关键词: 绿洲, 边界层, 数值模拟

Abstract: The nonhydrostatic mesoscale atmospheric model MM5 version 3.5 of National Center of Atmospheric Research(NCAR) was used to simulate the local circulation and boundary layer characteristics over an ideal cone mountain. The numerical experiment was done through multiple nesting under two conditions: one is E_oasis, there is a cone oasis existing atop the hill peak; the other is E_nooasis, there is no oasis in the research region. The sensitive heat flux and latent heat flux differ much between the mountain atop oasis and surroundings. It plays an obvious role in forcing oasis-desert local thermal circulation. The comparing results show that if there is no oasis on the mountain, the terrain height that affects the sensitive heat flux only, and it does not matter latent heat flux. In E_oasis, the existing of oasis atop the hill made the cold air over oasis sink with the downward movement, it could restrain the upward movement of warm and moist air caused by the terrain height. Horizontal circulation due to elevation shows convergence at the lower layer; and divergence at the higher layer over ground surface when there is no oasis, while on the contrary it is convergence at the higher layer, and divergence at the lower layer over ground surface when the oasis existing. The climatic effect of mountain atop oasis could restrain the upward movement led by the terrain height.

Key words: oasis, boundary layer, numerical simulation