全球大气位势高度场气候变率的球函数分析  

Analysis on Spherical Function Structures of Climatic Variability for Global Atmospheric Geopotential Height Fields

作　　者：闫巨盛[1] 王盘兴[1] 段明铿[1] 李巧萍[2] 叶玲萍 

机构地区：[1]南京信息工程大学大气科学系,南京210044 [2]国家气候中心,北京100081 [3]浙江省台州市椒江区气象局,台州318000

出　　处：《应用气象学报》2006年第2期145-151,共7页Journal of Applied Meteorological Science

基　　金：国家自然科学基金重点课题"江淮梅雨的年际和年代变化规律及其机制研究"(40233037)资助

摘　　要：为了研究全球大气位势高度场的气候变率,利用NCEP/NCAR再分析资料,按照距平高度场平均强度指数(Ia)分析发现,半球距平高度场强度呈年单周振荡,冬大夏小,冬季随高度单调增大,夏季有弱高、低值中心出现,而北、南半球的差异明显表现在季节变化上;进一步根据半球大气位势高度距平场球函数谱低维、低阶的基本特征,将半球环流异常分为半球均匀异常(H′00)、纬向均匀异常(H′0)、超长波尺度异常(H′ul)和长波尺度异常(H′l)4种类型,用波数域0≤m,k≤6上的球函数系数资料求得它们的方差贡献,给出了4类异常的方差贡献随高度、季节变化的规律以及它们的半球际差异。由此得到异常环流球函数谱结构的总体特征为:对流、平流层之间存在明显变化。从对流层进入平流层,一般由超长波异常为主转为纬向均匀异常为主(冬半球)或半球均匀为主(夏半球);半球均匀异常在对流层中不重要,长波尺度异常在平流层中不重要,它们拟合异常方差一般均小于10%;北、南半球最大差异表现在冬季平流层R′00和冬、夏季对流层R′0南半球大于北半球,冬、夏季对流层Rl′北半球大于南半球。The anomaly of height fields is set up based on the temporal decomposition of these fields, and even continuations from hemisphere to globe at certain level in certain month are made. During the study, two kinds of monthly averaged geopotential fields dataset is used, namely 2.5° by 2.5° resolution even rectangular grid data and spherical function coefficient data derived from 1958-1997 NCEP/NCAR reanalyzed geopotential height fields dataset. Firstly based on the previously defined intensity index of climate anomaly fields （Ia）, it demonstrates the intensity variations of hemispheric anomaly fields at the different height and seasons, and the differences between Northern and Southern Hemisphere are also investigated. Then according to the low-dimension and low-order characteristics of the spherical function spectrum in the hemispherical geopotential height anomaly fields, hemispherical circulation anomaly is divided into four types： hemispherical homogeneous anomaly, zonal homogeneous anomaly, ultra-long and long wave scale anomaly. The corresponding variance contributions （R′00, R′0, R′ul, R′l） are also calculated respectively by using spherical function coefficient data with the wavenumber of m ≥0, k≥6. Finally the variations and their hemispheric differences of the four anomalies above as the function of height and seasons are discussed in detail. The main results are as follows： ① Ia shows a yearly periodic oscillation and is stronger in winter than in summer. The index always increases with the height, especially in winter. However in summer Ia has a weak high （low） value center near the tropopause （the upper stratosphere） respectively. The difference between the two hemispheres is that the seasonal variation of Ia in the Southern is weaker than the Northern at the troposphere. ② For the spectral structure of the anomaly circulations, there are some obvious changes from the troposphere to the stratosphere. In the troposphere the ultra-long wave circulation is predomin

关 键 词：全球大气 位势高度场 气候变率 球函数分析 

分 类 号：P467[天文地球—大气科学及气象学]