Improving snow cover mapping in forests through the use of a canopy reflectance model

摘要: MODIS, the moderate resolution imaging spectroradiometer, will be launched in 1998 as part of first earth observing system (EOS) platform. Global maps land surface properties, including snow cover, created from MODIS imagery. The snow-cover mapping algorithm that used to produce daily global cover extent at 500 m is currently under development. With exception cloud largest limitation producing a product using presence forest canopy. A Landsat Thematic Mapper (TM) time-series southern Boreal Ecosystem-Atmosphere Study (BOREAS) study area Prince Albert National Park, Saskatchewan, was evaluate performance current varying types. reflectance model conjunction with canopy (GeoSAIL) snow-covered stand. Using these coupled models, effects type, density, grain size and solar illumination geometry on were investigated. both TM images two changes are proposed improve algorithm's classification accuracy forested areas. improvements include normalized difference index vegetation combination discriminate better between snow-free forests. minimum albedo threshold 10% visible wavelengths also proposed. This prevent dense forests very low albedos being classified incorrectly snow. These increase amount mapped scenes, decrease identified non-snow-covered scenes.