Influence of the North Atlantic SST Variability on the Atmospheric Circulation during the Twentieth Century
Influence of the North Atlantic SST Variability on the Atmospheric Circulation during the Twentieth Century
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DOI：
10.1175/jcli-d-14-00424.1
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发表时间：
2015-02-01
影响因子：
4.9
通讯作者：
Frankignoul, Claude
中科院分区：
文献类型：
--
作者：
Gastineau, Guillaume;Frankignoul, Claude
二十世纪期间，使用海面温度 (SST) 的最大协方差分析和 500 hPa 位势高度分析并对动态诊断（例如 Eady 增长率、波浪活动通量和速度势）进行回归来研究北大西洋的海洋-大气耦合。北大西洋涛动 (NAO) 产生所谓的海温异常三极子。一个相当相似的海温异常三极，副极地异常向东移动，副热带异常（被称为北大西洋马蹄形）反过来影响大气。在秋季和初冬，这种响应与 NAO 类似，主要是由以拉布拉多海和纽芬兰附近为中心的副极地强迫造成的。夏季，大气对海表温度的最大响应类似于东大西洋模式，是副极地和热带强迫共同作用的结果。为了强调年际到数十年的变化，在低通滤波后重复相同的分析。海温影响主要受大西洋数十年振荡（AMO）影响，其也呈马蹄形，但在副极地盆地振幅较大。温暖的 AMO 相位导致夏季仅限于对流层低层的大气变暖，而冬季则导致 NAO 负相位。 AMO 的冬季影响主要是受到北亚热带大西洋海温的影响。 AMO的这种影响出现在冬季而不是初冬，因为冬季海温异常具有更大的持续性，可能是因为海温再现。
The ocean-atmosphere coupling in the North Atlantic is investigated during the twentieth century using maximum covariance analysis of sea surface temperature (SST) and 500-hPa geopotential height analyses and performing regressions on dynamical diagnostics such as Eady growth rate, wave activity flux, and velocity potential. The North Atlantic Oscillation (NAO) generates the so-called SST anomaly tripole. A rather similar SST anomaly tripole, with the subpolar anomaly displaced to the east and a more contracted subtropical anomaly, which is referred to as the North Atlantic horseshoe pattern, in turn influences the atmosphere. In the fall and early winter, the response is NAO like and primarily results from subpolar forcing centered over the Labrador Sea and off Newfoundland. In summer, the largest atmospheric response to SST resembles the east Atlantic pattern and results from a combination of subpolar and tropical forcing. To emphasize the interannual to multidecadal variability, the same analysis is repeated after low-pass filtering. The SST influence is dominated by the Atlantic multidecadal oscillation (AMO), which also has a horseshoe shape, but with larger amplitude in the subpolar basin. A warm AMO phase leads to an atmospheric warming limited to the lower troposphere in summer, while it leads to a negative phase of the NAO in winter. The winter influence of the AMO is suggested to be primarily forced by the Atlantic SSTs in the northern subtropics. Such influence of the AMO is found in winter instead of early winter because the winter SST anomalies have a larger persistence, presumably because of SST reemergence.