Precipitation and Temperature Estimation Error at Alpine Treeline Ecotones Using the Mountain Climate Simulator Model (MT-CLIM)

In order to improve modeling of alpine treeline responses to climate change, estimations of snowfall at treeline sites are needed. The MT-CLIM climate model was evaluated for this purpose by extrapolating precipitation and temperature from standard weather stations at lower elevations to 30 alpine SNOTEL study sites across the western United States. Quantification of the topography between the base stations and the SNOTEL sites was used in inverse distance weighting and compared to straight-line weighting. The predicted temperature and precipitation under different weighting methods were compared to observed data over three months during the winter of 2006-2007. The errors were mapped and their spatial pattern analyzed. Error patterns indicate strong gradients, particularly in the Pacific Northwest, that are suggestive of areas where additional characteristics of atmosphere-land interactions and boundary layer climatology need to be considered in modeling applications.