An improved characterization of aerosols using new space-borne remote sensing capabilities based on Multi-Angle Polarimetry

Detailed knowledge of the optical and microphysical properties of aerosols plays a significant role in reducing one of the major sources of uncertainties in climate and air quality assessments. In recent years, the importance of exploiting the rich measurements from satellite observations for improved aerosol characterization has been widely recognized, prompting significant efforts to increase the information content of retrieval algorithms through synergies among measurements from single or multiple instruments.
The recent launch of EPS-SG (August 2025) with cutting-edge onboard instruments marks the beginning of new generation of exceptionally rich satellite observations. Notably, the Multi-View, Multi-Channel, Multi-Polarisation Imager (3MI) onboard  Metop-SG A1 has the core mission for aerosol characterization. The multi-angle polarimetric data acquisition implemented in 3MI builds on a long heritage, demonstrated since 1996 by POLDER and PARASOL (Polarization and Anisotropy of Reflectances for Atmospheric Science coupled with Observations from a Lidar). Compared to the POLDER/PARASOL era, new advances in 3MI instrument (e.g. broader spectral range), along with significant improvements in retrieval algorithms, have enabled the characterization of aerosols with additional optical, microphysical, and chemical properties beyond classical approaches and products. In addition, recent efforts to harmonize chemical component definitions in 3MI aerosol retrieval algorithm with those adopted by the broader scientific community and operational users have enhanced our understanding and stimulated new discussions on aerosol modelling.
This presentation focuses on the latest improvements in chemical component representation within the 3MI GRASP retrieval and its integration into the operational processor to meet near real time user needs. Validation results from real observations (PARASOL and AERONET) and comparison to models demonstrate improved aerosol characterization and the added value of new polarimetry products in building a bridge between satellite and modelling community. The validation also emphasizes the need for new in-situ measurements, both to support algorithmic assumptions and to strengthen product validation. Finally, the high potential of synergistic use of Metop-SG A1 sensors to address remaining gaps in characterization of aerosols and more specifically chemical components will be discussed, pointing towards a more comprehensive approach to operational aerosol monitoring.