台风的定常运动和螺旋斑图

应用控制台风的大气运动方程组求得了台风的三维定常流场以及相应的气压场和温度场,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。研究指出: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一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,地球的旋转和大气粘性对台风的螺旋结构是至关重要的。

The steady motion and spiral patterns in typhoon

-Starting from the equations describing typhoons in the atmosphere the steady three-dimensional stream field and thecorresponding pressure and temperature fields are obtained. The three-dimensional velocity fields construct a nonlinear autonomoussystem in the physical space. It is shown that the centre of typhoon is a local minimum pressure with positive vertical vorticity (cyclonic vorticity) and horizontal convergence in lower levels and a local maximum pressure with negative vertical vorticity (anticyclonic vortidty) and horizontal divergence in upper levels. Because there exist two saddle-focus points in the autonomous system sothere east the spiral patterns in which the winds blow spirally inside and outside the centre in lower and upper loveis in the NorthernHemisphere and cause the ascending motion near the centre. These are in conform fairly well with the observations. It implies thatthe rotation of the earth and viscosity of air play an important role in the spiral structure of typhoons.