Synergetic retrieval from multi-mission spaceborne measurements for enhanced aerosol and surface characterization

Abstract. Atmospheric aerosol is one of the main drivers of climate change. Currently, a number of different satellites in Earth orbit are dedicated to aerosol studies. Due to limited information content, the primary aerosol product of most satellite missions is AOD (Aerosol Optical Depth), while the accuracy of aerosol size and type retrieval from spaceborne remote sensing still requires improvement. Combining measurements from different satellites increases their information content and, therefore, can provide new possibilities for retrieving an extended set of both aerosol and surface properties. In this paper, we present the physical basis and concept of the recently developed synergetic approach for aerosol and surface characterization using diverse spaceborne measurements (hereinafter SYREMIS (SYnergetic REtrieval from Multi-MISsion instruments) approach). The approach was implemented in the GRASP (Generalized Retrieval of Atmosphere and Surface Properties) algorithm and has been tested on two types of synergetic measurements: (i) synergy of polar-orbiting satellites (LEO + LEO synergy combining Sentinel-5P/TROPOMI, Sentinel-3A/OLCI, and Sentinel-3B/OLCI instruments), (ii) synergy of polar-orbiting and geostationary satellites (LEO + GEO synergy based on Sentinel-5P/TROPOMI, Sentinel-3A/OLCI, Sentinel-3B/OLCI, and Himawari-8/AHI instruments). On the one hand, such a synergetic satellite constellation extends the spectral range of the measurements. On the other hand, it provides unprecedented global spatial coverage with high temporal resolution, which is crucial for a number of climate studies. It is shown that the SYREMIS/GRASP approach facilitates the transfer of information content from instruments with richer information content to those with lower one. This results in substantial enhancements in aerosol and surface characterization for all instruments within the synergy.