GRAPES模式预报误差订正的变分方法研究  

Variational method study to correct the forecast error of GRAPES model

作　　者：何邓新 周志敏[1] 康兆萍 徐桂荣[1] HE Dengxin;ZHOU Zhimin;KANG Zhaoping;XU Guirong(Institute of Heavy Rain,China Meteorological Administration,Wuhan 430074;Key Laboratory for Semi-Arid Climate Change of the Ministry of Education,College of Atmospheric Sciences,Lanzhou University,Lanzhou 730000)

机构地区：[1]中国气象局武汉暴雨研究所,武汉430205 [2]半干旱气候变化教育部重点实验室兰州大学大气科学学院,兰州730000

出　　处：《暴雨灾害》2020年第4期392-399,共8页Torrential Rain and Disasters

基　　金：湖北省青年科技人员专项基金(2018Q04);国家重点研发计划(2018YFC1507200)。

摘　　要：利用变分方法建立预报场和预报倾向场这一预报场组合与模式预报非系统性误差之间的映射关系,来估计GRAPES(Global/Regional Assimilation and PrEdiction System)模式的非系统性误差,从而对预报做出修正。采用两种不同的历史样本建立这一映射关系,其中,利用相同时刻历史样本建立映射关系的方法称为DEM方法;通过相似面积比选取“相似样本”来建立上述映射关系的方法称为SEM方法。以FNL分析资料作为评判预报误差的依据,根据2002—2010年7月GRAPES模式500 hPa高度场48 h预报的回报资料,利用两种不同的方案进行非系统性误差的估计及预报订正试验。对279个检验样本的试验结果表明:SEM方法和DEM方法都对非系统性误差有一定的估算能力,二者估算的非系统性误差空间分布和量级与模式非系统性误差较一致,SEM方法的修订效果略优于DEM方法,但并不明显。对预报做出系统性误差和非系统性误差两步订正后,DEM方法和SEM方法的订正有效率分别为98.566%和100%,可明显提高预报的准确性。In this study,forecast error is devived into two components,i.e.,systematic forecast error and non-systematic forecast error.After the correction of systematic forecast error,variational method is used to estimate and correct the non-systematic forecast error by building the mapping relationship between the state variable and non-systematic forecast error.The mapping relationship can be built by two schemes.One is by using the historical samples of the same period(DEM),and the other is by using“similarity samples”(SEM).The hind⁃cast data of 48 h forecast of 500 hPa height field generated by GRAPES model in July from 2002 to 2010 is used to test the effectiveness of the above two methods.The analysis data from NCEP-FNL is used as validation data to assess the result of the methods.The result shows that the correction efficiency is 98.566%for DEM and 100%for SEM.Both the DEM method and SEM method has certain capability to esti⁃mate the non-systematic forecast error.

关 键 词：预报误差订正 非系统性误差 变分方法 SVD分解 相似样本 GRAPES模式 

分 类 号：P456.7[天文地球—大气科学及气象学]