水汽空间分布对大气船舶重力波影响的数值试验

EFFECTS OF MOISTURE ON ATMOSPHERIC SHIP WAVES

利用中尺度数值模式ARPS模拟研究了水汽在山脉重力波和大气船波的产生和演变中的作用。研究发现水汽和非绝热效应对大气船波的影响与水汽的空间分布有关,大气船波的产生和演变对水汽的空间分布具有极端的敏感性,在一定条件下水汽的引入有可能减少大气船波的活动。对于3层模式结构的气流过山而言,如果初始的水汽分布在中层大气,则水汽和非绝热效应对大气船波的影响较小,而如果初始的水汽分布在中下层大气,则引入水汽后减少了大气船波的强度,但是如果初始的水汽分布在整个模式大气层,则水汽的引入减少了大气船波的活动。

Effects of moisture on the genesis and evolution of mountain gravity waves and atmospheric ship waves in the three-dimensional multi-layer moisture flow over topography are numerically investigated using the Advanced Regional Prediction System （ARPS5.0.0.0IHOP5）. The results show that the moist-trapped lee wave （the second diverging wave mode） in three dimensional three layer moisture flow over mountain is apparent in the downstream of the mountain lee side, and it consists of two diverging wave modes and a transverse wave mode. The genesis and evolution of atmospheric ship waves are extremely sensitive to the initial spatial distribution of moisture in the atmosphere, and under certain condition, the introduction of moisture might reduce the activities of ship waves in the atmosphere. For the three-dimensional three-layer flow over a isolated mountain, if the initial moisture is distributed on the middle layer, the impact of moisture and diabatic heating on atmospheric ship waves is minor; if the initial moisture is distributed on the middle and lower layers, then effects of moisture and diabatic heating reduce the intensity of atmospheric ship waves; and if the initial moisture is distributed on the all layers of the model, then the introduction of moisture into the model atmosphere will reduce the activities of atmospheric ship waves in the whole atmosphere.