Abstract. The Global Ozone Monitoring Experiment-2 (GOME-2) flies on the Metop series of satellites, the space component of the EUMETSAT Polar System. In this paper we will provide an overview of the instrument design, the on-ground calibration and characterization activities, inflight calibration, and level 0 to 1 data processing. The current status of the level 1 data is presented and points of specific relevance to users are highlighted. Long-term level 1 data consistency is also discussed and plans for future work are outlined. The information contained in this paper summarizes a large number of technical reports and related documents containing information that is not currently available in the published literature. These reports and documents are however made available on the EUMETSAT web pages and readers requiring more details than can be provided in this overview paper will find appropriate references at relevant points in the text.

GOME Level-1 Products were provided by DLR. The GOMETRAN radiative transfer model and the highresolution solar reference spectrum used in this study were supplied by J. Burrows (Univ. Bremen) and K. Chance (Harvard-Smithsonian Astrophysical Observatory), respectively.

[1] We present an assessment study of the Global Ozone Monitoring Experiment 2 (GOME-2) reflectance for the wavelength range 270-350 nm by comparing measurements with simulations calculated using the vector linearized discrete ordinate radiative transfer model (VLIDORT) and Microwave Limb Sounder (MLS) ozone profiles. The results indicate wavelength-and cross-track-position-dependent biases. GOME-2 reflectance is overestimated by 10% near 300 nm and by 15%-20% around 270 nm. Stokes fraction measurements made by onboard polarization measurement devices are also validated directly using the VLIDORT model. GOME-2 measurements agree well with the simulated Stokes fractions, with mean biases ranging from À1.0% to $2.9%; the absolute differences are less than 0.05. Cloudiness-dependent biases suggest the existence of uncorrected stray-light errors that vary seasonally and latitudinally. Temporal analysis indicates that reflectance degradation began at the beginning of the mission; the reflectance degrades by 15% around 290 nm and by 2.2% around 325 nm from 2007 through 2009. Degradation shows wavelength-and viewing-angle-dependent features. Preliminary validation of ozone profile retrievals with MLS, Michelson Interferometer for Passive Atmospheric Sounding, and ozonesonde reveals that the application of radiometric recalibration improves the ozone profile retrievals as well as reduces fitting residuals by 30% in band 2b.

The first operational European polar meteorological satellite system provides greatly enhanced capabilities, in particular for hyperspectral infrared atmospheric sounding and atmospheric trace gas monitoring.

Abstract. Peak stratospheric chlorofluorocarbon (CFC) and other ozone depleting substance (ODS) concentrations were reached in the mid-to late 1990s. Detection and attribution of the expected recovery of the stratospheric ozone layer in an atmosphere with reduced ODSs as well as efforts to understand the evolution of stratospheric ozone in the presence of increasing greenhouse gases are key current research topics. These require a critical examination of the ozone changes with an accurate knowledge of the spatial (geographical and vertical) and temporal ozone response. For such an examination, it is vital that the quality of the measurements used be as high as possible and measurement uncertainties well quantified.