airborne lidar, ultra-violet emission, ultra-light airplane, Chemical technology, TP1-1185
Abstract

We have developed a new airborne UV lidar for the forest canopy and deployed it in the Landes forest (France). It is the first one that: (i) operates at 355 nm for emitting energetic pulses of 16 mJ at 20 Hz while fulfilling eye-safety regulations and (ii) is flown onboard an ultra-light airplane for enhanced flight flexibility. Laser footprints at ground level were 2.4 m wide for a flying altitude of 300 m. Three test areas of ~500 × 500 m2 with Maritime pines of different ages were investigated. We used a threshold method adapted for this lidar to accurately extract from its waveforms detailed forest canopy vertical structure: canopy top, tree crown base and undergrowth heights. Good detection sensitivity enabled the observation of ground returns underneath the trees. Statistical and one-to-one comparisons with ground measurements by field foresters indicated a mean absolute accuracy of ~1 m. Sensitivity tests on detection threshold showed the importance of signal to noise ratio and footprint size for a proper detection of the canopy vertical structure. This UV-lidar is intended for future innovative applications of simultaneous observation of forest canopy, laser-induced vegetation fluorescence and atmospheric aerosols.

Published
2010
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5. Raman lidars for a better understanding of pollution in the Arctic System (PARCS)

Author

Patrick Chazette, Jean-Christophe Raut, Julien Totems, Xiaoxia Shang, Christophe Caudoux, Julien Delanoë, and Kathy Law

Subjects
Physics, QC1-999
Abstract

The development of oil and gas drilling and the opening of new shipping routes, in the Barents and Norway seas, poses new challenges for the Arctic environment due to the impact of air pollution emissions on climate and air quality. To improve our knowledge of the interactions between aerosols, water vapor and cloud cover, within the French PARCS (Pollution in the ARCtic System) project, Raman lidar observations were performed from the ground and from an ultra-light aircraft near the North Cape in northern Norway, and coupled with measurements from a 95 GHz ground-based Doppler radar.

Published
2018
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6. Mini N2-Raman Lidar Onboard Ultra-Light Aircraft for Aerosol Measurements: Demonstration and Extrapolation

Author

Patrick Chazette and Julien Totems

Subjects
N2-Raman Lidar, ultra-light aircraft, airborne, aerosol, optical properties, simulator, error budget, Science
Abstract

Few airborne aerosol research experiments have deployed N2-Raman Lidar despite its capability to retrieve aerosol optical properties without ambiguity. Here, we show the high scientific potential of this instrument when used with specific flight plans. Our demonstration is based on (i) a field-experiment conducted in June 2015 in southern France, involving a N2-Raman Lidar embedded on an ultra-light aircraft (ULA); and (ii) an appropriate algorithmic approach using two-level flight levels, aiming to solve the notorious instability of the airborne Lidar inversion for the retrieval of aerosol optical properties. The Lidar measurements include the determination of the aerosol extinction coefficient along ~500 m horizontal line of sight, and this value is used as a reference to validate the proposed algorithm. The Lidar-derived vertical profiles obtained during the flights are used as an input in a Monte Carlo simulation in order to compute the error budget in terms of biases and standard deviations on the retrieved aerosol extinction coefficient profile, as well as the subsequent optical thickness. The influence of the Lidar ratio (i.e., between aerosol extinction and backscatter) on the error budget is further discussed. Finally, from this end-to-end modeling, an optimal N2-Raman Lidar is proposed for airborne experiments, adapted to both small and large carriers.

Published
2017
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7. Raman Lidar Observations of Aerosol Optical Properties in 11 Cities from France to Siberia

Author

Elsa Dieudonné, Patrick Chazette, Fabien Marnas, Julien Totems, and Xiaoxia Shang

Subjects
aerosol optical properties, Raman lidar, lidar ratio, particle depolarization ratio, Russia, Science
Abstract

In June 2013, a ground-based mobile lidar performed the ~10,000 km ride from Paris to Ulan-Ude, near Lake Baikal, profiling aerosol optical properties in the cities visited along the journey and allowing the first comparison of urban aerosols optical properties across Eurasia. The lidar instrument was equipped with N2-Raman and depolarization channels, enabling the retrieval of the 355-nm extinction-to-backscatter ratio (also called Lidar Ratio (LR)) and the linear Particle Depolarization Ratio (PDR) in the urban planetary boundary or residual layer over 11 cities. The optical properties of pollution particles were found to be homogeneous all along the journey: no longitude dependence was observed for the LR, with most values falling within the 67–96 sr range. There exists only a slight increase of PDR between cities in Europe and Russia, which we attribute to a higher fraction of coarse terrigenous particles lifted from bad-tarmac roads and unvegetated terrains, which resulted, for instance, in a +1.7% increase between the megalopolises of Paris and Moscow. A few lower LR values (38 to 50 sr) were encountered above two medium size Siberian cities and in an isolated plume, suggesting that the relative weight of terrigenous aerosols in the mix may increase in smaller cities. Space-borne observations from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), retrieved during summer 2013 above the same Russian cities, confirmed the prevalence of aerosols classified as “polluted dust”. Finally, we encountered one special feature in the Russian aerosol mix as we observed with good confidence an unusual aerosol layer displaying both a very high LR (96 sr) and a very high PDR (20%), even though both features make it difficult to identify the aerosol type.

Published
2017
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8. Tropical Forests of Réunion Island Classified from Airborne Full-Waveform LiDAR Measurements

Author

Xiaoxia Shang, Patrick Chazette, Julien Totems, Elsa Dieudonné, Eric Hamonou, Valentin Duflot, Dominique Strasberg, Olivier Flores, Jacques Fournel, and Pierre Tulet

Subjects
tropical forest, airborne LiDAR, canopy height, Leaf Area Index, apparent foliage, Science
Abstract

From an unprecedented experiment using airborne measurements performed over the rich forests of Réunion Island, this paper aims to present a methodology for the classification of diverse tropical forest biomes as retrieved from vertical profiles measured using a full-waveform LiDAR. This objective is met through the retrieval of both the canopy height and the Leaf Area Index (LAI), obtained as an integral of the foliage profile. The campaign involved sites ranging from coastal to rain forest, including tropical montane cloud forest, as found on the Bélouve plateau. The mean values of estimated LAI retrieved from the apparent foliage profile are between ~5 and 8 m2/m2, and the mean canopy height values are ~15 m for both tropical montane cloud and rain forests. Good agreement is found between LiDAR- and MODIS-derived LAI for moderate LAI (~5 m2/m2), but the LAI retrieved from LiDAR is larger than MODIS on thick rain forest sites (~8 against ~6 m2/m2 from MODIS). Regarding the characterization of tropical forest biomes, we show that the rain and montane tropical forests can be well distinguished from planted forests by the use of the parameters directly retrieved from LiDAR measurements.

Published
2016
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9. Water vapor retrieval from mini Raman lidar HORUS in the framework of the WaLiNeAs campaign

Author

Frédéric Laly, Patrick Chazette, Julien Totems, and Jérémy Lagarrigue

Abstract

The Mediterranean Rim, and more particularly the western Mediterranean area, is one of the most sensitive regions to climate change. The associated environmental changes are already evident through periods of drought and intense rainfall. The predictions of these phenomena are a major societal issue, which led us to use lidar systems to constrain regional modelling. The Raman lidars HORUS-1 and -2 are each composed of two telescopes of 15 cm diameter. For each telescope N2 and H2O channels are associated. Lidars components have been specifically defined for this task and put into operation during the international Water vapor Lidar Network Assimilation (WaLiNeAs) campaign led by French research teams. Among the three stations managed by the LSCE team, two of them were equipped with HORUS lidar systems at the Port Camargue (43.52 N 4.13 E) and Coursan (43.23 N 3.06 E) sites. The main difference between the two HORUS lidars is the laser used. For HORUS-1 we used an ULTRA laser (optimally pumped by a flash lamp at 30 mJ/20Hz) which showed a good reliability since the beginning of the lidar installation. However, the MERION-C laser (optimally pumped by diodes at 30 mJ/100 Hz) installed in HORUS-2 did not live up to our expectations with several failures, to the point of stopping the measurements in Coursan. We will nevertheless discuss the relative interest of these two lasers in projection of future Raman lidar networks. Observations available from these two lidar systems will be presented and discussed with respect to the meteorological processes encountered during their operating periods.We give a special acknowledgment to the ANR grant #ANR-20-CE04-0001 for the contribution to the WaLiNeAs program and a special acknowledgment to Meteo France and to the CNRS INSU national LEFE program for their financial contribution for this project. The CEA is acknowledged for the provision of its staff and facilities.

Published
2023
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10. Water isotopic characterisation of the cloud-circulation coupling in the North Atlantic trades. Part 1: A process-oriented evaluation of COSMOiso simulations with EUREC4A observations

Author

Leonie Villiger, Marina Dütsch, Sandrine Bony, Marie Lothon, Stephan Pfahl, Heini Wernli, Pierre-Etienne Brilouet, Patrick Chazette, Pierre Coutris, Julien Delanoë, Cyrille Flamant, Alfons Schwarzenboeck, Martin Werner, Franziska Aemisegger, Institute for Atmospheric and Climate Science [Zürich] (IAC), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Institute for Environmental Decisions [ETH Zürich] (IED), Department of Environmental Systems Science [ETH Zürich] (D-USYS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Department of Meteorology and Geophysics [Vienna], Universität Wien, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire d'aérologie (LAERO), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut für Meteorologie [Berlin], Freie Universität Berlin, Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Physique (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), SPACE - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), TROPO - LATMOS, and Alfred Wegener Institute for Polar and Marine Research (AWI)

Subjects
[SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology
Abstract

Stable water isotope observations have the potential to provide information on cloud processes in the trade-wind region, in particular when combined with high-resolution model simulations. In order to evaluate this potential, nested convection-resolving COSMOiso simulations with horizontal grid spacings of 10, 5, and 1 km were carried out in this study over the tropical Atlantic for the time period of the EUREC4A field experiment. To keep the conditions in the domain as close as possible to the real meteorology, we applied a spectral nudging of horizontal winds towards reanalysis data. The comparison to airborne in situ and remote sensing observations shows that the three simulations are able to distinguish between different mesoscale cloud organisation patterns as well as between periods with comparably high and low rain rates. Precipitation, cloud fraction and liquid water content are sensitive to the grid spacing. Cloud fraction and liquid water content show a better agreement with aircraft observations with higher spatial resolution. Contrastingly, temperature, humidity, and isotopes in vapour remain fairly unaffected by the model resolution. A low-level cold-dry bias, including too depleted vapour in the subcloud and cloud layer and too enriched vapour in the free troposphere, is found in all three simulations. Furthermore, the simulated secondary isotope variable d-excess in vapour is overestimated compared to observations. Special attention is given to the cloud base level, the formation altitude of shallow cumulus clouds, which are rooted in the thermals of the subcloud layer. The temporal variability of the simulated isotope variables at cloud base agrees reasonably well with observations, with correlations of the flight-to-flight data as high as 0.69 for δ2H and 0.74 for d-excess. A close examination of different mesoscale cloud base features, including clouds and clear-sky dry-warm patches, and their isotopic characteristics shows that i) these features are represented faithfully in the model with similar frequency of occurrence, isotope signals and specific humidity anomalies as found in the observations (+2 ‰ to +5 ‰ [+2 g kg−1] for precipitating clouds vs. −3 ‰ to −4 ‰ [−2 g kg−1] in dry-warm patches for δ2H [q]) and ii) the δ2H of cloud base vapour at the hourly time scale is mainly controlled by mesoscale transport and not by local microphysical processes while the d-excess is mainly controlled by large-scale drivers. Overall, this evaluation of COSMOiso, including the isotopic characterisation of cloud base features, suggests that the simulations can be used for investigating the role of atmospheric circulations on different scales for controlling the formation of shallow cumulus clouds in the trade-wind region, as will be done in part 2 of this study. Additionally, we provide explicit recommendations for adaptations of the modelling setup to be tested in future research.

Published
2023

13. Mesoscale spatio-temporal variability of airborne lidar-derived aerosol properties in the Barbados region during EUREC4A

Author

Cyrille Flamant, Alexandre Baron, and Patrick Chazette

Subjects
Atmospheric Science, Lidar, 13. Climate action, Cloud cover, Mesoscale meteorology, Environmental science, Inversion (meteorology), Tropical Atlantic, Scale (map), Atmospheric sciences, Spatial heterogeneity, Aerosol
Abstract

From 23 January to 13 February 2020, 20 ATR-42 scientific flights were conducted in the framework of the EUREC4A field campaign over the tropical Atlantic, off the coast of Barbados (13∘30′ N, −58∘30′ W). By means of a sideway-pointing lidar, these flights allowed us to retrieve the optical properties of the aerosols found in the sub-cloud layer and below the trade wind inversion. Two distinct periods with significant aerosol contents were identified in relationship with the so-called trade wind and tropical regimes, respectively. For these two regimes, mixings of two air mass types encompassing dust and carbonaceous aerosols have been highlighted. Both were mainly from West Africa with similar optical contributions and linked to dust uptake above Sahara and biomass burning between Guinea-Bissau and Côte d'Ivoire. In the tropical transport regime, the wind within the planetary boundary layer is stronger and favours a contribution of marine aerosols (sulfate and sea salt aerosol components) in shallower aerosol layers than for the trade wind transport regime. The latter is responsible for advecting dust–biomass-burning-aerosol mixtures in the deeper, well-mixed layer, in part due to the complex interactions of the easterly flow from West Africa with mid-latitude dynamics. The aerosol vertical structures appear to be well reproduced using atmospheric composition reanalyses from CAMS when comparing with lidar-derived vertical profiles. The competition between the two types of transport regimes leads to strong heterogeneity in the optical properties of the horizontal aerosol field. Our study highlights the transport regime under which a significant mixture of dust and biomass burning aerosols from West Africa can be observed over the Caribbean and Barbados in particular, namely the trade wind regime.

Published
2022
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14. Supplementary material to 'Water isotopic characterisation of the cloud-circulation coupling in the North Atlantic trades. Part 1: A process-oriented evaluation of COSMOiso simulations with EUREC4A observations'

Author

Leonie Villiger, Marina Dütsch, Sandrine Bony, Marie Lothon, Stephan Pfahl, Heini Wernli, Pierre-Etienne Brilouet, Patrick Chazette, Pierre Coutris, Julien Delanoë, Cyrille Flamant, Alfons Schwarzenboeck, Martin Werner, and Franziska Aemisegger

Published
2023
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16. Extreme temperature events monitored by Raman lidar: Consistency and complementarity with spaceborne observations and modelling

Author

Patrick Chazette, Alexandre Albert Baron, Julien Totems, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Chimie Atmosphérique Expérimentale (CAE), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment
Abstract

International audience; Two extreme temperature events (ETEs), both triggered by atmospheric blocking situations, were monitored by a pure rotational Raman lidar 20 km south of Paris. The first ETE lasted 6 days in late February 2018 with the onset of a cold wave surging from Siberia, and the second was a short heatwave that

Published
2022
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17. Water vapor mixing ratio and temperature inter-comparison results in the framework of the Hydrological Cycle in the Mediterranean Experiment—Special Observation Period 1

Author

Cyrille Flamant, Donato Summa, Benedetto De Rosa, Marco Cacciani, Paolo Di Girolamo, Julien Totems, Olivier Bousquet, Patrick Chazette, Scuola di Ingegneria [Potenza], Università degli studi della Basilicata [Potenza] (UNIBAS), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de l'Atmosphère et des Cyclones (LACy), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Chimie Atmosphérique Expérimentale (CAE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Dipartimento di Fisica [Roma La Sapienza], Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome] (UNIROMA), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Météo France, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome]

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Mediterranean climate, 010504 meteorology & atmospheric sciences, Meteorology, Microwave radiometer, [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology, 010501 environmental sciences, 01 natural sciences, law.invention, law, Mixing ratio, Period (geology), Radiosonde, General Earth and Planetary Sciences, Environmental science, Measurement uncertainty, Water cycle, Water vapor, 0105 earth and related environmental sciences, General Environmental Science
Abstract

This paper reports results from an inter-comparison effort involving water vapor and temperature sensors, which took place in the North-Western Mediterranean in the period September–November 2012 in the framework of the first Special Observing Period of the Hydrological cycle in the Mediterranean Experiment. The involved sensors are the ground-based Raman lidars BASIL and WALI, the airborne water vapor differential absorption lidar LEANDRE 2, flying onboard the ATR42 aircraft, as well as additional water vapor and temperature sensors (radiosondes, aircraft in situ sensors, and a microwave radiometer). The main objective of the inter-comparison is the determination of the measurement uncertainty affecting these sensors. The effort benefitted from dedicated ATR42 flights in the framework of the EUropean Facility for Airborne Research (EUFAR) Project “WaLiTemp.” Comparisons between BASIL and LEANDRE 2 in terms of water vapor mixing ratio indicate a vertically averaged mean bias, $$ \overline{\mathrm{bias}} $$ bias ¯ , and mean absolute bias, $$ \left|\overline{\mathrm{bias}}\right| $$ bias ¯ , between the two sensors of − 0.08 g kg−1 (or − 2.50%) and 0.67 g kg−1 (or 2.77%), respectively. For all sensors’ pairs including LEANDRE 2, the inter-comparison range is 0.5–3 km, while for all other sensors’ pairs, the inter-comparison range is 0.5–6 km. Comparisons between BASIL and the microwave radiometer indicate $$ \overline{\mathrm{bias}} $$ bias ¯ and $$ \left|\overline{\mathrm{bias}}\right| $$ bias ¯ values between the two sensors of − 0.02 g kg−1 (or − 1.11%) and 0.22 g kg−1 (or 7.31%), respectively, for water vapor mixing ratio measurements, and a value for both $$ \overline{\mathrm{bias}} $$ bias ¯ and $$ \left|\overline{\mathrm{bias}}\right| $$ bias ¯ of 0.62 K for temperature measurements. Comparisons of BASIL with the radiosondes indicate $$ \overline{\mathrm{bias}} $$ bias ¯ and $$ \left|\overline{\mathrm{bias}}\right| $$ bias ¯ values of 0.28 g kg−1 (or 1.56%) and 0.51 g kg−1 (or 6.66%), respectively, for water vapor mixing ratio measurements, and − 0.43 K and 0.77 K, respectively, for temperature measurements, while comparisons of BASIL with aircraft in situ sensors indicate $$ \overline{\mathrm{bias}} $$ bias ¯ and $$ \left|\overline{\mathrm{bias}}\right| $$ bias ¯ values of 0.22 g kg−1 (or 1.17%) and 0.43 g kg−1 (or 4.62%), respectively, for water vapor mixing ratio measurements, and 0.15 K and 0.47 K, respectively, for temperature measurements. Comparisons of LEANDRE 2 with the radiosondes result in $$ \overline{\mathrm{bias}} $$ bias ¯ and $$ \left|\overline{\mathrm{bias}}\right| $$ bias ¯ values of 0.21 g kg−1 (or 0.76%) and 1.10 g kg−1 (or 11.05%), respectively, while comparisons of LEANDRE 2 with the aircraft in situ sensors indicate a value of both $$ \overline{\mathrm{bias}} $$ bias ¯ and $$ \left|\overline{\mathrm{bias}}\right| $$ bias ¯ of 0.76 g kg−1 (or 8.9%). Comparisons of in situ sensors with the radiosondes reveal $$ \overline{\mathrm{bias}} $$ bias ¯ and $$ \left|\overline{\mathrm{bias}}\right| $$ bias ¯ values of 0.36 g kg−1 (or 2.26%) and 0.36 g kg−1 (or 4.72%), respectively, for water vapor mixing ratio measurements, and 0.61 K and 0.62 K, respectively, for temperature measurements, while comparisons of in situ sensors with the microwave radiometer indicate $$ \overline{\mathrm{bias}} $$ bias ¯ and $$ \left|\overline{\mathrm{bias}}\right| $$ bias ¯ values of − 0.37 g kg−1 (or − 2.01%) and 0.58 g kg−1 (or 12.59%), respectively, for water vapor mixing ratio measurements, and a value of both $$ \overline{\mathrm{bias}} $$ bias ¯ and $$ \left|\overline{\mathrm{bias}}\right| $$ bias ¯ of 0.75 K for temperature measurements. Comparisons of the microwave radiometer with the radiosondes indicate $$ \overline{\mathrm{bias}} $$ bias ¯ and $$ \left|\overline{\mathrm{bias}}\right| $$ bias ¯ values of 0.13 g kg−1 (or 0.83%) and 0.20 g kg−1 (or 17.75%), respectively, for water vapor mixing ratio, and a value of both $$ \overline{\mathrm{bias}} $$ bias ¯ and $$ \left|\overline{\mathrm{bias}}\right| $$ bias ¯ of 0.74 K for temperature measurements. Our attention was also focused on the water vapor inter-comparison between BASIL and the transportable ground-based Raman lidar WALI, which took place in Candillargues on 30 October 2012, with results indicating $$ \overline{\mathrm{bias}} $$ bias ¯ and $$ \left|\overline{\mathrm{bias}}\right| $$ bias ¯ values between the two sensors of − 0.005 g kg−1 (or − 1.31%) and 0.24 g kg−1 (or 4.32%), respectively. Based on the available dataset and benefiting from the circumstance that BASIL could be compared with all other sensors, the overall bias of all sensors was also estimated. For water vapor mixing ratio measurements, the overall bias is 0.0079 g kg−1, 0.159 g kg−1, 0.084 g kg−1, − 0.201 g kg−1, 0.099 g kg−1, and − 0.141 g kg−1 for BASIL, LEANDRE 2, WALI, the radiosondes, the microwave radiometer, and the aircraft in situ sensor, respectively, being within ± 0.02 g kg−1 for all water vapor sensors. For temperature measurements, the overall bias is 0.11 K, 0.54 K, − 0.04 K, and − 0.51 K for BASIL, the radiosondes, the microwave radiometer, and the aircraft in situ sensor, respectively.

Published
2020
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18. Remote-sensing of aerosol atmospheric rivers over the southwest Indian Ocean in September 2017: origins, evolution and impacts

Author

Alexandre Baron, Valentin Duflot, Patrick Chazette, Marco Gaetani, Cyrille Flamant, Juan Cuesta, Guillaume Payen, Philippe Keckhut, Philippe Goloub, Laboratoire de l'Atmosphère et des Cyclones (LACy), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, Centre National d'Études Spatiales [Toulouse] (CNES), Observatoire des Sciences de l'Univers de La Réunion (OSU-Réunion), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Istituto Universitario di Studi Superiori (IUSS), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), TROPO - LATMOS, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), STRATO - LATMOS, Laboratoire d’Optique Atmosphérique - UMR 8518 (LOA), and Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)

Subjects
Aerosols, Remote Sensing, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Smoke Plumes, Troposphere, Southwest Indian Ocean, aerosol atmospheric river (AAR), Southern Hemisphere, Biomass, Spaceborne Lidar, Fires, Spectro-radiometer
Abstract

In the southern hemisphere, the dry season from June to October coincides with the occurrence of significant fires especially located along the tropical belt in Africa and South America. This fire activity is an important source of aerosols in the tropical troposphere and results in smoke plumes transported across long distances toward area generally aerosol-free. The atmospheric composition over the Indian Ocean is often influenced by biomass burning plumes shaped by the synoptic atmospheric circulation with high pressure over southern Africa and the movement of westerly waves that may embedded cut-off lows. The propagation over the Indian Ocean is then dependent on the position of the Mascarene High. The meandering shape of the plumes is then associated with an aerosol atmospheric river (AAR). Such a phenomenon has been sampled by spaceborne lidars and spectro-radiometers, and even observed above La Réunion (21.1°S, 55.3°E) during September 2017 by a ground-based lidar and a sun-photometer. The Li1200, an operational lidar in the frame of the Atmospheric Physics Reunion Observatory (OPAR), recorded the passage of an AAR during two nights. These measurements allow us to derive both the vertical structures of the plume and some vertically resolved aerosol optical properties. This information was used to constrain Lagrangian modelling tools to identify the pathways and origins of the biomass burning plume. These results have been corroborated by the spaceborne observations of CALIOP and CATS, and the passive sensor MODIS. Reanalysis of ECMWF with atmospheric composition outputs from the Copernicus Atmosphere Monitoring Service (CAMS) supports the understanding of the synoptic conditions leading to the formation of this aerosol plume configuration. We will present our scientific approach and discuss the environmental impact of these AARs in the southwest Indian Ocean.

Published
2022
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19. Demonstration of water vapor and Isotopes measurement from lidar using a multi-platform, multi-instrumental approach

Author

Jonas Hamperl, Patrick Chazette, Julien Totems, Jean-Baptiste Dherbecourt, Jean-Michel Melkonian, Philippe Nicolas, Myriam Raybaut, Aurélien Clémençon, Nicolas Geyskens, Pascal Geneau, Cyrille Flamant, Daniele Zannoni, Harald Sodemann, Hans Christian Steen-Larsen, Anne Monod, Amandine Durand, Sylvain Ravier, Alfons Schwarzenboeck, DPHY, ONERA, Université Paris Saclay [Palaiseau], ONERA-Université Paris-Saclay, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Division technique INSU/SDU (DTI), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Physique (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), TROPO - LATMOS, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Geophysical Institute [Bergen] (GFI / BiU), University of Bergen (UiB), Laboratoire Chimie de l'environnement (LCE), and Aix Marseille Université (AMU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Greenhouse Gases, Water Vapor, Lidar, Measurement Instrument, LEMON Instrument
Abstract

The Lidar Emitter and Multispecies greenhouse gases Observation iNstrument (LEMON) objective is the development and test of a new Differential Absorption Lidar (DIAL) sensor concept for greenhouse gases and water vapor for spaceborne, airborne or ground-based measurements. The innovative instrument is based on a versatile transmitter. The concept of the measurement was recently preliminarily tested for water vapor in a co-dedicated field campaign from 13 to 24 September 2021 over the Aubenas airfield (France, 44° 32' N 4° 22' E). This campaign was also an opportunity to test different approaches for the measurement of the vertical water vapor profile using classical meteorological probes embarked on meteorological balloons and on an airplane, a vibrational Raman lidar WALI (Weather Atmospheric LIdar), a cavity ring-down spectrometer (CRDS) and of course a first version of the LEMON lidar named WaVIL (Water Vapor and Isotope Lidar). The field campaign involved an instrumented van with two lidars and three ULAs carrying various payloads: a backscatter Rayleigh-Mie lidar to identify atmospheric structures from the local to regional scales, a CRDS for water vapor isotope measurements and in situ samplers to characterize cloud-related forcing on atmospheric water vapor concentrations. The measurement strategy adopted made it possible to follow the evaporation of water vapor throughout the course of a thunderstorm and to sample an intrusion of dry air from high altitudes. It also provided initial answers as to the potential of the WaViL instrument for measuring the main isotope of water vapor and its secondary isotope HDO. The measurement campaign will be presented, as well as the first associated results.

Published
2022
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20. Temporal and spatial variability of water vapor isotopic composition in the lower troposphere: insights from ultralight aircraft measurements

Author

Daniele Zannoni, Hans Christian Steen-Larsen, Harald Sodemann, Amandine Durand, Anne Monod, Aurélien Clémençon, Jean-Baptiste Dherbecourt, Jean-Michel Melkonian, Jonas Hamperl, Julien Totems, Nicolas Geyskens, Pascal Geneau, Patrick Chazette, Philippe Nicolas, Sylvain Ravier, Cyrille Flamant, Myriam Raybaut, Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Geophysical Institute [Bergen] (GFI / BiU), University of Bergen (UiB), Laboratoire Chimie de l'environnement (LCE), Aix Marseille Université (AMU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Division technique INSU/SDU (DTI), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), DPHY, ONERA, Université Paris Saclay [Palaiseau], ONERA-Université Paris-Saclay, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), TROPO - LATMOS, and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Water Vapor, Troposphere, UltraLight Aircraft, Measurement instrument
Abstract

The lower troposphere is where the surface evapotranspiration flux has a strong impact on the atmospheric water vapor isotopic composition, enabling the investigation of the hydro-ecological features of a specific study area. Even though several studies investigated in the last decade the spatial and temporal variability of tropospheric water vapor isotopic composition with ships, aircrafts, satellites and at fixed locations at ground level, vertical profiles and spatial observations acquired within the same time window in the lower troposphere (2 and in less than 0.12 hours. We hypothesize this large horizontal variability to be related to development of thermals within the boundary layer. Our next step will be to summarize the spatial and temporal variability of water vapor isotopic composition for allowing a fair comparison between high-resolution isotope-enabled general circulation models, remote sensing and water vapor observations in the boundary layer.

Published
2022
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21. Wet deposition in the remote western and central Mediterranean as a source of trace metals to surface seawater

Author

Paola Formenti, Karine Desboeufs, François Dulac, Araceli Rodríguez-Romero, Pascal Zapf, Antonio Tovar-Sánchez, Julie Disnaquet, Chiara Giorio, Jean-François Doussin, Cécile Guieu, Sylvain Triquet, Franck Maisonneuve, Anaïs Feron, Matthieu Bressac, Franck Fu, Patrick Chazette, Centre National de la Recherche Scientifique (France), Institut Français de Recherche pour l'Exploitation de la Mer, Commissariat à l'Ènergie Atomique et aux Ènergies Alternatives (France), Météo-France, Bressac, Matthieu, Tovar-Sánchez, Antonio, Giorio, Chiara, Chazette, Patrick, Julie Dinasquet, Rodríguez-Romero, Araceli, Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institute for Marine and Antarctic Studies [Hobart] (IMAS), University of Tasmania [Hobart, Australia] (UTAS), Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institute of Marine Sciences of Andalusia (ICMAN), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Laboratoire Chimie de l'environnement (LCE), Aix Marseille Université (AMU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Chimie Atmosphérique Expérimentale (CAE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Scripps Institution of Oceanography (SIO - UC San Diego), University of California [San Diego] (UC San Diego), University of California (UC)-University of California (UC), The authors wish to thank Thierry Alix, the captain of the R/V Pourquoi Pas?, as well as the whole crew and technical staff for their involvement in the scientific operation. We gratefully thank Thibaut Wagener for his involvement in the trace metals clean marine sampling and Mickaël Tharaud for the HRICP-MS analysis. We thank the Leosphere technical support team and especially Alexandre Menard for their remote assistance with lidar repair under difficult offshore conditions. Hélène Ferré and the AERIS/SEDOO service are acknowledged for real-time collection during the cruise of maps from operational satellites and forecast models used in this study, with appreciated contributions from EUMETSAT and AERIS/ICARE for the MSG/SEVIRI products. EUMETNET is acknowledged for providing the pan-European weather radar composite images through its OPERA programme.We acknowledge the US National Oceanic and Atmospheric Administration (NOAA) Air Resources Laboratory (ARL) for the provision of the HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) model, via the NOAA ARL READY website (http://ready.arl.noaa.gov, last access: 11 February 2022), used in this publication. This study is a contribution to the PEACETIME project (http://peacetime-project.org, last access: 5 April 2021), a joint initiative of the MERMEX and ChArMEx programmes supported by CNRS-INSU, IFREMER, CEA and Météo-France as part of the decadal meta-programme MISTRALS coordinated by CNRS-INSU. PEACETIME was endorsed as a process study by GEOTRACES and is also a contribution to IMBER and SOLAS international programmes. The authors gratefully thank Rachel Shelley and the anonymous reviewer for their useful comments and critiques that have contributed to improving the manuscript., Giorio, Chiara [0000-0001-7821-7398], Apollo - University of Cambridge Repository, Observatoire océanologique de Villefranche-sur-mer (OOVM), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, Mediterranean climate, Biogeochemical cycle, Atmospheric Science, 010504 meteorology & atmospheric sciences, QC1-999, Mineral dust, 01 natural sciences, Atmosphere, Mediterranean sea, 3708 Oceanography, 14. Life underwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, QD1-999, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 13 Climate Action, 010604 marine biology & hydrobiology, Physics, 37 Earth Sciences, Particulates, 14 Life Below Water, 6. Clean water, Chemistry, Deposition (aerosol physics), 13. Climate action, Environmental chemistry, 3701 Atmospheric Sciences, Environmental science, Seawater
Abstract

This study reports the only recent characterization of two contrasted wet deposition events collected during the PEACETIME (ProcEss studies at the Air–sEa Interface after dust deposition in the MEditerranean Sea) cruise in the open Mediterranean Sea (Med Sea) and their impact on trace metal (TM) marine stocks. Rain samples were analysed for Al, 12 TMs (Co, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V and Zn) and nutrient (N, P, dissolved organic carbon) concentrations. The first rain sample collected in the Ionian Sea (Rain ION) was a typical regional background wet deposition event, whereas the second rain sample collected in the Algerian Basin (Rain FAST) was a Saharan dust wet deposition event. Even in the remote Med Sea, all background TM inputs presented an anthropogenic signature, except for Fe, Mn and Ti. The concentrations of TMs in the two rain samples were significantly lower compared to concentrations in rains collected at coastal sites reported in the literature, due to the decrease in anthropogenic emissions during the preceding decades. The atmospheric TM inputs were mainly dissolved forms, even in dusty Rain FAST. The TM stocks in the mixed layer (ML, 0–20 m) at the FAST station before and after the event showed that the atmospheric inputs were a significant supply of particulate TMs and dissolved Fe and Co for surface seawater. Even if the wet deposition delivers TMs mainly in soluble form, the post-deposition aerosol dissolution could to be a key additional pathway in the supply of dissolved TMs. At the scale of the western and central Mediterranean, the atmospheric inputs were of the same order of magnitude as ML stocks for dissolved Fe, Co and Zn, highlighting the role of the atmosphere in their biogeochemical cycles in the stratified Med Sea. In case of intense dust-rich wet deposition events, the role of atmospheric inputs as an external source was extended to dissolved Co, Fe, Mn, Pb and Zn. Our results suggest that the wet deposition constitutes only a source of some of dissolved TMs for Med Sea surface waters. The contribution of dry deposition to the atmospheric TM inputs needs to be investigated., This study is a contribution to the PEACETIME project (http://peacetime-project.org; last access: 5 April 2021), a joint initiative of the MERMEX and ChArMEx programmes supported by CNRS-INSU, IFREMER, CEA and Météo-France as part of the decadal meta-programme MISTRALS coordinated by CNRS-INSU.

Published
2022
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22. Range-resolved detection of boundary layer stable water vapor isotopologues using a ground-based 1.98 μm differential absorption lidar

Author

Jonas Hamperl, Jean-Baptiste Dherbecourt, Myriam Raybaut, Julien Totems, Patrick Chazette, Laurence Régalia, Bruno Grouiez, Nicolas Geyskens, Oualid Aouji, Nadir Amarouche, Jean-Michel Melkonian, Rosa Santagata, Antoine Godard, Corinne Evesque, Valdas Pasiskevicius, Cyrille Flamant, DPHY, ONERA, Université Paris Saclay [Palaiseau], ONERA-Université Paris-Saclay, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Chimie Atmosphérique Expérimentale (CAE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Groupe de spectrométrie moléculaire et atmosphérique (GSMA), Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS), Division technique INSU/SDU (DTI), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), ONERA, Université Paris Saclay [Palaiseau], Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Royal Institute of Technology [Stockholm] (KTH ), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Atomic and Molecular Physics, and Optics
Abstract

This paper presents a first demonstration of range-resolved differential absorption LIDAR (DIAL) measurements of the water vapor main isotopologue H216O and the less abundant semi-heavy water isotopologue HD16O with the aim of determining the isotopic ratio. The presented Water Vapor and Isotope Lidar (WaVIL) instrument is based on a parametric laser source emitting nanosecond pulses at 1.98 µm and a direct-detection receiver utilizing a commercial InGaAs PIN photodiode. Vertical profiles of H216O and HD16O were acquired in the planetary boundary layer in the suburban Paris region up to a range of 1.5 km. For time averaging over 25 min, the achieved precision in the retrieved water vapor mixing ratio is 0.1 g kg−1 (2.5% relative error) at 0.4 km above ground level (a.g.l.) and 0.6 g kg−1 (20%) at 1 km a.g.l. for 150 m range bins along the LIDAR line of sight. For HD16O, weaker absorption has to be balanced with coarser vertical resolution (600 m range bins) in order to achieve similar relative precision. From the DIAL measurements of H216O and HD16O, the isotopic abundance δD was estimated as −51‰ at 0.4 km above the ground and −119‰ in the upper part of the boundary layer at 1.3 km a.g.l. Random and systematic errors are discussed in the form of an error budget, which shows that further instrumental improvements are required on the challenging path towards DIAL-profiling of the isotopic abundance with range resolution and precision suitable for water cycle studies.

Published
2022
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25. Mitigation of bias sources for atmospheric temperature and humidity in the mobile Raman Weather and Aerosol Lidar (WALI)

Author

Patrick Chazette, Alexandre Albert Baron, Julien Totems, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Chimie Atmosphérique Expérimentale (CAE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and ANR-20-CE04-0001,WaLiNeAs,Assimilation de réseau lidar vapeur d'eau(2020)

Subjects
010309 optics, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, Earthwork. Foundations, 010504 meteorology & atmospheric sciences, 13. Climate action, TA715-787, 0103 physical sciences, Environmental engineering, TA170-171, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 01 natural sciences, 0105 earth and related environmental sciences
Abstract

Lidars using vibrational and rotational Raman scattering to continuously monitor both the water vapor and temperature profiles in the low and middle troposphere offer enticing perspectives for applications in weather prediction and studies of aerosol–cloud–water vapor interactions by simultaneously deriving relative humidity and atmospheric optical properties. Several heavy systems exist in European laboratories, but only recently have they been downsized and ruggedized for deployment in the field. In this paper, we describe in detail the technical choices made during the design and calibration of the new Raman channels for the mobile Weather and Aerosol Lidar (WALI), going over the important sources of bias and uncertainty on the water vapor and temperature profiles stemming from the different optical elements of the instrument. For the first time, the impacts of interference filters and non-common-path differences between Raman channels, and their mitigation, in particular are investigated, using horizontal shots in a homogeneous atmosphere. For temperature, the magnitude of the highlighted biases can be much larger than the targeted absolute accuracy of 1 ∘C defined by the WMO (up to 6 ∘C bias below 300 m range). Measurement errors are quantified using simulations and a number of radiosoundings launched close to the laboratory. After de-biasing, the remaining mean differences are below 0.1 g kg−1 on water vapor and 1 ∘C on temperature, and rms differences are consistent with the expected error from lidar noise, calibration uncertainty, and horizontal inhomogeneities of the atmosphere between the lidar and radiosondes.

Published
2021
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27. A network of water vapor Raman lidars for improving heavy precipitation forecasting in southern France: introducing the WaLiNeAs initiative

Author

Cyrille Flamant, Rohith Thundathil, Andreas Behrendt, Clotilde Augros, Pierre Brousseau, Pascal Genau, Olivier Caumont, Marco Cacciani, Alexandre Baron, Alejandro Rodríguez-Gómez, Véronique Ducrocq, Julien Totems, Benedetto De Rosa, Diego Lange, Constantino Muñoz-Porcar, Laurent Labatut, Volker Wulfmeyer, Adolfo Comerón, Patrick Chazette, Donato Summa, Nadia Fourrié, Paolo Di Girolamo, Michaël Sicard, Universitat Politècnica de Catalunya. Departament de Teoria del Senyal i Comunicacions, Universitat Politècnica de Catalunya. RSLAB - Grup de Recerca en Teledetecció, TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Chimie Atmosphérique Expérimentale (CAE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Scuola di Ingegneria [Potenza], Università degli studi della Basilicata [Potenza] (UNIBAS), Institut für Physik und Meteorologie [Stuttgart] (IPM), Universität Hohenheim, Department of Signal Theory and Communications [Barcelona] (TSC), Universitat Politècnica de Catalunya [Barcelona] (UPC), Institut d'Estudis Espacials de Catalunya (IEEC-CSIC), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Météo France-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Western Mediterranean, Research groups, Numerical weather prediction model, Teledetecció, 010504 meteorology & atmospheric sciences, Meteorology, Human life, AROME, Mesoscale meteorology, [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology, Enginyeria de la telecomunicació::Radiocomunicació i exploració electromagnètica [Àrees temàtiques de la UPC], 01 natural sciences, 7. Clean energy, Weather forecasting, 010309 optics, Troposphere, 0103 physical sciences, Precipitation, 0105 earth and related environmental sciences, General Environmental Science, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Previsió del temps, Remote sensing, Numerical weather prediction, Radar òptic, Lidar, 13. Climate action, Assimilation, General Earth and Planetary Sciences, Environmental science, Water vapor
Abstract

The version of record is available online at: http://dx.doi.org/10.1007/s42865-021-00037-6 Extreme heavy precipitation events (HPEs) pose a threat to human life but remain difficult to predict because of the lack of adequate high frequency and high-resolution water vapor (WV) observations in the low troposphere (below 3 km). To fill this observational gap, we aim at implementing an integrated prediction tool, coupling network measurements of WV profiles, and a numerical weather prediction model to precisely estimate the amount, timing, and location of rainfall associated with HPEs in southern France (struck by¿~¿7 HPEs per year on average during the fall). The Water vapor Lidar Network Assimilation (WaLiNeAs) project will deploy a network of 6 autonomous Raman WV lidars around the Western Mediterranean to provide measurements with high vertical resolution and accuracy to be assimilated in the French Application of Research to Operations at Mesoscale (AROME-France) model, using a four-dimensional ensemble-variational approach with 15-min updates. This integrated prediction tool is expected to enhance the model capability for kilometer-scale prediction of HPEs over southern France up to 48 h in advance. The field campaign is scheduled to start early September 2022, to cover the period most propitious to heavy precipitation events in southern France. The Raman WV lidar network will be operated by a consortium of French, German, Italian, and Spanish research groups. This project will lead to recommendations on the lidar data processing for future operational exploitation in numerical weather prediction (NWP) systems.

Published
2021
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29. Smoke in the river: an AEROCLO-sA case study

Author

Juan Cuesta, Jean-Pierre Chaboureau, Patrick Chazette, Cyrille Flamant, Paola Formenti, Marco Gaetani, and Stuart Piketh

Subjects
Atmosphere, Smoke, Oceanography, Tropical wave, Mesoscale meteorology, Temperate climate, Trough (meteorology), Geology, Air mass, Aerosol
Abstract

The formation of a river of smoke crossing southern Africa is investigated during the Aerosols, Radiation and Clouds in southern Africa (AEROCLO-sA) campaign in September 2017. A complementary set of global and mesoscale numerical simulations as well as ground-based, airborne and space-borne observations of the dynamics, thermodynamics and composition of the atmosphere are used to characterize the river of smoke in terms of timing and vertical extent of the biomass burning aerosol (BBA) layer. The study area was under the synoptic influence of a coastal low rooted in a tropical easterly wave, a high-pressure system over the continent and westerly waves in mid-latitudes, one of which had an embedded cut-off low (CoL). The coastal low interacted with the second of two approaching westerly waves and ultimately formed a mid-level temperate tropical trough (TTT). The TTT created the fast moving air mass transported to the southwestern Indian Ocean as a river of smoke. The CoL, which developed and intensified in the upper levels associated with the first (easternmost) westerly wave, remained stationary above northern Namibia prior to the formation of the TTT and was responsible for the thickening of the BBA layer. This shows that the evolution of the river of smoke is very much tied to the evolution of the TTT while its vertical extent is related to the presence of the CoL. The mechanisms by which the CoL, observed over Namibia in the entrance region of the river of smoke, influences the vertical structure of the BBA layer is mainly associated with the ascending motion above the BBA layer. In the presence of the CoL, the top of the BBA layer over northern Namibia reaches altitudes above 8 km. This is much higher than the average height of the top of the BBA layer over the regions where the smoke comes from (Angola, Zambia, Zimbabwe, Mozambique) which is 5 to 6 km. The results suggest that the interaction between the TTTs and the CoLs which form during the winter may have a role in promoting the transport of BBA from fire-prone regions in the tropical band to the temperate mid-latitudes and southwestern Indian Ocean.

Published
2021

30. Microsecond-pulse master oscillator – power amplifier at 828 nm for a water-vapor differential absorption lidar

Author

Gaëlle Lucas-Leclin, Sylvie Janicot, Jeremy Lagarrigue, Patrick Chazette, Qin Liu, Julien Totems, Laboratoire Charles Fabry / Lasers, Laboratoire Charles Fabry (LCF), Institut d'Optique Graduate School (IOGS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Chimie Atmosphérique Expérimentale (CAE), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], Materials science, business.industry, Amplifier, Pulse (physics), Master oscillator, Microsecond, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Differential absorption lidar, Optoelectronics, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, business, Water vapor
Abstract

Poster; International audience; We describe the design and characterization of a master oscillator – power amplifier laser system operating under µs-pulse regime at 828 nm, with a view to its integration in an airborne lidar for tropospheric water-vapor measurements. The output energy reaches 6.2 µJ per pulse.

Published
2021
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32. Mitigation of bias sources for atmospheric temperature and humidity in the mobile Weather & Aerosol Raman Lidar (WALI)

Author

Julien Totems, Alexandre Baron, and Patrick Chazette

Subjects
Troposphere, symbols.namesake, Lidar, symbols, Humidity, Environmental science, Relative humidity, Atmospheric temperature, Physics::Atmospheric and Oceanic Physics, Raman scattering, Water vapor, Remote sensing, Aerosol
Abstract

Lidars using vibrational and rotational Raman scattering to continuously monitor both the water vapor and temperature profiles in the low and middle troposphere offer enticing perspectives for applications in weather prediction and studies of aerosol/cloud/water vapor interactions by deriving simultaneously relative humidity and atmospheric optical properties. Several heavy systems exist in European laboratories but only recently have they been downsized and ruggedized for deployment in the field. In this paper, we describe in detail the technical choices made during the design and calibration of the new Raman channels for the mobile Weather and Aerosol Lidar (WALI), going over the important sources of bias and uncertainty on the water vapor & temperature profiles stemming from the different optical elements of the instrument. For the first time, the impacts of interference filters and non-common-path differences between Raman channels, and their mitigation, are particularly investigated, using horizontal shots in a homogenous atmosphere. For temperature, the magnitude of the highlighted biases can be much larger than the targeted absolute accuracy of 1 °C defined by the WMO. Measurement errors are quantified using simulations and a number of radiosoundings launched close to the laboratory.

Published
2021
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33. Design and pre-development of an airborne multi-species differential absorption Lidar system for water vapor and HDO isotope, carbon dioxide, and methane observation

Author

Antoine Godard, R. Santagata, Julien Totems, Patrick Chazette, M. Strotkamp, H. Schäfer, Vincent Lebat, S. Rapp, Jonas Hamperl, Cyrille Flamant, Myriam Raybaut, J.-M. Melkonian, Harald Sodemann, D. Heinecke, J. F. Geus, Jean-Baptiste Dherbecourt, Hans Christian Steen-Larsen, Valdas Pasiskevicius, Marine Dalin, DPHY, ONERA, Université Paris Saclay [Palaiseau], ONERA-Université Paris-Saclay, TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Department of Applied Physics [Stockholm], Royal Institute of Technology [Stockholm] (KTH ), Spacetech GmbH, Fraunhofer-Institut für Lasertechnik (ILT), Fraunhofer Institute for Manufacturing Engineering and Automation (Fraunhofer IPA), Fraunhofer (Fraunhofer-Gesellschaft)-Fraunhofer (Fraunhofer-Gesellschaft), InnoLas Laser GmbH, Geophysical Institute [Bergen] (GFI / BiU), University of Bergen (UiB), Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Bruno Cugny, Zoran Sodnik, Nikos Karafolas (eds), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), ANR-16-CE01-0009,WaVIL,Lidar vapeur d'eau pour la mesure de l'isotope HDO dans la basse troposphère(2016), and European Project: 821868,LEMON

Subjects
OPOS, Materials science, 02 engineering and technology, 7. Clean energy, 01 natural sciences, law.invention, 010309 optics, Greenhouse Gases, Frequency comb, 020210 optoelectronics & photonics, Optics, law, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Parametric Sources, Common emitter, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Lidar, business.industry, Laser, Optical parametric amplifier, Signal beam, 13. Climate action, Laser beam quality, business
Abstract

International audience; We report on the current design and preliminary developments of the airborne Lidar Emitter and Multi-species greenhouse gases Observation iNstrument (LEMON), which is aiming at probing H2O and its isotope HDO at 1982 nm, CO2 at 2051 nm, and potentially CH4 at 2290 nm, with the Differential Absorption Lidar method (DIAL). The infrared emitter is based on the combination of two Nested Cavity OPOs (NesCOPOs) with a single optical parametric amplifier (OPA) line for high-energy pulse generation. This configuration is enabled by the use of high-aperture periodically poled KTP crystals (PPKTP), which provide efficient amplification in the spectral range of interest around 2 μm with slight temperature adjustments. The parametric stages are pumped with a Nd:YAG laser providing 200 mJ nanosecond double pulses at 75 Hz. According to parametric conversion simulations supported by current laboratory experiments, output energies in the 40 - 50 mJ range are expected in the extracted signal beam whilst maintaining a good beam quality (M2 < 2). The ruler for all the optical frequencies involved in the system is planned to be provided by a GPS referenced frequency comb with large mode spacing (1 GHz) against which the emitter output pulses can be heterodyned. The frequency precision measurement is expected to be better than 200 kHz for the optical frequencies of interest. The presentation will give an overview of the key elements of design and of preliminary experimental characterizations of sub-systems building blocks.

Published
2021
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34. On the imprint of the mesoscale organization of tradewind clouds at cloud base and below

Author

Nicolas Rochetin, Alfons Schwarzenboeck, Pierre-Etienne Brilouet, Julien Delanoë, Pierre Coutris, Marie Lothon, Patrick Chazette, Sandrine Bony, Bjorn Stevens, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire d'aérologie (LAERO), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Physique (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), SPACE - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Meteorologie (MPI-M), and Max-Planck-Gesellschaft

Subjects
Meteorology, Cloud base, Mesoscale meteorology, Environmental science, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract

Trade-wind clouds can exhibit different patterns of mesoscale organization. These patterns were observed during the EUREC4A (Elucidating the role of cloud-circulation coupling in climate) field campaign that took place in Jan-Feb 2020 over the western tropical Atlantic near Barbados: while the HALO aircraft was observing clouds from above and was characterizing the large-scale environment with dropsondes, the ATR-42 research aircraft was flying in the lower troposphere, characterizing clouds and turbulence with horizontal radar-lidar measurements and in-situ probes and sensors. By analyzing these data for different cloud patterns, we investigate the extent to which the cloud organization is imprinted in cloud-base properties and subcloud-layer heterogeneities. The implications of our findings for understanding the roots of the mesoscale organization of tradewind clouds will be discussed.

Published
2021
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36. Differential absorption lidar for water vapor isotopologues in the 1.98 µm spectral region: sensitivity analysis with respect to regional atmospheric variability

Author

Julien Totems, Jonas Hamperl, Patrick Chazette, Myriam Raybaut, Jean-Baptiste Dherbecourt, and Cyrille Flamant

Subjects
Troposphere, Lidar, Backscatter, 13. Climate action, Planetary boundary layer, Environmental science, Isotopologue, 7. Clean energy, Water vapor, Remote sensing, AERONET, Aerosol
Abstract

Improved understanding of the variability underlying the distribution of stable water isotopologues in the troposphere, using both observations and modelling, has proven to be invaluable to study processes related to the hydrological cycle on a local as well as global scale. To date though, existing observation means (CRDS from ground-based or airborne platforms, passive remote sensing from space) only provide a partial picture of the complexity of the process at play due to their limited spatial or temporal coverage. On the other hand, laser active remote sensing, and in particular differential absorption lidars (DIAL) can deliver reliable, continuous, highly resolved (150 m, 10 min) profiles of H216O and HD16O in the lower troposphere, thereby providing observational insights into small scale processes such as evapotranspiration above continental surfaces and mixing in the planetary boundary layer.Such a lidar system is currently in development (WaVIL project funded by ANR) that will operate at 1.98 µm where water isotopologues exhibit close but distinct absorption features, sensitive photodetectors are commercially available, and where pulsed laser emission over 10 mJ can be achieved using for instance parametric conversion.In order to assess the expected instrument performances and to evaluate the potential of a ground-based system for simultaneous measurement of H216O and HD16O, we performed an error budget based on an end-to-end simulator. Lidar backscatter signals were simulated for different instrument-specific and atmospheric parameters. On the instrument side, calculations were performed for a commercial InGaAs PIN photodiode and for a state of the art low-noise HgCdTe avalanche photodiode. The sensitivity to environmental factors was investigated exemplarily for mid-latitude, arctic, and tropical environments where both vertical water vapor and aerosol variability were accounted for. Vertical profiles of aerosol extinction and backscatter coefficients were derived from the AERONET database (https://aeronet.gsfc.nasa.gov/) and extrapolated to the 2 µm spectral region, taking statistical seasonality into account. Performance simulations have been also conducted using vertical profiles derived from a field campaign where water vapor isotopologue concentrations and aerosol extinction were measured. We will outline the majority biases for such a lidar system and how statistical errors can be mitigated in a view of a forthcoming airborne DIAL instrument.

Published
2021
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37. Significant sources of bias in temperature measurements by rotational Raman lidar, and mitigation in the French mobile system WALI

Author

Julien Totems, Alexandre Baron, and Patrick Chazette

Subjects
Raman lidar, Environmental science, Temperature measurement, Remote sensing
Abstract

Lidars using rotational Raman backscattering to monitor the temperature profile in the low troposphere offer enticing perspectives for applications in weather prediction, as well as studies of aerosol and water vapor interactions, when deriving simultaneously relative humidity and aerosol optical properties. We describe the technical choices made during the design and calibration of the new temperature Raman channels for the mobile Weather and Aerosol Lidar (WALI), going over the sources of bias and uncertainty stemming from the different optical elements of the instrument. The impacts of interference filters and non-common-path differences between Raman channels, and their mitigation, are particularly investigated; without countermeasures, we find the theoretical magnitude of the highlighted biases can be much larger than the targeted absolute accuracy of 1°C defined by the World Meteorological Organization (WMO). Effective measurement errors are quantified using numerical end-to-end simulations and numerous radiosoundings launched close to the lidar location. Our aim is to fully discuss design choices and sources of bias which have been little reported in the literature. An application of the WALI measurements during heat wave conditions in the summer of 2020 will also be presented, and compared to ERA5 weather model reanalyses.

Published
2021
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38. EUREC4A

Author

Bjorn Stevens, Sandrine Bony, David Farrell, Felix Ament, Alan Blyth, Christopher Fairall, Johannes Karstensen, Patricia K. Quinn, Sabrina Speich, Claudia Acquistapace, Franziska Aemisegger, Anna Lea Albright, Hugo Bellenger, Eberhard Bodenschatz, Kathy-Ann Caesar, Rebecca Chewitt-Lucas, Gijs de Boer, Julien Delanoë, Leif Denby, Florian Ewald, Benjamin Fildier, Marvin Forde, Geet George, Silke Gross, Martin Hagen, Andrea Hausold, Karen J. Heywood, Lutz Hirsch, Marek Jacob, Friedhelm Jansen, Stefan Kinne, Daniel Klocke, Tobias Kölling, Heike Konow, Marie Lothon, Wiebke Mohr, Ann Kristin Naumann, Louise Nuijens, Léa Olivier, Robert Pincus, Mira Pöhlker, Gilles Reverdin, Gregory Roberts, Sabrina Schnitt, Hauke Schulz, A. Pier Siebesma, Claudia Christine Stephan, Peter Sullivan, Ludovic Touzé-Peiffer, Jessica Vial, Raphaela Vogel, Paquita Zuidema, Nicola Alexander, Lyndon Alves, Sophian Arixi, Hamish Asmath, Gholamhossein Bagheri, Katharina Baier, Adriana Bailey, Dariusz Baranowski, Alexandre Baron, Sébastien Barrau, Paul A. Barrett, Frédéric Batier, Andreas Behrendt, Arne Bendinger, Florent Beucher, Sebastien Bigorre, Edmund Blades, Peter Blossey, Olivier Bock, Steven Böing, Pierre Bosser, Denis Bourras, Pascale Bouruet-Aubertot, Keith Bower, Pierre Branellec, Hubert Branger, Michal Brennek, Alan Brewer, Pierre-Etienne Brilouet, Björn Brügmann, Stefan A. Buehler, Elmo Burke, Ralph Burton, Radiance Calmer, Jean-Christophe Canonici, Xavier Carton, Gregory Cato Jr., Jude Andre Charles, Patrick Chazette, Yanxu Chen, Michal T. Chilinski, Thomas Choularton, Patrick Chuang, Shamal Clarke, Hugh Coe, Céline Cornet, Pierre Coutris, Fleur Couvreux, Susanne Crewell, Timothy Cronin, Zhiqiang Cui, Yannis Cuypers, Alton Daley, Gillian M. Damerell, Thibaut Dauhut, Hartwig Deneke, Jean-Philippe Desbios, Steffen Dörner, Sebastian Donner, Vincent Douet, Kyla Drushka, Marina Dütsch, André Ehrlich, Kerry Emanuel, Alexandros Emmanouilidis, Jean-Claude Etienne, Sheryl Etienne-Leblanc, Ghislain Faure, Graham Feingold, Luca Ferrero, Andreas Fix, Cyrille Flamant, Piotr Jacek Flatau, Gregory R. Foltz, Linda Forster, Iulian Furtuna, Alan Gadian, Joseph Galewsky, Martin Gallagher, Peter Gallimore, Cassandra Gaston, Chelle Gentemann, Nicolas Geyskens, Andreas Giez, John Gollop, Isabelle Gouirand, Christophe Gourbeyre, Dörte de Graaf, Geiske E. de Groot, Robert Grosz, Johannes Güttler, Manuel Gutleben, Kashawn Hall, George Harris, Kevin C. Helfer, Dean Henze, Calvert Herbert, Bruna Holanda, Antonio Ibanez-Landeta, Janet Intrieri, Suneil Iyer, Fabrice Julien, Heike Kalesse, Jan Kazil, Alexander Kellman, Abiel T. Kidane, Ulrike Kirchner, Marcus Klingebiel, Mareike Körner, Leslie Ann Kremper, Jan Kretzschmar, Ovid Krüger, Wojciech Kumala, Armin Kurz, Pierre L'Hégaret, Matthieu Labaste, Tom Lachlan-Cope, Arlene Laing, Peter Landschützer, Theresa Lang, Diego Lange, Ingo Lange, Clément Laplace, Gauke Lavik, Rémi Laxenaire, Caroline Le Bihan, Mason Leandro, Nathalie Lefevre, Marius Lena, Donald Lenschow, Qiang Li, Gary Lloyd, Sebastian Los, Niccolò Losi, Oscar Lovell, Christopher Luneau, Przemyslaw Makuch, Szymon Malinowski, Gaston Manta, Eleni Marinou, Nicholas Marsden, Sebastien Masson, Nicolas Maury, Bernhard Mayer, Margarette Mayers-Als, Christophe Mazel, Wayne McGeary, James C. McWilliams, Mario Mech, Melina Mehlmann, Agostino Niyonkuru Meroni, Theresa Mieslinger, Andreas Minikin, Peter Minnett, Gregor Möller, Yanmichel Morfa Avalos, Caroline Muller, Ionela Musat, Anna Napoli, Almuth Neuberger, Christophe Noisel, David Noone, Freja Nordsiek, Jakub L. Nowak, Lothar Oswald, Douglas J. Parker, Carolyn Peck, Renaud Person, Miriam Philippi, Albert Plueddemann, Christopher Pöhlker, Veronika Pörtge, Ulrich Pöschl, Lawrence Pologne, Michał Posyniak, Marc Prange, Estefanía Quiñones Meléndez, Jule Radtke, Karim Ramage, Jens Reimann, Lionel Renault, Klaus Reus, Ashford Reyes, Joachim Ribbe, Maximilian Ringel, Markus Ritschel, Cesar B. Rocha, Nicolas Rochetin, Johannes Röttenbacher, Callum Rollo, Haley Royer, Pauline Sadoulet, Leo Saffin, Sanola Sandiford, Irina Sandu, Michael Schäfer, Vera Schemann, Imke Schirmacher, Oliver Schlenczek, Jerome Schmidt, Marcel Schröder, Alfons Schwarzenboeck, Andrea Sealy, Christoph J. Senff, Ilya Serikov, Samkeyat Shohan, Elizabeth Siddle, Alexander Smirnov, Florian Späth, Branden Spooner, M. Katharina Stolla, Wojciech Szkółka, Simon P. de Szoeke, Stéphane Tarot, Eleni Tetoni, Elizabeth Thompson, Jim Thomson, Lorenzo Tomassini, Julien Totems, Alma Anna Ubele, Leonie Villiger, Jan von Arx, Thomas Wagner, Andi Walther, Ben Webber, Manfred Wendisch, Shanice Whitehall, Anton Wiltshire, Allison A. Wing, Martin Wirth, Jonathan Wiskandt, Kevin Wolf, Ludwig Worbes, Ethan Wright, Volker Wulfmeyer, Shanea Young, Chidong Zhang, Dongxiao Zhang, Florian Ziemen, Tobias Zinner, and Martin Zöger

Subjects
Profiling (computer programming), Meteorology, 010504 meteorology & atmospheric sciences, 010505 oceanography, business.industry, 0207 environmental engineering, Weather and climate, Cloud computing, 02 engineering and technology, 01 natural sciences, Earth system science, Current (stream), Atmosphere, Observatory, 13. Climate action, Range (aeronautics), General Earth and Planetary Sciences, Environmental science, business, 020701 environmental engineering, 0105 earth and related environmental sciences
Abstract

The science guiding the EUREC4A campaign and its measurements is presented. EUREC4A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC4A marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200 km) and larger (500 km) scales, roughly 400 h of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10 000 profiles), lower atmosphere (continuous profiling), and along the air–sea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EUREC4A explored – from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation – are presented along with an overview of EUREC4A's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement.

Published
2021
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39. Experimental investigation of the stable water isotope distribution in an Alpine lake environment (L-WAIVE)

Author

Harald Sodemann, Andrew Seidl, Julien Totems, Alexandre Baron, Anne Monod, Amandine Durand, Elsa Dieudonné, Pascal Doira, Hans Christian Steen-Larsen, Cyrille Flamant, Patrick Chazette, Sylvain Ravier, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Laboratoire Chimie de l'environnement (LCE), Aix Marseille Université (AMU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physico-Chimie de l'Atmosphère (LPCA), Université du Littoral Côte d'Opale (ULCO), ANR-16-CE01-0009,WaVIL,Lidar vapeur d'eau pour la mesure de l'isotope HDO dans la basse troposphère(2016), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), and Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-Institut de Chimie du CNRS (INC)

Subjects
0106 biological sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Atmospheric Science, 010504 meteorology & atmospheric sciences, Physics, QC1-999, 010604 marine biology & hydrobiology, Humidity, Terrain, Atmospheric sciences, 01 natural sciences, Atmosphere, Troposphere, Chemistry, Boundary layer, Lidar, 13. Climate action, Thermal, Environmental science, QD1-999, Intensity (heat transfer), 0105 earth and related environmental sciences
Abstract

In order to gain understanding on the vertical structure of atmospheric water vapour above mountain lakes and to assess its link with the isotopic composition of the lake water and with small-scale dynamics (i.e. valley winds, thermal convection above complex terrain), the L-WAIVE (Lacustrine-Water vApor Isotope inVentory Experiment) field campaign was conducted in the Annecy valley in the French Alps during 10 d in June 2019. This field campaign was based on an original experimental synergy between a suite of ground-based, boat-borne, and two ultra-light aircraft (ULA) measuring platforms implemented to characterize the thermodynamic and isotopic composition above and in the lake. A cavity ring-down spectrometer and an in-cloud liquid water collector were deployed aboard one of the ULA to characterize the vertical distribution of the main stable water isotopes (H216O, H218O and H2H16O) both in the air and in shallow cumulus clouds. The temporal evolution of the meteorological structures of the low troposphere was derived from an airborne Rayleigh–Mie lidar (embarked on a second ULA), a ground-based Raman lidar, and a wind lidar. ULA flight patterns were repeated several times per day to capture the diurnal evolution as well as the variability associated with the different weather events encountered during the field campaign, which influenced the humidity field, cloud conditions, and slope wind regimes in the valley. In parallel, throughout the campaign, liquid water samples of rain, at the air–lake water interface, and at 2 m depth in the lake were taken. A significant variability of the isotopic composition was observed along time, depending on weather conditions, linked to the transition from the valley boundary layer towards the free troposphere, the valley wind intensity, and the vertical thermal stability. Thus, significant gradients of isotopic content have been revealed at the transition to the free troposphere, at altitudes between 2.5 and 3.5 km. The influence of the lake on the atmosphere isotopic composition is difficult to isolate from other contributions, especially in the presence of thermal instabilities and valley winds. Nevertheless, such an effect appears to be detectable in a layer of about 300 m thickness above the lake in light wind conditions. We also noted similar isotopic compositions in cloud drops and rainwater.

Published
2021
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40. The lacustrine-water vapor isotope inventory experiment L-WAIVE

Author

Harald Sodemann, Julien Totems, Andrew Seidl, Amandine Durand, Elsa Dieudonné, Anne Monod, Alexandre Baron, Hans Christian Steen-Larsen, Pascal Doira, Patrick Chazette, Cyrille Flamant, Sylvain Ravier, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Chimie Atmosphérique Expérimentale (CAE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), University of Bergen (UiB), Laboratoire Chimie de l'environnement (LCE), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physico-Chimie de l'Atmosphère (LPCA), and Université du Littoral Côte d'Opale (ULCO)

Subjects
Annecy, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], 010504 meteorology & atmospheric sciences, Planetary boundary layer, aerosol, Humidity, airborne, Atmospheric sciences, 01 natural sciences, Aerosol, Troposphere, Lidar, 13. Climate action, valley, Mixing ratio, Environmental science, Spatial variability, L-WAIVE, lake, stable water isotopes, Water vapor, lidar, 0105 earth and related environmental sciences
Abstract

In order to gain understanding on the vertical structure of atmospheric water vapour above mountain lakes and to assess the respective influence of evaporation and advection processes, the L-WAIVE (Lacustrine-Water vApor Isotope inVentory Experiment) field campaign was conducted in the Annecy valley in the French Alps in June 2019. This campaign was based on a synergy between a suite of ground-based, boat-borne, and airborne measuring platforms implemented to characterise the thermodynamic and isotopic state above the lake environment using both in-situ and remote sensing instruments. Two ultra-light aircrafts (ULA), one equipped with a Rayleigh-Mie lidar, solar fluxmeters and an optical counter, and one equipped with a Cavity Ring-down Spectrometer (CRDS) and an in-cloud liquid water collector, were deployed to characterize the vertical distribution of the main stable water vapour isotopes (H216O, H218O and H2H16O), and their potential interactions with clouds and aerosols. ULA flight patterns were repeated several times per day to capture the diurnal evolution as well as variability associated with different weather events. ULA flights were anchored to continuous water vapour and wind profiling of the lower troposphere performed by two dedicated ground-based lidars. Additional flights have been conducted to map the spatial variability of the water vapour isotope composition regarding the lake and surrounding topography. Throughout the campaign, ship-borne lake temperature profiles as well as liquid water samples at the air-water interface and at 2 m depth were made, supplemented on one occasion by atmospheric water vapour isotope measurements from the ship. The campaign period included a variety of weather events leading to contrasting humidity and cloud conditions, slope wind regimes and aerosol contents in the valley. The water vapor mixing ratio values in the valley atmospheric boundary layer were found to range from 3–4 g kg−1 to more than 10 g kg−1 and to be strongly influenced by the subsidence of higher altitude air masses as well as slope winds. A significant variability of the isotopic composition was observed within the first 3 km above ground level. The influence of the lake evaporation was mainly detected in the first 500 m of the atmosphere. Well-mixed conditions prevailed in the lower free troposphere, mainly above the mean altitude of the mountain tops surrounding the lake.

Published
2020
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44. Three‐dimensional pathways of dust over the Sahara during summer 2011 as revealed by new Infrared Atmospheric Sounding Interferometer observations

Author

Maxim Eremenko, Marco Gaetani, Claudia Di Biagio, Andreas H. Fink, Cyrille Flamant, Paola Formenti, Gaëlle Dufour, Patrick Chazette, Peter Knippertz, Juan Cuesta, Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Science, Technology and Society [Pavia], Istituto Universitario di Studi Superiori (IUSS), Institute for Meteorology and Climate Research (IMK), Karlsruhe Institute of Technology (KIT), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Chimie Atmosphérique Expérimentale (CAE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Science, Technology and Society [Pavia] (IUSS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
Saharan Air Layer, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, 010504 meteorology & atmospheric sciences, Forcing (mathematics), Monsoon, Atmospheric sciences, 01 natural sciences, African easterly jet, 010305 fluids & plasmas, Earth sciences, Altitude, Haboob, 13. Climate action, 0103 physical sciences, ddc:550, Extratropical cyclone, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geology, 0105 earth and related environmental sciences, Orographic lift
Abstract

International audience; We present a new characterisation of the three-dimensional (3D) distribution of dust over the Sahara during summer, exemplified for June 2011. Our approach, called AEROIASI, is based on the innovative retrieval of vertical profiles of the dust extinction coefficient from daily cloud-free hyperspectral Infrared Atmospheric Sounder Interferometer (IASI) satellite observations. AEROIASI observations clearly agree with other widely used measurements (from lidar and radiometers). The 3D charac-terisation is focused on the dust maximum in June 2011, located in the central Sahara (17-23 • N, 1-7 • E) and linked to the major atmospheric dynamical drivers associated with the West African Monsoon (WAM) system. AEROIASI shows the near-surface dust load to be dominated by five major emission events occurring every 3-4 days. These all occur when the study region is under the influence of northward bursts of the WAM and convection-related cold pools, likely associated with orographic forcing by the Aïr Mountains. During the earliest (June 10) and the dustiest (June 17) cases, northward advection of moisture over the hotspot is favoured by the super-position of cyclonic circulations related to an extratropical disturbance northwest of the Sahara and to the Saharan heat low over Mauritania, respectively. Convec-tion over the hotspot also triggers wave-like disturbances that travel westwards. The three dustiest events are characterised by elongated dust fronts moving northwards, with a leading edge spanning 200-300 km horizontally and extending from the surface up to 2 km of altitude. Further south, the dust layer progressively elevates to 3.5 km along the slanted isentropes at the interface of the monsoon and the har-mattan, increasingly losing contact with the ground. When northerlies blow over the study region, elevated dust layers at 3-5 km are observed, which are transported southwards within the Saharan air layer and westwards along the northern edge of the African easterly jet (after June 13). K E Y W O R D S cold pools, dust vertical profile, haboobs, West African monsoon bursts Q J R Meteorol Soc. 2020;1-25. wileyonlinelibrary.com/journal/qj

Published
2020
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47. Analysis of a warehouse fire smoke plume over Paris with an N2 Raman lidar and an optical thickness matching algorithm

Author

Julien Totems, Xiaoxia Shang, and Patrick Chazette

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, 01 natural sciences, Plume, Aerosol, 010309 optics, Lidar, 13. Climate action, 0103 physical sciences, Depolarization ratio, Environmental science, Particle, Visibility, Monte Carlo algorithm, Blossom algorithm, 0105 earth and related environmental sciences, Remote sensing
Abstract

A smoke plume, coming from an accidental fire in a textile warehouse in the north of Paris, covered a significant part of the Paris area on 17 April 2015 and seriously impacted the visibility over the megalopolis. This exceptional event was sampled with an automatic N2 Raman lidar, which operated 15 km south of Paris. The industrial pollution episode was concomitant with the long-range transport of dust aerosols originated from the Sahara, and with the presence of an extended stratus cloud cover. The analysis of the ground-based lidar profiles therefore required the development of an original inversion algorithm, using a top-down aerosol optical thickness matching (TDAM) approach. This study is, to the best of our knowledge, the first lidar measurement of a fresh smoke plume, emitted only a few hours after an accidental warehouse fire. Vertical profiles of the aerosol extinction coefficient, depolarization ratio, and lidar ratio are derived to optically characterize the aerosols that form the plume. We found a lidar ratio close to 50±10 sr for this fire smoke aerosol layer. The particle depolarization ratio is low, ∼1±0.1 %, suggesting the presence of either small particles or spherical hydrated aerosols in that layer. A Monte Carlo algorithm was used to assess the uncertainties on the optical parameters and to evaluate the TDAM algorithm.

Published
2018
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48. Role of moisture patterns in the backbuilding formation of HyMeX IOP13 heavy precipitation systems

Author

Fanny Duffourg, Keun-Ok Lee, Cyrille Flamant, P. Di Girolamo, Véronique Ducrocq, and Patrick Chazette

Subjects
021110 strategic, defence & security studies, Atmospheric Science, Mesoscale convective system, 010504 meteorology & atmospheric sciences, Moisture, Advection, 0211 other engineering and technologies, 02 engineering and technology, Atmospheric sciences, 01 natural sciences, Convective available potential energy, Troposphere, 13. Climate action, Climatology, Environmental science, Precipitation, Air mass, 0105 earth and related environmental sciences, Evaporative cooler
Abstract

Mediterranean regions are regularly affected by heavy convective precipitation. During the Hydrological Cycle in the Mediterranean Experiment Intensive Observation Period 13 (HyMeX-IOP13), the multi-platform observation strategy allowed analysing the backbuilding convective systems which developed on 14 October 2012 as well as the associated moisture structures in the environment upstream of convection. The numerical simulation at 2.5-km horizontal resolution succeeds in reproducing the location and time evolution of the observed heavy precipitation systems and the main characteristics of the marine air mass. Convection develops in Southeastern France over the foothills closest to the coast when a moist conditionally unstable marine boundary layer topped by particularly dry air masses is advected inland. Cold air formed by evaporative cooling under the precipitating cells flows down the valleys slowly shifting the location of the backbuilding convective cells from the mountainsides to the coast and over the sea. Surface observations confirm that these simulated backbuilding mechanisms describe realistically the processes involved in the maintenance of the heavy precipitation event. A lagrangian analysis shows that the moisture supply to the convective system is provided by the moist conditionally unstable marine boundary layer while the dry air masses above are involved in the cold pool formation. Four days before the event, both, the dry and the moist air masses, come from the Atlantic Ocean in the lower half of the troposphere. The dry air mass involved in the cold pool formation results from both the advection of mid-level air masses and the drying of low-level air masses lifted up over Spain. For the moist air mass feeding the backbuilding convective systems, most of the air parcels overpass France before travelling almost 48 hours in the lowest 1000m above the Mediterranean. About 50 % of the moisture supply to the precipitating system originates from the evaporation over the sea.

Published
2018
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49. Springtime major pollution events by aerosol over Paris Area: From a case study to a multiannual analysis

Author

Philippe Royer and Patrick Chazette

Subjects
Pollution, Atmospheric Science, Entire population, 010504 meteorology & atmospheric sciences, media_common.quotation_subject, 010501 environmental sciences, Atmospheric sciences, 01 natural sciences, Aerosol, Geophysics, Lidar, 13. Climate action, Space and Planetary Science, Anticyclone, Western europe, Earth and Planetary Sciences (miscellaneous), Environmental science, Moderate-resolution imaging spectroradiometer, 0105 earth and related environmental sciences, media_common
Abstract

A study of the intense spring pollution events occurring between 2007 and 2016 on the Paris Area is presented using ground-based and spaceborne measurements. Emphasis is placed on 2011 where data included ground-based lidar measurements. This last period corresponds with the highest regional pollution levels of the past decade. The information threshold (daily average of PM10 > 50 μg m-3) was exceeded 16 times, whilst the alert threshold (daily average of PM10 > 80 μg m-3) was exceeded twice. The information (alert) threshold exists to protect the most fragile people (the entire population). Ground-based and spaceborne measurements demonstrate the benefit of their synergy as each is representative of specific space and time scales. The operational products of the spaceborne instruments Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) and the Moderate Resolution Imaging Spectroradiometer (MODIS) are used. For 2011, CALIOP vertical profiles are inversed to assess the backscatter to extinction ratio, which is then successfully compared with similar results derived from the CALIOP operational products, a ground-based lidar and sunphotometers. The aerosols are identified to be polluted continental and polluted dust aerosols following the criteria used for the inversion of the CALIOP profiles. Aerosol typing is consistent between the ground-based and spaceborne lidars, demonstrating the importance of CALIOP for other years where the ground-based lidar was not in operation. The main pollution sources responsible for the spring aerosol pollution, occurring during anticyclonic meteorological conditions, are identified as coming from Western Europe: Benelux, Rhine-Ruhr Area and the Lorraine Area.

Published
2017
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50. Relative humidity fields in the Annecy Alpine valley observed by Ro-Vibrational Raman lidar in the framework of L-WAIVE

Author

Patrick Chazette, Alexandre Albert Baron, and Julien Totems

Abstract

In June 2019, the Lacustrine-Water vApor Isotope inVentory Experiment (L-WAIVE) has been performed in the southern part of the Annecy lake (45°47' N, 6°12' E). The field campaign motivation is to bring a better comprehension on the evaporation processes above Alpine lakes influencing, along with orography, the complex atmospheric structuration. In particular, this two-week field campaign has involved the meteorological Raman lidar WALI (Weather and Aerosol LIdar). An ultra-light aircraft carrying a meteorological probe and a particle sizer performed several vertical profiles above the ground-based Raman lidar with a vertical resolution between 50 and 100 m for flights operated from the ground level (~0.5 km above the mean sea level (AMSL)) and ~4 km AMSL.This setup is an opportunity to experimentally assess the instrumental errors on both the temperature and the water vapour mixing ratio profiles derived from the ground-based lidar. The methodology used to calculate the error budget will be presented. It will take into account the different types of statistical noises associated with the lidar measurement. In particular, the importance of the spectral filtration in the accuracy of the results will be discussed. The uncertainties associated with the lidar calibration procedure will be quantified. Following this detailed study, the first results of relative humidity will be presented, taking into account the associated error bars.

Published
2020
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