Potential vorticity structure of simulated hurricanes
Potential vorticity structure of simulated hurricanes
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DOI：
10.1175/jas3601.1
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发表时间：
2006-01-01
影响因子：
3.1
通讯作者：
Schubert, WH
中科院分区：
文献类型：
--
作者：
Hausman, SA;Ooyama, KV;Schubert, WH
为了更好地理解热带气旋发展过程，作者使用基于非静水力学、平衡热力学和体微观物理学的二维模型模拟了轴对称的热带气旋状涡旋。导出了这种非静水、潮湿、降水大气的位涡原理。干位涡的适当推广为 P=rho(-1){(-偏导数 upsilon/偏导数 z) (偏导数 theta(rho)/偏导数 r) + [f+偏导数(r upsilon)/r 偏导数 r] (偏导数 theta(rho)/偏导数 z)}，其中 rho 是总密度，upsilon 是速度的方位角分量， theta(p) 是虚拟位温。结果表明，P 携带了有关平衡风场和质量场的所有基本动力学信息。在完全发展的准稳态气旋中，P 场和 theta(p) 场被锁定在一起，每个场在眼壁云的内边缘上都有一个向外倾斜的峰值区域。在这个非凡的结构中，P场由一个狭窄的斜塔组成，其中P的值可以达到数百个位涡（PV）单位。敏感性实验表明，模拟气旋对冰的影响很敏感，主要是通过降低冰点以上降水的下降速度而不是通过聚变潜热，以及对降水垂直熵传递的影响。
To better understand the processes involved in tropical cyclone development, the authors simulate an axisymmetric tropical-cyclone-like vortex using a two-dimensional model based on nonhydrostatic dynamics, equilibrium thermodynamics, and bulk microphysics. The potential vorticity principle for this nonhydrostatic, moist, precipitating atmosphere is derived. The appropriate generalization of the dry potential vorticity is found to be P=rho(-1){(-partial derivative upsilon/partial derivative z) (partial derivative theta(rho)/partial derivative r) + [f+partial derivative(r upsilon)/r partial derivative r] (partial derivative theta(rho)/partial derivative z)}, where rho is the total density, upsilon is the azimuthal component of velocity, and theta(p) is the virtual potential temperature. It is shown that P carries all the essential dynamical information about the balanced wind and mass fields. In the fully developed, quasi-steady-state cyclone, the P field and the theta(p) field become locked together, with each field having an outward sloping region of peak values on the inside edge of the eyewall cloud. In this remarkable structure, the P field consists of a narrow, leaning tower in which the value of P can reach several hundred potential vorticity (PV) units.Sensitivity experiments reveal that the simulated cyclones are sensitive to the effects of ice, primarily through the reduced fall velocity of precipitation above the freezing level rather than through the latent heat of fusion, and to the effects of vertical entropy transport by precipitation.