###
DOI:
本文二维码信息
华南前汛期强降雨个例模式降水预报误差成因初探
胡宁, 符娇兰
(国家气象中心)
Analysis of the Source of Model Precipitation Prediction Bias in the Pre-flood Season in South China
Hu Ning, Fu Jiaolan
(National Meteorological Center of CMA#$TAB,100081)
摘要
相似文献
本文已被:浏览 97次   下载 32
投稿时间:2019-07-16    修订日期:2020-05-27
中文摘要: 2015年5月19日至20日,华南出现一次暴雨过程。检验表明EC全球确定性模式(简称EC)预报的20日强降水落区在广东境内较实况明显偏北,高估了天气尺度系统附近的降水强度,漏报了其南侧暖区内中尺度对流系统(mesoscale convective system, MCS)造成的降水,华东中尺度模式预报明显优于EC。利用高分辨率中尺度模式WRF(简称WRF)对该暴雨过程进行了模拟,对比EC降水物理过程,初步探索了EC降水预报误差的成因,结果表明:(1)20日位于广东暖区内的对流组织发展成MCS,并造成明显的低层冷池出流和中高层潜热加热,二者共同作用使得中低层气旋式环流在广东中东部发展,配合其南侧的强西南风水汽输送,在气旋式切变附近不断触发新的对流并南移使得广东中南部暖区内出现强降水,WRF能较好地模拟出该过程,而EC未能预报出暖区对流及其反馈,从而导致其漏报了广东中南部的强降水;(2)EC预报的降水与天气尺度环流之间的正反馈进一步加大了降水的预报偏差。其预报的20日白天的强降水主要位于华南北部切变线附近,且以层状云降水为主,降水产生的潜热使得对流层低层切变线附近减压更明显,预报的切变线辐合较分析场明显偏强,使得其预报的切变线附近降水较实况偏强。
Abstract:For the heavy rainfall event on 19-20 May 2015, ECMWF-IFS model(EC model) overestimates its rainfall intensity near the large-scale shear line, while underestimates the heavy rainfall induced by the mesoscale convective systems(MCSs) in warm sector, resulting in a northward displacement bias of the forecasted rainfallcompared with the observation in Guangdong Province on 20 May.A high resolution numerical simulation of WRF model is performed to explore the source of forecasting error ofEC model. The results indicatethat: the well-organized MCSs in the warm sector inducea significant cold pool outflow, which converges with the strong warm and moist southwestflow. New MCSs are triggered along the convergence line continually and produce heavy rainfall in the warm sector. WRF model successfully depictsthe whole process, while EC model fails to present the above mechanism and causes the underestimated rainfall in the warm sector. A positive rainfall feedback mechanism through latent heating can modulate the synoptic-scale circulation in model, thus the rainfall again. Convective rainfall developed in warm sector can generate potential vorticity perturbation, which changes the synoptic scale flow over upper and middle level and alter the rainfall distribution finally. The feedback of convective rainfall to synoptic scale flow in South China can be described by WRF model, which can simulate the well-organized MCSs.Most of the rainfall in EC model is the stratiform rainfall caused by the shear line, which may further strengthen the circulation in the middle and low level and increase the precipitation along the shear line in turn. The underestimate of convective rainfall in warm sector and a strong stratiform rainfall feedback work together to cause a northward displacement bias of the forecasted rainfall in EC model.
文章编号:201907160283     中图分类号:    文献标志码:
基金项目:国家重点研发项目(2018YFC1507703)、中国气象局预报员专项(CMAYBY2018-089)、国家科技支撑计划(2015BAC03B02),灾害天气国家重点实验室开放课题(LASW2014-B05)
引用文本:
胡宁,符娇兰,0.[en_title][J].Meteor Mon,():-.
Hu Ning,Fu Jiaolan,0.Analysis of the Source of Model Precipitation Prediction Bias in the Pre-flood Season in South China[J].Meteor Mon,():-.