Expected Level 2 Performance of GMES Sentinel 4 UVN on MTG
Bovensmann, Heinrich¹; Noel, Stefan¹; Bramstedt, Klaus¹; Burrows, John P.¹; Siddans, Richard²; Standfuss, Carsten³; Dufour, Emmanuelle³; Veihelmann, Ben^4
1University of Bremen, GERMANY; ²RAL, UNITED KINGDOM; ³NOVELTIS, FRANCE; ⁴ESA ESTEC, NETHERLANDS

The Sentinel 4 UVN instrument is an UV-VIS-NIR spectrometer and part of the geostationary Meteosat Third Generation (MTG) satellite to be launched in 2019. It builds on the GOME and SCIAMACHY heritage and the GeoSCIA and GeoTROPE concepts developed between 1997 and 2004. UVN is designed to measure total and tropospheric columns of several atmospheric constituents relevant in the context of air pollution, especially O3, NO2, SO2 and HCHO. Furthermore, aerosol information shall be obtained from high resolution measurements in the Oxygen A-band. During the last years the instrument performance was consolidated; within an ESA funded activity the impact of instrument performance on the expected Level 2 quality is currently under assessment. A special area of concern is the impact of scene inhomogeneity (inhomogeneous slit filling) on Level 2 product quality and potential mitigation options. This paper will present results on the quantification of this effect and will summarise findings on how to mitigate the impact of inhomogeneous slit illumination on Level 2 data products derived from measurements of the Sentinel-4 UVN imaging spectrometer. Furthermore, the paper will present an updated assessment of the expected Level 2 data quality.