Microwave Emission From Snow and Glacier Ice

作者：Tzu‐Ching Chang, Per Gloersen, Thomas J. Schmugge, Thomas T. Wilheit, H. Jay Zwally · 发表于：Journal of Glaciology · 年份：1976 · DOI：10.1017/s0022143000031415 · 被引用次数：235 · 研究领域：Cryospheric studies and observations、Atmospheric aerosols and clouds、Thermal Radiation and Cooling Technologies

Abstract The microwave emission from a model snow field, consisting of randomly spaced ice spheres which scatter independently, is calculated. Mie scattering and radiative transfer theory are applied in a manner similar to that used in calculating microwave and optical properties of clouds. The extinction coefficient is computed as a function of both microwave wavelength and ice-particle radius. Volume scattering by the individual ice particles in the snow field significantly decreases the computed emission for particle radii greater than a few hundredths of the microwave wavelength. Since the mean annual temperature and the accumulation rate of dry polar firn mainly determine the grain sizes upon which the microwave emission depends, these two parameters account for the main features of the 1.55 cm emission observed from Greenland and Antarctica with the Nimbus-5 scanning radiometer. For snow particle sizes normally encountered, most of the calculated radiation emanates from a layer on the order of 10 m in thickness at a wavelength of 2.8 cm, and less at shorter wavelengths. A marked increase in emission from wet versus dry snow is predicted, a result which is consistent with observations. The model results indicate that the characteristic grain sizes in the radiating layers, dry-firn accumulation rales, areas of summer melting, and physical temperatures, can be determined from multispectral microwave observations.