北半球500hPa位势高度场时空频谱特征分析  

Spatial-Temporal Spectral Analysis of the Northern Hemisphere 500-hPa Geopotential Height

作　　者：孙诚[1,2] 李建平[1] 

机构地区：[1]中国科学院大气物理研究所大气科学和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

出　　处：《大气科学》2011年第6期1079-1090,共12页Chinese Journal of Atmospheric Sciences

基　　金：国家重点基础研究发展计划2010CB950400;国家自然科学基金资助项目41030961;40821092

摘　　要：利用1979～2004年NCEP2再分析资料,对逐日的北半球(20°N～90°N)500hPa的位势高度进行二维傅里叶的谱展开,并分析了不同波数下的谱展开系数的频域特征。对全年序列分析的结果表明:当纬向波数k和经向波数l均为0时,其谱展开系数表现为显著的低频(10～30天)变化特征;当经向波数l=0时,其谱展开系数的频域特征随纬向波数k的变化较大,表现为大尺度波动以低频变化为主而小尺度波动则以高频(4～8天)变化为主;当纬向波数k=0时,其谱展开系数的频域特征随经向波数l的变化不大,均表现为很强的低频特征;当纬向波数k和经向波数l均不为0时,其谱展开系数的低频分量主要表现为经向1波(l=1)的空间结构,这与中高纬低频环流异常多以经向偶极子的特征出现是对应的。对冬、夏半年序列分别分析的结果与全年序列分析的结果并无显著差别。经典的纬向基流罗斯贝波频散关系可部分解释上述特征。Using NCEP2 reanalysis data from 1979 to 2004,the daily 500-hPa geopotential height in the Northern Hemisphere（20°N-90°N） has been expanded into double Fourier series and the signals in the frequency domain have been analyzed for different spatial scales.For the daily series in the entire year,when both the zonal wave number k and the meridional wave number l equal zero,the signals series are characterized by a significant low-frequency variation（10-30 days）.When the meridional wave number l equals zero,the signals in the frequency domains vary with the zonal wave number k significantly.The coefficient series consist of a low-frequency variation at larger spatial scales and a high-frequency variation（4-8 days） at smaller spatial scales.When the zonal wave number k equals zero,the signals in the frequency domains vary little with the meridional wave number l.The coefficient series are characterized by a low-frequency variation.When both k and l are not equal to zero,the spatial scales of low-frequency variations mainly concentrate on l=1,corresponding to the dipole structure of low-frequency flows in the mid-high latitudes.The results for daily series during the winter or summer half year are similar to those during the entire year.The diagnosis results can be explained,to a certain extent,by the dispersion relation for the Rossby wave.

关 键 词：二维傅里叶分解 标准化功率谱 频散关系 位势高度 经向偶极子 

分 类 号：P434[天文地球—大气科学及气象学]