| 扰动位能理论及其应用——扰动位能的概念、表达及其时空结构 |
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| 引用本文： | 李建平,高丽.扰动位能理论及其应用——扰动位能的概念、表达及其时空结构[J].大气科学,2006,30(5):834-948. |
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| 作者姓名： | 李建平 高丽 |
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| 作者单位： | 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 |
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| 摘 要： | 针对局地环流能量转换问题,该工作系列讨论扰动位能理论及其应用.此文是第一篇,提出了扰动位能的新概念,将其分解为大气扰动位能(简称扰动位能)和表面扰动位能两个部分,给出了扰动位能各阶矩项的数学表达形式,结合资料指出二阶以上的扰动位能高阶矩项相对于其一阶矩项和二阶矩项来说是小量,可忽略,并指出扰动位能二阶矩项的全球平均恰好等于传统的有效位能,但两者在物理意义上明显不同.结合NCEP/NCAR再分析资料,研究了扰动位能的时空结构以及与大气动能之间的联系.扰动位能一阶矩项在热带地区为正、高纬度地区为负; 二阶矩项在热带和高纬度地区出现极大值,在副热带及中纬度地区出现极小值,即在南北方向上呈现三峰二谷的特征; 在局地上,由于一阶矩项在数值上较二阶矩项绝对占优,因此,扰动位能的分布与其一阶矩项的情形相似.在垂直方向上,扰动位能主要集中在对流层下层,其数值随高度的增加而迅速减少,在50 hPa以上均可以忽略不计.扰动位能有明显的季节变化,其在高纬度地区在冬半球比夏半球大很多; 南、北半球平均的扰动位能一阶矩项季节变化的幅度约是相应二阶矩项的二十倍.随着季节变化扰动位能定常波的槽脊在北半球有显著的东西方向移动,而在南半球则只表现为振幅上的增减.分析表明,从区域或局地尺度上大气动能的季节变化与扰动位能一阶矩项的关系密切,二者呈显著反向变化关系,而与二阶矩项的关系不确定; 但在全球或半球尺度上,大气动能与扰动位能二阶矩项的比率随季节基本保持不变,约是20%.此外,对大气总动能时空结构的分析也得到了与前人不同的新结果.关于利用此文提出的概念和理论对局地环流能量收支的分析、表面扰动位能的作用以及它们在大气环流变化研究中的应用,将在以后的文章中给出.
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| 关 键 词： | 扰动位能 能量 有效位能 大气参考状态 动能 |
| 文章编号： | 1006-9895（2006）05-0834-15 |
| 收稿时间： | 2006-05-12 |
| 修稿时间： | 2006-05-122006-06-07 |
Theory on Perturbation Potential Energy and Its Applications-Concept, Expression and Spatio-Temporal Structures of Perturbation Potential Energy |
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| LI Jian-Ping and GAO Li.Theory on Perturbation Potential Energy and Its Applications-Concept, Expression and Spatio-Temporal Structures of Perturbation Potential Energy[J].Chinese Journal of Atmospheric Sciences,2006,30(5):834-948. |
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| Authors: | LI Jian-Ping and GAO Li |
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| Institution: | 1 State Key Laboratory of Numerical Modelling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029; 2 Graduate University of the Chinese Academy of Sciences, Beijing 100049 |
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| Abstract: | 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. |
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| Keywords: | perturbation potential energy energetics available potential energy atmospheric reference state kinetic energy |
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