Axisymmetric Constraints on Cross-Equatorial Hadley Cell Extent
Axisymmetric Constraints on Cross-Equatorial Hadley Cell Extent
复制标题
DOI：
10.1175/jas-d-18-0306.1
复制
发表时间：
2018-10
影响因子：
3.1
通讯作者：
S. Hill;S. Bordoni;Jonathan L. Mitchell
中科院分区：
文献类型：
--
作者：
S. Hill;S. Bordoni;Jonathan L. Mitchell
我们认为，从每个隐藏的定理，角动量守恒（AMC）模型，和跨赤道Hadley细胞的程度上的等面积模型的相关性已知的约束。这些理论分别指出，哈德利环流必须跨越所有纬度的辐射对流平衡（RCE）的绝对角动量满足或或RCE的绝对涡度满足;所有纬度的RCE纬向风超过AMC纬向风;并在一定范围内，这样的深度平均位温是连续的，能量守恒。AMC模式需要上升纬度的知识，它不需要等于RCE强迫最大纬度。无论的值，我们证明，AMC细胞必须至少延伸到冬季半球的夏季半球。等面积模型预测，总是把它放在。当向极移动时（在给定的热Rossby数下），等面积预测的Hadley环流变得难以置信地大，而两者都变得越来越向基于Hide定理的最小单元范围的极移动（即，超临界强迫）。在一个理想化的干大气环流模式中，产生了跨赤道的哈德利环流圈，有些横跨两极。所有的均匀角动量不完美，大致对称的赤道范围内，并出现在超临界强迫的跨度控制的范围内。
We consider the relevance of known constraints from each of Hide’s theorem, the angular momentum–conserving (AMC) model, and the equal-area model on the extent of cross-equatorial Hadley cells. These theories respectively posit that a Hadley circulation must span all latitudes where the radiative–convective equilibrium (RCE) absolute angular momentum satisfies or or where the RCE absolute vorticity satisfies ; all latitudes where the RCE zonal wind exceeds the AMC zonal wind; and over a range such that depth-averaged potential temperature is continuous and that energy is conserved. The AMC model requires knowledge of the ascent latitude , which needs not equal the RCE forcing maximum latitude . Whatever the value of , we demonstrate that an AMC cell must extend at least as far into the winter hemisphere as the summer hemisphere. The equal-area model predicts , always placing it poleward of . As is moved poleward (at a given thermal Rossby number), the equal-area-predicted Hadley circulation becomes implausibly large, while both and become increasingly displaced poleward of the minimal cell extent based on Hide’s theorem (i.e., of supercritical forcing). In an idealized dry general circulation model, cross-equatorial Hadley cells are generated, some spanning nearly pole to pole. All homogenize angular momentum imperfectly, are roughly symmetric in extent about the equator, and appear in extent controlled by the span of supercritical forcing.