基于南海夏季风季节内振荡的降水延伸预报试验  

Extended Range Forecast Experiment for Rainfall Based on the Real-time Intraseasonal Oscillation

作　　者：陈官军[1] 魏凤英[1] 姚文清[1] 周璇[2] 

机构地区：[1]中国气象科学研究院灾害天气国家重点实验室,北京100081 [2]北京市气象台,北京100089

出　　处：《应用气象学报》2016年第3期273-284,共12页Journal of Applied Meteorological Science

基　　金：公益性行业(气象)科研专项(GYHY201406022;GYHY200906016)

摘　　要：利用代表南海夏季风季节内振荡特征的850 hPa纬向风EOF分解的前两个主成分,定义南海夏季风季节内振荡指数,并利用美国国家环境预测中心第2代气候预报系统(NCEP Climate Forecast System Version 2,NCEP/CFSv2)提供的1982 2009年逐日回算预报场计算了南海夏季风季节内振荡指数的预报值,用于我国南方地区持续性强降水的预报试验。试验结果表明:利用南海夏季风季节内振荡实时监测指数与模式直接预报降水量相结合的统计动力延伸预报方法,能够有效提高季节内降水分量的预报效果。同时,该方法能够避免末端数据损失,修正了对模式预报降水直接进行带通滤波而导致的负相关现象,并起到消除模式系统误差的作用。Intraseasonal oscillation （ISO） in South China Sea summer monsoon （SCSSM） plays a key role in con- trolling the intraseasonal variations of rainfalls over southern China, and it can be described with the lead- ing pair of empirical orthogonal functions （EOFs） for the 110°- 120°E averaged 850 hPa zonal wind （U850）. An index for monitoring the SCSSM ISO is built on a pair of principal component （PC） time se- ries of EOFs mentioned above, and then the NCEP Climate Forecast System Version 2 （NCEP/CFSv2） hindcasts and stepwise regression statistical method are employed, to explore extended range forecast （ERF） of rainfall intraseasonal variations. First, southern China is divided into three regions using rotated empirical orthogonal functions （RE OFs）, where the incidence rate of regionally persistent heavy rainfall （RPHR） is closely linked to the in- traseasonal variation in rainfall. Based on the spatial structure of the first three REOFs, three intraseason- al rainfall indices are constructed by averaging the 30--60-day filtered precipitation over the typical regions and taken as predictands. Second, EOF1 of the 850 hPa zonal wind over the SCS and southern China main- ly represent the ISO mode controlling the intraseasonal rainfall south of the Yangtze River, while EOF2 leads to the intraseasonal out-of-phase rainfall over South China and the Yangtze-Huai River Basins. Pro- jection of the daily data onto the leading pair EOFs of 850 hPa zonal wind yields PC time series that serves as an effective filter for ISO without the need for bandpass filtering and making the PC time series two ef- fective indices for real-time use. The pair of PC time series that form indices are called real-time indices for SCSSM ISO. Finally, 28 years of NCEP/CFSv2 reforecasts are used which include wind at 850 hPa and grid values of rainfall extending up to 30-day lead time. Characteristics of SCSSM ISO are also found simi- lar to observations in the NCEP/CFSv2 reforecasts. Forecast models are built

关 键 词：南海夏季风季节内振荡 实时监测指数 延伸预报 NCEP/CFSv2 

分 类 号：P457.6[天文地球—大气科学及气象学]