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21.
In the present study, a gross quality control (QC) procedure is proposed for the Global Navigation Satellite System Occultation Sounder (GNOS) Global Positioning System radio occultation (GPS RO) refractivity data to remove abnormal data before they are assimilated. It consists of a climate extreme check removing data outside the range of the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) climate maxima and minima over approximately five years, and a vertical gradient check that rejects profiles containing super-refractions. These two QC steps were applied sequentially to identify outliers in GNOS GPS RO refractivity data during boreal winter 2013/2014. All of the abnormal refractivity profiles and the outliers at each level of the GNOS GPS RO observations were effectively removed by the proposed QC procedure. The post-QC GNOS GPS RO refractivity observations were then assimilated in the Global/ Regional Analysis and PrEdiction System (GRAPES) using the three-dimensional variational (3D-Var) system. The impacts of the GNOS refractivity observation on GRAPES analysis and forecasting were evaluated and analyzed using an observation system experiment run over one whole winter season of 2013 / 2014. The experiment results demonstrated a positive impact of GNOS GPS RO data on analysis and forecast quality. The root mean squared error of GRAPES analysis temperature was reduced by 1% in the Southern Hemisphere (SH) extratropics and in the tropics, and the anomaly correlation scores of the forecasted 500-hPa geopotential height over the SH increased significantly during days 1 to 5. Overall, the benefits of using GNOS GPS RO data are significant in the SH and tropics. 相似文献
22.
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。 相似文献