For the past two decades, precipitation radars (PR) onboard low-orbiting satellites such as Tropical Rainfall Measuring Mission (TRMM) have provided invaluable insight into global precipitation variability and led to advancements in numerical weather prediction through data assimilation. Building upon this success, planning has begun on the next generation of satellite-based PR instruments, with the consideration for a future geostationary-based PR (GPR), bringing the advantage of higher observation frequency over previous and current PR satellites. Following the successful demonstration by a recent study to test the feasibility of a GPR to obtain three-dimensional precipitation data, this study takes the first step to investigate the potential usefulness of GPR observations for numerical weather prediction by performing a perfect model observing system simulation experiment (OSSE) for a West Pacific tropical cyclone (TC). Data assimilation experiments are performed assimilating reflectivity observations obtained for a range of beam sampling spans, following a previous finding that oversampling improves observation quality. Results showed observations obtained with finer sampling spans of 5 km and 10 km were able to better capture key tropical cyclone features in analyses, including the eye, heavy rainfall associated with the eyewall, and outer convective rainbands. Results also showed that through increased moistening and upward velocity within the inner storm environment, assimilation of observations drove an intensification of the secondary circulation and deepening of the storm, leading to an improvement in TC intensity error. Intensity forecasts were found improved for assimilation of observations obtained with increasingly finer beam sampling span, suggesting an important benefit of oversampling.

中文翻译：

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来自地球静止降水雷达卫星的过采样反射率观测：对完美模型 OSSE 框架内台风预报的影响

在过去的二十年里，热带降雨测量任务 (TRMM) 等低轨道卫星上的降水雷达 (PR) 为全球降水变异提供了宝贵的见解，并通过数据同化促进了数值天气预报的进步。在这一成功的基础上，已经开始规划下一代基于卫星的 PR 仪器，并考虑未来的基于地球静止的 PR (GPR)，带来比以前和当前 PR 卫星更高的观测频率的优势。继最近的一项研究成功证明了探地雷达获取三维降水数据的可行性之后，本研究迈出了第一步，通过对西太平洋热带气旋 (TC) 进行完美模式观测系统模拟实验 (OSSE)，研究 GPR 观测对数值天气预报的潜在有用性。数据同化实验是在对一系列光束采样跨度获得的反射率观测结果进行同化后进行的，此前发现过采样可提高观测质量。结果表明，通过 5 公里和 10 公里的更精细采样跨度获得的观测结果能够更好地捕捉分析中的关键热带气旋特征，包括风眼、与眼墙相关的强降雨和外部对流雨带。结果还表明，通过增加内部风暴环境中的湿度和上升速度，观测的同化推动了二次环流的加强和风暴的加深，导致了台风强度误差的改善。强度预测被发现可以更好地同化随着越来越细的波束采样跨度获得的观测结果，这表明过采样的一个重要好处。