The linearity of the El Niño teleconnection to the Amundsen Sea region.
The linearity of the El Niño teleconnection to the Amundsen Sea region.
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厄尔尼诺现象与阿蒙森海地区遥相关的线性。
DOI：
10.1002/qj.3731
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Yiu YYS
中科院分区：
文献类型：
--
作者：
Yiu YYS
厄尔尼诺/南方涛动（ENSO）通过改变阿蒙森海地区（ASR）的大气环流，驱动南极西部气候的年际变化。厄尔尼诺-ASR遥相关在南方冬季和春季最强，但其与厄尔尼诺振幅的变化尚未得到充分研究。本研究使用HadGEM 3 ‐A气候模式的实验来研究一系列从弱（0.75 K）到强（3 K）振幅的强加SST扰动的厄尔尼诺-ASR遥相关。在南半球冬季，厄尔尼诺-ASR遥相关在2.25 K以下呈线性，但在较强强迫（3 K）下减弱。副热带南太平洋Rossby波源异常随厄尔尼诺振幅的增大而单调增大。然而，最初位于南太平洋西部的Rossby波反射面随着厄尔尼诺幅度的增加而逐渐向东延伸，减少了进入ASR的波传播。波反射面与对流层上部纬向风的曲率有关，在厄尔尼诺强迫下，随着副热带急流的加强，纬向风的曲率会加强。与此相反，厄尔尼诺-ASR遥相关在南半球夏季，这更接近于南方环形模，被发现线性增加厄尔尼诺振幅高达3 K。结果明确表明，根据最近历史上观测到的厄尔尼诺振幅范围，厄尔尼诺遥相关对ASR的线性近似是合理的。
El Niño Southern Oscillation (ENSO) drives interannual variability in West Antarctic climate through altering atmospheric circulation in the Amundsen Sea region (ASR). The El Niño–ASR teleconnection is known to be strongest in austral winter and spring, but its variation with El Niño amplitude is underexplored. This study uses experiments from the HadGEM3‐A climate model to investigate the El Niño–ASR teleconnection for a range of imposed SST perturbations spanning weak (0.75 K) to strong (3 K) amplitudes. In austral winter, the El Niño–ASR teleconnection behaves linearly for El Niño amplitudes up to 2.25 K, but is found to weaken for stronger forcing (3 K). The anomalous Rossby wave source in the subtropical South Pacific increases monotonically with El Niño amplitude. However, a Rossby wave reflection surface originally located in the western South Pacific sector extends progressively eastward with increasing El Niño amplitude, reducing wave propagation into the ASR. The wave reflection surface is associated with curvature in the upper tropospheric zonal winds which intensifies as the subtropical jet strengthens under El Niño forcing. In contrast, the El Niño–ASR teleconnection in austral summer, which more closely resembles the Southern Annular Mode, is found to increase linearly for El Niño amplitudes up to 3 K. The results explicitly demonstrate that a linear approximation of the El Niño teleconnection to the ASR is reasonable based on the range of El Niño amplitudes observed in recent history.