Remote Sensing for Agriculture, Ecosystems and Hydrology III
Remote Sensing for Agriculture, Ecosystems and Hydrology III
复制标题
农业、生态系统和水文遥感 III
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
E. Engman
中科院分区：
文献类型：
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作者：
E. Engman
在水文、气候变化和天气预报领域，对遥感土壤湿度的科学需求已经得到了很好的确立。尽管有充分的科学需要，但目前没有飞行或资助的卫星飞行任务来进行这一非常重要的地球物理测量。已经有许多实验飞机项目证明了使用长波微波传感器估计土壤水分的可行性。不幸的是，土壤湿度这一科学驱动力对卫星传感器系统提出了非常困难的技术要求。全球土壤湿度是由20至30公里的空间分辨率驱动的，需要每两至三天进行一次测量，才能对科学界有用。完成土壤水分测量的主要传感器是L波段的被动微波辐射计，要达到空间和时间上的要求，需要一个非常大的天线。本文描述了几种方案，以解决非常大的天线挑战，同时仍满足辐射计的灵敏度要求。文中还讨论了为获得必要的辅助数据以表征地表粗糙度、地表温度和地球物理参数所需植被的衰减影响而考虑的替代方案。最后，本文讨论了拟议的任务以及它们将在多大程度上满足科学要求。
The science need for remotely sensed soil moisture has been well established in the hydrologic, climate change and weather forecasting communities. In spite of this well documented science need there are currently no satellite missions flying or funded to make this very important geophysical measurement. There have been a number of experimental aircraft programs that have demonstrated the feasibility of using long wave microwave sensors for estimating soil moisture. Unfortunately, this science driver, soil moisture, imposes very difficult technical requirements for a satellite sensor system. Global soil moisture is driven by a spatial resolution on the order of 20 to 30 km and measurements need to be taken every two to three days to be useful to the science community. The principal sensor to accomplish the soil moisture measurements is an L- band passive microwave radiometer and achieving the spatial and temporal requirements requires a very large antenna. This paper describes the several alternatives to solve the very large antenna challenge and still meet the radiometer sensitivity requirement. The paper also discusses the alternatives considered to obtain the necessary ancillary data for characterizing the surface roughness, the surface temperature and the attenuation affects of vegetation needed to derive the geophysical parameter. Finally, the paper discusses proposed missions and how well they will meet the science requirements.