New Space-borne Remote Sensing Capabilities Based on Polarimetry and the Implication in term of Aerosol Chemical Components and the needs for in-situ Measurements

With the launch of EPS-SG in 2025, a new era for a long-term operational Near-Real-Time provision of aerosol product is starting. If most of the potential for such a new remote sensing polarimetry has been demonstrated since 1996 with the 3 POLDER and PARASOL missions, the recent advance in term of retrieval but also analysis and exploitation of the data reveal more and more the potential. Indeed, polarimeters allow the observation of aerosols with a significantly improved information content which will feed the retrieval. On top of the aerosol optical thickness classically retrieved, an additional set of parameters characterizing the aerosol properties can now be derived such as the fraction of aerosol chemical components, which contributes to filling the gap between satellite retrieval and modelling community by going beyond aerosol typing, the new retrieved parameters also highlights the need for in-situ measurements to support on one hand the assumptions that could be needed in the algorithm (constraints, definition of aerosol chemical components…), and on the other hand contribute to the validation of the products. This set of new parameters is also stimulating new discussion about aerosol modelling.