Overview of first images of the EPS-SG/3MI Polarimeter Instrument and Level-1 Performances

3MI is a new mission launched in August 2025 on board of the EPS-SG A satellite. The purpose of 3MI is to provide multi-spectral, multi-polarisation, and multi-angular images of the Earth TOA outgoing radiance to characterise the microphysical properties of the atmosphere.

The design consists of two detectors (SWIR and VNIR) and a rotating filter and polariser wheel. The instrument acquires images under 12 spectral bands ranging from 410 nm to 2130 nm. Nine of the bands acquire polarised images at 60°, 0° and -60°. The multi-view is achieved by several successive overlapping acquisitions of the same Earth-Atmosphere target under 14 different angles, thanks to the large FOV of 3MI.

At L1, 3MI provides two different products to users: L1B, which represent the acquisitions as the satellite orbits the Earth; and L1C, which contain, for each point on the surface, the multiple angles under which it is observed.

After a successful SIOV, the instrument is undergoing the commissioning phase. Here we will present the first assessment of the 3MI performance at L1 in both the radiometric and geometric aspects, the lessons learned with respect to the ground calibration and, briefly, the potential for the L2 aerosol and cloud products.