The evaluation of SCIAMACHY CO and CH_4 scientific data products, using ground-based FTIR measurements

摘要

In the framework of the European EVERGREEN project, three scientific algorithms, namely WFM-DOAS, IMAPDOASudand IMLM, have been developed to retrieve the total column amounts of key atmospheric trace gases includingudCO and CH_4 from SCIAMACHY nadir observations in its near-infrared channels. These channels offer the capability touddetect trace gases in the planetary boundary layer, potentially making the associated retrieval products suited forudregional source-sink studies.udThe retrieval products of these three algorithms, in their present status of development, have been compared toudindependent data from a ground-based quasi-global network of Fourier-transform infrared (FTIR) spectrometers, for theudyear 2003. Comparisons have been made for individual data, as well as for monthly averages. To maximize the numberudof coincidences that satisfy the temporal and spatial collocation criteria, the individual SCIAMACHY data points haveudbeen compared with a 3rd order polynomial interpolation of the ground-based data with time. Particular attention hasudbeen paid to the question whether the products reproduce correctly the seasonal and latitudinal variabilities of the targetudspecies. We present an overall assessment of the data quality of the currently available latest versions of the CO and CH4udtotal column products from the three scientific retrieval algorithms.