Abstract

The polar stratosphere remains largely unexplored in the summertime compared to polar winter ozone depletion issues. Former studies mainly focused on the summer chemical ozone loss processes. However, several significant gaps remain regarding 1) the knowledge of the dynamical state and of the compound content characterizing the polar summer stratosphere and 2) the ability of models to simulate properly the involved mechanisms. These uncertainties have an impact on the understanding of the processes controlling the ozone budget and consequently of the ozone–climate interactions.

In the frame of the International Polar Year a balloon campaign operated by CNES (French National Space Agency) is proposed for sounding the Arctic stratosphere in the summertime for which a dynamical transition regime towards the conditions settling the winter stratosphere is expected. A dedicated balloon flight strategy will be employed taking advantage of the experience from numerous previous campaigns. UV–visible and infrared, remote and in situ sensing spectrometers will provide detailed information on vertical distributions of numerous valuable chemical tracers and reactive species. A set of in situ optical aerosol counters, a UV–visible remote spectrometer for the aerosol extinction and a photopolarimeter will provide information on the nature and size distribution of the stratospheric aerosols. These high precision and high vertical resolution measurements are relevant to characterize vortex remnants, air masses originating from the tropics and tropospheric boreal forest fire impacts on the stratosphere. Satellite observations offer a comprehensive set of data and a large spatial coverage for the region of interest. Data analysis will be made using relevant dynamical models (trajectory calculations, contour advection model) and chemistry–transport models (CTM) to highlight the major mechanisms that particularly control the distribution of tracers, aerosols and bromine.

Supported by ANR decision BLAN08–1_316271
©January 2009 - Marc-Antoine Drouin
Last update 11/16/2011