Development of an Algorithm for Precipitation over the Global Land by Using Space-based Microwave Radiometer

这项研究旨在为利用天基微波无线电仪开发全球陆地降水算法奠定基础。为了有效地将地表比辐射率和地表温度作为大气辐射传输模型的边界条件，提出了一种适用于2002年发射的先进微波扫描辐射计(AMSR&AMSR-E)的算法。首先考虑了土层消光和植被层吸收和辐射的影响，建立了基于物理的辐射传输模型。然后，利用卫星传感器数据给出了一种反演算法。通过在协调增强观测项目(CEOP)蒙古参考点的算法验证，该算法具有较好的精度。因此，通过将该算法应用于AMSR-E，在蒙古生成了一个土壤湿度数据集。第二步，利用微波辐射传输模式，开发了一个用于反演大气参数“综合云液态水含量”和“雪率”的算法，并将其应用于2003年1月在福井进行的AMSR/AMSR-E验证活动期间获得的实验数据。从分离辐射传输的四个组成部分所收集的见解出发，进行了进一步的计算，以获得不同频率的亮温之间的关系--这些亮温要么在目前的卫星平台上使用，要么在福井实验期间使用--与要观测的大气参数之间的关系。在此基础上，提出了一种基本算法，并将其应用于实验数据。与地面测量数据的比较表明，在某些情况下符合得很好，而在另一些情况下，两种方法之间似乎没有相关性。

This research targeted to develop bases for development of an algorithm for precipitation over the global land by using space-based microwave radiometers.To monitor the land. surface emissivity and land land surface temperature as the boundary conditions of the radiative transfer model in atmosphere effectively, an algorithm for the Advanced Microwave Scanning Radiometers (AMSR & AMSR-E) launched in 2002 was developed in this research. A physically based radiative transfer model was developed by considering the effects of extinction in soil layer and absorption and radiation in vegetation layer at first. Then, a retrieval algorithm by using the satellite sensor data. A good accuracy of the algorithm is obtained through the algorithm validation in the Mongolia reference site of the Coordinated Enhanced Observation Project (CEOP). Consequently, a soil moisture data set is generated in Mongolia by applying the algorithm to the AMSR-E.As the second step, an algorithm for retrieval of the atmospheric parameters 'integrated cloud liquid water content' and 'snow rate' was developed using a microwave radiative transfer model and its application to experiment data obtained during the AMSR/AMSR-E validation campaign in Fukui in January 2003. Starting from the insights gathered from the separation of the four components of radiative transfer, further calculations were carried out, in order to obtain relations between the brightness temperatures at different frequencies -which are either in use on current satellite platforms or were used during the Fukui-experiment -and the atmospheric parameters to be observed. Based on these results, a basic algorithm was developed and applied to experiment data. The comparison with ground based gauge data shows good agreement for some cases while there seems to be no correlation between the two methods in others.