Articles | Volume 10, issue 6
Research article
18 Nov 2016
Research article |  | 18 Nov 2016

Surface energy balance sensitivity to meteorological variability on Haig Glacier, Canadian Rocky Mountains

Samaneh Ebrahimi and Shawn J. Marshall

Abstract. Energy exchanges between the atmosphere and the glacier surface control the net energy available for snow and ice melt. This paper explores the response of a midlatitude glacier in the Canadian Rocky Mountains to daily and interannual variations in the meteorological parameters that govern the surface energy balance. We use an energy balance model to run sensitivity tests to perturbations in temperature, specific humidity, wind speed, incoming shortwave radiation, glacier surface albedo, and winter snowpack depth. Variables are perturbed (i) in isolation, (ii) including internal feedbacks, and (iii) with co-evolution of meteorological perturbations, derived from the North American regional climate reanalysis (NARR) over the period 1979–2014. Summer melt at this site has the strongest sensitivity to interannual variations in temperature, albedo, and specific humidity, while fluctuations in cloud cover, wind speed, and winter snowpack depth have less influence. Feedbacks to temperature forcing, in particular summer albedo evolution, double the melt sensitivity to a temperature change. When meteorological perturbations covary through the NARR forcing, summer temperature anomalies remain important in driving interannual summer energy balance and melt variability, but they are reduced in importance relative to an isolated temperature forcing. Covariation of other variables (e.g., clear skies, giving reduced incoming longwave radiation) may be partially compensating for the increase in temperature. The methods introduced in this paper provide a framework that can be extended to compare the sensitivity of glaciers in different climate regimes, e.g., polar, maritime, or tropical environments, and to assess the importance of different meteorological parameters in different regions.

Short summary
Atmospheric–glacier surface interactions govern melt, where each variable has a different impact depending on the region and time of year. To understand these impacts and their year-to-year variability on summer melt extent, we examine melt sensitivity to different meteorological variables at a glacier in the Canadian Rockies. Cloud conditions, surface albedo, temperature, and humidity are all important to melt extent and should be considered in models of glacier response to climate change.