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Downward Transport of Upper Atmospheric NOx in the Polar Winters During 2002 and 2003

Bernd Funke(1), M. Lopez-Puertas(1), S. Gil-Lopez(1), H. Fischer(2), N. Glatthor(2), Udo Grabowski(2), M. Höpfner(2), S. Kellmann(2), M. Kiefer(2), A. Linden(2), M. Milz(2), T. Reddmann(2), T. Steck(2), G. Stiller(2) and T. von Clarmann(2)

(1) Instituto de Astrofisica de Andalucia, CSIC, Apdo. 3004, 18008 Granada, Spain
(2) Forschungszentrum Karlsruhe, Postfach 3640, D-76021 Karlsruhe, Germany

Abstract

NOx is produced in the upper atmosphere by auroral processes and energetic particle precipitation. Favored by dark conditions and dynamics during polar winter, large amounts of upper atmospheric NOx can be transported downwards into the stratosphere, where it acts as an important source of NOy in addition to the N2O oxidation. In this paper we use NOx measurements taken by the MIPAS instrument on Envisat to study the NOx downward transport during the 2003 Antarctic and 2002/2003 Arctic winters. MIPAS CO measurements are also used as a dynamics tracer. We found that significant amounts of NOx was deposited into the stratosphere (9% of the annual hemispheric N2O oxidation source) during the Antarctic winter 2003 while, due to unfavorable dynamical conditions, the upper atmospheric NOx contribution to the 2002/2003 Arctic winter stratosphere is negligible. The stratospheric NOx deposition derived from MIPAS data is compared to KASIMA 3D model calculations initialized with MIPAS NOx data at the upper boundary. The model calculations are also used to estimate the effects on the global ozone.

 

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry