Is the Brewer‐Dobson circulation increasing or moving upward?
Is the Brewer‐Dobson circulation increasing or moving upward?
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DOI：
10.1002/2015gl067545
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发表时间：
2016-02
影响因子：
5.2
通讯作者：
Sophie Oberländer‐Hayn;E. Gerber;J. Abalichin;H. Akiyoshi;A. Kerschbaumer;A. Kubin;M. Kunze;U. Langematz;Stefanie Meul;M. Michou;O. Morgenstern;L. Oman
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文献类型：
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作者：
Sophie Oberländer‐Hayn;E. Gerber;J. Abalichin;H. Akiyoshi;A. Kerschbaumer;A. Kubin;M. Kunze;U. Langematz;Stefanie Meul;M. Michou;O. Morgenstern;L. Oman
预计平流层的经向环流或布鲁尔-多布森环流（BDC）会随着温室气体（GHG）浓度的增加而加速。加速度通常通过给定压力面的热带向上质量通量 (Ftrop) 的变化来量化。同时，模型预测整个大气环流会因温室气体而升高；值得注意的是，对流层顶在本世纪上升了约一公里。本研究表明，大部分 BDC 趋势与流通量的上升有关。使用化学气候模型 (CCM)，将 100 hPa 的 Ftrop 趋势与对流层顶的趋势进行对比：虽然 100 hPa 的 Ftrop 每十年增加 1-2%，但进入对流层顶上方大气的质量通量实际上会减少。其他 CCM 也发现了类似的结果，这表明 BDC 的变化可以更好地描述为环流的向上移动，而不是增加，这对机制和平流层-对流层交换具有影响。
The meridional circulation of the stratosphere, or Brewer‐Dobson circulation (BDC), is projected to accelerate with increasing greenhouse gas (GHG) concentrations. The acceleration is typically quantified by changes in the tropical upward mass flux (Ftrop) across a given pressure surface. Simultaneously, models project a lifting of the entire atmospheric circulation in response to GHGs; notably, the tropopause rises about a kilometer over this century. In this study, it is shown that most of the BDC trend is associated with the rise in the circulation. Using a chemistry‐climate model (CCM), Ftrop trends across 100 hPa are contrasted with those across the tropopause: while Ftrop at 100 hPa increases 1–2 %/decade, the mass flux entering the atmosphere above the tropopause actually decreases. Similar results are found for other CCMs, suggesting that changes in the BDC may better be described as an upward shift of the circulation, as opposed to an increase, with implications for the mechanism and stratosphere‐troposphere exchange.