青藏高原东北部地区一次强降水过程的灰色尺度积云对流参数化敏感性研究  

Sensitivity Study of Cumulus Convective Parameterization at a Gray Zone during a Heavy Precipitation Process over the Northeastern Tibetan Plateau

作　　者：吴迪 田洁 胡田田 傅宁[1] WU Di;TIAN Jie;HU Tiantian;FU Ning(Department of Aviation Meteorology,College of Air Traffic Management,Civil Aviation University of China,Tianjin 300300;Meteorological Observatory of Chongqing Sub-bureau of Southwest China Regional Air Traffic Management Bureau,Civil Aviation Administration of China,Chongqing 401120;Tianjin Central Observatory for Oceanic Meteorology,Tianjin 300074)

机构地区：[1]中国民航大学航空气象系,天津300300 [2]中国民用航空西南地区空中交通管理局重庆分局气象台,重庆401120 [3]天津海洋中心气象台,天津300074

出　　处：《大气科学》2023年第4期1247-1266,共20页Chinese Journal of Atmospheric Sciences

基　　金：国家重点研发计划项目2020YFB1600103;国家自然科学基金项目42005004、42075008;中央高校基本科研业务专项3122019137、3122015C023。

摘　　要：本文利用WRF(Weather Research and Forecasting)V4.0模式对2016年8月17~18日发生在青藏高原东北部青海省的一次强对流过程开展了3 km高分辨率数值模拟,基于观测小时降水数据、FY-2E卫星资料、探空资料和再分析资料等,通过四组敏感性试验对比分析了在模式对流灰色尺度中使用完全显式方案(EXP试验)、传统参数化方案(KF试验)以及尺度感知参数化方案(Multi-Scale KF;MSKF试验)对对流降水模拟的差异及其影响机制。结果表明:不同的湿物理过程处理对青藏高原地区灰色尺度内对流降水强度和落区的模拟存在较大差异。KF试验模拟的18小时累积降水在降水落区和强度上较EXP和MSKF试验与实况最为接近,这与Kain-Fritsch eta(KFeta)参数化方案在降水中心区域产生的对流性降水对总降水的相对贡献较大有关。而EXP和MSKF试验模拟的降水潜热释放产生的300~400 hPa正位涡(Potential Vorticity;PV)异常,受较强的垂直风切变影响随高度向下游倾斜明显,使得其低层500 hPa正PV异常大值区较KF试验呈现出超前特征,进而导致了下游地区低层的局地风场特征、水汽通量输送及大气稳定度的改变,最终导致强降水落区较KF试验和实况向东北方向(下游)偏移。以上分析表明,在青藏高原灰色尺度内,仍然需要依赖对流参数化方案隐式地描述次网格对流过程来弥补显式方案的模拟偏差;而MSKF方案似乎对该地区的对流描述还存在一些不确定性。Model simulations of a heavy convective process that occurred in the northeastern Tibetan Plateau(TP)on August 17 and 18,2016,were performed using the 3-km high-resolution Weather Research and Forecasting V4.0 model.Based on the observed hourly precipitation products,FY2E satellite,observation sounding,and reanalysis datasets,a set of four sensitivity tests were performed to compare and analyze the differences and influence mechanisms of convective precipitation using a fully explicit convection scheme(EXP experiment),traditional parameterized convection scheme(KF experiment),and scale-aware parameterization scheme(multiscale KF;MSKF experiment)in a model convective gray zone.The major conclusions were as follows.Considerable variations in heavy precipitation simulation of intensity and location in grayscale over the northeastern TP were observed with various treatments of moist physical processes.Compared with those simulated by the EXP and MSKF experiments,the 18-h total precipitation simulated by the KF experiment was closest to the observed precipitation in terms of precipitation amount and location,which is associated with the relative contribution of Kain–Fritsch Eta generated precipitation to total precipitation in the central rain area.Furthermore,the 300–400 hPa positive potential vorticity(PV)anomalies generated by the latent heat release of precipitation in the EXP and MSKF experiments tended to tilt more downstream with altitude because of their strong vertical wind shears,leading to more advanced positive PV anomalies at a lower level of 500 hPa than that in the KF experiment.This further resulted in the alteration of the low-level local wind fields,moisture flux transport fields,and atmospheric stability,ultimately generating heavy precipitation northeastward(downstream)versus the KF experiment and observation.The above investigation results suggested that it may be necessary to employ the convective parameterization scheme at the gray zone over the TP region,treating the subgrid-scale convectiv

关 键 词：积云对流参数化 灰色尺度 对流降水 数值模拟 

分 类 号：P435[天文地球—大气科学及气象学]