Changes of interannual NAO variability in response to greenhouse gases forcing

被引:43
作者
Dong, Buwen [1 ]
Sutton, Rowan T. [1 ]
Woollings, Tim [1 ]
机构
[1] Univ Reading, Dept Meteorol, Natl Ctr Atmospher Sci, Reading RG6 6BB, Berks, England
关键词
The North Atlantic Oscillation (NAO); NAO interannual variability; Greenhouse gases forcing; SST forcing; NORTH-ATLANTIC OSCILLATION; STORM-TRACK VARIABILITY; WINTER CLIMATE; TROPOSPHERIC CIRCULATION; EASTWARD SHIFT; WAVE; TRENDS; STRATOSPHERE; PATTERNS; LINK;
D O I
10.1007/s00382-010-0936-6
中图分类号
P4 [大气科学(气象学)];
学科分类号
0706 ; 070601 ;
摘要
Observations show that there was change in interannual North Atlantic Oscillation (NAO) variability in the mid-1970s. This change was characterized by an eastward shift of the NAO action centres, a poleward shift of zonal wind anomalies and a downstream extension of climate anomalies associated with the NAO. The NAO interannual variability for the period after the mid-1970s has an annular mode structure that penetrates deeply into the stratosphere, indicating a strengthened relationship between the NAO and the Arctic Oscillation (AO) and strengthened stratosphere-troposphere coupling. In this study we have investigated possible causes of these changes in the NAO by carrying out experiments with an atmospheric GCM. The model is forced either by doubling CO2, or increasing sea surface temperatures (SST), or both. In the case of SST forcing the SST anomaly is derived from a coupled model simulation forced by increasing CO2. Results indicate that SST and CO2 change both force a poleward and eastward shift in the pattern of interannual NAO variability and the associated poleward shift of zonal wind anomalies, similar to the observations. The effect of SST change can be understood in terms of mean changes in the troposphere. The direct effect of CO2 change, in contrast, can not be understood in terms of mean changes in the troposphere. However, there is a significant response in the stratosphere, characterized by a strengthened climatological polar vortex with strongly enhanced interannual variability. In this case, the NAO interannual variability has a strong link with the variability over the North Pacific, as in the annular AO pattern, and is also strongly related to the stratospheric vortex, indicating strengthened stratosphere-troposphere coupling. The similarity of changes in many characteristics of NAO interannual variability between the model response to doubling CO2 and those in observations in the mid-1970s implies that the increase of greenhouse gas concentration in the atmosphere, and the resulting changes in the stratosphere, might have played an important role in the multidecadal change of interannual NAO variability and its associated climate anomalies during the late twentieth century. The weak change in mean westerlies in the troposphere in response to CO2 change implies that enhanced and eastward extended mid-latitude westerlies in the troposphere might not be a necessary condition for the poleward and eastward shift of the NAO action centres in the mid-1970s.
引用
收藏
页码:1621 / 1641
页数:21
相关论文
共 87 条
[51]   Stratosphere-troposphere evolution during polar vortex intensification [J].
Limpasuvan, V ;
Hartmann, DL ;
Thompson, DWJ ;
Jeev, K ;
Yung, YL .
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 2005, 110 (D24) :1-15
[52]  
Limpasuvan V, 2000, J CLIMATE, V13, P4414, DOI 10.1175/1520-0442(2000)013<4414:WMAMOC>2.0.CO
[53]  
2
[54]   The changing relationship between the NAO and northern hemisphere climate variability [J].
Lu, J ;
Greatbatch, RJ .
GEOPHYSICAL RESEARCH LETTERS, 2002, 29 (07) :52-1
[55]   A possible mechanism for the eastward shift of interannual NAO action centers in last three decades [J].
Luo, Dehai ;
Gong, Tingting .
GEOPHYSICAL RESEARCH LETTERS, 2006, 33 (24)
[56]   Sensitivity of northern hemisphere surface climate to simulation of the stratospheric polar vortex [J].
Norton, WA .
GEOPHYSICAL RESEARCH LETTERS, 2003, 30 (12) :29-1
[57]  
Osborn T.J., 2006, Weather, V61, P353, DOI [10.1256/wea.190.06, DOI 10.1256/WEA.190.06]
[58]   Simulating the winter North Atlantic Oscillation: the roles of internal variability and greenhouse gas forcing [J].
Osborn, TJ .
CLIMATE DYNAMICS, 2004, 22 (6-7) :605-623
[59]   Downward coupling between the stratosphere and troposphere: The relative roles of wave and zonal mean processes [J].
Perlwitz, J ;
Harnik, N .
JOURNAL OF CLIMATE, 2004, 17 (24) :4902-4909
[60]   Evidence of nonlinear dynamics in the eastward shift of the NAO [J].
Peterson, KA ;
Lu, J ;
Greatbatch, RJ .
GEOPHYSICAL RESEARCH LETTERS, 2003, 30 (02) :2-1