环境风场对绿洲冷岛效应影响的数值模拟研究

Simulation on the Influence of Background Wind Fields to Oasis "Cool Island" Effect

利用中尺度数值模式MM5对模拟的金塔绿洲效应偏离进行了敏感性试验研究,发现环境场对造成绿洲冷岛、高湿中心的偏离的作用起着非常重要的作用,而同时绿洲的存在对于冷岛、高湿起决定作用。模拟结果显示风场风速越小,冷岛效应越显著;风速越强,偏离中心程度越大,但增大至一定量值后,冷中心将无法激发,即不再呈现出冷岛作用。

The model MM5 was used to study the sensitivity of ＂Cool Island＂ effect of Jinta oasis to background environmental conditions. On August 1^st of 2003, the simulated result showed that the center of the ＂Cool Island＂ was far from the geometric center of the Jinta oasis. In order to know how the phenomenon happened, we designed two kinds of treatments： changing landform and changing wind field respectively in the initial condition of the simulation. We found out that there was not cold-wet field under no-oasis landform, and the center of ＂Cool Island＂ deviated from the oasis geometric center when there was local wind field. The bigger the wind velocity, the larger the deviation, and the ＂Cool Island＂ of oasis even couldn＇t be triggered if the wind velocity became strong enough.