GCOM-W AMSR2资料在CMA_GFS四维变分中的同化应用  

Assimilation of GCOM-W AMSR2 radiance data in CMA_GFS 4D Var

作　　者：肖弘毅 韩威[1,2] 白一泓 XIAO Hongyi;HAN Wei;BAI Yihong(CMA Earth System Modeling and Prediction Centre(CEMC),Beijing 100081,China;State Key Laboratory of Severe Weather(LaSW),Beijing 100081,China;Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites,National Satellite Meteorological Center(National Center for Space Weather),CMA,Beijing 100081,China;Innovation Center for FengYun Meteorological Satellite(FYSIC),Beijing 100081,China)

机构地区：[1]中国气象局地球系统数值预报中心,北京100081 [2]灾害天气国家重点实验室,北京100081 [3]中国气象局中国遥感卫星辐射测量和定标重点开放实验室/国家卫星气象中心(国家空间天气监测预警中心),北京100081 [4]许健民气象卫星创新中心,北京100081

出　　处：《气象学报》2022年第5期777-790,共14页Acta Meteorologica Sinica

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK0105);国家自然科学基金项目(42075155)。

摘　　要：卫星微波仪器的辐射率资料,由于兼具卫星观测的全天空优势和微波观测的全天候特性,成为数值天气预报系统同化的日益重要的角色。微波成像仪作为被动微波辐射计的重要一类,其在数值预报中的应用潜力亟待进一步的检验和更充分的挖掘。针对全球水循环变化观测卫星GCOM-W上搭载的第2代先进微波扫描辐射计AMSR2的10个通道,建立了半径200 km的稀疏化方案;研发了包含9项检验的质量控制方案,对于污染低频通道观测的太阳耀光现象和无线电信号干扰等因素进行屏蔽;设计基于经典预报因子的偏差订正方案,对仪器系统偏差进行有效的校正;采用基于变分同化后验估计的观测误差统计,克服了观测误差难以准确估计的问题。通过以上方法,GCOM-W AMSR2共有10个通道辐射率资料在中国自主研发的全球/区域同化预报系统(CMA_GFS,原名为GRAPES_GFS)3.0版的四维变分同化系统(4DVar)中实现了直接同化应用。1个月的批量试验证明,同化GCOM-W AMSR2后,CMA_GFS湿度分析场得到了一定的改进,各量级定量降水中期预报评分有所提高,同时,GCOM-W AMSR2辐射率直接同化对CMA_GFS南半球和赤道地区预报有明显正贡献。研究证实AMSR2能够很好地弥补常规观测资料稀疏区的资料匮乏,发挥水汽敏感特性,改进湿度分析和降水预报的技巧。The radiance data of satellite microwave radiometers play a more and more important role in the assimilation of numerical prediction systems due to the all-sky advantage of satellite observations and the all-weather availability of microwave soundings.As an important category of passive microwave radiometer,the application potential of microwave imager in numerical weather forecasting needs further verification and more sufficient exploration.Focusing on the Advanced Microwave Scanning Radiometer 2(AMSR2)carried on the Global Change Observation Mission–Water(GCOM-W),the thinning scheme within 200 km radius is applied;a quality control scheme including nine issues of checks is developed to screen those contaminations including the sun-glint phenomenon and radio-frequency interferences which can disturb the low-frequency channels;a bias correction scheme on the basis of conventional predictors is employed to effectively reduce systematic deviations of instrument;the difficulty related to observation error evaluation is overcome by posteriori verification.Ten channels of GCOM-W AMSR2 are directly assimilated into the Global/Regional Assimilation and Prediction System–Global Forecast System(CMA_GFS,i.e.,the GRAPES_GFS)version 3.0by the four-dimensional variational(4DVar)assimilation method independently developed by the Numerical Weather Prediction Center of China Meteorological Administrator.A pair of batch experiments for one month indicates that,with the GCOM-W AMSR2assimilation,the depiction of humidity analysis field is improved,the medium forecasting skills of various precipitation are also improved,and the prediction score card shows obvious positive impacts on the southern hemisphere and the equatorial region.Thus,direct assimilation of the GCOM-W AMSR2 into the CMA_GFS 4DVar is confirmed to be useful for improving the amount of observations in poor-data regions,and it can take advantage of the water vapor sensitivity to promote the skills of humidity analysis and precipitation prediction.

关 键 词：GCOM-W AMSR2 CMA_GFS 四维变分同化 卫星资料同化 

分 类 号：P407.7[天文地球—大气科学及气象学]