三类物理过程对台风强度影响的研究
A PRELIMINARY STUDY ON EFFECTS OF THREE KINDS OF PHYSICAL PROCESSES ON TYPHOON INTENSITY CHANGES
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摘要: 文中设计了一个极坐标系的准地转正压模式,一个直角坐标系定常台风环流条件下的准地转正压模式和一个直角坐标系非定常台风环流的准地转正压模式,其径向或水平格距均为2km,以研究三类物理过程对台风强度的影响,即沿方位角方向的线性平流,沿径向的线性平流以及非线性平流对中尺度涡旋涡量内传和台风强度变化的影响。结果指出:沿方位角方向的线性平流可导致螺旋状涡带的形成;沿径向的线性平流在一定的参数集合可使涡量内传,台风略有增强;定常台风环流条件下扰动涡量的非线性平流可使内传涡量明显增加,台风明显增强;非定常台风环流条件下非线性平流的作用具有两重性,一方面可使内传涡量增多,有利于台风的增强,另一方面,在涡量内传过程中,原先呈同心圆轴对称的台风基流结构受到破坏,形成复杂流型,这又使台风趋于减弱。最后讨论了这些结果在台风强度预测方面的可能应用。Abstract: The quasigeost rophic barotropical vonticity equation models in the cylindrical and the Cartesion coodinate systems are designed,with the radial or horizdmal space being 2 km respectively.By using them,eightexperiments are performed in order to investigate the effects of three kinds of physical processes including the linear azimuthal advection,the linear radial advection and the nonlinear advection on the vorticity radially propagating to the near coreregion and typhoon intensity changes.Results show that the azimuthal advection can result in the formation of a spiral vorticity zone,that the radial advection can make the vorticity propagation of the mesoscale vort exlocated in the out sideregion initially to the inside core,that in the condition of stationary typhoon circulation the nonlinear advection of the perturbational vorticity can increase the inward propagating vorticity and intensify the typhoon vortex obvioursly,and that in the case of nonstationary typhoon circulation,on the one hand,the nonlinear advection can also increase the inward vorticity,on the other hand,it may distort the initial symmetric structure of the typhoon exhibiting the complex flow pattern which is able to resist the typhoon intensification.Finally we discuss the possible application of these results to typhoon intensity prediction.