三维变分同化雷达资料暴雨个例试验  

GRAPES-3DVAR radar data assimilation and numerical simulation experiments with a torrential rain case

作　　者：刘红亚[1] 薛纪善[2] 顾建峰[1] 徐海明[3] 

机构地区：[1]上海中心气象台,上海200030 [2]中国气象科学研究院灾害天气国家重点实验室,北京100081 [3]南京信息工程大学,南京210044

出　　处：《气象学报》2010年第6期779-789,共11页Acta Meteorologica Sinica

基　　金：十一五国家科技支撑计划项目(2006BAC02B00);973国家重点基础研究项目(2004CB418306;2004CB418301);国家自然科学基金项目(40518001);江苏省六大人才高峰项目;山西省气象局开放课题

摘　　要：采用中国新一代数值预报模式及其同化系统开展雷达资料的三维变分同化和数值模拟研究。通过一次暴雨个例的对比试验,结果表明:不考虑垂直运动影响的情况下,仅同化多普勒雷达经向风资料可以增加初始场中的中小尺度系统信息,并在一定程度上改善预报开始阶段的降水;同化由反射率因子导出的垂直速度、雨水混合比并令上升区饱和,可以较大改善降水预报结果;联合同化径向速度和反射率因子资料将得到它们的共同影响。模拟的β中尺度对流系统6 h的演变过程与观测十分一致,基本消除了旋转加强现象。发展旺盛阶段的对流单体南北方向范围约50km,最大上升速度位于500hPa附近,超过3.0m/s;雨水最大含量在400 hPa附近,超过5.0 g/kg;云水最大值位于600 hPa,约0.5 gkg;造成的降水强度可达30mm/h,具有明显β中尺度系统的特征。初始场中水汽是否达到β中尺度降水维持所需条件是至关重要的,如果初始场中水汽条件较差,即使含有云水、雨水、垂直速度的信息,这些信息也会很快消亡,难以维持下去;此外,雷达资料的质量控制也是十分重要的。The new generation numerical weather prediction system of China,named GRAPES（the Global and Regional Assimilation and Prediction System）,and the three-dimensional variational assimilation（3DVAR） system are used to assimilate radar data and to simulate a torrential rain case.The experimental results show that（1） without considering the impact of vertical motion,assimilating of radial velocity can enhance the information of mesoscale weather system in initial field and improve the prediction of early precipitation in some extent;（2） assimilating retrieved vertical velocity and rain water mixing ratio,with the vapor of ascending domain set to be saturation,conduces significant improvement of precipitation;（3） combining radial velocity with reflectivity information to assimilate is able to ameliorate initial field.The simulated 6h precipitation process is similar to the observation with the spin-up phenomenon eliminated almost.The meso-βscale features are notable for the convective cell at ripe stage：its north - south width is about 50 km：the maximum of updraft vertical velocity is beyond 3.0 m s around 500 hPa;the maximum of cloud water com content is about 0.5 g kg at the level of 600 hPa：the maximum rain water content is over 5.0 g/kg around 400 hPa;and the caused precipitation even exceeds 30 mm/h.The vapor condition of initial field generated by assimilating radar data is crucial for the meso-βscale precipitation to maintain,and poor vapor condition could result in precipitation dying out promptly.At last,the professional quality control of radar data is expected.

关 键 词：三维变分 径向风 反射率因子 云微物理量 垂直速度 

分 类 号：P456.7[天文地球—大气科学及气象学]