AN INVESTIGATION OF TERRAIN IRRADIANCE IN A MOUNTAIN-GLACIER BASIN

A remotely sensed method of assessing radiative-transfer processes, wh ich considers distinctive zones in the mountain-glacier drainage basin , increases the potential for comprehensive radiative-exchange analysi s. By investigating terrain-reflected and terrain-emitted radiation us ing Landsat-5 Thematic Mapper images and digital elevation data, the o bjective of this study is to demonstrate the importance of local excha nge in the computation of net shortwave and longwave radiation. The re sults show that terrain-reflected radiation estimates are required to calculate the total shortwave spectral irradiance in all parts of the basin. This is necessary to compute accurate surface-cover reflectance and albedo values from the satellite imagery. Furthermore, the assess ment of the terrain-emitted radiation explains why, especially on a cl ear day, the snow and ice covers in many parts of the basin have a ver y small longwave radiation deficit.