降水条件下台风的定常运动和螺旋斑图

在牛顿第二运动定律的基础上,在垂直方向的运动方程中加入了扰动降水量一项,并讨论了加入这一项的合理性和物理意义.重点考虑了在降水条件下台风的运动特征,同时求得了三维定常流场中的水平速度,其中的三维流场构成了物理空间的一个非线性自治动力系统.研究表明:根据台风运动的定常解,台风的下层中心是低气压且是正垂直涡度(气旋式涡度)和水平辐合,上层中心是高气压(反气旋式涡度)和水平辐散.根据台风自治动力系统所获得的两个鞍-焦点很好地说明了台风的螺旋斑图,下层空气螺旋向内,引起台风中心附近的上升运动,上层空气螺旋向外引起台风外围的下沉运动,这些都与实际台风结构相似.文中阐明:在考虑降水量的影响后,台风仍然具有螺旋斑图的特征.

The Steady Motion and Spiral Pattern in Typhoon with Condensed Water

On the basis of Newton's second motion law, the perturbation\|condensed water is added to the motion equation in vertical direction, and then the rationality and physical meaning for this addition are discussed. In this paper, the focus is laid on the analysis for characteristics of typhoon, at the same time, the steady three dimensional stream field and the corresponding pressure and temperature fields are obtained. The three dimensional velocity fields construct a nonlinear autonomous system in the physical space. It is shown that the center of typhoon is a local minimum pressure with positive vertical vorticity and horizontal divergence in the upper levels. Because there are two saddle focus points in the autonomous system, there exist the spiral patterns, in which the winds blow spirally in and out of the center in the lower and upper levels in the Northern Hemisphere, which causes the ascending motion near the center and descending motion near the edge, respectively. All these are consistent with the observations. It implies that the typhoons still have the spiral structure characteristics even the condensed water is included.