The effect of potential vorticity fluxes on the circulation of the tropical upper troposphere
The effect of potential vorticity fluxes on the circulation of the tropical upper troposphere
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DOI：
10.1002/qj.3261
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发表时间：
2018-04
影响因子：
8.9
通讯作者：
S. Ortega;P. Webster;V. Toma;Hai-Ru Chang
中科院分区：
文献类型：
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作者：
S. Ortega;P. Webster;V. Toma;Hai-Ru Chang
通过简单的分析论证，我们认为副热带西风急流、赤道东风、西风导管(即赤道西风区)和热带对流层高空槽是通过位涡(PV)动力学耦合的。我们认为，热带深对流导致副热带西风急流上的平流PV通量向极地流动，从而触发急流上的Rossby波，并在Rossby波在西风导管上方破裂时导致平流PV通量向赤道方向流动。此外，我们还证明了向极地的平流PV通量与向赤道的平流PV通量是紧密平衡的，并且从不渗透定理中可以预料到这种紧密的平衡。我们认为，这些平流通量的小的不平衡在维持热带大气的对流层高层平均气流方面起着重要作用。
With simple analytical arguments, we suggest that the subtropical westerly jets, the equatorial easterly winds, the westerly ducts (i.e. regions of westerly winds over the Equator), and the tropical upper tropospheric troughs, are coupled via potential vorticity (PV) dynamics. We suggest that deep tropical convection leads to advective PV fluxes towards the Poles over the subtropical westerly jets, triggering Rossby waves on the jet, and leading to advective PV fluxes towards the Equator when the Rossby waves break over the westerly ducts. Moreover, we show that the advective PV fluxes towards the Poles closely balance those towards the Equator, and suggest that this close balance is to be expected from the impermeability theorem. We then argue that small imbalances of these advective PV fluxes play an important role in maintaining the upper tropospheric mean flow of the tropical atmosphere.