Theory on Perturbation Potential Energy and Its Applications—Concept,Expression and Spatio-Temporal Structures of Perturbation Potential Energy
Theory on Perturbation Potential Energy and Its Applications—Concept,Expression and Spatio-Temporal Structures of Perturbation Potential Energy
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发表时间：
2006
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通讯作者：
Li Jian
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作者：
Li Jian
针对局部环流中的能量转换问题，对微扰势能理论及其应用进行了一系列的研究。首先，在本系列的第一部分中提出了微扰势能的新概念。PPE可分为大气截面（简称PPE）和表面截面（简称PPE），并给出了PPE各阶矩项的数学表达式。结合数据分析可知，PPE的两阶以上的高阶矩项与PPE的一阶和二阶矩项相比，量级较小，可以忽略不计；PPE的二阶矩项在全球范围内的平均值刚好等于传统的有效势能（APE），但两者在物理意义上存在明显差异。基于NCEP/NCAR再分析资料，探讨了PPE的时空结构及其与大气动能（AKE）的关系。PPE的一阶矩项在热带地区为正，在高纬度地区为负，而PPE的二阶矩项在热带和高纬度地区均为最大值，在亚热带和中纬度地区均为最小值，即在经向方向上表现为三峰两谷。局部，由于PPE的一阶矩项在数量级上优于二阶矩项，因此PPE的分布与一阶矩项非常相似。在垂直方向上，PPE主要存在于对流层低层，随着高度的增加，PPE的量级迅速减小，在50 hPa高度以上可以忽略；另一方面，高纬度地区的PPE具有明显的季节变化特征，冬季半球大于夏季半球。南半球或北半球平均PPE的一阶矩项的季节变化幅度比相应的二阶矩项的季节变化幅度大20倍。随着季节的变化，PPE驻波槽脊在北半球表现出明显的纬向运动，而南半球的驻波槽脊只表现出振幅的变化。进一步分析表明，在局地尺度上，AKE与季节行军的一阶矩PPE存在显著的负相关关系，但AKE与二阶矩项的关系不确定。然而，在全球或半球尺度上，AKE与PPE二阶矩项的比值基本不变，约为20%。此外，对总AKE的时空结构分析也有一些不同于以往研究的新结果。在此基础上，本文还将进一步探讨局部环流能量收支分析、地表PPE的作用及其在大气环流变率研究中的应用等相关问题。
On the issue of energy transform in local circulation,the theory on perturbation potential energy(PPE) and its application are investigated in a series of researches.First of all,a new concept on perturbed potential energy is presented in part I of the series.The PPE may be partitioned into the atmospheric section(denoted as the PPE) and the surface section(termed the surface PPE),and mathematical expressions of every-order moment term of the PPE are given.Combined with data analyses,it can be pointed out that all of higher order moment terms of the PPE than two order are small in magnitude and may be omitted in comparison with the first and second order moment terms of the PPE,and that the second-order moment term of the PPE averaged over the globe just is equal to traditional available potential energy(APE),but there is evident difference in physical sense between them.Based on the NCEP/NCAR reanalysis data,the spatio-temporal structures of the PPE and their linkages with the atmospheric kinetic energy(AKE) are examined.The first-order moment term of the PPE is positive over the tropics and negative over high-latitude regions,whereas the second-moment term of the PPE is featured by maxima over both the tropics and high latitudes and by minima over both the subtropics and middle-latitude regions,that is to say,which is featured by three peaks and two valleys in the meridional direction.Locally,as the first-order moment term of the PPE is superior to the second-order one in order of magnitude,the distributions of the PPE are quite similar to the first-order moment term.In the vertical direction,the PPE mostly exists in the low troposphere and quickly decreases in magnitude as height increases,which can be omitted above 50 hPa level.On the other hand,the PPE is characterized clearly by evident seasonal variations and is larger in the winter hemisphere than in the summer hemisphere over high-latitude regions.The amplitudes of seasonal variations for the first-order moment term of the PPE averaged in the Southern or Northern Hemispheres are appropriately twenty times larger than those of the corresponding second-order moment term.Against the seasons,the troughs and ridges of the PPE stationary waves show significant zonal movements in the Northern Hemisphere,however,those in the Southern Hemisphere only show the changes in amplitudes.The analyses further show that on local-regional scales,there exists a significant negative correlation between the AKE and the first-order moment PPE on seasonal march,but the relationship between the AKE and the second-order moment term is uncertain.However,on global or hemispheric scale,the ratios of the AKE to the second-order moment term of the PPE are basically invariable and about 20%.Furthermore,the analyses on the spatio-temporal structures of the total AKE exhibit some new results different from those of the previous researches.Moreover,some further relative problems explored by using the concept and theory of the PPE,such as analysis of energy budget in local circulation,role of the surface PPE,and their applications to the studies on atmospheric general circulation variability,will be given in the future papers of the series.