Single‐layer axisymmetric model for a Hadley circulation with parameterized eddy momentum forcing
Single‐layer axisymmetric model for a Hadley circulation with parameterized eddy momentum forcing
复制标题
DOI：
10.3894/james.2009.1.10
复制
发表时间：
2009-03
影响因子：
6.8
通讯作者：
A. Sobel;T. Schneider
中科院分区：
文献类型：
--
作者：
A. Sobel;T. Schneider
轴对称单层模型用于研究哈德利环流与温带涡流的相互作用。涡动量通量通过理想化干环流模型 (GCM) 的计算所激发的简单闭包进行参数化。进行计算时，加热被参数化为温度向规定的辐射对流平衡 (RCE) 状态的牛顿弛豫。最高 RCE 温度出现的纬度会发生变化，以代表季节变化。在轴对称模型中，与 GCM 一样，当 RCE 温度最大值远离赤道超过阈值纬度时，纬向动量收支会发生质的变化。对于靠近赤道的RCE温度最大值，涡动量通量在纬向动量收支中起主导作用，非线性较弱，经向环流是关于赤道不对称程度的弱函数。对于距离赤道足够远的 RCE 温度最大值，纬向动量预算变得更加非线性，角动量更加接近守恒，并且环流是赤道不对称程度的更强函数。由于轴对称模型可以捕获这种行为，同时比 GCM 简单得多，因此它可能是迈向更全面的纬向平均大气环流理论的有用一步。
An axisymmetric single‐layer model is used to study interactions of the Hadley circulation with extratropical eddies. Eddy momentum fluxes are parameterized using a simple closure motivated by calculations with an idealized dry general circulation model (GCM). Calculations are performed in which the heating is parameterized as Newtonian relaxation of temperatures toward a prescribed radiative‐convective equilibrium (RCE) state. The latitude at which the maximum RCE temperature occurs is varied to represent seasonal variations. In the axisymmetric model, as in the GCM, qualitative changes in the zonal momentum budget occur as the RCE temperature maximum moves away from the equator past a threshold latitude. For RCE temperature maxima closer to the equator, eddy momentum fluxes play a dominant role in the zonal momentum budget, nonlinearity is weak, and the meridional circulation is a weak function of the degree of asymmetry about the equator. For RCE temperature maxima sufficiently far from the equator, the zonal momentum budget becomes more nonlinear, angular momentum is more nearly conserved, and the circulation is a stronger function of the degree of asymmetry about the equator. Since the axisymmetric model can capture this behavior while being much simpler than the GCM, it may be a useful step towards a more comprehensive theory of the zonal‐mean general circulation.