Abstract:In this paper, coupling with the Noah land surface model and CLM lake model, the WRF model is used to simulate a gale event in the Erhai basin, Dali of Yunnan Province on 23 January 2015. An analysis is made of the characteristics of 3D dynamic and thermal structure in the onset, prevailing and retreat periods of the gale and its mechanism is analyzed. In the onset period of gale, the west wind dominated in the upper atmosphere, the local small cyclone appeared at the height of 1 km around the central Erhai basin, and the east wind dominated on the ground. The westerly flow in the upper atmosphere created fluctuation disturbance over Mt. Cangshan, and the cavity zone and secondary vertex in the leeward slope, and unstable wave region in the lowerlevel atmosphere. The unstable wave broke in the lowerlevel atmosphere, where the turbulences were quite active. The energy in the upper atmosphere was transported downwards. In the prevailing period of the gale, the upper atmosphere over the south and north parts of the Erhai basin was controlled by two westerly flows, while the upper atmosphere over the central part of the basin was a weak divergence field. This structure over the Erhai basin brought about disturbance in the upper atmosphere, which made the shallow inversion layer near the surface layer over the east part of Mt. Cangshan disappear, and temperature above this shallow inversion layer increase with height. The atmosphere was unstable and beneficial to momentum being transported downwards from the upper atmosphere. In the retreat period of the gale, the west wind in the upper atmosphere weakened, the disturbance disappeared, turbulent kinetic energy dissipated, and the wind at ground level decreased.
