OHD/HL/DIMP2 - Areal Extent of Snow Cover

Areal Extent of Snow Cover

The Satellite Hydrology Program captures AVHRR data directly from the NOAA polar orbiting satellites.
Full resolution, GVAR formatted GOES-east and GOES-west data are purchased from a private vendor and acquired over a dedicated T1 line. All satellite data are reprojected to a 30 arc-second latitude/longitude grid.

Each AVHRR visible and near-infrared (channels 1 and 2) and each GOES visible (GVAR channel 1) pixel is normalized to solar noon using a simple cosine correction to compensate for variations in solar illumination and sun angle across each image. The normalized imagery and infrared imagery are processed using the theta algorithm to classify each pixel and produce and areal extent of snow cover raster.

For more information on this product, see

Hartman, R.K., Rost, A.A., and Anderson, D.M. (1995) Operational processing of multi-source snow data. Presented at the 63rd Annual Western Snow Conference; Sparks, Nevada; 1995 April 17-19.

Maxson, R.W., Allen, M.W., Szeliga, T.L. (1996) , theta - Image classification by comparison of angles created between multi-channel vectors and an empirically selected reference vector.