大气分层扰动位能控制方程及其应用——南海夏季风活动的能量收支  

Governing Equations of Atmospheric Layer Perturbation Potential Energy and Its Applications—Energy Budget of the South China Sea Summer Monsoon Activity

作　　者：汪雷[1,2] 李建平[1] 郭彦[3] 

机构地区：[1]中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室,北京100029 [2]中国科学院研究生院,北京100049 [3]北京师范大学地表过程与资源生态国家重点实验室,北京100875

出　　处：《大气科学》2012年第4期769-783,共15页Chinese Journal of Atmospheric Sciences

基　　金：国家重点基础研究发展计划项目2010CB950400

摘　　要：针对局地环流能量转换问题,本文推导了分层扰动位能一阶矩(LPPE1)和动能(KE)的控制方程,分析了方程中各能量项的空间分布和季节变化特征,并以南海夏季风为例,诊断了夏季风活动各相位的能量收支特征。结果表明,850hPa高度上在赤道辐合带、大部分季风区、风暴轴地区是LPPE1的源区,副热带的大洋东部和高纬度地区是LPPE1的汇区,强源、汇的中心与LPPE1的纬向偏差场的脊、槽分布对应较好。LPPE1向KE的转化项(CK)取决于垂直速度和大气稳定度,是连接KE和LPPE1的纽带,在暖(冷)空气上升(下沉)时,转化项为正,LPPE1向KE转化能量,反之KE转化为LPPE1。在850hPa高度上CK的分布特征是在赤道辐合带以及大部分季风区有大值分布,北半球风暴轴和南半球西风带有连续分布的正值区。将这应用到南海夏季风活动的能量收支,在南海夏季风恢复相位,CK增大,在南海夏季风活跃相位,CK达到最大,且为边界输入能量的2～3倍,CK是南海夏季风恢复、活跃的最重要因素。探讨了南海夏季风活跃的条件,当LPPE1等于南海季风区的夏季气候平均值时,上升速度大于临界速度的情形,有利于南海夏季风由中断相位向活跃相位的转变。On the issue of energy transform in local circulation, the governing equations of layer perturbation potential energy order 1 （denoted as LppE1） and kinetic energy （KE） are derived and the spatial distribution and seasonal variation of the related terms are investigated, the energy budgets of South China Sea summer monsoon （SCSSM） activity in different phases are studied. At 850 hPa level, the sources of LppE1 locate in the Intertropical Convergence Zone, most monsoon regions, and storm track regions, while the sinks of LI, I, E1 locate in the subtropical eastern oceans and high latitudes. In general, the strong sources （sinks） of LppE1 coincide with the ridges （troughs） in its zonal departure distribution. The conversion term （CK）, which links LppE1 and KE, is determined by the vertical velocity and atmospheric stability. Corresponding to warm air ascending or cold air descending, the conversion term is positive, indicating that LpI, E1 transforms to KE, and vice verse. At 850 hPa, the conversion term is featured by the maxima over the Intertropical Convergence Zone and most monsoon regions, and CK is also positive over the storm track region in the Northern Hemisphere and in the westerly belt in the Southern Hemisphere. This is applied to the energy budget of SCSSM activity; the conversion term grows rapidly in the phase of SCSSM revival and subsequently dominates in the active phase of SCSSM. In the active phase of SCSSM, the conversion term is about 2-3 times as much as the energy flux transported through the boundary, indicating that the conversion term plays a crucial role in SCSSM revival and active SCSSM. In addition, the condition of active SCSSM is explored, the results show that when LppEI equals its summer climatological normals, SCSSM tends to be active if the ascending velocity exceeds the threshold velocity.

关 键 词：南海夏季风 扰动位能 动能 能量循环 季风中断 活跃 

分 类 号：P433[天文地球—大气科学及气象学]