Time series of global mean age of stratospheric air from MIPAS for 2002 to present
Gabriele P. Stiller(1), Thomas von Clarmann(1), Norbert Glatthor(1), Bernd Funke(2), Andrea Linden(1), Udo Grabowski(1), Michel Grutter de la Mora(1), Michael Höpfner(1), Sylvia Kellmann(1), Michael Kiefer(1) and Manuel Lopez-Puertas(2)
(1) Forschungszentrum Karlsruhe, P.O. Box 3640, 76021 Karlsruhe, Germany
(2) Instituto de Astrofísica de Andalucía (CSIC), P.O. Box 3004, 18080 Granada, Spain
MIPAS provides spectral information on the atmospheric trace constituent SF6. SF6 is produced purely anthropogenically, and has a pronounced trend in the troposphere of about 0.2 pptv per year (about 3%). Since its only atmospheric sink is in the mesosphere, it can be used to determine the so-called stratospheric mean age of air, i.e. the time an air parcel needs to travel from the tropopause to a certain position in the stratosphere. This is a quantity under vivid discussion currently, since many climate chemistry models predict an intensification of the Brewer-Dobson circulation due to climate change. This would lead to reduced mean age of air in the stratosphere and impact the stratospheric chemical composition, which would, in turn, provide feedback on climate change and impact the recovery of the ozone hole.
SF6 and age-of-air global distributions for the full-spectral-resolution period of MIPAS (September 2002 to March 2004) have already been published (Stiller et al., ACP, 2008). Here we present global distributions of SF6 for the whole mission lifetime of MIPAS/Envisat (2002 to present) and derive global distributions of mean age of stratospheric air from this quantity. We analyse the time series of mean age of air in terms of its temporal and spatial variability and discuss a potential trend.