南海夏季风爆发早晚的海温预报指数

Sea Surface Temperature Prediction Indices for the South China Sea Summer Monsoon Onset

使用1979—2009年美国国家环境预报中心再分析气候预测系统(CFSR)的日平均资料,确定了1979—2009年南海夏季风爆发的具体日期。使用英国Hadley中心提供的海表面温度月平均资料,根据南海夏季风爆发时间和海温距平的相关场,定义热带西太平洋海温距平指数(WPI)和赤道中太平洋海温距平指数(CEPI)。通过对季风爆发早晚年和正常年的分析对比,定义客观标准:(1)WPI和CEPI从前1年秋季9月到季风爆发前3月份基本保持相反的位相,并且WPI没有发生正负位相转换;(2)WPI从前1年9月到该年3月这7个月的月平均指数的绝对值≥0.2;(3)满足(1)(2)条件后,当WPI<-0.2且CEPI>0,则南海夏季风爆发可能异常偏晚,而当WPI>0.2且CEPI<0时,南海夏季风爆发可能异常偏早;(4)当WPI·CEPI>0时,季风可能正常时间爆发,而满足条件(1)但不满足(2)时季风正常时间爆发的可能性较大。并对2010、2011和2012年南海夏季风爆发早晚做出了比较合理的预测。

With the National Centers for Environmental Prediction （NCEP） Climate Forecast System Reanalysis （CFSR） data, the South China Sea summer monsoon （SCSSM）onset index Uscs defined by Wang et al. （2004）is selected to define the onset date of individual years during 1979--2009. According to the correlation between the SCSSM onset time and the sea surface temperature anomaly （SSTA）, two SSTA indies have been defined. The area mean SSTA over tropical western Pacific （0°-20°N, 125°E-155°E） has been defined as WP index （WPI）, while the area averaged SSTA over the central equatorial Pacific （5°S-5°N, 180°-135°W） has been defined as the CEP index （CEPI）. Define the objective standard （1） WPI and CEPI must keep opposite phase from previous September to the next March, and no transforma- tion happened to WPI~ （2）the absolute value of the averaged monthly （from previous September to the next March） WPI must greater than or equal to 0. 2 （3） When satisfy criterions （1） and （2）, The SCSSM may set up late when WPI and CEPI distribute in the second quadrant （WPI〈0 and CEPI〉0）, while the SCSSM may set up early when they distribute in fourth quadrant （WPI〉0 and CEPI〈0） （4） When the two indices are located in the first and third quadrant （WPI× CEPI〈0）, the SCSSM may set on normally, satisfying （1） but not （2） the SCSSM also set on more normally. The two indices have been applied to predict 2010, 2011 and 2012 SCSSM onset time reasonably.