ИСТИНА

We study possible trajectories of a long time existing vortex in a model of the atmosphere dynamics, where the vortex can be interpreted as a tropical cyclone. The model can be obtained from a system of primitive equations governing the motion of air over the Earth surface after averaging over the height. We consider equations used in geophysics for modeling of middle scale atmospherical processes and equations on the whole sphere as well. We associate with a cyclone a special class of smooth solutions having a form of a localized steady non-singular vortex moving with a bearing field. It is proved that the solutions satisfy the equations of the model either exactly or with a discrepancy which is small in a neighborhood of the trajectory of the center of vortex. We show both analytically and numerically that the trajectory of a localized vortex keeps the features of trajectory of vortex with a linear profile of velocity, where the exact solution can be obtained. We perform direct numerical computation of the moving vortex in the 2D models and compare the position of the center of vortex with the result obtained by our method. The numerics demonstrates a very good compliance with the theory. Further we study the influence of a friction to the shape and position of the vortex.