Seasonality of peroxyacetyl nitrate (PAN) in the upper troposphere and lower stratosphere using the MIPAS-E instrument
- ISSN: 16807316
- DOI: 10.5194/acp-10-6117-2010
The Michelson Interferometer for Passive Atmospheric Sounding onboard\nENVISAT (MIPAS-E) offers the opportunity to detect and spectrally\nresolve many atmospheric minor constituents affecting atmospheric\nchemistry. In this paper, we retrieve global, seasonal PAN volume mixing\nratio (vmr) data from MIPAS-E measurements made in January, March,\nAugust and October 2003 and present results from this scheme between\napproximately 300 and 150 hPa. The total error on a single PAN retrieval\nis better than 20% outside the tropics and better than 50% in the\ntropics where uncertainties in water vapor dominate the total error\nbudget. We observe clear differences in the seasonal cycle of PAN in our\ndata, linked closely to biomass burning regions and growing seasons.\nHighest Northern Hemisphere mid-latitude PAN vmrs were observed in\nAugust (300-600 pptv on average) compared with the January and October\ndata (less than 250 pptv on average). In the March 2003 data we observe\nhighest PAN vmrs in the tropics with evidence of vmrs between 600 and\n1000 pptv over Eastern Asia and over the Central Pacific at 333 hPa. The\nvertical distribution of PAN as a function of latitude (i.e. the zonal\nmean) highlights the strong inter-annual variability of PAN in the upper\ntroposphere and lower stratosphere (UTLS), most pronounced poleward of\n40 degrees N (up to 400 pptv over the year). The variability of PAN in\nthe tropical UTLS is also significant and we derive a variability of up\nto 250 pptv in the averages between January and October 2003. These\nresults represent the first seasonal observations of PAN in the UTLS.