华南西南季风活跃期间大气热量和动量的收支

HEAT AND MOMENTUM BUDGETS IN SOUTH CHINA DURING ACTIVE SW MONSOON PERIOD

摘要:

本文讨论了西南季风活跃期华南区域平均对流层运动学特征和热量水汽,动量的收支。计算表明,我国西南季风活跃期对流层特征既不同于冷空气活动期也不同南海季风活跃期。此时华南整层对流层处反气旋流场中,无辐散层位于700毫巴,下层辐散上层辐合。西南季风层为下沉运动,上层为上升运动。热量收支表明,季风层为视热汇和视水汽源,东风层为视热源。切变层以上水汽源汇数值很小,不起明显作用。水热源汇主要由垂直运动造成。动量收支表明,在季风层动量基本上是准平衡的,只有在对流层上层和近地面层有动量盈亏,动量收支主要来自地转偏差。最后,我们简单讨论了次网格尺度涡旋对水热平衡的贡献,认为西南季风期垂直涡旋输送十分活跃,其输送水热的作用超过气团变性过程所起的作用。

Abstract:

In this paper,the kinetic characteristics and heat moisture and momenturn budgets of troposphere averaged over South China are discussed.The calculation result indicates that the characteristics during active monsoon period are different either from that during cold air outbreaks or from that during the active monsoon period over South China Sea.There exists downward motion in the sw monsoon layer and upward motion above.The heat budget indicates that there is apparent heat sink and apparent moisture source in the monsoon layer and apparent heat source in the easterly layer. The sources and sinks are mainly caused by vertical motion. The momentum budget indicates that the momentum profit and loss come largely from ageostrophic wind.Further,the contribution of the sub-grid eddies to the balance of moisture and heat is primarily discussed.The vertical transport is very active during sw monsoon period.It plays a greater role than it does in the process of air-mass transformation.