Modelling Glacier Surface Temperature Using Weather Station Data and Historical Climate Reconstructions

Models of glacier response to climate change and snow/ice melt require knowledge of air temperatures at the glacier surface. This can be directly measured at selected locations, but distributed models of glacier melt require temperature information over an entire surface. Furthermore, in many practical applications, temperature must be estimated for locations where no data is available. A new and more accurate model to extrapolate temperature has been developed at the Haig Glacier in Alberta to meet this need. Air temperature measurements collected at an array of sites since 2001, including an expanded station network in the summer of 2008 to examine the effects of proximity to a south-facing valley wall, are used to create the model. Air temperatures 1.5 m above the surface of the Haig Glacier are then computed using the new model from data collected at a weather station located at the foot of the glacier. Temperature and precipitation data collected from this station is supplemented with digital elevation models and synoptic reanalysis data from the National Center for Environmental Prediction. The new temperature model accounts for differences in the effect of elevation, incoming solar radiation, albedo, regional weather systems, and valley walls on temperature between the weather station and a point on the glacier surface. This model yields hourly air temperature values across the glacier to a 25 m horizontal resolution. The new method of temperature extrapolation shows a considerable improvement over the constant lapse rate model in terms of accuracy and increased spatial variability. This model can be applied to simulations of summer melt and runoff from the Haig Glacier and from neighbouring ice masses, providing a tool for estimating catchment-scale melt water discharge and the sensitivity of glacier runoff to climate warming.