Computing streamfunction and velocity potential near the Tibetan Plateau

The Tibetan Plateau (TP) exerts a considerable influence on weather and climate of China and the global circulations. Data holes of arbitrary shape emerge when low level isobaric surfaces intercept with the high altitude and huge horizontal extent of the TP. It brings complications in identifying the discrete boundaries of TP at different heights and in calculating streamfunction and velocity potential nearby. The study designs an automated algorithm and checks its utility and flexibility with idealized experiments when the terrain heights are over 4000 m and 3000 m. Streamfunction and velocity potential are accurately computed and directly used in diagnosing a TP vortex over the plateau. It is found that the close circle of the velocity potential represents the trace of the TP vortex from the genesis to dispassion.