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Abstract:
In 2023 a new version of the Global Multisensor Automated Snow and Ice Mapping System (GMASI) was implemented at NOAA NESDIS. The primary purpose of the system consists in providing operational information on the snow and ice cover distribution for NOAA numerical weather prediction, hydrological and climate models. The new system is upgrade of the older version of the system which was operated by NESDIS since 2006. The retrieval algorithm uses combined satellite observations in the visible/infrared and in the microwave spectral bands to deliver daily spatially continuous (gap-free) maps of snow and ice cover. The new system, compared to its previous version, features an enhanced retrieval algorithm and improved from 4km to 2km spatial resolution of the output maps. In the presentation we provide details of the data processing algorithm and of the output product focusing on the improvements and upgrades. The output of the new GMASI system is shown to closely match the accuracy of snow maps produced within NOAA Interactive Multisensor Snow and Ice Mapping System (IMS) and to agree well to in situ station snow depth report. It is shown that improvements to the algorithm mostly affected reproduction of small-scale features in the snow and ice cover distribution. In the same time, the large-scale climatologically important features as the continental and hemisphere snow and ice extent estimated with the new snow and ice maps remain consistent with the previous version of the system product.
