Atmos. Chem. Phys. Discuss., 7, 13627-13652, 2007
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Retrieval of global upper tropospheric and stratospheric formaldehyde (H2CO) distributions from high-resolution MIPAS-Envisat spectra
T. Steck1, N. Glatthor1, T. von Clarmann1, H. Fischer1, J. M. Flaud2, B. Funke3, U. Grabowski1, M. Höpfner1, S. Kellmann1, A. Linden1, A. Perrin2, and G. P. Stiller1
1Institut für Meteorologie und Klimaforschung, Forschungszentrum Karlsruhe, Germany
2Laboratoire Interuniversitaire des Systemes Atmospheriques (LISA), Paris, France
3Instituto de Astrofísica de Andalucía, Granada, Spain

Abstract. The Fourier transform spectrometer MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) on Envisat measures infrared emission of the Earth's atmosphere in a limb viewing mode. High spectral resolution measurements of MIPAS are sensitive to formaldehyde from the upper troposphere to the stratopause. Formaldehyde single profile retrieval is formally possible, however with a large noise error (more than 60%), which is the dominant error source. The number of degrees of freedom for single profile retrieval ranges from 2 to 4.5 depending on latitude and number of cloud-free tangent altitudes. Calculation of zonal mean values for 30 days of data during 8 September 2003 and 1 December 2003 reduces the noise induced error by a factor of 20 or more. In the upper tropical troposphere zonal mean values of about 70 parts per trillion by volume (pptv) were found, which have been attributed to biomass burning emissions. In the stratosphere, formaldehyde values are determined by photochemical reactions. In the upper tropical stratosphere, formaldehyde zonal mean maximum values can reach 130 pptv. Diurnal variations in this region can be up to 50 pptv. Comparisons with other satellite instruments show generally good agreement in the region of upper troposphere and lower stratosphere as well as in the upper stratosphere.

Citation: Steck, T., Glatthor, N., von Clarmann, T., Fischer, H., Flaud, J. M., Funke, B., Grabowski, U., Höpfner, M., Kellmann, S., Linden, A., Perrin, A., and Stiller, G. P.: Retrieval of global upper tropospheric and stratospheric formaldehyde (H2CO) distributions from high-resolution MIPAS-Envisat spectra, Atmos. Chem. Phys. Discuss., 7, 13627-13652, doi:10.5194/acpd-7-13627-2007, 2007.
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