南海海表面温度的季节内变化特征

基于TRMM/TMI卫星遥感海表面温度(SST)数据,采用谐波分析方法和经验正交函数分解(EOF)方法对南海SST的季节内变化规律进行了分析,探讨了其对声速变化规律的影响。结果表明:南海SST季节内空间分布的第一模态呈现南北负正反对称分布;第二模态的空间分布为以越南外海的负值为中心。分析相应的时间系数功率谱可知其显著周期为5、6、8、11、12周。分析表明SST的季节内振荡与纬向风分量、经向风应力有密切关系。探讨潜热通量可发现其显著周期为54～69天,存在显著的季节内变化;冬夏季变化的最大区域分别集中在越南外海和南海北部,且第一模态的时间函数与潜热通量的最大相关系数可达到40%,相关系数的大值区域主要集中在越南上升流区域。南海海表声速较大但随季节变化不明显,与温度同相变化与盐度反相变化。

Intraseasonal Variabilities of Sea Surface Temperature in the South China Sea

Based on the TRMM/TMI satellite remote sensing data during 1998 to 2010, the intra -seasonal variabilities of the sea surface temperature （SST） in the South China Sea are analyzed by using empirical orthogonal function （EOF） meth- od and harmonic analysis, and the possible mechanism for generating the intra - seasonal SST variabilities is also discussed. The effect on sound speed is analyzed. The spatial mode of the first EOF indicates the SST variation is north - south antisym- metric. The center of the second EOF is the coastal sea of Vietnam. Their significant variation period is 5,6,8,11,12 weeks, the variation is closely related to zonal wind component and meridional wind stress. The significant period of latent heat flux is from 54 days to 69 days. The biggest values are in the coastal sea of Vietnam in summer and in northern South China Sea in winter. The time series of the first mode associated with latent heat flux and the correlation coefficient is 40%. The sound speed in the South China Sea is high, and its variation is not significant. The phase of sound speed changes with SST and has a reversed phase with salinity.