Axisymmetric balance dynamics of tropical cyclone intensification: Diabatic heating versus surface friction
Axisymmetric balance dynamics of tropical cyclone intensification: Diabatic heating versus surface friction
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热带气旋增强的轴对称平衡动力学：非绝热加热与表面摩擦
DOI：
10.1002/qj.3389
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发表时间：
2018
影响因子：
8.9
通讯作者：
Shanghong Wang
中科院分区：
文献类型：
--
作者：
Roger K. Smith;Shanghong Wang
利用最近发展的一个可预报的轴对称平衡模式，研究了非绝热加热率和近地表摩擦力的规定分布所强迫的理想化热带气旋式涡旋的演变。从给定的切向风场开始，在保持摩擦力公式不变的情况下，进行了一系列的计算，其中改变了非绝热加热率的强度。当加热率的强度低于某一值时，它产生的二次环流不再能够对抗边界层在边界层上方的对流层下部产生流出层的趋势。在这种情况下，这种净流出使绝对动量面向外平移到边界层上方，那里的切向速度下降。在平衡模式中，假设在现实中，切向速度的增强要求非绝热加热率足够强，以通风摩擦边界层中的流入，从而避免摩擦诱导的流出恰好在边界层上方。在现实中，非绝热加热的强度和位置将受到边界层动力学和热力学的强烈影响，而这一耦合在当前的模式公式中不存在。
The evolution of an idealized tropical‐cyclone‐like vortex forced by a prescribed distribution of diabatic heating rate and near‐surface frictional force is studied using a recently developed, prognostic, axisymmetric balance model. Starting with a prescribed tangential wind field, a series of calculations is carried out in which the strength of the diabatic heating rate is varied while keeping the formulation for the frictional force the same. When the strength of the heating rate falls below a certain value, the secondary circulation it generates is no longer able to oppose the tendency of the boundary layer to produce a layer of outflow in the lower troposphere, above the boundary layer. In these circumstances, this net outflow advects absolute momentum surfaces outwards above the boundary layer and the tangential velocity there declines. In the balance model, and presumably in reality, intensification of the tangential velocity requires the diabatic heating rate to be strong enough to ventilate the inflow in the frictional boundary layer, thereby averting frictionally induced outflow just above the boundary layer. In reality, the strength and location of diabatic heating will be strongly influenced by the boundary‐layer dynamics and thermodynamics, a coupling not present in the current model formulation.