Winter Subtropical Highs, the Hadley Circulation and Baroclinic Instability
Winter Subtropical Highs, the Hadley Circulation and Baroclinic Instability
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DOI：
10.1029/2023jd039604
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发表时间：
2023-11
期刊：
影响因子：
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通讯作者：
Weiteng Qiu;M. Collins;Adam A. Scaife
中科院分区：
文献类型：
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作者：
Weiteng Qiu;M. Collins;Adam A. Scaife
副热带高压对邻近大陆的天气和气候有着深远的影响。在本研究中，我们利用再分析数据调查了1979年至2021年冬季副热带高压的年际变化和趋势。我们发现了副热带高压强度、哈德利和费雷尔环流强度以及易增长率（EGR）之间的动态关系。 EGR最大值向极地移动与费雷尔环流和哈德利环流下降分支的加强、副热带对流层绝热变暖以及副热带高压强度增加和向极地移动有关。极地 EGR 的变化主要由垂直风切变的变化决定，而垂直风切变又与温度的变化和趋势处于热风平衡状态。副热带高压增强的机制涉及高频瞬变涡流的反馈。强烈的北太平洋和南太平洋副热带高压与拉尼娜现象有关。我们还表明，年际变化的机制与高点趋势的机制相似。
Subtropical highs have a profound influence on the weather and climate of adjacent continents. In this study, we use reanalysis data to investigate the interannual variability and trends in winter subtropical highs from 1979 to 2021. We find dynamical relationships between subtropical high intensity, the Hadley and Ferrel Circulation intensity, and the Eady Growth Rate (EGR). A poleward shift of the maximum in EGR is associated with a strengthening of the descending branches of the Ferrel and Hadley Cells, with subtropical troposphere adiabatic warming and an increased intensity and poleward movement of the subtropical highs. Shifts in the poleward EGR are dominated by changes in vertical wind shear which, in turn, are in thermal wind balance with variations and trends in temperature. The mechanism for the intensification of the subtropical highs involves feedbacks from high‐frequency transient eddies. Strong North Pacific and South Pacific Subtropical highs are associated with La‐Niña conditions. We also show that the mechanisms for interannual variations are similar to those for trends in the highs.