南海冷涌期大气动力学与能量学特征

CHARACTERISTICS IN ATMOSPHERIC DYNAMICS AND ENERGETICS DURING THE SOUTH CHINA SEA COLD SURGE PERIODS

本文利用FGGEⅡb探空资料,通过三角形法计算分析了南海冷涌期中低纬度有关动力学和能量学特征量的时空分布,结果表明,在冷涌爆发期,南海南、北海区无论在动力学或能量学的特征上均存在着显著差异。表现在北部下沉气流的加强,“干燥层”降低,大气迅速趋于稳定。南部却相反,上升运动加强,“干燥层”抬升,整层大气湿度增大。与此同时,Hadley环流也得到明显加强;能量学特征主要表现在对中低纬度、高低空水平的和垂直的能量输送,并通过辐散辐合将中低纬度环流连接起来,进而维持南海上空大气能量的平衡。

The temporal and spatial distributions of atmospheric characteristics in dynamics and energetics are calculated and analysed based on FGGEⅡb aerometeorological data. The results indicate that evident differences in the characteristics of dynamics and energetics exist between southern and northern South China Sea during cold surge periods. Around northern South China Sea, the subsidence of air flow is strengthened, 'dry layer' lowers down, and the atmosphere tends to be stable rapidly. However, over southern South China Sea, ascending movement is strengthened, 'dry layer' lifts up and the atmospheric humidity of the whole layer increases. Meanwhile, hadley circulation is obviously intensified. In the aspect of energetics, horizontal and vertical transports of energy occur in the lower and upper troposphere at low and mid latitudes. Moreover, the low and mid latitude circulations are linked through divergence and convergence, and hence the atmospheric energy over the South China Sea is maintained.