State-of-the-art climate models predict the zonal mean mid-latitude circulation will undergo a poleward shift and seasonally and hemispherically dependent intensity changes in the future. Here I review the mechanisms put forward to explain the zonal mean mid-latitude circulation response to increased carbon dioxide (CO₂) concentration. The mechanisms are grouped according to their thermodynamic starting point, which are thought to arise from processes independent of the zonal mean mid-latitude circulation response. There are 24 mechanisms and 8 thermodynamic starting points: (i) increased latent heat release aloft in the tropics, (ii) increased dry static stability and tropopause height outside the tropics, (iii) radiative cooling of the stratosphere, (iv) Hadley cell expansion, (v) increased specific humidity following the Clausius-Clapeyron relation, (vi) cloud radiative effect changes, (vii) turbulent surface heat flux changes, and (viii) decreased surface meridional temperature gradient. I argue progress can be made by testing the thermodynamic starting points. I review recent tests of the increased latent heat release aloft in the tropics starting point, i.e., prescribing diabatic perturbations, quantifying the transient response to an abrupt CO₂ increase and imposing latitudinally dependent CO₂ concentration. Finally, I provide a future outlook for improving our understanding of predicted changes in the zonal mean mid-latitude circulation.

中文翻译：

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纬向平均中纬度环流未来变化的预测机制

最新的气候模型预测，未来纬向平均纬度环流将发生极移，并随季节和半球而变化。在这里，我回顾了提出的机制来解释纬向平均纬度中纬度环流对二氧化碳（CO ₂） 浓度。根据其热力学起点对这些机理进行了分组，认为它们是独立于纬向平均中纬度环流响应的过程而产生的。有24种机制和8个热力学起点：（i）在热带高空释放潜热，（ii）在热带以外增加干静态稳定性和对流层顶高度，（iii）平流层的辐射冷却，（iv）哈德利电池膨胀；（v）遵循克劳修斯（Clausius）-克拉珀龙（Clauperon）关系的比湿增加；（vi）云辐射效应变化；（vii）湍流表面热通量变化；（viii）表面子午温度梯度降低。我认为可以通过测试热力学起点来取得进展。我回顾了最近关于热带起点i的潜热释放增加的测试。₂增加并强加了纬度依赖性的CO ₂浓度。最后，我为改善我们对纬向平均中纬度环流预测变化的理解提供了未来展望。