大气涡旋速度场和螺旋形成机理OA

Based on the principle of force equilibrium,this study employed the Navier-Stokes equations in cylindrical coordinates(r,θ,z)to derive the three-dimensional spiral vortex velocity fields of mid-latitude cyclones,typhoons,and tornadoes.Singular points(critical points or equilibrium states),at which the three-dimensional velocity of these vortices becomes zero,were identified.All such points were classified as saddle-focus points.Mid-latitude cyclones exhibited two singular points:one at the surface of the Earth and the other at the top of the troposphere.Tornadoes possessed a single singular point at the base of the supercell storm cloud.Typhoons also exhibited two singular points:one at the eyewall surface and the other at the center of the eyewall on the surface.From the derived velocity fields,the horizontal divergence(D),vertical vorticity(ωz),and vortex shape surface were obtained,and these results were consistent with observational data.The findings indicated that the formation mechanisms of the three spiral vortices differ.Specifically,mid-latitude cyclones are caused by horizontal convergence associated with surface friction and cross-isobar flow,tornadoes are generated by vortex tube stretching resulting from strong horizontal convergence at the base of storm clouds,and typhoons are caused by the large-scale upward motion of the cumulus cloud belt over the ocean,with divergence and convergence remaining invariant with respect to height.