IMPROVED ESTIMATES OF THE AREAL EXTENT OF SNOW COVER FROM AVHRR DATA

Satellite data provide the only practical way to obtain the necessary spatial and temporal coverage of areal extent of snow cover required f or hydrometeorological applications. A new procedure has been develope d which: (1) accurately separates snow and cloud from clear land in a terrestrial scene; and (2) uses other criteria to separate both cold, high clouds and warm, low clouds from snow. A mixed pixel class is als o identified and pixels in this class can be assigned a percentage com position (cloud, snow, and land) using a linear mixing model. The proc edure has been ground-truthed with both Landsat data and SNOTEL (SNOwT ELemetry) observations. Classification skill, based on a statistical c omparison with SNOTEL observations, is about 97%. Application of the p rocedure to a wide variety of terrestrial environments is demonstrated . (C) 1998 Elsevier Science B.V.