大气波动不稳定与林区降水分布(Ⅰ)

<正>本文从描述大气运动的涡度方程出发,用参数展开法求得二维平面运动的波动解。指出在气流受到森林或林区山地的阻挡时,在林区中心线两侧,可以形成不同类型的水平气流切变,这种气流切变通过产生波动不稳定能量而造成了林区降水的特殊分布。当基本气流为西风气流时,平地林区中心线北侧降水量明显大于南侧;对于山地林区,这种因气流切变造成的波动不稳定能量使得偏北坡降水日数增多,甚至多于水气含量较充沛的偏南坡。用我国小兴安岭林区和长白山林区的降水资料分别作为平地和山地的代表,对上述理论结果作了验证,得出了令人满意的结果。

THE INSTABILITY OF ATMOSPHERIC WAVES AND THE PRICIPITATION DISTRIBUTION IN FOREST RIGIONS

In this paper, the writer has found the solutions of the two horizontal dimension waves by use of parameter explaining method with respect to the barotropic vorticity equation of atmospheric motions. It was pointed out that when the air flow was resisted by the forest or mountain areas with forest, the unlike horizontal wind speed shear would be formed on both sides of the central line of the forest. The wind speed shear would result in special precipitation distribution for the forest regions by producing unstable wave energy. When the basic flow was west, for flat forest regions, the rain fall in the north area of the central line was heavier than that in the south area; while in the mountain regions this unstable energy provided by the wind speed shear would produce much more rainy days on the north slope of the mountains than those on the south slope, even though where the moisture is abundant. A check was made against the theory which was derived above by use of the preciptation data of the Xiao Xin An mountains forest to represent the data for flat forest regions located in the eastern low mountain area of the Northeast, and of the Chang Bai Mountains forest for mountain forest regions respectively. The agreement of the theory and observation data was quite satisfactory.