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UP: Umweltphysik
UP 23: Atmosph
äre und Klima
UP 23.3: Fachvortrag
Mittwoch, 15. März 2006, 17:00–17:15, D
Satellite Chartography of Atmospheric Methane and carbon monoxide from SCIAMACHY onboard ENVISAT — •Christian Frankenberg — IUP Heidelberg
The UV/Vis/near infrared spectrometer SCIAMACHY onboard the European ENVISAT satellite enables total column retrieval of atmospheric methane with high sensitivity to the lower troposphere. We apply an Iterative Maximum A Posteriori DOAS approach to derive vertical column densities of methane and carbon monoxide. The retrievals have been compared with methane abundances derived from the atmospheric transport models TM4 and TM5. High correlations between observed and simulated global CH4 column averaged mixing ratios are calculated for the entire 2-year period from 2003 through 2004. The theoretical retrieval precision of about 1.8% corresponds well with the observed average standard deviation between observations and simulations, which is on the order of 30 ppb. On the global scale, the most pronounced CH4 signal arises from source regions over India and South East Asia, broadly consistent with model simulations. SCIAMACHY retrievals, however, indicate higher CH4 abundances over tropical Africa and tropical America, pointing to hitherto underestimated CH4 emissions from tropical landmasses. Apart from the presentation of the retrieved methane abundances, we discuss the retrieval algorithm and quantify possible impact factors on precision and accuracy (such as clouds and aerosols). Further, latest results of carbon monoxide retrievals revealing the seasonal patterns in biomass burning regions are shown.