GDP 4.0 TRANSFER TO SGP 3.0 FOR SCIAMACHY OZONE COLUMN PROCESSING: VERIFICATION WITH SDOAS/GDOAS PROTOTYPE ALGORITHMS AND DELTA-VALIDATION WITH NDACC AND WOUDC NETWORK DATA

摘要

Until mid 2006, SCIAMACHY data processors for the operational retrieval of ozone (O{sub}3) vertical column data were based on the historical version 2 of the GOME Data Processor (GDP). On top of known problems inherent to GDP 2, ground-based validations of SCIAMACHY O{sub}3 data also revealed issues specific to SCIAMACHY, like a large cloud-dependent bias occurring in Northern fall. In 2006, the GDOAS prototype algorithm of the improved GDP version 4 was transferred to the off-line SCIAMACHY Ground Processor (SGP) version 3.0. In parallel, the calibration of SCIAMACHY radiometric data was upgraded. Before operational switch-on of SGP 3.0 and public release of upgraded SCIAMACHY O{sub}3 columns, we investigated the accuracy of the algorithm transfer: (a) by checking the consistency of SGP 3.0 with prototype algorithms and with GDP 4.0; and (b) by comparing SGP 3.0 O{sub}3 column data with ground-based observations performed by the Brewer, Dobson and UVVIS networks. This delta-validation study showed that the Northern fall bias has disappeared and that the GDP 2 inherited solar zenith angle and latitude dependences have decreased significantly, concluding that SGP 3.0 is a significant improvement with respect to the previous processor IPF 5.04.