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Contribution Française au projet : Collaboration européenne pour les recherches sur la chimie et la dynamique stratosphérique.

Acronyme
COF-ENRICHED

Référence
1084

Domaine de recherche
Sciences de l'atmosphère

Région
Arctique

Kiruna

Responsable du projet
Nathalie HURET

Laboratoires
Laboratoire de Physique et Chimie de l'Environnement et de l'Espace - LPC2E (CNRS, Université d'Orléans)

Date
Archives : Programmes terrestres

Résumé

La région polaire arctique est particulièrement sensible aux effets du changement climatique à l'échelle globale. Les manifestations de ces changements sont plus rapides dans cette région que dans les autres régions du globe. La composition chimique de cette région évolue en fonction des saisons.

Au cours de l'hiver le développement d'un tourbillon au dessus de cette région conduit à l'isolement des masses d'air. Le fort refroidissement associé permet la formation de nuages stratosphériques polaires à la surface desquels se développent des réactions chimiques hétérogènes qui permettent d'activer les composés halogénés. Au printemps, au retour du soleil, ce tourbillon se délite. Les composés halogénés actifs perturbent le cycle de production/destruction de l'ozone et conduisent à la formation du "trou d'ozone". De plus, au cours du délitement de ce tourbillon et avant l'établissement de la circulation d'été, des échanges de masses des intrusions de masses d'air des régions tropicales se produisent. Ces masses d'air de teneur faible en ozone peuvent contribuer à renforcer les teneurs faibles observées dans ces régions.

Ce projet se propose d'échantillonner l'atmosphère de 10 km à 35 km d'altitude, à l'aide d'instruments embarqués sous ballons stratosphériques et sur satellites, capables de mesurer la plupart des composés chimiques gazeux et les aérosols stratosphériques. Avec les mesures d'espèces à longue durée de vie, les phénomènes de mélange de masses d'air se déroulant dans cette région pourront être caractérisés. Nous mesurerons également les espèces clés régissant la chimie de l'ozone.

Campagne 2011

Année 1/1

It is proposed to study the evolution of stratospheric chemical and dynamical conditions in the Arctic region from vortex to springtime conditions by balloon-borne observations. The data analysis will first be made by direct comparison of the different geophysical conditions to highlight the main characteristics of the system and its evolution as a function of time. The data set obtained will be enriched by satellite data which offers the global distribution of some species. Model simulations will be performed to establish the spatial and temporal link between the different measurements. A systematic comparison of measurements and modelling results will allow to evaluate the ability of models to represent the evolution of the system. With the aid of sensitivity tests on chemical and dynamical processes within the model, it will be possible to perform detailed process studies and also to improve the model.
The measurements to be obtained are the core of the project. To investigate chemistry it is necessary to know the dynamical geophysical conditions and the evolution of the dynamical conditions constraining the chemical species abundance and ozone. Balloon instrumentations will thus allow to perform cross comparisons on each payload and with ground measurements and to contribute to satellite validation. Satellite measurements will give the spatial coverage evolution needed. All measurements will be integrated to constraint models in order to perform detailed process studies.
The present project is connected with the ENRICHED (European collaboratioN for research on stratospherIc CHEmistry and Dynamics) project submitted at CNES Call for proposal for 2011 balloon campaign. This project is also linked the STRAPOLETE project funded by ANR (2009-2012) CNES(2009-2012) and IPEV(2009).

Abstract

The Arctic polar region is especially sensitive to the consequences of climate change at the global scale.Expressions of these changes are faster in this region than in the other ones of the globe.At the end of the winter and the beginning of the spring, the polar ozone depletion is mainly controlled by chemical physics processes involving chlorine and bromine compounds activated at the surface of the polar stratospheric clouds (PSC). During summer, the greater temperatures due to high insolation do not enable PSC formation. However ozone decay still goes on due to catalytic cycles implying nitrogen oxides.During springtime the polar vortex breaks-down and tropical air mass intrusions occur. These air masses with low ozone abundance couls enhanced the ozone loss.This project undertakes to sound the atmosphere from 10 to 35 km height using stratospheric balloon and satellite instruments, able to measure most of the stratospheric gaseous species and aerosols. With the long-lived species measurements, air masses mixing processes occurring in this region will be characterized. Measurements of key species for stratospheric ozone chemistry will also be performed.

Campaign 2011

Year 1/1

It is proposed to study the evolution of stratospheric chemical and dynamical conditions in the Arctic region from vortex to springtime conditions by balloon-borne observations. The data analysis will first be made by direct comparison of the different geophysical conditions to highlight the main characteristics of the system and its evolution as a function of time. The data set obtained will be enriched by satellite data which offers the global distribution of some species. Model simulations will be performed to establish the spatial and temporal link between the different measurements. A systematic comparison of measurements and modelling results will allow to evaluate the ability of models to represent the evolution of the system. With the aid of sensitivity tests on chemical and dynamical processes within the model, it will be possible to perform detailed process studies and also to improve the model.
The measurements to be obtained are the core of the project. To investigate chemistry it is necessary to know the dynamical geophysical conditions and the evolution of the dynamical conditions constraining the chemical species abundance and ozone. Balloon instrumentations will thus allow to perform cross comparisons on each payload and with ground measurements and to contribute to satellite validation. Satellite measurements will give the spatial coverage evolution needed. All measurements will be integrated to constraint models in order to perform detailed process studies.
The present project is connected with the ENRICHED (European collaboratioN for research on stratospherIc CHEmistry and Dynamics) project submitted at CNES Call for proposal for 2011 balloon campaign. This project is also linked the STRAPOLETE project funded by ANR (2009-2012) CNES(2009-2012) and IPEV(2009).

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