南海西南季风爆发的气候特征

CLIMATOLOGICAL CHARACTERISTICS ON THE ONSET OF THE SOUTH CHINA SEA SOUTHWEST MONSOON

中文关键词:  南海  西南季风爆发  气候特征

英文关键词:Southe China Sea  Southwest monsoon onset  Climatological characteristics

中文摘要:

      利用多年的海洋船舶、岛屿站和沿岸站观测记录及卫星观测的高反射云(HRC)资料,揭示南海西南季风爆发和建立时期的环流特征及要素变化。在南海,西南季风爆发的平均时间为5月中旬,北部略早(5月12日),南部略迟(5月20日),但年际差别可达一个月左右。伴随着西南季风的爆发,南海云量和降水量增多,对流加强,但海区之间具有很大的不均匀性。西南季风建立以后,强对流区稳定于南海中部,季风雨带没有明显的跳跃现象。西南季风爆发之前,南海表层温度迅速升高,其开始时间较季风爆发约提前一个月,海面水温的升高为季风爆发提供了热量和水汽条件。4-5月,南海海面热交换分量(海面吸收的太阳辐射、潜热输送等)发生明显的改变,特别是潜热交换和蒸发量明显增大,它可能是西南季风首先在南海爆发的原因之一。

英文摘要:

      Based on the marine ship obser vation data, records of the meteorological stations and HRC data by satellite remote sensing with long terms, the circulation patterns and variability in elements during the onset and the established periods of the South China Sea south west(SW) monsoon have studied. The averaged date of the SW monsoon onset over the SCS occurs in the middle of May climatically. The correspo nding date for the northern part is little earlier(May 12) and those for the southern parts are little later, May 20, respectively. The interannual range of the onset dates is about one month. Following the onset of the SW monsoon, the cloud amornt and the precipitation increase while the convection activities enhance over the SCS. But there is a strong spatial variation within the domain. After onset of the SW monsoon the strong convective area moves north wards, while the SCS rain band moves to the center and north. The sea surface temperature increases rapidly before the onset and the leading time is one month. The increment of SST supplies heat and vapor for the onset. In April, the surface heat fluxes display obvious changes, e. g., latent heat exchange and evaporation enhancement. It is one of the reasons why the SW monsoon bursts firstly over the SCS.