THE EUMETSAT POLAR SYSTEM – SECOND GENERATION (EPS-SG) PASSIVE MICROWAVE IMAGERS, MWI AND ICI: LAST PREPARATORY ACTIVITIES BEFORE LAUNCH

V. Mattioli¹, F. De Angelis¹, C. Accadia¹, V. Barlakas¹, T. Hewison¹, R. Munro¹, M. Labriola¹, G. Bruni¹, L. Salghetti Drioli², D. Schobert², A. Graziani², M. Sunda¹, C. Mas¹, D. Ori³, J. Lu³, S. Villamil⁴, D. Biamonti⁴

¹EUMETSAT, Eumetsat-Allee 1, 64295 Darmstadt, Germany, ²ESA-ESTEC, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands, ³CS Group – Germany GmbH, Berliner Allee 65, 64295 Darmstadt, Germany, ⁴Telespazio VEGA Deutschland GmgH, Europapl. 5, 64293 Darmstadt, Germany

The second generation of the EUMETSAT Polar System (EPS-SG) programme includes two conical-scanning radiometer imaging missions, the Microwave Imager (MWI) and the Ice Cloud Imager (ICI), which will be flown on the Metop-SGB satellites.

MWI features 18 channels covering frequencies from 18 to 183 GHz, enabling the retrieval of cloud and precipitation products, including bulk microphysical variables and all-weather surface imagery. It strengthens the legacy of major microwave imager missions such as the Special Sensor Microwave Imager (SSM/I), the Advanced Microwave Scanning Radiometer 2 (AMSR2), and the Global Precipitation Measurement (GPM) Microwave Imager (GMI). Notably, MWI includes channels near the 50–60 GHz oxygen band and at 118 GHz, an innovative capability for an imager that enhances sensitivity to weak precipitation and snowfall, which are especially relevant at high latitudes. Dual polarization observations are available up to 89 GHz.

In contrast, ICI represents a completely novel mission dedicated to the remote sensing of cloud ice. With 11 channels spanning 183–664 GHz, it operates in both millimetre and sub-millimetre frequencies, making it sensitive to a wide range of ice crystal sizes. This capability fills a critical gap in microwave observations and significantly improves global measurements of ice clouds. ICI will also extend operational radiometry into the sub-millimetre range, bridging the spectral gap between the microwave and far-infrared regions of the spectrum. Dual polarization observations are available at 243 and 664 GHz MWI and ICI share common requirements for incidence angle and rotation speed. Together, the two radiometers will deliver an unprecedented set of passive microwave measurements from 18.7 GHz to 664 GHz over a 1700 km swath, all from the same platform.

The launch of the Metop-SGB1 satellite is approaching, currently planned in 2026. Therefore, the preparatory activities for the on-ground characterization of the instruments and for the validation of the centrally generated Level 1B (L1B) and Level 2 (L2) products during the commissioning phase are now being finalized.

This work presents an initial assessment of the expected in-orbit performances of the MWI and ICI first flight models, based on analyses of pre-launch data. Our analysis is designed to support the L1 operational processor and specific studies in preparation for on calibration/validation (Cal/Val). Recent updates on Cal/Val tools and procedures are also provided, with particular focus on the validation of the radiometric bias requirements.

Finally, the last versions (V3) of MWI and ICI L1 and L2 test data packages have been released by EUMETSAT. These test data are also introduced in this work.