Research on the development of data correction algorithm for expanding the observation area by the spaceborne precipitation radar

星载降水雷达可以定量观测雨量，是观测空间降水的主要传感器。然而，当天线试图覆盖更大的条带时，来自天线主瓣方向的降雨回波由于来自天线旁瓣方向的地面杂波的增加而急剧恶化。针对未来的星载降水雷达，研究了当来自天线旁瓣方向的地面杂波影响时，对降雨雷达数据进行校正的可行性。在此研究期间，我们利用35.5 GHz偏振散射计编制了不同条件下土壤、植被和水面的散射系数σ^0数据库。我们收集了不同入射角和不同收发极化下的数据，同时改变了土壤的含水率和表面粗糙度，植被的叶面积指数值和t…上的风速利用TRMM 13.8 GHz的降水雷达资料，建立了一个大降水模式，模拟了该雷达在太空观测降水的情况。通过与该模型的雨率进行比较，考察了海面杂波对观测雨率的影响程度，海面杂波随天线扫描角的增大而变化。在仿真中，我们使用了实际TRMM降水雷达的理想高斯型天线方向图和平面相控阵天线方向图。结果表明，当我们采用后一种天线方向图时，即使天线波束扫描角增加到30度，远大于实际的TRMM扫描角17度，观测雨率与模型雨率之间的相关系数也高达0.74。我们的研究结果表明，采用更大的天线扫描角是一种很好的可能性，并且在改进地杂波对雨回波恶化的校正算法方面也有很好的前景。较少

Spaceborne precipitation radar can observe rain rate quantitatively, and is the main sensor to observe rain from space.Unfortunately when the antenna tries to cover a wider swath, the rain echo from the antenna mainlobe direction is sharply deteriorated due to the increase of the ground clutter from the antenna sidelobe direction.This study, for the future spaceborne precipitation radars, aims at examining the feasibility of developing the algorithm that corrects the rain radar data when it is affected by the ground clutter from the antenna sidelobe direction.During this research period, we compiled the database of scattering coefficients σ^0 of soil, vegetation and water surface in various conditions using the 35.5 GHz polarimetric scatterometer. We collected the data at different incidence angles and with different transmit-receive polarizations, while changing the moisture contents and surface roughness of the soil, the leaf area index values of vegetation and the wind speeds over t … More he water surface.Based on the TRMM precipitation radar data at 13.8 GHz, we established a large rain model to simulate rain observation from space by the radar. By comparing with the rain rates of this model, we examined how much the observed rain rate is deteriorated by the effects of the sea surface clutter, which happens with the increase of the antenna scan angle. In the simulation, we used the ideal Gaussian type antenna pattern and the planar phased array antenna pattern of the actual TRMM precipitation radar. As a result, when we applied the latter antenna pattern, the correlation coefficients between the observed rain rates and the model rain rates were as high as 0.74 even though the antenna beam scan angle increases as large as 30 degrees, which is far larger than the actual TRMM scan angle of 17 degrees. We also worked on the evaluation of the effects of partial beam filling of rainThe results we obtained from our research has shown us a good possibility of larger antenna scan angles and also a good prospect in developing the algorithms to correct the deterioration of rain echo by the ground clutters. Less