Trace Gas Column Observations from the GOME-2 instruments on MetOp-A and B
Valks, Pieter¹; Hao, Nan¹; Hedelt, Pascal¹; Zimmer, Walter¹; Loyola, Diego¹; Pinardi, Gaia²; Van Roozendael, Michel²; De Smedt, Isabelle²; Theys, Nicolas²; Lambert, Jean-Christopher²; Koukouli, MariLiza³; Balis, Dimitris^3
1DLR, GERMANY; ²BIRA/IASB, BELGIUM; ³AUTH, GREECE

This contribution focuses on the operational GOME-2 trace gas column products developed in the framework of EUMETSAT’s Satellite Application Facility on Ozone and Atmospheric Chemistry Monitoring (O3M-SAF). We present an overview of the retrieval algorithms and exemplary results for the ozone, NO2, BrO, SO2 and formaldehyde columns using the GOME-2 instrument (FM3) on MetOp-A (launched in Sep. 2007) and the new GOME-2 instrument (FM2) on MetOp-B (launched in Oct. 2012). The trace gas column products are retrieved from GOME-2 solar backscattered measurements in the UV and VIS wavelength regions, and are generated operationally by DLR using the GOME Data Processor (GDP) version 4.6.

The retrieval of total ozone columns from GOME-2 uses an optimized Differential Optical Absorption Spectroscopy (DOAS) algorithm, with air mass factor conversions calculated using the LIDORT model. Total and tropospheric NO2 is retrieved with the DOAS method in the visible wavelength region around the 435 nm. SO2 emissions from volcanic and anthropogenic sources can be measured by GOME-2 using the UV wavelength region around 320 nm. The ozone, NO2 and SO2 column products are available for the users in near real time, i.e. within two hours after sensing by GOME-2. For BrO and formaldehyde, optimal DOAS fitting windows have been determined for GOME-2 in the UV wavelength region. The GOME-2 trace gas column products have reached the operational O3M-SAF status, and are routinely available to the users.

More than six years of operational trace gas column measurements are now available from GOME-2 on MetOp-A. Initial results from ~6 months of GOME-2 measurements from MetOp-B will be available as well. We present intercomparisons of the GOME-2 measurements from MetOp-A and B, validation results using ground-based measurements, as well as comparisons with other satellite products. Furthermore, the use of tropospheric NO2, SO2 and formaldehyde columns from GOME-2 for air quality applications will be presented.