Pole-to-pole validation of the ERS-2 GOME level 2 products with the SAOZ ground-based network

The comparison results between GOME level 2 products (mainly total ozone and nitrogen dioxide) from July through December 1996 and correlative ground-based observations from the SAOZ UV-visible network are presented over a wide range of latitudes from the Arctic to the Antarctic, including 1996 ozone hole conditions in Antarctica. Possible reasons for the observed discrepancies have been identified and quantified. On average the GOME version 2.0 and the SAOZ total ozone are in close agreement. However the comparison still shows a clear dependence on the solar zenith angle of the GOME measurement as well as a difference in sensitivity. When combined together, the SZA dependence and the reduced sensitivity result in a high ozone column underestimation which amplifies at large SZA. During ozone hole conditions in Antarctica, GOME and the ground-based instruments observe the high day-to-day variability similarly, although GOME overestimates the lowest ozone columns. Agreement between GOME and ground-based total NO2 is found to depend strongly on the NO2 profiles used as input in the AMF calculation, and particularly on the tropospheric content.