Multi-viewing Multi-channel Multi-polarisation Imager

The Multi-viewing Multi-channel Multi-polarisation Imager (3MI) is a passive optical instrument aboard the Metop-SG A1 satellite, operated by EUMETSAT as part of the EPS-SG programme.^[1] It builds on the heritage of the POLDER-3/PARASOL instrument design.^[2]

3MI samples 12 spectral channels spanning 410 to 2130 nm, of which nine carry polarimetric capability: 410 nm, 443 nm, 490 nm, 555 nm, 670 nm, 865 nm, 1370 nm, 1650 nm, and 2130 nm. The remaining three channels at 763 nm (narrow), 765 nm (broad), and 910 nm are non-polarised.^[3] Ground sampling distance at nadir is 4 km with a 2200 km swath.^[3] VNIR viewing acquires 14 directional angles; SWIR viewing angles are recorded as 12 by WMO OSCAR, though eoPortal describes approximately 6 to 7 angles for the SWIR module.^[3][2]

The instrument targets aerosol optical depth, aerosol particle size and type, aerosol refractive index and sphericity, cloud microphysics and optical properties, top-of-atmosphere bidirectional reflectance, and upward shortwave irradiance.^[3] These retrievals support air quality forecasting, climate monitoring, and numerical weather prediction.^[3] 3MI launched on 2025-08-13 and achieved first light on 2025-08-28.^[3]