VALIDATION OF MIPAS AND SCIAMACHY DATA BY GROUND-BASEDSPECTROSCOPY AT KIRUNA, SWEDEN, AND IZANA, TENERIFE ISLAND (AOID-191)

摘要

Within this ENVISAT validation project [AOID-191]rnground-based measurements of different techniquesrnhave been performed at Kiruna in the Arctic and onrnTenerife Island in the subtropics. These ground-basedrndata were used to validate SCIAMACHY and MIPASrndata.rnUsing MIPAS 4.61 O_3 profiles on a pressure scale andrndegrading their vertical resolution to that of the FTIRrnprofiles a good agreement is demonstrated. Thernprecision of FTIR O_3 profiles is about 10 %. Therndifferences between MIPAS and FTIR are within therncombined error bar.rnMIPAS 4.61 HNO_3 profiles differ about 10 to 15 % forrnaltitudes above 15 km. The corresponding columnrnamounts differ by 8.2 +/- 7.0 %. These differences canrnbe explained by a scaling factor in the spectroscopicrndata base for HNO_3 which has been applied in versionrn4.61.rnSCIAMACHY O_3 and NO_2 column amounts of versionsrn5.01 agree much better as compared to previousrnversions: The difference of SCIAMACHY O_3 columnrnamounts is about 8 % when compared to FTIR datarnfrom Kiruna and about 2 % when compared with DOASrndata from Izaña, respectively. The difference ofrnSCIAMACHY NO_2 column amounts to Izaña DOASrndata is about 9 %.rnFurthermore, O_3 limb profiles from SCIAMACHY havernbeen compared for the first time. The mean differencesrnare up to 20%. However, shifting the SCIAMACHYrnprofiles by +1.5 km reduces the discrepanciesrnsignificantly. Then the mean relative difference isrnsmaller than 10% for all altitude levels between 10 andrn35 km. This shift is consistent with the erroneous heightrnassignment of MIPAS profiles.