Carbon monoxide, methane and carbon dioxide columns retrieved from SCIAMACHY by WFM-DOAS: year 2003 initial data set

Abstract

Abstract. The near-infrared nadir spectra measured by SCIAMACHY on-board ENVISAT contain information on the vertical columns of important atmospheric trace gases such as carbon monoxide (CO), methane (CH 4 ), and carbon dioxide (CO 2 ). The scientific algorithm WFM-DOAS has been used to retrieve this information. For CH 4 and CO 2 also column averaged mixing ratios (XCH 4 and XCO 2 ) have been determined by simultaneous measurements of the dry air mass. All available spectra of the year 2003 have been processed. We describe the algorithm versions used to generate the data (v0.4; for methane also v0.41) and show comparisons of monthly averaged data over land with global measurements (CO from MOPITT) and models (for CH 4 and CO 2 ). We show that elevated concentrations of CO resulting from biomass burning have been detected in reasonable agreement with MOPITT. The measured XCH 4 is enhanced over India, south-east Asia, and central Africa in September/October 2003 in line with model simulations, where they result from surface sources of methane such as rice fields and wetlands. The CO 2 measurements over the Northern Hemisphere show the lowest mixing ratios around July in qualitative agreement with model simulations indicating that the large scale pattern of CO 2 uptake by the growing vegetation can be detected with SCIAMACHY. We also identified potential problems such as a too low inter-hemispheric gradient for CO, a time dependent bias of the methane columns on the order of a few percent, and a few percent too high CO 2 over parts of the Sahara.

Global estimates of CO sources with high resolution by adjoint inversion of multiple satellite datasets (MOPITT, AIRS, SCIAMACHY, TES)

“…SCIAMACHY measures solar backscattered radiation at 2.3 µm, which allows for nearly uniform sensitivity through the tropospheric column though with no vertical resolution (Buchwitz et al, 2004(Buchwitz et al, , 2005de Laat et al, 2006). Global coverage is obtained by SCIAMACHY for its nadir measurements in 6 days, but actual coverage is much reduced because of the low ocean reflectivity and the presence of clouds in the relatively large pixels (30 km×120 km) (Buchwitz et al, 2007;Gloudemans et al, 2005Gloudemans et al, , 2008.…”

“…Global coverage is obtained by SCIAMACHY for its nadir measurements in 6 days, but actual coverage is much reduced because of the low ocean reflectivity and the presence of clouds in the relatively large pixels (30 km×120 km) (Buchwitz et al, 2007;Gloudemans et al, 2005Gloudemans et al, , 2008. We use the version 0.6 retrieval from the University of Bremen (Buchwitz et al, 2004(Buchwitz et al, , 2005(Buchwitz et al, , 2007. The retrieval provides CO columns,ŷ, with vector averaging kernels a, related to the true vertical profile (z) by the following equation:…”

Terrestrial carbon sink observed from space: variation of growth rates and seasonal cycle amplitudes in response to interannual surface temperature variability

“…We analyse XCO 2 retrieved from SCIAMACHY onboard ENVISAT using Weighting Function Modified DOAS (WFM-DOAS) (Buchwitz et al, 2005;Schneising et al, 2008Schneising et al, , 2011Schneising et al, , 2012Heymann et al, 2012) for the entire operational lifespan of the satellite. To minimise residual systematic retrieval biases, an additional (post-processing) correction based on multivariate linear regression is applied (Wunch et al, 2011b;Schneising et al, 2013;Guerlet et al, 2013a).…”

Cloud and surface classification using SCIAMACHY polarization measurement devices

“…Therefore sun glint areas need to be flagged out of the aerosol retrievals (de Graaf and Stammes, 2005). -Trace-gas (Buchwitz et al, 2005) and aerosol (von Hoyningen-Huene et al, 2006) retrievals are known to be very sensitive to the existence of even small fractions of clouds in the field of view need a reliable cloudflagging algorithm.…”