Global carbon monoxide as retrieved from SCIAMACHY by WFM-DOAS

Abstract

Abstract. First results concerning the retrieval of tropospheric carbon monoxide (CO) from satellite solar backscatter radiance measurements in the near-infrared spectral region (∼2.3 µm) are presented. The Weighting Function Modified (WFM) DOAS retrieval algorithm has been used to retrieve vertical columns of CO from SCIA-MACHY/ENVISAT nadir spectra. We present detailed results for three days from the time periode January to October 2003 selected to have good overlap with the daytime CO measurements of MOPITT onboard EOS Terra. Because the WFM-DOAS Version 0.4 CO columns presented in this paper are scaled by a constant factor of 0.5 to compensate for an obvious overestimation we focus on the variability of the retrieved columns rather than on their absolute values. It is shown that plumes of CO resulting from, e.g. biomass burning in Africa, are detectable with single overpass SCIA-MACHY data. Globally, the SCIAMACHY CO columns are in reasonable agreement with the Version 3 CO column data product of MOPITT. For example, for measurements over land, where the quality of the data is typically better than over ocean due to higher surface reflectivity, the standard deviation of the difference with respect to MOPITT is in the range 0.4-0.6×10 18 molecules/cm 2 and the linear correlation coefficient is between 0.4 and 0.7. The level of agreement between the data of both sensors depends on time and location but is typically within 30% for most latitudes. In the southern hemisphere outside Antarctica SCIAMACHY tends to give systematically higher values than MOPITT. More studies are needed to find out what the reasons for the observed differences with respect to MOPITT are and how the algorithm can be modified to improve the quality of the CO columns as retrieved from SCIAMACHY.

Simulated retrievals for the remote sensing of CO<sub>2</sub>, CH<sub>4</sub>, CO, and H<sub>2</sub>O from geostationary orbit

“…As CO absorbs weakly, the uncertainty in XCO is only reduced by 47.2 %, which is significantly less than that for the other gases. The weak absorption of CO and the interferences from other strong absorbing gases such as CH 4 and H 2 O in the near-infrared are also noted by Buchwitz et al (2004) and Galli et al (2012). Our results corroborate Galli et al's findings that, due to interferences, the quality of the XCO retrieval is systematically influenced by the shortcomings in CH 4 and H 2 O spectroscopy.…”

“…The Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) instrument was operational for measurements of atmospheric compositions from 2002 to 2012, with CO 2 , CH 4 , CO, and H 2 O as four of its target species (Buchwitz et al, 2004(Buchwitz et al, , 2007Schrijver et al, 2009;Schneising et al, 2011). The Greenhouse gases Observing SATellite (GOSAT), developed by the Japan Aerospace Exploration Agency and launched in January 2009, is the world's first mission dedicated to the monitoring of CO 2 and CH 4 (Yokota et al, 2009;Butz et al, 2011;Yoshida et al, 2011).…”

Carbon monoxide column retrieval for clear-sky and cloudy atmospheres: a full-mission data set from SCIAMACHY 2.3 µm reflectance measurements

“…2). Hence, the corresponding null-space error is small (Buchwitz et al, 2004;Gloudemans et al, 2008) and a direct comparison of the retrieved column with CO column reference measurements is possible while neglecting the effect of column averaging kernels (Borsdorff et al, 2016). For cloudy retrievals the comparison must account for averaging kernel effects.…”

“…The SWIR measurements around 2.3 µm of SCIAMACHY have been used to retrieve the vertical column densities of various atmospheric trace gases: HDO Scheepmaker et al, 2015), water vapour ) and CO (Frankenberg et al, 2005;Buchwitz et al, 2004;Gloudemans et al, 2008;Gimeno García et al, 2011;Borsdorff et al, 2016). In particular, the SCIA-MACHY CO product has been used to analyse biomass burning events (Buchwitz et al, 2004), monitor the transport of atmospheric pollutants (Gloudemans et al, 2006) and detect pollution from mega cities (Buchwitz et al, 2007).…”

“…In particular, the SCIA-MACHY CO product has been used to analyse biomass burning events (Buchwitz et al, 2004), monitor the transport of atmospheric pollutants (Gloudemans et al, 2006) and detect pollution from mega cities (Buchwitz et al, 2007).…”