Radiative Characteristics at 89 and 36 GHz for Satellite-Based Cloud Water Estimation Over Land
Radiative Characteristics at 89 and 36 GHz for Satellite-Based Cloud Water Estimation Over Land
复制标题
陆地上空卫星云水估算的 89 和 36 GHz 辐射特性
DOI：
10.1109/tgrs.2020.2996239
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发表时间：
2021
影响因子：
8.2
通讯作者：
Kanae Shinjiro
中科院分区：
文献类型：
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作者：
Seto Rie;Aida Kentaro;Koike Toshio;Kanae Shinjiro
卫星被动微波遥感是研究大尺度云含水量分布的重要手段。然而，大多数CWC估计方法没有实现在陆地上，因为高异质性的陆地辐射，和微波（MW）辐射传输的陆地和大气之间的详细特征，包括云还没有阐明。本研究的目的是阐明这些特点，并揭示了足够的CWC估计在土地上使用基于卫星的PMW在各种CWC条件下的土地发射率表示的准确性。首先，从理论上确定了在有云存在的情况下，与陆地和大气之间在CWC相关频率下的MW辐射传输有关的重要参数。接下来，这些参数的误差和用于CWC估计的亮度温度之间的关系是澄清通过考虑基于辐射传输方程。然后，利用地基PMW观测和数值模拟，揭示了这些重要参数的实际值和误差大小。最后，结果表明，对于任何云液态水路径（LWP）值大于1.6 kg/m2在89 GHz和5 kg/m2在36 GHz，我们可以合理地忽略发射率和辐射的不均匀性从陆地表面的CWC估计。然而，当LWP值低于阈值时，89和36 GHz数据的地面发射率表示误差应保持在0.015以下，土壤体积含水量的误差应低于5%-6%。
Satellite-based passive microwave (PMW) remote sensing is an essential technique to clarify long-term and large-scale distribution patterns of cloud water content (CWC). However, most CWC estimation methods are not implemented over land because of high heterogeneity of land radiation, and the detailed characteristics of microwave (MW) radiative transfer between land and atmosphere including clouds have not been elucidated. This study aims to elucidate these characteristics and reveal the accuracy of land emissivity representation necessary for adequate CWC estimation over land using satellite-based PMW under various CWC conditions. First, important parameters related to MW radiative transfer between land and atmosphere at CWC-relevant frequencies in the presence of clouds are determined theoretically. Next, the relationship between errors in these parameters and the brightness temperatures used for CWC estimation is clarified through considerations based on radiative transfer equations. Then, ground-based PMW observations and numerical simulation are used to reveal the actual values of these important parameters and the size of errors. Finally, the results show that for any cloud liquid water path (LWP) value greater than 1.6 kg/m2at 89 GHz and 5 kg/m2at 36 GHz, we can reasonably neglect the heterogeneity of emissivity and radiation from the land surface for CWC estimation. However, when LWP values are below the threshold, the error in the representation of land emissivity should be kept below 0.015 for both 89- and 36-GHz data, and volumetric soil moisture content should have an error lower than 5%-6% for both frequencies.
陆地上云水含量估算及其使用 A-train 卫星的验证
DOI：
--
发表时间：
2020
期刊：
影响因子：
--
作者：
Rie Seto;Toshio Koike and Shinjiro Kanae
通讯作者：
Toshio Koike and Shinjiro Kanae