© Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License. Atmospheric Chemistry and Physics Large-scale upper tropospheric pollution observed by MIPAS HCN

Abstract. We present global upper tropospheric HCN and C2H6 amounts derived from MIPAS/ENVISAT limb emis-sion spectra. HCN and C2H6 are retrieved in the spectral regions 715.5–782.7 cm−1 and 811.5–835.7 cm−1, respec-tively. The datasets consist of 54 days between Septem-ber 2003 and March 2004. This period covers the peak and decline of the southern hemispheric biomass burning period and some months thereafter. HCN is a nearly unambiguous tracer of biomass burning with an assumed tropospheric life-time of several months. Indeed, the most significant fea-ture in the MIPAS HCN dataset is an upper tropospheric plume of enhanced values caused by southern hemispheric biomass burning, which in September and October 2003 ex-tended from tropical South America over Africa, Australia to the Southern Pacific. The spatial extent of this plume agree