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13 results on '"Christophe Caudoux"'

1. Surpact: A SMOS Surface Wave Rider for Air-Sea Interaction

Author

Gilles Reverdin, Simon Morisse, Denis Bourras, Nicolas Martin, Antonio Lourenço, Jacqueline Boutin, Christophe Caudoux, Jordi Font, and Joaquín Salvador

Subjects
Surpact, drifter, wave rider, SSMIS, sea state, atmospheric sea level pressure, Oceanography, GC1-1581
Abstract

A new small wave rider called Surpact was developed for air-sea investigations. It was designed to attach to a drifter or a mooring and to float upon the surface waves in order to measure sea state and atmospheric sea level pressure as well as temperature and salinity at a small fixed depth from the surface. Wind speed is derived from Surpact sea state measurements, and the data are calibrated with co-located Special Sensor Microwave Imager Sounder (SSMIS) wind retrievals during a four-month deployment in the North Atlantic subtropics. Individual 15-minute wind estimates present a root mean square difference on the order of 15% with the SSMIS wind retrievals for wind speeds less than 12 m s–1. The wind retrievals might lag the actual wind changes for moderate to strong winds by an hour. This article discusses the accuracy of these wind retrievals based on in situ data collected during the Strasse cruise in August and September 2012. Temperature and salinity data are also examined. The authors find, under some sunny conditions, radiative warming of the temperature probe reduces the accuracy of some of the daytime temperature data and also affects corresponding salinity estimates. Nonetheless, small realistic daily cycles of near-surface salinity (0.01 psu amplitude) were observed. Also, examples of wind time series collected during salinity drops caused by rainfall during late 2012 in the North Atlantic subtropics indicate no intensification of wind during these rain events.

Published
2013

2. Analysis of RFI Identification and Mitigation in CAROLS Radiometer Data Using a Hardware Spectrum Analyser

Author

Christophe Caudoux, Mickaël Pardé, Mehrez Zribi, Monique Dechambre, and Pascal Fanise

Subjects
RFI, CAROLS, L-band, radiometry, Chemical technology, TP1-1185
Abstract

A method to identify and mitigate radio frequency interference (RFI) in microwave radiometry based on the use of a spectrum analyzer has been developed. This method has been tested with CAROLS L-band airborne radiometer data that are strongly corrupted by RFI. RFI is a major limiting factor in passive microwave remote sensing interpretation. Although the 1.400–1.427 GHz bandwidth is protected, RFI sources close to these frequencies are still capable of corrupting radiometric measurements. In order to reduce the detrimental effects of RFI on brightness temperature measurements, a new spectrum analyzer has been added to the CAROLS radiometer system. A post processing algorithm is proposed, based on selective filters within the useful bandwidth divided into sub-bands. Two discriminant analyses based on the computation of kurtosis and Euclidian distances have been compared evaluated and validated in order to accurately separate the RF interference from natural signals.

Published
2011
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3. 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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4. Development of Tropical Cyclones from African Easterly Waves : comparative study of three African Easterly Wave events during the CADDIWA campaign

Author

Tanguy Jonville, Cyrille Flamant, Christophe Lavaysse, Julien Delanoë, Pascal Richard, Sophie Bounissou, Quiterie Cazenave, Hélène Colomb, Christophe Caudoux, Philippe Peyrillé, and Erwan Cornillault

Abstract

During the CADDIWA (Cloud-Atmospheric Dynamics-Dust Interaction in West Africa) airborne campaign that took place in September 2021, three tropical disturbances initiated from African Easterly Waves were sampled. Two of them reached the Tropical Storm state and were named Rose and Peter by the National Hurricane Center. The last one, later named Pierre-Henri, failed to develop. After a validation of reanalysis data for september 2021 against the data collected during the campaign, a comparative study of the three events will be conducted using ERA5, satellite and campaign data, with a focus on energy budgets. Several processes that may be catalysts or inhibiters for tropical cyclogenesis (AEW-Monsoon -, AEW-AEW -, dust-dynamics interaction ...) will especially be discussed.

Published
2023
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5. Overview and first analysis of the in situ microphysical measurement dataset collected during the CADDIWA mission

Author

Pierre Coutris, Guy Febvre, Louis Jaffeux, Clément Bazantay, Clémantyne Aubry, Christophe Caudoux, Julien Delanoë, Alfons Schwarzenboeck, and Cyrille Flamant

Abstract

In the frame of the Joint Aeolus Tropical Atlantic Campaigns, an airborne field campaign took place in Sal island of Cape-Verde from the 8th to 21st of September 2021, as part of the French CADDIWA mission. During this campaign, the SAFIRE F20 research aircraft equipped with in situ and remote sensing instruments performed nine 3 to 4 hour long flights sampling tropical environment underneath AEOLUS satellite tracks and performing exploration flights within the convective cloud systems of tropical disturbances. In this study, an overview of the available aerosol and cloud in situ dataset is given first, presenting the instrumental and methodological approaches relevant to the collection of data from a set of four instruments: the UHSAS (aerosol size range : 40 – 1000 nm, Cai et al. 2008), the SPP-300 (aerosol 0.3 – 20 µm, Baumgardner 1992) and the CDP-2 (droplets 2-50 µm, Lance et al. 2010) scattering probes, and the 2D-S imager (10-1280 µm, Lawson et al. 2006). Then a detailed microphysical analysis is conducted on two case studies: a tropical perturbation referred to as Pierre-Henri in this study (unnamed/numbered by NOAA National Hurricane Center (NHC)), sampled during F20 flight #7/8, and the Tropical Storm Rose (# AL172021 according to NOAA NHC) sampled during flights #12/13. The analysis includes a discussion on the main microphysical properties such as Particle Size Distribution (PSD), Ice Water Content (IWC) retrieved at different locations in the cloud convective systems, complemented by 95GHz reflectivity and Doppler vertical velocity measured by the airborne cloud radar RASTA (Delanoe et al. 2013). The data supporting this study is illustrated in the figure below: the vertical velocity (derived from 3 Doppler non colinear measurements of the radar) and PSD time series are given on top of two samples ice crystal images taken by the 2DS imager at different location in the TS Rose. A newly developed image classification algorithm (Jaffeux et al. 2022) is applied to the 2D-S data to derive statistics on the ice particles morphological properties, yielding to a discussion on the microphysical ice growth processes occurring in these systems.

Published
2023
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7. Thinice : campagne de mesure aéroportée dédiée à l'étude des dépressions arctiques et des interactions avec les nuages et la banquise

Author

Gwendal Rivière, Léa Raillard, Julien Delanoë, Sophie Bounissou, Christophe Caudoux, Laure Cossalter, Kevin Huet, Capucine Cozzolino, Olivier Jourdan, Christophe Gourbeyre, Clémantyne Aubry, Eric Bazile, Yann Seity, Vincent Douet, Jérémie Trules, James D. Doyle, Florient Pantillon, and Meryl Wimmer

Published
2022
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8. Ash sedimentation by fingering and sediment thermals from wind-affected volcanic plumes

Author

Jean-Paul Vinson, Frédéric Peyrin, A.M. Jellinek, Franck Donnadieu, Julien Delanoë, Thierry Latchimy, Valentin Freret-Lorgeril, Sébastien Valade, Christophe Caudoux, Claude Hervier, Johanand Gilchrist, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Department of Earth Sciences [Geneva], Université de Genève = University of Geneva (UNIGE), Department of Earth, Ocean and Atmospheric Sciences [Vancouver] (UBC EOAS), University of British Columbia (UBC), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), 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), 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), Dipartimento di Scienze della Terra [Firenze] (DST), Università degli Studi di Firenze = University of Florence (UniFI), German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ), ANR-10-LABX-0006,CLERVOLC,Clermont-Ferrand centre for research on volcanism(2010), ANR-16-IDEX-0001,CAP 20-25,CAP 20-25(2016), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS), University of Geneva [Switzerland], Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-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)-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 Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI)

Subjects
geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Sediment, Volcanology, Sedimentation, 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, Wind speed, Geophysics, Disdrometer, Settling, Volcano, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Geology, 0105 earth and related environmental sciences, Volcanic ash
Abstract

International audience; Ash fallout and volcanic plume dispersion represent critical hazards for local and global human populations for minutes to years after the onset of an eruption. Understanding the key processes governing the sedimentation of ash particles is a major challenge in modern volcanology from modeling and risk management perspectives. Recent experiments predict that sedimentation from eruption clouds rich in fine-grained ash can be driven by convective phenomena in the form of ∼100 m to km-scale ash fingers related to the intermittent formation and detaching of ash-rich particle boundary layer. Remote sensing observations of mammatus and cloud veils from numerous eruptions over recent years as well as field observations of spatially discontinuous ash deposits are consistent with this prediction. Indeed, this mode of ash sedimentation is predicted to be the predominant mechanism of fine ash removal for a significant fraction of eruptions in the geological records. Here, we use a novel combination of 3 millimeter-wavelength Doppler radar observations and time series of optical disdrometer data to characterize for the first time in real-time the time-varying structure and sedimentation properties of volcanic ash plumes under steady wind conditions. As a case study, we apply this new method to weak short-lived plumes from Stromboli Volcano. 96% of the disdrometer proximal sedimentation data highlight pulsatory phases of increased sedimentation rate that are 20–60 s apart and characterized by particle size distribution variation with bulk concentrations up to 681 mg/m3. Radar data also record intermittent periods of higher reflectivity (i.e. a factor of 3 in mass concentration) inside the ash sedimentation interspersed by 30 to 50 s and interpreted as ash fingers crossing the radar beam. From time series of radar signals and ground-based disdrometer measurements, together with simple analog experiments, we develop a conceptual model for intermittent sedimentation from wind-affected ash plumes. In particular, we show that when wind speeds are comparable to or greater than ash settling velocities, the dynamics of wind-driven rolls in ash clouds can govern the production of gravitational instabilities and the occurrence and timing of ash fingers that form descending sediment thermals in turn. This study suggests that ambient wind should affect the maximum size and minimum concentration of ash particles needed to form fingers but also control where and when fingers form at the base of wind-drifted ash plumes. These novel predictions highlight the need for future work aimed at refining our understanding of ash finger formation under windy conditions from the perspectives of in-situ characterization, numerical modeling and risk assessment of fine ash dispersal from the most frequent style of eruptions on Earth.

Published
2020
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9. BASTA: A 95-GHz FMCW Doppler Radar for Cloud and Fog Studies

Author

Jean-Paul Vinson, Fabrice Bertrand, Jean-Charles Dupont, Ruben Hallali, Julien Delanoë, Laurent Barthès, Williams Brett, Alain Protat, Jacques Parent du Chatelet, Christophe Caudoux, Martial Haeffelin, SPACE - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-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 de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Australian Bureau of Meteorology [Melbourne] (BoM), Australian Government, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-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 recherches météorologiques (CNRM), 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), Institut Pierre-Simon-Laplace (IPSL), 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)-Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-Centre National de la Recherche Scientifique (CNRS), CNES (Centre National d'Etudes Spatiales), INSU (Institut National des Sciences de l'Univers), Ecole Polytechnique, Région Ile de France, Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), and École normale supérieure - Paris (ENS Paris)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, Doppler radar, Ocean Engineering, [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology, 010502 geochemistry & geophysics, 01 natural sciences, law.invention, Man-portable radar, Bistatic radar, Radar engineering details, law, Radar imaging, Environmental science, Radar, Low-frequency radar, Radar configurations and types, 0105 earth and related environmental sciences, Remote sensing
Abstract

Doppler cloud radars are amazing tools to characterize cloud and fog properties and to improve their representation in models. However, commercially available cloud radars (35 and 95 GHz) are still very expensive, which hinders their widespread deployment. This study presents the development of a lower-cost semioperational 95-GHz Doppler cloud radar called the Bistatic Radar System for Atmospheric Studies (BASTA). To drastically reduce the cost of the instrument, a different approach is used compared to traditional pulsed radars: instead of transmitting a large amount of energy for a very short time period (as a pulse), a lower amount of energy is transmitted continuously. By using a specific signal processing technique, the radar can challenge expensive radars and provide high-quality measurements of cloud and fog. The latest version of the instrument has a sensitivity of about −50 dBZ at 1 km for 3-s integration and a vertical resolution of 25 m. The BASTA radar currently uses four successive modes for specific applications: the 12.5-m vertical resolution mode is dedicated to fog and low clouds, the 25-m mode is for liquid and ice midtropospheric clouds, and the 100- and 200-m modes are ideal for optically thin high-level ice clouds. The advantages of such a radar for calibration procedures and field operations are also highlighted. The radar comes with a set of products dedicated to cloud and fog studies. For instance, cloud mask, corrected Doppler velocity, and multimode products combining the high-sensitivity mode and high-resolution modes are provided.

Published
2016
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10. Surpact: A SMOS Surface Wave Rider for Air-Sea Interaction

Author

Jacqueline Boutin, Joaquín Salvador, Simon Morisset, Gilles Reverdin, Antonio Lourenço, Nicolas Martin, Jordi Font, Denis Bourras, Christophe Caudoux, Échanges dans la couche de surface : des pôles aux tropiques (SURF), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), ESTER - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-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 de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Développement Instrumental et Techniques Marines (DITM), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of Marine Sciences / Institut de Ciències del Mar [Barcelona] (ICM), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), 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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and 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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636))

Subjects
Salinity measurements, 010504 meteorology & atmospheric sciences, Meteorology, Temperature salinity diagrams, SSMIS, Wind stress, Sea state, Oceanography, 7. Clean energy, 01 natural sciences, Wind speed, lcsh:Oceanography, Wind shear, lcsh:GC1-1581, wave rider, Pacific warm pool, 0105 earth and related environmental sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], 010505 oceanography, drifter, Mooring, Surpact, Drifter, 13. Climate action, Environmental science, sea state, atmospheric sea level pressure
Abstract

10 pages, 4 figures, A new small wave rider called Surpact was developed for air-sea investigations. It was designed to attach to a drifter or a mooring and to float upon the surface waves in order to measure sea state and atmospheric sea level pressure as well as temperature and salinity at a small fixed depth from the surface. Wind speed is derived from Surpact sea state measurements, and the data are calibrated with colocated Special Sensor Microwave Imager Sounder (SSMIS) wind retrievals during a four-month deployment in the North Atlantic subtropics. Individual 15-minute wind estimates present a root mean square difference on the order of 15% with the SSMIS wind retrievals for wind speeds less than 12 m s-1. The wind retrievals might lag the actual wind changes for moderate to strong winds by an hour. This article discusses the accuracy of these wind retrievals based on in situ data collected during the Strasse cruise in August and September 2012. Temperature and salinity data are also examined. The authors find, under some sunny conditions, radiative warming of the temperature probe reduces the accuracy of some of the daytime temperature data and also affects corresponding salinity estimates. Nonetheless, small realistic daily cycles of near-surface salinity (0.01 psu amplitude) were observed. Also, examples of wind time series collected during salinity drops caused by rainfall during late 2012 in the North Atlantic subtropics indicate no intensification of wind during these rain events, This effort is part of ESA SMOS cal-val projects, and is supported nationally in France by CNES/TOSCA with the Gloscal project, and in Spain at ICM/CSIC by the Spanish national R+D plan (project AYA2010-22062-C05)

Published
2013
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11. A new platform for the determination of air-sea fluxes (OCARINA): Overview and first results

Author

Simon Morisset, Louis Marié, Alain Weill, Nicolas Geyskens, Gilles Reverdin, Lucio Baggio, Christophe Caudoux, Rémi Cambra, Danièle Hauser, Denis Bourras, Gérard Caudal, Hubert Branger, ESTER - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-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 de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche sur les Phénomènes Hors Equilibre (IRPHE), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Interactions et Processus au sein de la couche de Surface Océanique (IPSO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), 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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), 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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences de l'Univers (INSU/SPU), Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Division technique INSU/SDU (DTI), and Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Low altitude, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, Turbulent measurement, 010505 oceanography, Turbulence, Ocean Engineering, Air-sea fluxes, Surface observations, Atmospheric sciences, 01 natural sciences, Research vessel, In situ oceanic observations, Surface boundary layer, In situ atmospheric observations, Physics::Space Physics, Environmental science, 14. Life underwater, Wind-wave interactions, Physics::Atmospheric and Oceanic Physics, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences
Abstract

The present paper describes a new type of floating platform that was specifically designed for estimating air–sea fluxes, investigating turbulence characteristics in the atmospheric surface boundary layer, and studying wind–wave interactions. With its design, it can be deployed in the open ocean or in shallow-water areas. The system is designed to be used from a research vessel. It can operate for ~10 h as a drifting wave rider and 3 h under power. Turbulence and meteorological instrument packages are placed at a low altitude (1–1.5 m). It was deployed for validation purposes during the Front de Marée, Variabilité (FROMVAR), 2011 experiment off the west coast of Brittany, France. Wind friction velocity and surface turbulent buoyancy flux were estimated using eddy covariance, spectral, bulk, and profile methods. The comparisons of the four methods show a reasonable agreement except for the spectral buoyancy flux. This suggests that the platform design is correct. Also, the wind measured at a fixed height above the sea shows spectral coherence with wave heights, such that wind and swell are in phase, with the largest wind values on top of swell crests. This result in qualitative agreement with current model predictions supports the capability of the Ocean Coupled to Atmosphere, Research at the Interface with a Novel Autonomous platform (OCARINA) to investigate wind–swell interactions.

Published
2014
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12. Analysis of RFI Identification and Mitigation in CAROLS Radiometer Data Using a Hardware Spectrum Analyser

Author

Mehrez Zribi, Mickaël Pardé, Monique Dechambre, Christophe Caudoux, Pascal Fanise, ESTER - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-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 de Versailles Saint-Quentin-en-Yvelines (UVSQ)-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 d'études spatiales de la biosphère (CESBIO), 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)-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 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 National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-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 d'Etudes Spatiales (CNES): TOSCA/CNES program., Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
L band, Spectrum analyzer, Time Factors, 010504 meteorology & atmospheric sciences, Computer science, Statistics as Topic, 0211 other engineering and technologies, RFI, radiometry, 02 engineering and technology, lcsh:Chemical technology, 01 natural sciences, Biochemistry, CAROLS, Electromagnetic interference, Article, Analytical Chemistry, [INFO.INFO-TS]Computer Science [cs]/Signal and Image Processing, lcsh:TP1-1185, Electrical and Electronic Engineering, Radiometry, Instrumentation, Atlantic Ocean, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, Remote sensing, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Radiometer, Computers, Spectrum Analysis, Bandwidth (signal processing), Temperature, Atomic and Molecular Physics, and Optics, Radio Frequency Identification Device, L-band, Brightness temperature, Calibration, France, [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing, Algorithms
Abstract

International audience; A method to identify and mitigate radio frequency interference (RFI) in microwave radiometry based on the use of a spectrum analyzer has been developed. This method has been tested with CAROLS L-band airborne radiometer data that are strongly corrupted by RFI. RFI is a major limiting factor in passive microwave remote sensing interpretation. Although the 1.400-1.427 GHz bandwidth is protected, RFI sources close to these frequencies are still capable of corrupting radiometric measurements. In order to reduce the detrimental effects of RFI on brightness temperature measurements, a new spectrum analyzer has been added to the CAROLS radiometer system. A post processing algorithm is proposed, based on selective filters within the useful bandwidth divided into sub-bands. Two discriminant analyses based on the computation of kurtosis and Euclidian distances have been compared evaluated and validated in order to accurately separate the RF interference from natural signals.

Published
2011
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13. EUREC4A observations from the SAFIRE ATR42 aircraft

Author

Sandrine Bony, Marie Lothon, Julien Delanoë, Pierre Coutris, Jean-Claude Etienne, Franziska Aemisegger, Anna Lea Albright, Thierry André, Hubert Bellec, Alexandre Baron, Jean-François Bourdinot, Pierre-Etienne Brilouet, Aurélien Bourdon, Jean-Christophe Canonici, Christophe Caudoux, Patrick Chazette, Michel Cluzeau, Céline Cornet, Jean-Philippe Desbios, Dominique Duchanoy, Cyrille Flamant, Benjamin Fildier, Christophe Gourbeyre, Laurent Guiraud, Tetyana Jiang, Claude Lainard, Christophe Le Gac, Christian Lendroit, Julien Lernould, Thierry Perrin, Frédéric Pouvesle, Pascal Richard, Nicolas Rochetin, Kevin Salaün, Alfons Schwarzenboeck, Guillaume Seurat, Bjorn Stevens, Julien Totems, Ludovic Touzé-Peiffer, Gilles Vergez, Jessica Vial, Leonie Villiger, and Raphaela Vogel

Subjects
13. Climate action, General Earth and Planetary Sciences
Abstract

As part of the EUREC4A (Elucidating the role of cloud–circulation coupling in climate) field campaign, which took place in January and February 2020 over the western tropical Atlantic near Barbados, the French SAFIRE ATR42 research aircraft (ATR) conducted 19 flights in the lower troposphere. Each flight followed a common flight pattern that sampled the atmosphere around the cloud base level, at different heights of the subcloud layer, near the sea surface and in the lower free troposphere. The aircraft's payload included a backscatter lidar and a Doppler cloud radar that were both horizontally oriented; a Doppler cloud radar looking upward; microphysical probes; a cavity ring-down spectrometer for water isotopes; a multiwavelength radiometer; a visible camera; and multiple meteorological sensors, including fast rate sensors for turbulence measurements. With this instrumentation, the ATR characterized the macrophysical and microphysical properties of trade-wind clouds together with their thermodynamical, turbulent and radiative environment. This paper presents the airborne operations, the flight segmentation, the instrumentation, the data processing and the EUREC4A datasets produced from the ATR measurements. It shows that the ATR measurements of humidity, wind and cloud base cloud fraction measured with different techniques and samplings are internally consistent; that meteorological measurements are consistent with estimates from dropsondes launched from an overflying aircraft (the High Altitude and LOng Range Research Aircraft, HALO); and that water-isotopic measurements are well correlated with data from the Barbados Cloud Observatory. This consistency demonstrates the robustness of the ATR measurements of humidity, wind, cloud base cloud fraction and water-isotopic composition during EUREC4A. It also confirms that through their repeated flight patterns, the ATR and HALO measurements provided a statistically consistent sampling of trade-wind clouds and of their environment. The ATR datasets are freely available at the locations specified in Table 11.

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