基于贝叶斯方案的雷达反射率反演水汽及其同化试验  

RETRIEVAL OF WATER VAPOR FROM RADAR REFLECTIVITY BASED ON BAIYESIAN SCHEME AND ITS ASSIMILATION TEST

作　　者：张诚忠[1] 薛纪善[2] 冯业荣[1] 黄燕燕[1] 戴光丰[1] ZHANG Chen-zhong;XUE Ji-shan;FENG Ye-rong;HUANG Yan-yan;DAI Guang-feng(Guangzhou Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of RegionalNumerical Weather Prediction, CMA, Guangzhou 510640, China;Chinese Academy of Meteorological Sciences,Beijing 10081,China)

机构地区：[1]中国气象局广州热带海洋气象研究所/广东省区域数值天气预报重点实验室,广东广州510640 [2]中国气象科学研究院,北京100081

出　　处：《热带气象学报》2019年第2期145-153,共9页Journal of Tropical Meteorology

基　　金：自然科学基金项目(41675099;41705089);973项目(2015CB452802);广州市科技计划项目(201604020012;GYHY201406003)共同资助

摘　　要：雷达资料是目前为数不多有能力为高分辨率预报模式提供高分辨率信息资料的资料之一。为充分利用该资料所包含的中小尺度信息,文中基于雷达反射率,利用贝叶斯方法反演出大气相对湿度;将质控后的资料引入3Dvar系统进行同化分析,为高分辨率模式提供初值场。以台风"妮妲"登陆为例,通过一维反演及三维变分系统分析,有效地订正了实况有回波而模式预报无回波区域的大气湿度趋于合理,增加背景场的湿度,减小模拟回波比观测偏强的区域的大气湿度;同化大气湿度后模式在前6小时报出的台风外围回波分布、演变更合理,改进了降水雨带的分布与强度。1个月的批量试验反映1D+3Dvar同化雷达资料后,大气对流层中低层(850～400 h Pa)增湿明显,其增湿影响程度可延续12小时以上。其逐时降水预报在前12小时的TS均比控制试验高,而大于5 mm以上降水预报偏差则与控制试验的大略一致或更接近1。Doppler radar data are among a few that could provide convective scale information for high-resolution numerical weather prediction model (NWP). To make use of these data for initial condition of NWP, in this paper, a one-dimensional (Baiyesian) retrieval of relative humidity followed by a three-dimensional variational data assimilation (1D+3Dvar)technique is adopted. Quality control is conducted before the retrieval data enters 3Dvar system. Take a case of landing typhoon as an example, the one-dimensional Baiyesian retrieval effectively revises the humidity by moistening those areas where the model is unable to reproduce reflectivity and drying those areas where the intensity of simulating reflectivity is greater than that of reflectivity with observation. An experiment with assimilation of humidity indicates that it could successfully predict the distribution and evolution of reflectivity on the periphery of typhoon, and subsequently improve the skill of predicting distribution and intensity of six-hour accumulative precipitation. With the 1D + 3Dvar scheme, one month of experiment indicates that the troposphere from middle to lower level (850~400 hPa) humidity is significantly moistened, and the degree of its impact can be extended for more than 12 hours. TS(threat score ) for hourly precipitation forecast is higher in the first 12 hours, and the forecast bias for precipitation greater than 5 mm/h is closer to 1 or remains unchanged compared with the control experiment.

关 键 词：雷达反射率 湿度反演 贝叶斯方法 同化 试验 

分 类 号：P435[天文地球—大气科学及气象学]