Limits on the Extent of the Solsticial Hadley Cell: The Role of Planetary Rotation
Limits on the Extent of the Solsticial Hadley Cell: The Role of Planetary Rotation
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DOI：
10.1175/jas-d-18-0341.1
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发表时间：
2019-06
影响因子：
3.1
通讯作者：
Martin S. Singh
中科院分区：
文献类型：
--
作者：
Martin S. Singh
利用水行星环流模式在永久至日条件下的理想模拟，研究了行星自转在限制跨赤道至日社会哈德利环流（SHC）范围中的作用。与以往包括季节周期的研究一致，SHC程度随着自转速率的降低而增加，并且在足够低的行星自转速率下它占据整个地球。建立了一个关于SHC夏季半球范围的简单理论，其中假设SHC占据了物理上无法达到假设的辐射-对流平衡状态的区域。该理论预测，随着旋转速率的降低，SHC进一步延伸到夏季半球，定性地再现了模拟的行为，但它通常低估了模拟的SHC程度。基于斜对流中性和Hadley单体角动量守恒的假设，提出了夏季半球SHC范围的诊断理论。该理论将夏季半球SHC的结构与动态平衡模拟中边界层熵的分布联系起来。由此得到的SHC范围诊断推广了privprive和Plumb基于对流准平衡的约束，其中雨带的位置与低层熵分布的最大值有关。
The role of planetary rotation in limiting the extent of the cross-equatorial solsticial Hadley cell (SHC) is investigated using idealized simulations with an aquaplanet general circulation model run under perpetual-solstice conditions. Consistent with previous studies that include a seasonal cycle, the SHC extent increases with decreasing rotation rate, and it occupies the entire globe for sufficiently low planetary rotation rates. A simple theory for the summer-hemisphere extent of the SHC is constructed in which it is assumed that the SHC occupies regions for which a hypothetical radiative–convective equilibrium state is physically unattainable. The theory predicts that the SHC extends farther into the summer hemisphere as the rotation rate is decreased, qualitatively reproducing the behavior of the simulations, but it generally underestimates the simulated SHC extent. A diagnostic theory for the summer-hemisphere SHC extent is then developed based on the assumptions of slantwise convective neutrality and conservation of angular momentum within the Hadley cell. The theory relates the structure of the SHC in the summer hemisphere to the distribution of boundary layer entropy in the dynamically equilibrated simulations. The resultant diagnostic for the SHC extent generalizes the convective quasi-equilibrium-based constraint of Privé and Plumb, in which the position of rain belts is related to maxima in the low-level entropy distribution.