Initial validation of ENVISAT/SCIAMACHY columnar CO by FTIR profile retrievals at the Ground-Truthing Station Zugspitze

摘要

Carbon monoxide vertical profile retrievals from ground-based solar FTIRmeasurements at the Permanent Ground-Truthing Station Zugspitze (47.42° N,10.98° E, 2964m a.s.l.), Germany are used to validate columnar COretrieved from ENVISAT/SCIAMACHY spectra (WFM-DOAS version 0.4). TheWFM-DOAS retrievals of CO include an empirical column scaling factor of 0.5.Therefore, not absolute column levels are validated, but the proper responseof the SCIAMACHY retrievals to the atmospheric inter-annual variability isquantitatively assessed in comparison to the Zugspitze FTIR results.Although CO WFM-DOAS data for only 33 days were available for thisstudy (datacovering January-October 2003), it is possible to retrieve information on the COannual cycle (≈10% amplitude) in a statistically significantfit out of the scatter of the SCIAMACHY WFM-DOAS data. To obtain this, allpixels within a minimum radius of 2000km around Zugspitze had to beaveraged for each day.