西藏高原地形扰动对其降水分布影响的研究

利用离散谱空间变换中谱能不变性约束下的谱分析方法和引进相对地形高程(地形扰动)概念,研究了西藏高原地形强迫对该区降水分布的影响机制。研究表明,在相对最大降水高度之下,所谓地形-降水分布剖面一致性(即降水分布曲线相似于地形起伏曲线,雨峰雨谷和山峰山谷基本一一对应)的经典结论在西藏高原不能完全满足。频谱空间中的地形-降水锁相关系能够更本质地反映出地形性降水分布的物理特征。揭示出,两种不同的地形-降水锁相关系即分别对应西藏高原的两种地形-降水分布形态,即雨峰雨谷和山峰山谷基本一一对应的共振分布型;降水随地形增高或增或减的漂移分布型。

Effect of topographic perturbation on the precipitation distribution in Tibetan Plateau

A method for spatial spectral analysis under the constraint of spectrum power conservation and a presentation for relative terrain height(topographic perturbation with respect to mean topographic trend) are proposed,in order to analyze the effect of topographic forcing on precipitation distribution in Tibetan Plateau.The results show that below the relative maximal precipitation height,the ordinary 'classical coherent relationship' between topographic height and the precipitation profile(i.e.,the distributing profile of precipitation is similar to the undulating profile of topography,and the ridges and peaks of precipitation correspond well to those of terrain) are very complex and the terrain-rainfall pattern in Tibetan Plateau can not correctly describe.It is further found that the so-called lock-phase relationship between terrain and precipitation to be presented in a spectral space can essentially measure the coherent degree and the profile agreement between terrains and precipitation.This paper reveals that the two different phase-locked patterns can depict well the topography-precipitation relationship in Tibetan Plateau.One is the resonance-pattern that the ridges and peaks of precipitation are well correspondent to that of terrain.Another one is the shift-pattern,in which the precipitation increases or decreases with the terrain decreases or increases,respectively.