National Aeronautics and Space Administration

The standard NASA Moderate Resolution Imaging Spectroradiometer (MODIS) daily global fractional snow map product is generated at 0.05° spatial resolution. However current climate models often use 0.25° resolution input data sets. In response to modelers’ input requirements, a MODIS daily global fractional snow map at 0.25° resolution is created from the standard 0.05° MODIS daily global climate modeling grid (CMG) snow map product. Similarities and differences between the daily fractional snow maps at the two resolutions within a season and between different seasons, as well as effects of the averaging method that includes or excludes no snow (0% snow) data are discussed. Differences were found in the snow maps due to both resolution differences and averaging method differences. Differences were greatest in the lower snow fractions having greatest effect at the snow field edges or in patchy snow regions. Comparative analysis of the MODIS daily global FSC maps at 0.05° and 0.25° resolution reveals that the general synoptic pattern of snow extent is very similar and consistent in different seasons between the maps. However, fractional snow cover amounts especially at high and low fractions can vary considerably within regions with the differences affected by spatial resolution and difference in averaging method.