|
|
 |
Dynamical origin of strong NO2 enhancement in the polar stratosphere and mesosphere observed by GOMOS ion ENVISAT
Alain Hauchecorne(1)
(1)
CNRS,
BP3,
91371 Verrières le Buisson,
France
Abstract
A strong enhancement of NO2 has been observed by GOMOS/ENVISAT instrument in winter 2004 at high north latitude. A layer with high NO2 concentration is detected at 65 km in Mid-January and goes down to the stratosphere in February. Such NO2 enhancement has been already observed after a strong solar proton event. In the present case there is no particular particle precipitation event at the time of the NO2 increase. We propose another explanation based on the dynamics of the middle atmosphere. If a strong air descent occurs in the polar mesosphere, for instance due to a wave breaking event, it will transport NOx from the upper mesosphere/lower thermosphere at 65 km. The further descent of NOx to the upper stratosphere is explained by the radiative diabatic descent into thewinter polar vortex. This hypothesis is supported by temperature observations of SABER/TIMED showing a strong temperature increase around 70 km at high latitudes at the time of NO2 increase. This increase is an indication of a strong adiabatic warming related to the air descent.
|
workshops
