Extratropical Transition

 

 

When a tropical cyclone reaches higher latitudes it will undergo a structur change from its symmetric, tropical appearance to a more unsymmetric, extratropical appearance. This is due to the strong baroclinicity and thus higher vertical windshear, the increase of the Coriolis force and the lower sea surface temperature and thereby less heat flux. This structure change is called extratropical transition (ET).

     
ET of tropical storm Karl (2016).
The predictability of the midlatitude weather systems is frequently compromised by tropical cyclones that undergo ET in the far upstream region because of the uncertainties in the evolution of ET-systems that project onto the midlatitude Rossby-wave trains.The main focus of our research lies on the predictability of the sturm structure during ET, mainly how the cold and dry, low-Θe air is transported into the inner core convection of the warm, high-Θe core of the storm and how the uncertainties in the deep convection of an ET-system amplify and project onto the structure change of the storm system and the interaction with the upstream trough.