Influence of precipitation phase on the form of mountain ranges

Abstract

Observations of precipitation fall speeds and precipitation patterns suggest that precipitation phase (rain versus snow) is a significant control on the relationship between precipitation patterns and topography, due to the potential for increased downwind advection of snow relative to rain. A coupled model of orographic precipitation and surface erosion shows that for a range of climate variables, steady-state precipitation patterns vary from nearly uniform and maximizing over the highest topography, to highly spatially variable, closely coupled to topography and reaching a maximum on low slopes. Precipitation patterns are a first-order control on modeled range scale and ridge-valley scale relief, channel concavity, and the position of the drainage divide. An association between cool climates, spatially uniform precipitation, and efficient erosion of high topography is indicated. The importance of precipitation phase to the evolution of precipitation patterns and topography further demonstrates the fundamental importance of the coupled climate, erosion, and tectonic system in the evolution of mountain topography.