Multi-instrument synergetic retrieval of aerosol and surface properties with GRASP algorithm

Big variety of different satellites on Earth orbit are dedicated to aerosol studies. However, due to limited information content, the main aerosol products of the most of satellite missions is AOD while the accuracy of aerosol size and type retrieval from space-borne remote sensing still requires essential improvement. . The combination of measurements from different satellites essentially extends their information content and, therefore, can provide new possibility for much better retrieval of extended set of both aerosol and surface properties. In the frame of ESA SYREMIS project GRASP algorithm was adapted for synergetic retrieval from combined space-borne instruments: (i) synergy from polar-orbiting (LEO) satellites (in particular, synergy of Sentinel-5p/TROPOMI, Sentinel-3A, -3B/OLCI instruments) and (ii) synergy of LEO and geostationary (GEO) satellites (in particular, synergy of Sentinel-5p/TROPOMI, Sentinel-3A, -3B/OLCI and HIMAWARI/AHI sensors). On one hand such synergy constellation extends the spectral range of the measurements. On another hand it provides unprecedented global spatial coverage with several measurements per day which is crucial for global climate studies and air-quality monitoring. In this talk we discuss physical basis and concept of the LEO-LEO and LEO-GEO synergies used in GRASP retrieval. It will be demonstrated that SYREMIS/GRASP synergetic approach allows transition of information from the instruments with richest information content  to the instruments with lower one. This results in increased performance of AOD, aerosol size and absorption properties retrieval and more consistent surface BRDF characterization.