南海表层水温场的时空特征与长期变化趋势

Spatial and temporal oscillation and long-term variation in sea surface temperature field of the South China Sea

本文利用月平均表层水温（SST）、850hPa经向风和西太平洋副热带高压等资料分析了南海表层水温距平（SSTA）场的时空特征和长期变化趋势，并探讨了SST的年际和长期变化原因．结果表明，南海SSTA场分别存在着以全域同位相振荡和东南一西北向反位相振荡的两个主要模态．其中，前者是主要模态，以年际振荡为主，而后者则是次要模态，以季节振荡为主．进一步分析发现，南海中部的SST存在着显著的年际和年代际变化，并在1981年前后发生了一次由低到高的气候转变，而且南海中部SST的长期变化趋势非常明显，在1950—2006年间增温0．92℃．相关和合成分析表明，南海SST的年际和长期变化可能是由南海上空的经向风异常和西太平洋副热带高压的纬向变动引起的．

Based on monthly mean sea surface temperature （SST） ,850hPa wind and subtropical high index over the western Pacific during 1950 - 2006 ,the spatial and temporal oscillation and long-term variation in SST field of the South China Sea （SCS） are analyzed by using empirical orthogonal function （EOF）, polynomial function and spectrum analysis, and then the causes of SST interarmual and long-term variation are discussed by using correlation and composite analysis. The results show that SST anomaly fields have two major patterns. SSTs over the South China Sea have spatially in-phase interannual variation and seasonal oscillation with out-of-phases between the west and east South China Sea. The SST in the central South China Sea exhibit significant interannual and interdeeadal variations,and experienced a climate jump in 1981. The annual mean SST in the central South China Sea has increased by 0.92℃ from 1950 to 2006. It is also suggested that the interannual and long-term variations in SST of the South China Sea may be resulted from the meridional wind anomaly and zonal migration of the subtropical high over the western Pacific.