GRASP is a state-of-the-art retrieval algorithm for generating enhanced aerosol and surface products from diverse space-borne and ground-based measurements (Dubovik et al. 2011, 2014, 2021). GRASP retrieval is implemented as a highly advanced statistically optimized fitting of all available observations. For example, GRASP uses an innovative multi-pixel concept in which the fitting is realized simultaneously for a large group of “pixels” (coordinated observations). This principle is especially useful for improving satellite retrievals where it allows to benefit from known a priori limitations on space and time variability of different surface and aerosol parameters. This helps reliable discrimination between aerosol and surface contributions in observation that is generally known as a challenging issue.
The GRASP multi-pixel retrieval concept has already been successfully applied to the observations of different single space-borne instruments: polar-orbiting like POLDER/PARASOL, MERIS, AATSR/ENVISAT, OLCI/Sentinel-3, TROPOMI/S-5p and geostationary, for example, Himawari, satellites. Moreover, the synergetic approaches were successfully approved on the synergy of MERIS and AATSR measurements (ESA CAWA-2 project) as well as on the synergy of the ground-based and satellite (AERONET+OLCI, AERONET+ TROPOMI/Sentinel-5p etc retrieval) measurements (ESA GROSAT project).
GRASP algorithm is planned to be used for aerosol and surface near-real-time characterization from future space-borne polarimetric mission like 3MI, CO2M MAP, GAPMAP etc.
