Study on a unified signal processing algorithm for spaceborne precipitation radar

日本MU雷达是为TRMM降水雷达提供准确地面真值的重要候选雷达之一。它可以提供高精度、高空间分辨率的雾滴大小分布数据和背景大气风数据。介绍了利用MU雷达进行TRMM验证的特殊观测方案，并给出了该方案的初步试验结果。利用高分辨率MU雷达数据进行数值模拟，验证了TRMM PR数据分析的降雨反演算法。在已知的降雨反演误差源中，利用MU雷达资料进行了数值模拟，分析了雨滴大小分布的垂直变化和部分波束填充效应的意义。结果表明，这些因素会严重影响TRMM降水反演的精度，有必要建立统计补偿手段。然而，建议的改进传统α平差方法的方法需要仔细处理，以免引入新的误差来源。

The MU radar of Japan is one of important candidates for providing accurate ground truth for the TRMM precipitation radar. It can provide the dropsize distribution data together with the background atmospheric wind data with high accuracy and high spatial resolution.Special observation scheme developed for TRMM validation using the MU radar is described, and preliminary results from its test experiment are shown. The high-resolution MU radar data are also used in numerical simulations to validate the rain retrieval algorithm for the TRMM PR data anlysis. Among known sources of errors in the rain retrieval, the vertical variability of the dropsize distribution and the partial beam-filling effect are examined in terms of their significance with numerical simulations based on the MU radar data.It is shown that these factors may seriously affect the accuracy of the TRMM rain retrieval, and that it is necessary to establish statistical means for compensation. However, suggested means to improve the conventional alpha-adjustment method require careful treatment so that they do not introduce new sources of errors.