月内尺度北半球环状模水平和垂直活动特征分析  

Meridional and vertical propagation characteristics of the submonthly Northern Hemisphere Annular Mode

作　　者：李晓峰[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地球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：《气象学报》2011年第6期1046-1061,共16页Acta Meteorologica Sinica

基　　金：中国科学院知识创新工程重要方向项目(KZCX2-YW-Q11-01);国家重点基础研究发展规划项目(2010CB950400);国家自然科学基金资助项目(40905040);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自由探索项目

摘　　要：采用李建平等定义的更好表征北半球环状模变化的指数,利用NCEP/NCAR逐日再分析资料,从对流层的角度分析了北半球环状模在月内时间尺度上的相关环流的垂直和水平传播特征。结果表明,在水平方向上,温度异常在对流层,尤其是近地层,表现为由极区和高纬度地区向中低纬度地区强的南传特征,而在平流层则为由中低纬度地区向高纬度地区弱的北传特征;纬向风场异常则表现为整层由高纬度地区向中低纬度地区的南传特征。垂直方向上,温度异常在中纬度地区具有较强的自下对流层向平流层上传现象,在高纬度和热带地区则为下传特征;纬向风异常在北半球大部分地区都表现为明显的上传特征。在水平方向上,与北半球环状模月内主要特征尺度(即准1周、准2周和准3周)上相关的环流传播特征比较相似;在垂直方向上,北半球环状模准1周和准2周时间尺度上的环流传播特征较为相似,而准3周尺度上的环流传播特征与它们差异稍大。在对流层中低层,上述环流异常较强的南传特征表明,在月内时间尺度上中高纬度环流异常对中低纬度环流异常可能具有重要的预测意义;而在北半球中纬度地区月内北半球环状模对应温度异常和纬向风场异常信号存在明显的上传特征表明,与北半球环状模异常活动相关的天气变化并非完全源于平流层,在较短时间尺度上,对流层的信号可以突破对流层顶,上传达到平流层。From a ＂troposphere view＂, the related horizontal and vertical circulation anomalies propagation characteristics of the Northern Hemisphere Annular Mode （NAM） in submonthly timescales （5 - 30 d） are studied by using the NCEP/NCAR rean- alysis daily data and Li and Wang＇s new NAM index, which can express better variation structure of the NAM. The results show that in the horizontal direction, the temperature anomaly shows intense southward propagation in the troposphere from the polar region and high latitudes to the equator, especially in the surface layer, while it shows weak northward propagation in the stratosphere from the midqow latitudes to the high latitudes. And the zonal wind anomaly exhibits obviously southward propagation characteristics from the high latitudes to the equator nearly in all levels. In the vertical direction, the temperature anomaly shows upward propagation from the troposphere to the stratosphere in the middle latitudes and downward propagation from the stratosphere to the troposphere in the high and low latitudes. And the zonal wind anomaly propagates upward nearly in all the latitudes in the Northern Hemisphere. The horizontal propagation characteristics are similar on the main submonthly character time scales （quasi-week, quasi-two-week and quasi-three-week）, but the vertical propagation characteristics are simi- lar on quasi-week and quasi-two-week, but the vertical circulation anomalies propagation on quasi-three-week is different from the other two submonthly character time scales. The atmosphere general circulation anomalies related to the NAM propagate strongly from the polar region to the equator in the troposphere of the Northern Hemisphere on submonthly timescales, which implies that the atmosphere anomalies in the mid high latitudes may have predictive skills to atmospheric anomalies in the mid-low latitudes on the relative short timescales; and the characteristics of upward propagation of the temperature and zonal wind anomalies on submonthly timescales i

关 键 词：北半球环状模 月内时间尺度 水平传播 垂直传播 

分 类 号：P434[天文地球—大气科学及气象学]