Retrieval of precipitation for grassland based on the multi-temporal Sentinel-1 SAR data
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摘要: 水资源对草原地区牧草生长至关重要,准确获取降水量信息对陆地生态系统和水循环研究具有重要意义.基于降水过程前后土壤含水量变化引起的介电常数变化,会导致后向散射系数变化这一事实,提出了基于多时相SAR数据反演降水量的方法.以二连浩特和锡林浩特2个观测站点为例,利用降水过程前后Sentinel-1A SAR数据和降水量数据进行研究及对比验证.结果表明,降水过程前后后向散射系数差值与降水量的回归关系较好;采用该方法可以获得植被覆盖度较低地区真实的降水量空间分布;二连浩特地区2015年9月21日的降水量空间分布与考虑影像获取时间和大气运动后的MODIS大气可降水量产品数据空间分布一致性较高.
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关键词:
- Sentinel-1A /
- SAR /
- 后向散射系数 /
- 多时相 /
- 降水量
Abstract: Water resource is indispensable to the growth of meadows in prairie, and the precise acquisition of the amount of precipitation is of great significance to the continental ecosystem and hydrological circle. This study proposed a novel technique to retrieve the precipitation on the basis of multi-temporal SAR imagery based on the fact that variations of the dielectric constant give rise to modifications of the soil moisture before and after the process of precipitation, allowing for the immediate changes in soil backscattering coefficients. Sentinel-1A SAR and actual measurements of rainfall in the meteorological stations of Erlianhot and Xilinhot were used to verify the retrieval results, which indicated the superb exponential regressive model between the difference values of backscattering coefficient before and after the process of precipitation and the real precipitation measurements. Thus, the spatial distribution of the retrieved precipitation on September 21, 2015 was obtained in the use of this method with Erlianhot as an example, meanwhile, the result shows the favorable spatial distribution consistency of the derived one in comparison with the product of MODIS atmospheric precipitable water considering the atmospheric motion and the acquisition time of imagery. Therefore, this pragmatic method is contrived to yield the actual rainfall spatial distribution in low vegetation coverage regions.-
Key words:
- Sentine1-1 A /
- SAR /
- backscattering /
- multi-temporal /
- precipitation
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