Interaction of binary tropical storms in a idealized background flow

The results of numerical simulations of interaction and motion of binary tropical cyclones are presented. The numerical experiments are conducted using a multi-nested coupled tropical cyclone-ocean model. In the present study the interaction and motion of binary storms developed from weak vortices imbedded into a background flow are studied.

The flow is designed in such a way to reproduce general features of large-scale atmospheric circulation in tropics, such as trade winds with their eastern velocity component and the transition to westerlies northwards. The influence of the background flow on the interaction regimes is investigated. Depending on initial disposition of interacting binary storms in the background flow the latter favors either their approach or their repulsion. The motion of binary storms in case of capture of one of them by the western flow is studied. The numerical experiments are conducted with ocean coupling and without it. It is shown that the ocean coupling is of crucial importance for prediction of binary storm intensity and tracks. A significant effect of the SST spatial inhomogeneity was observed. It was shown that background flow could significantly change regimes of binary tropical storms interaction and storm tracks.

Some specific features of complicated tracks of observed binary storms were successfully reproduced.