雷达资料GSI分析系统对一次特大暴雨的试验研究
Study of the Effect of Radar Data Analysis with GSI on Heavy Rainfall Prediction
中文摘要：
GSI是目前美国NCEP业务上使用的资料分析系统，本文以北京“7·21”特大暴雨为例，通过对雷达资料GSI同化后的模式初始场和强降水预报结果对比分析，检验GSI同化系统对本地雷达资料的融合能力和对强降水的预报效果。通过试验对比可知，经过GSI雷达资料同化后的分析场，可将风场和水汽场进行有效的调整，较好地反映了同时刻大气实际状况，并且水汽增量由加入雷达反射率同化后产生，而雷达径向风的同化只能改变风场结构。对北京“7·21”强降水发生的累积降水预报和逐小时降水预报的不同试验方案对比分析可知，经过GSI雷达资料同化后的初始场对强降水预报有很好的正效应，且同时同化雷达径向风和反射率后预报效果最好，不但对整个雨带位置进行整体调整和改善，而且对强降水中心强度和位置都进行了调整和修正。
中文关键词：
雷达资料，GSI同化系统，特大暴雨，数值预报
KeyWords：
radar data, GSI assimilation, rainfall, prediction
Abstract：
The assimilation of radar data using Gridpoint Statistical Interpolation (GSI) analysis system was employed for prediction of “7·21” Beijing heavy rainfall. It is shown that the assimilation of radar data introduces reasonable modification to the initial analysis. The vapor increment associated with the assimilation of radar reflectivity, and the modified horizontal wind field due to the assimilated radar radial velocity provided a better initial analysis for precipitation prediction. This may effectively improve the prediction of the spatial distribution and the intensity of heavy rain. Thus the sensitivity simulations of “7·21” Beijing heavy rainfall validate a good effect of the assimilation of both radar radial velocity and reflectivity on the heavy rainfall prediction.