<論文>JERS-1衛星搭載合成開口レーダによる石狩平野の積雪観測

概要

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L band JERS-1 Synthetic Aperture Radar (SAR) data reveals that the normalized radar cross section (NRCS) of snow covered rice paddy in the Ishikari Plains, Hokkaido, is greater than that of the same area in Spring or in Autumn when the paddy is hare and there is no snow on it. To explain this observation, a model computation is made using a small perturbation method. The model assumes a dry snow cover with a peffect flat surface and a slightly rough soil surface. The model computation indicates that the L-band NRCS of snow covered soil can be greater than that for there being no snow because of the following two reasons : (1) the refracted wave in the snow cover makes a steeper incidence of the wave to the soil, and (2) NRCS increases with a decreasing angle of incidence to the soil. Though the main reasons are thus very simple and elementary, the dependence of NRCS on the dielectric constant of soil makes the problem complicated.
1999-03-25