李艳,赵南,董敏. 2009. 下边界条件对北极涛动影响的数值模拟研究[J]. 气象学报, 67(3):388-396, doi:10.11676/qxxb2009.038
下边界条件对北极涛动影响的数值模拟研究
A numerical simulation study of the influence of the low boundary condition on the Arctic Oscillation
投稿时间:2007-10-23  修订日期:2008-03-14
DOI:10.11676/qxxb2009.038
中文关键词:  北极涛动/环状模,下边界条件,波-流相互作用,数值模拟
英文关键词:Arctic Oscillation, Annular mode,Low boundary condition,Wave and mean flow interaction, Numerical simulation
基金项目:国家攀登A计划 南海季风试验项目(SCSMEX),中国气象局新技术推广项目(CMATG2006M07)
作者单位
李艳 中国气象科学研究院灾害天气国家重点实验室北京100081 
赵南 中国气象科学研究院灾害天气国家重点实验室北京100081 
董敏 国家气候中心北京100081 
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中文摘要:
      利用NCAR大气模式CAM3.0探讨了包括山脉和海陆分布等下边界条件对北极涛动(AO)或北半球环状模(NAM)形成的影响。主要进行了控制试验和两个地形敏感性数值试验,对比了控制试验结果与资料分析结果。控制试验和NCEP/NCAR资料分析结果对比指出,CAM3.0模式能够较好地模拟出AO的水平环状结构和垂直相当正压结构。在去除山脉的敏感性试验中发现,AO中纬度北太平洋和北大西洋两个活动中心的强度、范围和位置发生变化。在水球敏感性试验中发现,AO两个大洋上的活动中心被环绕极地主活动中心的环状结构代替。两个敏感性试验共同表明,AO是大气内部某种过程作用的结果,它的存在本身不取决于下边界条件的改变。山脉和海陆分布主要影响的是AO的具体形态。通过控制试验和两个敏感性试验对比,又分析了准定常波和瞬变波对AO 的影响。去除山脉和海陆分布热力差异共同强迫的准定常波,AO纬向平均纬向风高纬地区平流层异常最大值活动中心消失,这表明在平流层准定常波和纬向平均流的相互作用与AO活动关系密切。在只有对流层瞬变波作用时,AO仍然存在,表明准定常波不是AO存在的必要条件。平流层准定常波与平均流的相互作用和对流层瞬变波与平均流的相互作用与AO形成之间的具体关系有待通过E-P通量诊断进一步确定。
英文摘要:
      The Arctic Oscillation (AO) or the Northern Hemisphere annular mode (NAM) is the leading mode of the wintertime variability of sea level pressure over the Northern Hemisphere. The studies on the AO are receiving more and more attention because of its important role in the world's weather and climate. In this paper, the influences of topography and land-sea contrast on the AO or the NAM were examined by use of the NCAR GCM CAM3.0, and the interaction between the wave-mean flow associated with the AO in the stratosphere and that in the troposphere were explored preliminarily. A comparison between the control simulation results and the NCEP/NCAR reanalysis data indicates that CAM3.0 is able to simulate to a great extent the horizontal annular structure and vertical barotropic structure of the AO. Two sensitive experiments were carried out. In the first experiment the topography was removed, and in the second experiment the globe was covered fully by water (an aqua-planet experiment). The first experiment shows that mountains can influence the intensity, range and position of the Pacific and the Atlantic action centers of the AO. The second experiment reveals that the two action centers would disappear and instead a ring structure was found surrounding the Arctic action center, should the globe be covered by water. Both experiments indicate that the existence of the AO is basically independent of the low boundary condition, i.e., the AO is probably the result of some internal processes in the atmosphere, however, the spatial structure of the AO does depend on it. The influences of quasi-stationary waves in the stratosphere and transient waves in the troposphere on the AO were also examined by the comparison between the control and sensitive experiments. The maximum zonal wind speed center in the stratosphere associated with the AO index disappears when the quasi-stationary waves forced by the topography and land-sea contrast are absent, indicating that the AO activities are related to the interaction between the quasi-stationary wave and the zonal flow in the stratosphere. The fact that the AO still exists under only the transient waves in the troposphere indicates that quasi-stationary waves in the stratosphere are not necessary for the existence of the AO. The relationship between the quasi-stationary/transient wave and the mean flow in the stratosphere/troposphere and the origin of the AO may be obtained through an E-P flux diagnosis in the future.
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