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United States Department of Agriculture

Agricultural Research Service

Title: Effects of Snow Crystal Shape on the Scattering of Passive Microwave Radiation

Authors
item Foster, James - NASA
item Hall, Dorthy - NASA
item Change, Alfred - NASA
item Rango, Albert
item Wergin, William
item Erbe, Eric

Submitted to: IEEE Transactions on Geoscience and Remote Sensing
Publication Type: Proceedings
Publication Acceptance Date: October 2, 1998
Publication Date: N/A

Technical Abstract: In developing and tuning passive microwave algorithms, which are used to estimate snow extent and depth, much of the effort has been towards better accounting for the effects of snow crystal size on the microwave response, and relatively little effort has been given to the role crystal shape plays in this regard. However, crystal size alone does not account for all of the scattering or energy distribution. In this study, a discrete dipole scattering model is used to measure the passive microwave radiation scattered by spheroids, ellipsoids, cylinders, cubes, tetrah, and edrons hexahedrons of sizes ranging between 0.1 mm to 0.9 mm in radius. In conjunction with the modeling, snow crystals were collected in the field and anlyzed in detail with an electron microscope in order to assess the variation and range of crystal shapes encountered in different geographic areas. The model results demonstrate that the shape of the snow crystal is insignificant in scattering microwave energy in the 37 GHz region of the spectrum. Therefore, the assumption used in radiative transfer approaches, where snow crystals are modeled as spheres, is adequate to account for the transfer of microwave energy emanating from the ground and passing through a snowpack.

Last Modified: 9/3/2014
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