On the Seasonality of the El Niño Teleconnection to the Amundsen Sea Region
On the Seasonality of the El Niño Teleconnection to the Amundsen Sea Region
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论阿蒙森海区厄尔尼诺遥相关的季节性
DOI：
10.1175/jcli-d-18-0813.1
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发表时间：
2019
影响因子：
4.9
通讯作者：
Maycock A
中科院分区：
文献类型：
--
作者：
Maycock A
阿蒙森海低压（英语：Amundsen Sea low）是一个影响西南极气候的准定常低压系统。以往的研究表明，厄尔尼诺-南方涛动（ENSO）调制的位置和强度的ASL与最强的遥相关发现在南冬季，尽管ENSO事件的振幅通常是最大的南秋季/夏季。这项研究调查厄尔尼诺遥相关的季节性背后的机制，阿蒙森海地区（ASR）使用的实验与HadGEM 3气候模式被迫与一个理想化的固定厄尔尼诺海表温度异常存在全年。厄尔尼诺-ASR遥相关的季节性是由南太平洋大尺度纬向风的季节性差异引起的。在南半球冬季，与副热带急流相关的30°S附近的强绝对涡度区，加上厄尔尼诺扰动引起的对流层上层散度的变化，充当了南半球夏季基本上不存在的异常Rossby波源。此外，在南太平洋夏季，热带来源的Rossby波向极地传播到ASR被南太平洋部门的强极锋急流抑制，这导致Rossby波反射远离ASR。在南半球冬季，Rossby波能够传播到ASR中，形成太平洋南美洲型的一部分。热带太平洋Rossby波源的缺乏和波传播的有利条件的缺乏解释了与冬季相比，夏季南部的厄尔尼诺-ASR遥相关较弱。
The Amundsen Sea low (ASL) is a quasi-stationary low pressure system that affects climate in West Antarctica. Previous studies have shown that El Niño–Southern Oscillation (ENSO) modulates the position and strength of the ASL with the strongest teleconnection found in austral winter despite the amplitude of ENSO events generally being largest in austral autumn/summer. This study investigates the mechanisms behind the seasonality of the El Niño teleconnection to the Amundsen Sea region (ASR) using experiments with the HadGEM3 climate model forced with an idealized fixed El Niño sea surface temperature anomaly present throughout the year. The seasonality of the El Niño–ASR teleconnection is found to originate from seasonal differences in the large-scale zonal winds in the South Pacific sector. In austral winter, the region of strong absolute vorticity near ~30°S associated with the subtropical jet, in combination with the changes to upper-tropospheric divergence due to the El Niño perturbation, acts as an anomalous Rossby wave source that is largely absent in austral summer. Furthermore, in austral summer the poleward propagation of tropically sourced Rossby waves into the ASR is inhibited by the strong polar front jet in the South Pacific sector, which leads to Rossby wave reflection away from the ASR. In austral winter, Rossby waves are able to propagate into the ASR, forming part of the Pacific South America pattern. The lack of the Rossby wave source in the tropical Pacific and the absence of favorable conditions for wave propagation explains the weaker El Niño–ASR teleconnection in austral summer compared to austral winter.
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DOI：
10.1002/joc.965
发表时间：
2004-01
期刊：
International Journal of Climatology
影响因子：
--
作者：
J. Turner
通讯作者：
J. Turner
南极洲周围地形强迫斜压的西格玛坐标计算
影响因子：
1.7
作者：
K. Walsh;I. Simmonds;M. Collier
通讯作者：
M. Collier
年周期如何影响对 ENSO 的温带响应
影响因子：
--
作者：
Daeho Jin;B. Kirtman
通讯作者：
B. Kirtman
影响因子：
4.6
作者：
J. Turner;J. Hosking;G. Marshall;T. Phillips;T. Bracegirdle
通讯作者：
J. Turner;J. Hosking;G. Marshall;T. Phillips;T. Bracegirdle
影响因子：
6.3
作者：
J. Keeble;P. Braesicke;N. Abraham;H. Roscoe;J. Pyle
通讯作者：
J. Keeble;P. Braesicke;N. Abraham;H. Roscoe;J. Pyle