三层模式中背风波存在条件的理论分析

本文针对边界层附近为弱稳定层结或不稳定层结下的背风波，建立了一个三层理论模式，其三层Seorer参数在中层最大、高层次之、下层最小。分两种情况对该类型背风波的存在的条件作了分析，结果表明，在第一种情况下三层背风波的存在条件与二层模式相同，而第二种情况下其存在条件则是二层模式不能描述的。三层模式背风波的存在条件要比两层模式宽松。并用二个例子对这二种情况下的条件进行了检验。

Theoretical analysis of the existent condition of lee waves in three-layer model

In this paper, considering a kind of lee waves that occur when the stratification in the boundary layer is slightly stable or unstable, a three-layer theoretical model is established, which satisfies that the largest Scorer parameter is in the middle layer, the second large one in the upper layer, and the smallest one in the lower layer. Using this model, the existence condition of a kind of lee waves is analyzed from two cases. The results show that in the first case the existence condition of lee waves in three-layer model is the same as that of the two-layer model. But in the second case, the existence condition of the three-layer model cannot be described by the two-layer model. So the existence condition of the three-layer model is more easily satisfied. In addition, two examples are used to verify the existence conditions.