Satellite observations of snowcover in the Sierra Nevadas during the great California drought

Images from the NOAA polar orbiting satellites are used to assess the extent of snowcover in the Sierra Nevada mountain range during the 1977 drought year. A real snowcover measurements derived from late April satellite imagery reveal the entire mountain range to have less than one third the snowcover that was present at a comparable date in 1975. Ratios of 1977 to 1975 snowcover for individual basins of the Sierra Nevadas ranged from a low of 1:9 in low elevation watersheds to a high of 1:2 in high elevation watersheds. Reduction of the satellite data was accomplished through the use of a density slicer, a color additive viewer, and an optical rectification device.