詳細な積雪分布観測 のための偏波レーダ活用技術開発

由于雪是一种与能量通量、风、湿度、水汽和压力结合在一起的高度动态介质，因此利用多频SAR数据对积雪覆盖地区进行综合观测可以在绘制和监测雪的性质和动态方面发挥重要作用。本研究旨在评估l波段星载合成孔径雷达（SAR）对季节性积雪地区的探测能力。利用日本ALOS/PALSAR系统研究了雪山生态系统后向散射的季节变化。本研究的重点是利用全极化散射观测，最大限度地了解积雪的季节变化。选择的研究地点是新泻县南部的Uonuma地区。这个地区位于日本阿尔卑斯山的北部边缘，由于冬季季风从西伯利亚吹到日本岛屿，这里是日本降雪量最大的地区之一。本研究初步研究了l波段信号的矢量散射信息及其积雪引起的变化。地形和积雪厚度对SAR信号的影响是新发现的。基于极化参数的季节变化特征，提出了一种基于信息融合的积雪区制图新方法。结合极化指数可以成功地识别积雪范围。本研究表明，l波段全极化星载SAR，如ALOS-2，将提供足够的季节积雪信息。

Since snow is a highly dynamic media in conjunction with energy fluxes, wind, moisture, water vapor, and pressure, integrated observation of snow-covered areas from multi-frequency SAR data can play an important role in mapping and monitoring snow properties and dynamics. This study aims to evaluate the capability of L-band space-borne Synthetic Aperture Radar (SAR) for detection of seasonal snow-covered areas. The seasonal change of backscattering from a snow-covered mountainous ecosystem was studied using the Japanese ALOS/PALSAR system. This study places the focus on utilization of the fully polarimetric scattering observation, maximizing information on the seasonal changes of snow-cover. The selected study site is Uonuma area in Southern Niigata Prefecture. This area is on the northern edge of the Japanese Alps and has some of the heaviest snowfall in the country due to a winter monsoon blowing from Siberia to the islands of Japan.In this study, vector scattering information of L-band signal and its snow-induced changes have been originally investigated. The effect of topography as well as snowpack thickness on SAR signal has been newly discovered. Based on the characteristic seasonal changes of polarimetric parameters, a new method to map snow-covered areas has been developed using an information fusion approach. Snow extent can be identified successfully by combining polarimetric indices. This study has elucidated that the L-band fully polarimetric spaceborne SAR, such as ALOS-2, will provide sufficient information on seasonal snow.