Scanning Multichannel Microwave Radiometer (SMMR), Special Sensor Microwave/Imager (SSM/I), and Advanced Microwave Scanning Radiometer aboard EOS (AMSR-E) data have been used to produce a data set of the snow water equivalent (SWE) gridded onto a Lambert-Azimuthal Equal Area grid with 25 km grid resolution. For each grid cell, the data set includes daily values of SWE and its standard deviation, the latter giving a measure of the retrieval uncertainty.
First, using an empirical relationship between brightness temperatures and snow properties wet / melting snow areas are masked out. Next, snow depth is obtained from brightness temperatures for grid cells co-located with weather station data using an emission model. This model uses the snow grain size as a scalable input parameter which is chosen such that the difference between observed and computed snow depth becomes minimal. The set of grain sizes obtained together with the snow depth is used to construct a kriging interpolated distribution of the effective snow grain size which is subsequently used in the emission model inversion to obtain the snow depth distribution. Observed snow density values are finally used to convert snow depth into SWE. More details about the used approach can be found in the Product Guide.
Please also read the data quality section further below.
We are offering daily and monthly average data. The daily data include the retrieval uncertainty. The monthly data are based on weekly aggregation of the daily SWE distributions and contain in addition to the mean SWE also the maximum SWE according to the weekly SWE distributions.
This is version 2.0 of the product.
Last data update: May 8 2014.