© Author(s) 2006. This work is licensed under a Creative Commons License. Atmospheric Chemistry and Physics The ASSET intercomparison of ozone analyses: method and first results

Abstract. This paper aims to summarise the current per-formance of ozone data assimilation (DA) systems, to show where they can be improved, and to quantify their errors. It examines 11 sets of ozone analyses from 7 different DA sys-tems. Two are numerical weather prediction (NWP) systems based on general circulation models (GCMs); the other five use chemistry transport models (CTMs). The systems exam-ined contain either linearised or detailed ozone chemistry, or no chemistry at all. In most analyses, MIPAS (Michelson In-terferometer for Passive Atmospheric Sounding) ozone data are assimilated; two assimilate SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Char-tography) observations instead. Analyses are compared to independent ozone observations covering the troposphere, stratosphere and lower mesosphere during the period July t