基于GRAPES四维变分的静止轨道微波观测系统模拟试验研究

地球静止轨道微波观测同时具有高频次、大视场和穿透云雨的全天候观测能力,因此中国在规划第二代静止轨道气象卫星“风云四号”系列时已经明确提出对静止轨道微波观测的需求。基于中国候选的50、118、183、380和425 GHz五频段静止轨道微波辐射计载荷方案,开展了地球静止轨道微波观测系统模拟试验,理解其观测时间分辨率、频段选取和观测误差对台风预报的影响。试验基于GRAPES全球四维变分同化系统,同化静止轨道微波模拟观测资料,以2018年台风“玛利亚”和“山竹”为例分析了静止轨道微波资料同化对台风预报的影响。试验结果表明,对于静止轨道微波资料同化应用,提高观测资料的时间分辨率、增加通道数量和降低噪声水平能够有效提升台风数值预报性能。 

Geostationary microwave observation system simulation experiments using the GRAPES 4D-Var

The geostationary microwave (GEO-MW) observation system has the all-weather observation capability with high frequency of real-time observation, large field-of-view and cloud-penetrating ability, which makes it a necessity in China''s second-generation geostationary meteorology satellite "Fengyun-4" series development. Observation System Simulation Experiments (OSSEs) are conducted to understand how the characteristics of GEO-MW such as the time resolution, the frequency band selection and observation errors affect the performance of typhoon numerical prediction based on the candidate instrumental concept for China GEO-MW satellite mission with five bands of 50, 118, 183, 380 and 425 GHz. The OSSEs assimilate the simulated GEO-MW observation data using the GRAPES global 4D-Var data assimilation system and demonstrate the impact of GEO-MW observations on forecasts of two typhoon cases, "Maria" and "Mangkhut", in 2018. The experiment results indicate that improving the time resolution, increasing the number of frequency band and decreasing the noise level of GEO-MW observation data can effectively improve the performance of typhoon numerical prediction by the application of data assimilation.