基于1982年1月—2006年12月NOAA Optimum Interpolation Sea Surface Temperature(OISST)的逐月平均海面温度(SST)资料,采用经验正交函数分解(EOF)方法分析了南海南部海面温度异常场典型的空间分布形态及其时间变化特征。结果表明,南海南部海域海面温度异常场空间上主要表现为三种典型的分布结构,即以研究区域北部为中心的海盆尺度的单涡结构、东西反相的经向偶极子分布结构和南北反相的纬向偶极子分布结构,这三种分布结构都以2—4年的年际变化周期为主,反映了研究海域海面温度异常与ENSO现象高度相关。此外,研究海域还存在显著的半年和季节内周期变化,这种变化周期主要以南北反相的纬向偶极子分布结构(第三模态)存在,反映了大气动力强迫和热力强迫共同影响的结果。
Based on the monthly averaged sea surface temperature (SST) derived from the optimum interpolation sea surface temperature (OISST) from January 1982 to December 2006, the authors analyze the spatial and temporal variability of SST anomalies (SSTA) in southern South China Sea using the Empirical Orthogonal Function (EOF) method. The results show the existence of three major SSTA spatial patterns, which include the basin-scale single gyre pattern with the center in the northern area, the west-eastward antiphase dipole pattern, and the north-southward antiphase dipole pattern. The three modes all have interannual variations, which reflect the relationship between the SSTA of southern South China Sea and ENSO phenomena. The semi-annual and the intraseasonal variations are also found in Mode 3, which results from wind forcing and heat budget.