The Response of an Idealized Atmosphere to Localized Tropical Heating: Superrotation and the Breakdown of Linear Theory
The Response of an Idealized Atmosphere to Localized Tropical Heating: Superrotation and the Breakdown of Linear Theory
复制标题
理想化大气对局部热带加热的响应：超自转和线性理论的崩溃
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
N. Lutsko
中科院分区：
文献类型：
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作者：
N. Lutsko
在一个理想化的干大气环流模式中加入了一个模拟西太平洋上空强非绝热加热的赤道热源。对于小的(<；0.5K天−1)加热率，响应与线性Matsuno-Gill理论的预期非常接近，尽管响应的幅度亚线性地增加。这一“线性”区域在较大的加热率下被打破，研究发现，这是因为热带大气的稳定性增加。与此同时，赤道风的超旋程度也越来越高。这种超旋转是由加热激发的波产生的定常涡动动量通量驱动的，并受到平均气流对低动量空气的垂直平流的抑制，以及在大加热率下由瞬变涡动动量的发散所抑制。在改变赤道到极地温度梯度的附加实验中，我们探索了这些动力学。当较大的加热率被应用于相对较弱的装置时，会产生非常强的超旋转。
AbstractAn equatorial heat source mimicking the strong diabatic heating above the west Pacific is added to an idealized, dry general circulation model. For small (<0.5 K day−1) heating rates the responses closely match the expectations from linear Matsuno–Gill theory, though the amplitudes of the responses increase sublinearly. This “linear” regime breaks down for larger heating rates and it is found that this is because the stability of the tropical atmosphere increases. At the same time, the equatorial winds increasingly superrotate. This superrotation is driven by stationary eddy momentum fluxes by the waves excited by the heating and is damped by the vertical advection of low-momentum air by the mean flow and, at large heating rates, by the divergence of momentum by transient eddies.These dynamics are explored in additional experiments in which the equator-to-pole temperature gradient is varied. Very strong superrotation is produced when a large heating rate is applied to a setup with a relatively wea...