Moist Hadleycirculation : possible role ofwave-convection coupling inaqua-planet experiment
Moist Hadleycirculation : possible role ofwave-convection coupling inaqua-planet experiment
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湿哈德利环流：波对流耦合在水行星实验中的可能作用
DOI：
10.1175/jas-d-11-0149.1
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
T
中科院分区：
文献类型：
--
作者：
Horinouchi;T
对给定海面温度 (SST) 进行水上行星模拟，以阐明哈德利环流和热带辐合带 (ITCZ) 中瞬态变化的可能作用。全球统一的 SST 可以最好地说明他们的作用。对于这样的海表温度，几乎赤道对称的 ITCZ 和哈得来环流会自发出现。它们的强度变化很大，从微弱到气候显着，具体取决于模型积云参数化的可调参数。在某些情况下，不对称哈德利环流与长期热带气旋一起形成。可调参数影响热带降水的瞬时变化。在形成明确的近对称 ITCZ 的过程中，热带降水表现出对流耦合赤道波的清晰特征。这些波浪可以解释降水集中到赤道地区，从而引发哈德利环流。此外，模拟ITCZ的经向结构与与赤道主波模式相关的辐合/发散分布一致。即使引入极赤道温度梯度，环流强度对瞬态扰动的依赖性仍然存在。因此，瞬时变率对热带气候及其数值模拟的影响可能比我们想象的更广泛。海温梯度较弱时可能出现多种环流的原因是因为环流形成时潜热分布可以交互调节。角动量预算不提供有效的热力学约束，因为斜压不稳定性会重新分配角动量。
Aquaplanet simulations for a given sea surface temperature (SST) are conducted to elucidate possible roles of transient variability in the Hadley circulation and the intertropical convergence zone (ITCZ). Their roles are best illustrated with globally uniform SSTs. For such SSTs, an ITCZ and a Hadley circulation that are nearly equatorially symmetric emerge spontaneously. Their strength varies over a wide range from being faint to climatologically significant depending on a tunable parameter of the model’s cumulus parameterization. In some cases asymmetric Hadley circulations formed along with long-lived tropical cyclones.The tunable parameter affects the transient variability of tropical precipitation. In the runs in which well-defined near-symmetric ITCZs formed, tropical precipitation exhibited clear signatures of convectively coupled equatorial waves. The waves can explain the concentration of precipitation to the equatorial region, which induces the Hadley circulation. Also, the meridional structures of simulated ITCZs are consistent with the distribution of convergence/divergence associated with dominant equatorial wave modes.Even when the pole–equator temperature gradient is introduced, the dependence of the strength of the circulation to transient disturbances remains. Therefore, transient variability may have a broader impact on tropical climate and its numerical modeling than has been thought.The reason that a wide variety of circulation is possible when the SST gradient is weak is because the distribution of latent heating can be interactively adjusted while a circulation is formed. Angular momentum budget does not provide an effective thermodynamic constraint, since baroclinic instability redistributes the angular momentum.