Dynamics and chemistry of the Arctic stratosphere during summmer

Within the frame of the International Polar Year (2007-2009), the Atmosphere group from LPCE-CNRS plans to perform a stratospheric balloon campaign in the Arctic during the summer with the SALOMON-N2 and SPIRALE spectrometers and the aerosol counter (STAC). In this period, prolonged solar illumination results in stratospheric ozone decreases. The dynamical conditions are characterized by large scale air motion with presence of air masses from lower latitude origin. On this synoptic dynamical feature superimpose very fine specific structures. SPIRALE high resolution observations will help to determine whether these structures result from 'fossil debris' of vortex air or from other processes. Mixing processes between air masses originating from various latitudes and occurring at the edge of the fine structures will be thoroughly analyzed. Moreover we propose to study the ability of chemistry-transport models to simulate nitrogen species chemistry both in this large-scale dynamical environment and inside the fine structures. In this context of somewhat perturbed dynamical conditions we will also quantify the impact of possible species concentration local inhomogeneities on the vertical profile retrievals from remote-sensing instruments. Particular emphasis will be put on the study of soot aerosols present in the stratosphere at these latitudes and likely to be enhanced by boreal forest fire events. Finally we will focus on the determination of the stratospheric bromine budget through observations of BrO by SALOMON-N2 and its impact on ozone loss in the lower stratosphere.

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Year 1/2