Dominant SST Mode in the Southern Hemisphere Extratropics and its Influence on Atmospheric Circulation
Dominant SST Mode in the Southern Hemisphere Extratropics and its Influence on Atmospheric Circulation
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南半球温带海温主导模态及其对大气环流的影响
DOI：
10.1007/s00376-017-7162-7
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发表时间：
--
影响因子：
5.8
通讯作者：
Liu Ting
中科院分区：
文献类型：
--
作者：
Zheng Fei;Li Jianping;Fred Kucharski;Ding Ruiqiang;Liu Ting
南大洋(SO)海表面温度(SST)的变率因其独特的物理特征而受到越来越多的关注，因此，本文研究了SST异常的时间特征及其对温带外大气环流的影响。经验正交函数分析结果表明，SOSSTA的主模呈现类偶极子结构，表明中高纬度SSTA之间存在负相关，本文称之为SO偶极子(SOD)。超氧化物歧化具有很强的纬向对称性，可以反映50%以上的海温变率。我们发现，亚南极和南极极锋的较强(较弱)与超氧化物歧化指数的正(负)位相有关，也与大尺度SSTA经向梯度的初级变率有关。在12-1-2月期间，由于SSTA的变化，费雷尔环流和极地急流向南极移动，这可能与超氧化物歧化酶的正位相有关，并伴随着副热带急流的极移。在6-7-8月期间，伴随着一个正的超氧化物歧化酶，费雷尔环流和极地急流加强，伴随着一个加强的副热带急流。这些季节差异与南半球极地急流和副热带急流的形态不同有关。
The variability in the Southern Ocean (SO) sea surface temperature (SST) has drawn increased attention due to its unique physical features; therefore, the temporal characteristics of the SO SST anomalies (SSTA) and their influence on extratropical atmospheric circulation are addressed in this study. Results from empirical orthogonal function analysis show that the principal mode of the SO SSTA exhibits a dipole-like structure, suggesting a negative correlation between the SSTA in the middle and high latitudes, which is referred to as the SO Dipole (SOD) in this study. The SOD features strong zonal symmetry, and could reflect more than 50% of total zonal-mean SSTA variability. We find that stronger (weaker) Subantarctic and Antarctic polar fronts are related to the positive (negative) phases of the SOD index, as well as the primary variability of the large-scale SO SSTA meridional gradient. During December–January–February, the Ferrel cell and the polar jet shift toward the Antarctic due to changes in the SSTA that could be associated with a positive phase of the SOD, and are also accompanied by a poleward shift of the subtropical jet. During June–July–August, in association with a positive SOD, the Ferrel cell and the polar jet are strengthened, accompanied by a strengthened subtropical jet. These seasonal differences are linked to the differences in the configuration of the polar jet and the subtropical jet in the Southern Hemisphere.