边界层Scorer参数对背风波波长的影响

Analysis of the Influence of the Boundary Layer on the Wavelength of Trapped Lee Waves

利用一个中层Scorer参数较大,上、下层Scorer参数较小的3层背风波模型,讨论了边界层(下层)Scorer参数对背风波波长的影响。结果表明,当边界层Scorer参数减小时,波长增大,反之波长减小;当中高层的Scorer参数较小时,背风波波长对边界层的Scorer参数敏感。利用该结果结合观测事实分析后发现,由于地表加热的日变化影响了边界层的Scorer参数,故造成了背风波波长在夜间缩短,在午后增加;此外还发现,因夏季的Scorer参数要比冬季小,这可导致波长变化率在夏季比冬季更大。

A three-layer theoretic model, in which the Scorer parameter is larger in the middle layer and smaller in the upper and boundary layer, is established. Using this model, the influence of the variation of the Scorer parameter in the boundary layer on the wavelength of trapped lee waves is studied. The conclusion shows that if the Scorer parameter in the bot,ndary layer decreases, the wavelength will increase. On the contrary, the wavelength will decrease. And, the smaller the Scorcr parameter in the middle and upper layer is, the more sensitive of the wavelength to the Scorer parameter of the boundary layer is. By use of theoretic conclusions and observational results, we found that the wavelength usually decreasing in the night and increasing in the afternoon is due to diurnal heating which effect wavelengths by the variation of the Scorer paranleter in the boundary layer. We also found that changes in wavelength in summer may larger than that in winner since that the Scorer parameter is smaller in summer than that in winner.