Atmos. Chem. Phys. Discuss., 7, 1391-1420, 2007
www.atmos-chem-phys-discuss.net/7/1391/2007/
doi:10.5194/acpd-7-1391-2007
© Author(s) 2007. This work is licensed under the
Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Global peroxyacetyl nitrate (PAN) retrieval in the upper troposphere from limb emission spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)
N. Glatthor1, T. von Clarmann1, H. Fischer1, B. Funke2, U. Grabowski1, M. Höpfner1, S. Kellmann1, M. Kiefer1, A. Linden1, M. Milz1, T. Steck1, and G. P. Stiller1
1Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung, Karlsruhe, Germany
2Instituto de Astrofísica de Andalucía (CSIC), Granada, Spain

Abstract. We use limb emission spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard the ENVIronmental SATellite (ENVISAT) to derive the first global distribution of peroxyacetyl nitrate (PAN) in the upper troposphere. PAN is generated in tropospheric air masses polluted by fuel combustion or biomass burning and acts as a reservoir and carrier of NOx in the cold free troposphere. Since PAN exhibits continuum-like broadband structures in the mid-infrared region, we have applied a contiguous analysis window covering the wavenumber region 775–800 cm−1 for retrieval. The interfering species CCl4, HCFC-22, H2O, ClONO2, CH3CCl3 and C2H2 were fitted along with PAN, whereas pre-fitted profiles were used to model the contribution of other contaminants like ozone. Sensitivity tests consisting in retrieval without consideration of PAN have demonstrated the existence of PAN signatures in MIPAS spectra obtained from polluted air masses. The analysed dataset consists of 10 days between 4 October and 1 December 2003. This period covers the end of the biomass burning season in South America and South and East Africa, in which generally large amounts of pollutants are produced and distributed over wide areas in the southern hemispheric free troposphere. Elevated PAN amounts of 200–700 pptv were measured in a large plume extending from Brasil over the Southern Atlantic, Central and South Africa, the South Indian Ocean as far as Australia at altitudes between 8 and 16 km. Enhanced PAN values were also found in a much more restricted area between northern subtropical Africa and India. The most significant northern midlatitude PAN signal in MIPAS data is an area extending at 8 km altitude from China into the Chinese Sea. The average mid and high latitude PAN amounts found at 8 km were around 125 pptv in the northern, but only between 75 and 50 pptv in the southern hemisphere. The PAN distribution found in the southern hemispheric tropics and subtropics is highly correlated with the jointly fitted acetylene (C2H2), which is another pollutant produced by biomass burning, and agrees reasonably well with the CO plume detected during end of September 2003 at the 275 hPa level (~10 km) by the Measurement of Pollution in the Troposphere (MOPITT) instrument on the Terra satellite. Similar southern hemispheric PAN amounts were also observed by previous airborne measurements performed in September/October 1992 and 1996 above the South Atlantic and the South Pacific, respectively.

Citation: Glatthor, N., von Clarmann, T., Fischer, H., Funke, B., Grabowski, U., Höpfner, M., Kellmann, S., Kiefer, M., Linden, A., Milz, M., Steck, T., and Stiller, G. P.: Global peroxyacetyl nitrate (PAN) retrieval in the upper troposphere from limb emission spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), Atmos. Chem. Phys. Discuss., 7, 1391-1420, doi:10.5194/acpd-7-1391-2007, 2007.
 
Search ACPD
Discussion Paper
    XML
    Citation
    Final Revised Paper
    Share