Effects of vegetation, albedo, and solar radiation sheltering on the distribution of snow in the Valles Caldera, New Mexico

The effects of radiation scattering and sheltering on snow distributions are poorly understood in montane regions of the southwestern United States. To examine this, we develop a single-layer, distributed snow model (DSM) that includes canopy interception, and radiation scattering and sheltering. In our simulations, we distinguish between local and remote controls on shortwave radiation. This allows us to vary the representation of the effective albedo of the surrounding terrain from a vegetated to a snow-covered landscape and examine the impact this has on snow accumulation and melt. The distributed model is applied to La Jara catchment in the Valles Caldera, New Mexico, during the 2004-2005 winter season. Results indicate that a landscape-scale albedo controlled by vegetation has little effect on local scale-processes, such as incoming shortwave radiation and maximum snow water equivalent (SWE). This implies that increases from scattered light are nearly equal to the losses of radiation from remote sheltering. In contrast, when landscape-scale albedo is controlled by snow cover or by a proposed dynamic method accounting for snow in the vegetation canopy, there are large deviations in the spatiotemporal distributions of shortwave radiation and SWE due to scattered radiation exceeding the sheltering effects of remote topography. Our study results indicate that remote interactions of radiation, vegetation and topography are critical to consider in snow ecohydrological studies in regions with high solar flux and rugged topography. Copyright (C) 2008 John Wiley & Sons, Ltd.