Simulating wind fields and snow redistribution using terrain-based parameters to model snow accmulation and melt over a semi-arid mountain catchment

Authors: Winstral, Adam; Marks, Daniel

Submitted to: Hydrological Processes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2002
Publication Date: 8/30/2002
Citation: Winstral, Adam, Marks, Danny., Simulating wind fields and snow redistribution using terrain-based parameters to model snow accumulation and melt over a semi-arid mountain catchment. Hydrological Processes 2002, v. 16, p. 3585-3603.

Interpretive Summary: In mountainous regions, wind plays a prominent role in determining snow accumulation patterns and turbulent heat exchanges strongly affecting the timing and magnitude of snowmelt runoff. In this study, digital terrain analysis was employed to quantify aspects of the upwind topography related to wind shelter and exposure, to efficiently develop a distributed time-series of snow accumulation rates and wind speeds to force a distributed snow model. Parameters are presented that determined each grid cell¿s topographic exposure and potential for drift development relative to observed winds. Using meteorological data taken from both an exposed and a sheltered site in a small mountain catchment in southwestern Idaho, the terrain features were used to distribute rates of snow accumulation and wind speeds at an hourly time-step for input to a snow model. A comprehensive dataset consisting of a time-series of aerial photographs taken during meltout, measured runoff, and snow data from the sheltered meteorological site were used to validate the simulations. Using the modeled accumulation rates and wind fields generated from terrain features we accurately modeled the observed snow distribution including the formation of drifts and scoured wind-exposed ridges, and snowmelt runoff for all three years of study.

Technical Abstract: In mountainous regions, wind plays a prominent role in determining snow accumulation patterns and turbulent heat exchanges strongly affecting the timing and magnitude of snowmelt runoff. In this study, digital terrain analysis was employed to quantify aspects of the upwind topography related to wind shelter and exposure, to efficiently develop a distributed time-series of snow accumulation rates and wind speeds to force a distributed snow model. Parameters are presented that determined each grid cell¿s topographic exposure and potential for drift development relative to observed winds. Using meteorological data taken from both an exposed and a sheltered site in a small mountain catchment in southwestern Idaho, the terrain features were used to distribute rates of snow accumulation and wind speeds at an hourly time-step for input to a snow model. A comprehensive dataset consisting of a time-series of aerial photographs taken during meltout, measured runoff, and snow data from the sheltered meteorological site were used to validate the simulations. Using the modeled accumulation rates and wind fields generated from terrain features we accurately modeled the observed snow distribution including the formation of drifts and scoured wind-exposed ridges, and snowmelt runoff for all three years of study.