南海夏季风降水的区域差异及其突变特征

使用1950~1997年NCAR/NCEP再分析逐日降水资料,采用聚类和相关分析相结合的方法对南海夏季风降水进行了区域划分,分析了南海夏季风降水爆发前后南海降水的突变特征。结果表明:南海 105~120°E,0~20°N区域可划分为 SCS1区、SCS2区、SCS3区和SCS4区4个小区域,每个区域的降水有其各自不同的变化特征。前三个区域的降水变化不显著,不能反映南海夏季风降水爆发的突然性,变化最显著的是SCS4区,它最好地刻画了南海夏季风降水的变化特征,因此,我们选取它作为今后工作中南海夏季风降水的研究范围。突变检验表明,5月17日,南海SCS4区降水发生明显的突变,与5月15日相比,SCS4区降水场形势发生明显变化,其区域平均降水突增超过6 mm/day,标志着南海夏季风降水的爆发。

DIFFERENT CHARACTERISTICS OF PRECIPITATION OVER FOURSUB-REGIONS OF SOUTH CHINA SEA DURING SUMMERMONSOON AND THE ABRUPT CHANGE

Using NCAR/NCEP reanalyzed daily precipitation data from 1950 to 1997, different characteristics of precipitation over four sub-regions over South China Sea (SCS) and the abrupt change associated with the onset of SCS summer monsoon are studied. The results show that there are great differences in precipitation over four sub-regions, and the precipitation of the fourth region (SCS4) (110-120°E, 10-20°N) can best depict the summer monsoon precipitation over SCS. On May 17^th, the precipitation of SCS changes abruptly, the regional averaged precipitation increases and exceeds 6 mm/day, which indicates the onset of SCS summer monsoon.