南海蒸发和净淡水通量的季节和年际变化

以19年（1988～2006年）的SSM/I（Special Sensor Microwave/ Imager）卫星观测为基础，计算了南海的逐月海面蒸发量，并结合SSM/I的降雨观测，得到了南海的逐月净淡水通量，并分析其季节和年际变化.研究结果表明：南海的蒸发量年变化基本呈双峰型结构，降雨和净淡水通量呈单峰型结构.1988～2001年，南海的蒸发量呈上升趋势，增长速率为1 mm/yr；2001～2006年，以1.9 mm/yr的速率减少.南海的降雨量和净淡水通量与Nino3指数成负相关，相关系数为-0.62和-0.58.在1997～1998厄尔尼诺暖事件期间，降雨量和净淡水通量均显著下降，且以其为界，降雨量在此之前以1.3 mm/yr的速率增长，净淡水通量升降趋势不明显；而在此之后，降雨以8.5 mm/yr的速率下降，净淡水通量的下降速率为7.5 mm/yr.

Seasonal and interannual variabilities of evaporation and net freshwater flux in the South China Sea

The 19-year (1988～2006) Special Sensor Microwave/ Imager (SSM/I) data were used to acquire the spatial and temporal distribution characteristics of sea surface evaporation, precipitation and net freshwater flux in the South China Sea. The seasonal and interannual variabilities and their long-term linear trends were also studied. The results show that there exist obvious seasonal and interannual variabilities. The seasonal cycle of sea surface evaporation has a double-peak curve, while precipitation and net fresh water flux show a single-peak curve. Sea surface evaporation has an increasing rate of 1 mm/yr during 1988~2001 and a decreasing rate of 1.9 mm/yr during 2001~2006. Noticeable declines in precipitation and net freshwater flux happened during 1997~1998 El Nino event. The annual rates of decreasing precipitation and net freshwater flux after the warm event are 8.5 mm/yr and 7.5 mm/yr, respectively.