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7 results on '"Ghysels, An"'

1. Pico-Light H2O: intercomparison of in situ water vapour measurements during the AsA 2022 campaign.

Author

Ghysels, Mélanie, Durry, Georges, Amarouche, Nadir, Hurst, Dale, Hall, Emrys, Xiong, Kensy, Dupont, Jean-Charles, Samake, Jean-Christophe, Frérot, Fabien, Bejjani, Raghed, and Riviere, Emmanuel D.

Subjects
*WATER vapor, *ATMOSPHERIC water vapor measurement, *TUNABLE lasers, *SEMICONDUCTOR lasers, *HUMIDITY, *MID-infrared lasers, *STRATOSPHERE
Abstract

The mid-infrared lightweight tunable diode laser hygrometer, "Pico-Light H 2 O", the successor to Pico-SDLA H 2 O, is presented and its performances are evaluated during the AsA 2022 balloon-borne intercomparison campaign conducted at the CNES Aire-sur-l'Adour (AsA, 43.70° N; 0.25° W) balloon launch facility and the Aeroclub d'Aire-sur-l'Adour in France. The Pico-Light instrument has primarily been developed for sounding of the upper troposphere and stratosphere, although during the AsA 2022 campaign we expand the range of comparison to include additionally the lower troposphere. Three different types of hygrometer and two models of radiosonde were flown, operated by the French Space Agency (CNES) and the NOAA Global Monitoring Laboratory (GML) scientific teams: Pico-Light H 2 O, the NOAA Frost Point Hygrometer (FPH), the micro-hygrometer (in an early phase of development), and M20 and iMet-4 sondes. Within this framework, we intend to validate measurements of Pico-Light H 2 O through a first intercomparison with the NOAA FPH instrument. The in situ monitoring of water vapour in the upper troposphere–lower stratosphere continues to be very challenging from an instrumental point of view because of the very small amounts of water vapour to be measured in these regions of the atmosphere. Between the lapse rate tropopause (11–12.3 km) and 20 km, the mean relative difference between water vapour mixing ratio measurements by Pico-Light H 2 O and NOAA FPH was 4.2 % ± 7.7 %, and the mean tropospheric difference was 3.84 % ± 23.64 %, with differences depending on the altitude range considered. In the troposphere, relative humidity (RH) over water comparisons led to agreement between Pico-Light and NOAA FPH of - 0.2 % on average, with excursions of about 30 % RH due to moisture variability. Expanding the comparison to meteorological sondes, the iMet-4 sondes agree well with both Pico-Light and FPH between the ground and 7.5 km (within ± 3 % RH), as do the M20 sondes, up to 13 km, which are wet-biased by 3 % RH and dry-biased by 20 % in cases of saturation. [ABSTRACT FROM AUTHOR]

Published
2024
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2. Pico-Light H2O: Intercomparison of in situ water vapour measurements during the AsA 2022 campaign.

Author

Ghysels, Mélanie, Durry, Georges, Amarouche, Nadir, Hurst, Dale, Hall, Emrys, Kensy Xiong, Dupont, Jean-Charles, Samake, Jean-Christophe, Frérot, Fabien, Bejjani, Raghed, and Riviere, Emmanuel D.

Subjects
*WATER vapor, *ATMOSPHERIC water vapor measurement, *HUMIDITY, *HYGROMETERS, *RESEARCH teams, *TROPOSPHERE, *STRATOSPHERE
Abstract

The mid-infrared lightweight stratospheric hygrometer, "Pico-Light H2O", the successor of Pico-SDLA H2O, is presented and its performances are evaluated during the AsA 2022 balloon-borne intercomparison campaign conducted at CNES Aire-sur-l'Adour (AsA) balloon launch facility and the Aeroclub d'Aire-sur-l'Adour. The Pico-Light instrument primarily been developed for sounding of the upper troposphere and stratosphere. Though, during the AsA 2022 campaign we expand the range of comparison including the lower troposphere additionally. Three different types of hygrometers and two models of radiosonde were flown, operated by the French Space Agency (CNES) and the NOAA Global Monitoring Laboratory (GML) scientific teams: Pico-Light H2O, the NOAA Frost Point Hygrometer (FPH), the micro hygrometer (in an early phase of development), M20 and iMet-4 sondes. In this frame, we intend to validate measurements of Pico-Light H2O through a first intercomparison with the NOAA FPH instrument. The in situ monitoring of water vapour in the UT-LS keeps being very challenging from an instrumental point of view because of the very small amounts of water vapour to be measured in these regions of the atmosphere. Between the lapse rate tropopause (11 to 12.3 km) and 20 km, the mean relative difference between water vapour mixing ratio measurements by Pico-Light H2O and NOAA FPH was (4.2 ± 7.7) %, mean tropospheric difference is was (3.84 ± 23.64)%, with differences depending on the altitude range considered. In the troposphere, relative humidity over water (RH) comparisons leads to an agreement between both Pico-Light and NOAA FPH of -0.2% on average, with excursions of about 30% RH due to moisture variability. Expanding the comparison to meteorological sondes, the iMet-4 sondes agree well with both Pico-Light and FPH between ground and 7.5 km (within ± 3% RH) and so does for M20 sondes, up to 13 km, which are wet biased by 3% RH and dry biased by 20% in case of saturation. [ABSTRACT FROM AUTHOR]

Published
2023
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3. A lightweight balloon-borne mid-infrared hygrometer to probe the middle atmosphere: Pico-Light H2O. Comparison with Aura-MLS v4 and v5 satellite measurements

Author

E. D. Rivière, Mélanie Ghysels, Fabien Frérot, Jean-Christophe Samake, Georges Durry, and Nadir Amarouche

Subjects
Troposphere, Atmosphere, Hygrometer, Potential vorticity, Environmental science, Satellite, Tropopause, Atmospheric sciences, Stratosphere, Water vapor
Abstract

Newly developed mid-infrared lightweight hygrometer, Pico-Light H2O has been tested in-flight on February 19, 2019 and October 16, 2019. It has been flown under a 1200 g rubber balloon operated by CNES from the Aire-sur-l'Adour facility (France) within the E.U. funded HEMERA WP11. During these two flights, we were able to obtain coincident MLS v4 and v5 water vapor and temperature profiles, leading to an inter-comparison between Pico-Light and Aura-MLS water vapor and temperature retrievals. Results from the comparison are in line with previous reported studies . Here, differences in the mid-latitude stratosphere and upper troposphere (20–316 hPa) are within 7 % and 64 % respectively. Largest differences with MLS v4 occurring within the upper troposphere nearby the cold point tropopause. The v5 MLS data have been corrected for observed dry bias nearby the tropopause, allowing to partially solve the observed discrepancies. Additionally, on February 19, the hygrometer has flown within an air filament from polar latitudes most of the flight for which a signature is observed on the water vapor profile and confirmed with ozone reanalysis from ERA 5and potential vorticity from MIMOSA advection model.

Published
2020

4. On the cross-tropopause transport of water by tropical convective overshoots: a mesoscale modelling study constrained by in situ observations during the TRO-Pico field campaign in Brazil.

Author

Behera, Abhinna K., Rivière, Emmanuel D., Khaykin, Sergey M., Marécal, Virginie, Ghysels, Mélanie, Burgalat, Jérémie, and Held, Gerhard

Subjects
ATMOSPHERIC models, STRATOSPHERE, MODELS & modelmaking, WATER vapor, TROPOPAUSE, HYDRATION
Abstract

Deep convection overshooting the lowermost stratosphere is well known for its role in the local stratospheric water vapour (WV) budget. While it is seldom the case, local enhancement of WV associated with stratospheric overshoots is often published. Nevertheless, one debatable topic persists regarding the global impact of this event with respect to the temperature-driven dehydration of air parcels entering the stratosphere. As a first step, it is critical to quantify their role at a cloud-resolving scale before assessing their impact on a large scale in a climate model. It would lead to a nudging scheme for large-scale simulation of overshoots. This paper reports on the local enhancements of WV linked to stratospheric overshoots, observed during the TRO-Pico campaign conducted in March 2012 in Bauru, Brazil, using the BRAMS (Brazilian version of the Regional Atmospheric Modeling System; RAMS) mesoscale model. Since numerical simulations depend on the choice of several preferred parameters, each having its uncertainties, we vary the microphysics or the vertical resolution while simulating the overshoots. Thus, we produce a set of simulations illustrating the possible variations in representing the stratospheric overshoots. To better resolve the stratospheric hydration, we opt for simulations with the 800 m horizontal-grid-point presentation. Next, we validate these simulations against the Bauru S-band radar echo tops and the TRO-Pico balloon-borne observations of WV and particles. Two of the three simulations' setups yield results compatible with the TRO-Pico observations. From these two simulations, we determine approximately 333–2000 t of WV mass prevailing in the stratosphere due to an overshooting plume depending on the simulation setup. About 70 % of the ice mass remains between the 380 and 385 K isentropic levels. The overshooting top comprises pristine ice and snow, while aggregates only play a role just above the tropopause. Interestingly, the horizontal cross section of the overshooting top is about 450 km 2 at the 380 K isentrope, which is similar to the horizontal-grid-point resolution of a simulation that cannot compute overshoots explicitly. In a large-scale simulation, these findings could provide guidance for a nudging scheme of overshooting hydration or dehydration. [ABSTRACT FROM AUTHOR]

Published
2022
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5. Modeling the TTL at continental scale for a wet season: An evaluation of the BRAMS mesoscale model using TRO-Pico campaign, and measurements from airborne and spaceborne sensors

Author

Jean-Pierre Pommereau, Mélanie Ghysels, Sergey Khaykin, Gerhard Held, Claud Chantal, Jean-François Rysman, Jérémie Burgalat, Emmanuel Rivière, Abhinna Behera, Georges Durry, Genevieve Seze, Nadir Amarouche, Virginie Marécal, Groupe de spectrométrie moléculaire et atmosphérique - UMR 7331 ( GSMA ), Université de Reims Champagne-Ardenne ( URCA ) -Centre National de la Recherche Scientifique ( CNRS ), Centre national de recherches météorologiques ( CNRM ), Météo France-Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de Météorologie Dynamique (UMR 8539) ( LMD ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -École polytechnique ( X ) -École des Ponts ParisTech ( ENPC ) -Centre National de la Recherche Scientifique ( CNRS ) -Département des Géosciences - ENS Paris, École normale supérieure - Paris ( ENS Paris ) -École normale supérieure - Paris ( ENS Paris ), Division technique INSU/SDU ( DTI ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), TROPO - 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 ), SHTI - LATMOS, Instituto de Pesquisas Meteorológicas ( IPMet ), Universidade Estadual Paulista, UFR Sci Exactes & Naturelles, CNRS, Universidade de São Paulo (USP), Ecole Polytech, INSU, UPMC Univ Paris 06, Universidade Estadual Paulista (Unesp), Groupe de spectrométrie moléculaire et atmosphérique (GSMA), Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), 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), 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), 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), STRATO - LATMOS, Instituto de Pesquisas Meteorológicas (IPMet), Universidade Estadual Paulista Júlio de Mesquita Filho = São Paulo State University (UNESP), 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), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), 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
Convection, Tropical tropopause layer, Atmospheric Science, 010504 meteorology & atmospheric sciences, Mesoscale meteorology, 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, 7. Clean energy, Water vapor budget, Earth and Planetary Sciences (miscellaneous), BRAMS, Stratosphere, 0105 earth and related environmental sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Stratospheric overshooting convection, Inertia-gravity waves, Microwave Limb Sounder, Geophysics, Microwave humidity sounder, Mesoscale Modeling, [ PHYS.PHYS.PHYS-AO-PH ] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], 13. Climate action, Space and Planetary Science, Environmental science, Satellite, Tropopause, Water vapor
Abstract

Made available in DSpace on 2018-11-26T17:48:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-03-16 Agence Nationale de la Recherche (ANR) region Champagne-Ardenne in France Direction Generale de l'Armement (PRECIP-CLOUD project) European Union's Framework Program MUSIC project LEFE project Overshoots a grande echelle Centre National d'Etudes Spatiales (CNES) Centre de Calcul ROMEO In order to better understand the water vapor (WV) intrusion into the tropical stratosphere, a mesoscale simulation of the tropical tropopause layer using the BRAMS (Brazilian version of Regional Atmospheric Modeling System (RAMS)) model is evaluated for a wet season. This simulation with a horizontal grid point resolution of 20kmx20km cannot resolve the stratospheric overshooting convection (SOC). Its ability to reproduce other key parameters playing a role in the stratospheric WV abundance is investigated using the balloon-borne TRO-Pico campaign measurements, the upper-air soundings over Brazil, and the satellite observations by Aura Microwave Limb Sounder, Microwave Humidity Sounder, and Geostationary Operational Environmental Satellite 12. The BRAMS exhibits a good ability in simulating temperature, cold-point, WV variability around the tropopause. However, the simulation is typically observed to be warmer by approximate to 2.0 degrees C and wetter by approximate to 0.4 ppmv at the hygropause, which can be partly affiliated with the grid boundary nudging of the model by European Centre for Medium-Range Weather Forecasts operational analyses. The modeled cloud tops show a good correlation (maximum cross-correlation of approximate to 0.7) with Geostationary Operational Environmental Satellite 12. Furthermore, the overshooting cells detected by Microwave Humidity Sounder are observed at the locations, where 75% of the modeled cloud tops are higher than 11km. Finally, the modeled inertia-gravity wave periodicity and wavelength are comparable with those deduced from the radio sounding measurements during TRO-Pico campaign. The good behavior of BRAMS confirms the SOC contribution in the WV abundance, and variability is of lesser importance than the large-scale processes. This simulation can be used as a reference run for upscaling the impact of SOC at a continental scale for future studies. UFR Sci Exactes & Naturelles, GSMA, CNRS, UMR 7331, Reims, France CNRS, CNRM, Meteo France, UMR3589, Toulouse, France UPMC Univ Paris 06, Sorbonne Univ, PSL Res Univ,ENS, LMD,IPSL,CNRS,UMR 8539,Ecole Polytech,Univ Paris, Palaiseau, France Ecole Polytech, ENS, CNRS, LMD,IPSL,UPMC, Paris, France INSU, Div Tech, Pl Aristide Briand, Meudon, France UPMC Univ Paris 06, UVSQ Univ Paris Saclay, CNRS, LATMOS,IPSL, Guyancourt, France Univ Estadual Paulista, Inst Pesquisas Meteorol, Bauru, Brazil Univ Estadual Paulista, Inst Pesquisas Meteorol, Bauru, Brazil Agence Nationale de la Recherche (ANR): ANR-2010-BLAN-609-01 European Union's Framework Program: 603608 MUSIC project: ANR-14-CE01-0014 Centre de Calcul ROMEO: 669

Published
2018

6. Evidence of horizontal and vertical transport of water in the Southern Hemisphere Tropical Tropopause Layer (TTL) from high-resolution balloon observations

Author

S. M. Khaykin, J.-P. Pommereau, E. D. Riviere, G. Held, F. Ploeger, M. Ghysels, N. Amarouche, J.-P. Vernier, F. G. Wienhold, D. Ionov, TROPO - 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), STRATO - LATMOS, Groupe de spectrométrie moléculaire et atmosphérique (GSMA), Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS), Instituto de Pesquisas Meteorológicas (IPMet), Universidade Estadual Paulista Júlio de Mesquita Filho = São Paulo State University (UNESP), Institut für Energie- und Klimaforschung - Stratosphäre (IEK-7), Forschungszentrum Jülich GmbH | Centre de recherche de Juliers, Helmholtz-Gemeinschaft = Helmholtz Association-Helmholtz-Gemeinschaft = Helmholtz Association, Chemical Science and Technology Laboratory, National Institute of Standards and Technology [Gaithersburg] (NIST), NASA Langley Research Center [Hampton] (LaRC), Science Systems and Applications, Inc. [Lanham] (SSAI), Institute for Atmospheric and Climate Science [Zürich] (IAC), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), V.A. Fock Institute of Physics (NIF), St Petersburg State University (SPbU), Agence Nationale de la Recherche (ANR), ANR-10-BLAN-0609,TRO-Pico,Bilan multiéchelle de l'eau dans la haute troposphère et la basse stratosphère des régions TROpicales.(2010), Université de Versailles St Quentin, Université de Reims Champagne Ardenne and CNRS, Universidade Estadual Paulista (Unesp), Forschungszentrum Jülich, CNRS, Science Systems and Applications Inc, NASA Langley Research Center, Institute for Atmospheric and Climate Science, St. Petersburg State University, National Institute of Standards and Technology, 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 ), SHTI - LATMOS, Groupe de spectrométrie moléculaire et atmosphérique - UMR 7331 ( GSMA ), Université de Reims Champagne-Ardenne ( URCA ) -Centre National de la Recherche Scientifique ( CNRS ), Instituto de Pesquisas Meteorológicas ( IPMet ), Universidade Estadual Paulista, Institut für Energie- und Klimaforschung - Stratosphäre ( IEK-7 ), Forschungszentrum Jülich GmbH, National Institute of Standards and Technology [Gaithersburg] ( NIST ), NASA Langley Research Center [Hampton] ( LaRC ), Science Systems and Applications, Inc. [Lanham] ( SSAI ), Institute for Atmospheric and Climate Science [Zürich] ( IAC ), Swiss Federal Institute of Technology in Zürich ( ETH Zürich ), V.A. Fock Institute of Physics ( NIF ), St Petersburg State University ( SPbU ), and ANR-2010-BLAN-609-01,TRO-pico,TRO-pico project

Subjects
Convection, Atmospheric Science, 010504 meteorology & atmospheric sciences, Atmospheric sciences, 01 natural sciences, law.invention, lcsh:Chemistry, 010309 optics, law, 0103 physical sciences, ddc:550, Extratropical cyclone, Stratosphere, 0105 earth and related environmental sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], lcsh:QC1-999, Microwave Limb Sounder, Depth sounding, lcsh:QD1-999, [ PHYS.PHYS.PHYS-AO-PH ] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], 13. Climate action, HYSPLIT, Radiosonde, Environmental science, lcsh:Physics, Water vapor
Abstract

Made available in DSpace on 2018-12-11T17:06:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-09-29 High-resolution in situ balloon measurements of water vapour, aerosol, methane and temperature in the upper tropical tropopause layer (TTL) and lower stratosphere are used to evaluate the processes affecting the stratospheric water budget: horizontal transport (in-mixing) and hydration by cross-Tropopause overshooting updrafts. The obtained in situ evidence of these phenomena are analysed using satellite observations by Aura MLS (Microwave Limb Sounder) and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) together with trajectory and transport modelling performed using CLaMS (Chemical Lagrangian Model of the Stratosphere) and HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) model. Balloon soundings were conducted during March 2012 in Bauru, Brazil (22.3°ĝ€S) in the frame of the TRO-Pico campaign for studying the impact of convective overshooting on the stratospheric water budget. The balloon payloads included two stratospheric hygrometers: FLASH-B (Fluorescence Lyman-Alpha Stratospheric Hygrometer for Balloon) and Pico-SDLA instrument as well as COBALD (Compact Optical Backscatter Aerosol Detector) sondes, complemented by Vaisala RS92 radiosondes. Water vapour vertical profiles obtained independently by the two stratospheric hygrometers are in excellent agreement, ensuring credibility of the vertical structures observed. A signature of in-mixing is inferred from a series of vertical profiles, showing coincident enhancements in water vapour (of up to 0.5ĝ€ppmv) and aerosol at the 425ĝ€K (18.5ĝ€km) level. Trajectory analysis unambiguously links these features to intrusions from the Southern Hemisphere extratropical stratosphere, containing more water and aerosol, as demonstrated by MLS and CALIPSO global observations. The in-mixing is successfully reproduced by CLaMS simulations, showing a relatively moist filament extending to 20°ĝ€S. A signature of local cross-Tropopause transport of water is observed in a particular sounding, performed on a convective day and revealing water vapour enhancements of up to 0.6ĝ€ppmv as high as the 404ĝ€K (17.8ĝ€km) level. These are shown to originate from convective overshoots upwind detected by an S-band weather radar operating locally in Bauru. The accurate in situ observations uncover two independent moisture pathways into the tropical lower stratosphere, which are hardly detectable by space-borne sounders. We argue that the moistening by horizontal transport is limited by the weak meridional gradients of water, whereas the fast convective cross-Tropopause transport, largely missed by global models, can have a substantial effect, at least at a regional scale. LATMOS CNRS Université de Versailles St Quentin GSMA Université de Reims Champagne Ardenne and CNRS Instituto de Pesquisas Meteorológicas (IPMet) UNESP Forschungszentrum Jülich Division Technique de l'Insu CNRS Science Systems and Applications Inc NASA Langley Research Center ETH Zurich Institute for Atmospheric and Climate Science St. Petersburg State University National Institute of Standards and Technology Instituto de Pesquisas Meteorológicas (IPMet) UNESP

Published
2016

7. Intercomparison of in situ water vapor balloon-borne measurements from Pico-SDLA H2O and FLASH-B in the tropical UTLS.

Author

Ghysels, Mélanie, Riviere, Emmanuel D., Khaykin, Sergey, Stoeffler, Clara, Amarouche, Nadir, Pommereau, Jean-Pierre, Held, Gerhard, and Durry, Georges

Subjects
*WATER spectra, *WATER vapor, *CONVECTION (Meteorology), *STRATOSPHERE, *FLIGHT, *METEOROLOGICAL research
Abstract

In this paper we compare water vapor mixing ratio measurements from two quasi-parallel flights of the Pico-SDLA H2O and FLASH-B hygrometers. The measurements were made on 10 February 2013 and 13 March 2012, respectively, in the tropics near Bauru, São Paulo state, Brazil during an intense convective period. Both flights were performed as part of a French scientific project, TRO-Pico, to study the impact of the deep-convection overshoot on the water budget. Only a few instruments that permit the frequent sounding of stratospheric water vapor can be flown within small-volume weather balloons. Technical difficulties preclude the accurate measurement of stratospheric water vapor with conventional in situ techniques. The instruments described here are simple and lightweight, which permits their low-cost deployment by non-specialists aboard a small weather balloon. We obtain mixing ratio retrievals which agree above the cold-point tropopause to within 1.9 and 0.5 % for the first and second flights, respectively. This level of agreement for balloon-borne measured stratospheric water mixing ratio constitutes one of the best agreement reported in the literature. Because both instruments show similar profiles within their combined uncertainties, we conclude that the Pico-SDLA H2O and FLASH-B data sets are mutually consistent. [ABSTRACT FROM AUTHOR]

Published
2016
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