韩荣青,李维京,董敏. 2010. 副热带北太平洋大气季节内振荡时空特征的诊断研究[J]. 气象学报, 68(4):520-528, doi:10.11676/qxxb2010.050
副热带北太平洋大气季节内振荡时空特征的诊断研究
A diagnostic study of the temporal and spatial characteristics of the intraseasonal oscillation over the subtropical northern Pacific
投稿时间:2008-08-13  修订日期:2009-05-26
DOI:10.11676/qxxb2010.050
中文关键词:  副热带,经向风,季节内振荡(ISO),气候特征
英文关键词:Subtropics, Meridional wind, Intraseasonal oscillation (ISO), Climatic characteristics
基金项目:国家重点基础研究发展计划项目(2006CB403606)、国家自然科学基金项目(40575027,40905035)和国家行业专项项目(GYHY200806004)
作者单位
韩荣青 国家气候中心, 北京, 100081 
李维京 国家气候中心, 北京, 100081 
董敏 国家气候中心, 北京, 100081 
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中文摘要:
      用时空谱分析和小波变换方法,对1958—2002年NCEP/NCAR再分析资料经、纬向风速和位势高度的年时间序列进行了波谱分析,并重点研究了北太平洋副热带区域经向风30—60天振荡(ISO)的时空特征。研究结果表明,北半球经向风与纬向风和位势高度的30—60天振荡特征迥然不同,代表风场经向低频扰动的经向风ISO在副热带和中高纬度最为活跃,而在热带地区的活动十分微弱;北半球副热带850 hPa高度场和纬向风在10—90天内(季节内)振荡的主要能量集中在纬圈波数为1、周期为30—60天的波动上,而850 hPa经向风季节内振荡的主要能量集中在纬圈波数为4—6、周期为30—60天以及70—90天的波动上,上述3个物理量30—60天振荡向西传播的能量都强于向东传播的能量。一年当中,东亚到北太平洋的副热带地区,经向风ISO在东亚—西北太平洋与东北太平洋两个区域的活动最强,且在这两个区域存在明显的季节振荡,即东北太平洋的ISO在冬季最强在夏季最弱,而东亚—西北太平洋区域的ISO在夏季最强冬季最弱。 850 hPa经向风ISO的年际和年代际变化分析表明,在东亚副热带区域其活动1958—1975年较强,1976—1990年明显减弱,而1991—2000年最强;其在ENSO发生期间有较为明显的异常活动,但其强弱变化没有显著的定势,然而2—7年的带通滤波分析表明西北太平洋ISO的年际活动含有较显著的ENSO信号,9年的低通滤波分析表明,年代际时间尺度上,西北太平洋ISO的活动与ENSO循环有较为显著的反相关特征,而东北太平洋区域ISO与ENSO循环有较为显著的正相关关系。
英文摘要:
      Because the intraseasonal oscillation (ISO) was found as a strong signal for the summer precipitation in the East Asia as shown in the recent studies, its climatic characteristics in the boreal subtropics and especially in the subtropical northern Pacific were revealed in this paper using the spatio temporal spectrum method and wavelet analysis based on the NCEP NCAR Reanalysis Data for the period of 1958—2002. The specific results show as follows. The variance ratio of the ISO to all waves for the meridional wind over the subtropics is strikingly bigger than that in tropics, which is distinct from those for the zonal wind and height. At 850 hPa level, the waves with zonal wave numbers 4—6 and periods of 30—60 d or 70—90 d are dominant with the meridional wind for the intraseasonal scale (10—90 d) in despite of the dominant waves with zonal wave number 1 and periods of 30—60 d with the height and zonal wind. The power spectra of the westward propagation are all stronger than those of the eastward propagation for the above three variables. And it is found that an interseasonal “seesaw” of meridional wind ISO swings between the two regions, that is, the region from East Asia to the northwestern Pacific and the region of the northeastern Pacific, in which the power spectra of 30—60 d oscillations are the strongest in summer and weakest in winter in the former region and the reverse in the latter region, with the boreal spring and autumn just as the transition phases for the ISO activities for both the regions. In addition, the decadal and interannual variation characteristics of ISO over the subtropical North Pacific are presented in this paper which show that the ISO activities over the subtropical northwestern Pacific are moderate during 1958—1975, weak during 1976—1990, and robust during 1991—2000. During ENSO events occurring, the subtropical ISO presents quite different behaviors from those in the tropics and appears irregularly. However, the results of 2—7 year band pass filter reveal that the ISO over the northwestern Pacific holds notable ENSO signals, while the 9 year low pass filtered results manifest that the ISO variation over the northwestern Pacific are negatively correlated with the ENSO cycle and positively correlated over the northeastern Pacific.
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