2000年南海季风爆发前后西沙海域海-气热量交换特征

The air-sea heat exchange at Xisha areas during the onset of southwest monsoon in 2000

利用2000年5月6日至6月17日在西沙海域进行的第二次南海海-气通量观测资料,计算了南海季风爆发前后海洋-大气间的辐射收支、感热通量、潜热通量及海洋热量净收支;发现季风爆发后海-气热量交换突然发生变化,其中潜热通量、海洋热量净收支变化尤为显著。讨论了季风爆发前后各种天气过程影响下海-气热量、水汽交换特点和海洋热量净收支变化,说明季风爆发前海洋是一个能量积累过程,季风爆发期海洋是一个能量释放过程,季风中断期海洋是一个能量再积累过程;季风爆发后西南大风期持续时间和强度,强烈影响水汽蒸发量大小,进而影响我国大陆上夏季降水,通过南海与阿拉伯海、孟加拉湾、西太平洋暖池等不同海域资料对比,分析了它们在海-气热量交换上的差别,指出这种差别是爆发后南海SST基本稳定而阿拉伯海、孟加拉湾SST明显降低的主要原因。

Using the observational data of the Second SCS Air - Sea Flux Experiment on the Xisha air - sea flux research tower during May 7 to June 17, 2000, the radiation budget, latent and sensible heat fluxes and net oceanic heat budgets before and after summer monsoon onset were calculated. It is found that there are considerable changes on air - sea fluxes, especially on latent heat fluxes and net oceanic heat budget after summer monsoon onset. Furthermore, the analyzed results of five synoptic stages are compared and the special characteristics of flux transfer during the different stages around onset of SCS monsoon are discussed. The fluxes change shows that there is an oceanic heat accumulating process in pre-onset and break period and an oceanic heat loss process in the onset period. Also the latent fluxes and water vapor transported to continent can be influenced by the duration and intension of the southwester especially, further influence on the rainfall appearance in China continent. Finally, through comparison of the Xisha fluxes with those obtained from Indian Ocean and western Pacific Ocean, their differences may be seen. It can explain why after monsoon onset, the SST can keep stable values over the SCS while over the Arabian Sea and the Bay of Bengal they decrease quickly.