Modelling Sensitivity of Surface Energy Balance and Melt on an Alpine Glacier: Its Past and Future Under a Changing Climate
Abstract
Glacier surface melt is governed by the atmosphere-glacier surface interactions. This study, uses full energy balance (EB) model to investigate the physical mechanisms governing melt energy, in the past and future. First, a new parameterization for estimating the atmospheric emissivity was derived as a function of near surface vapour pressure, relative humidity and sky clearness index. Testing this model’s transferability to a different site showed that it can be easily transferred to other glaciers with similar skill. This is a step forward in expanding the application of a full EB model on glacierized regions. Secondly, this thesis used a point-scale first-order profile model to present new data on Haig Glacier’s EB. Climate sensitivity analysis was run using in situ observations. The perturbation approach was adapted to construct the longterm past EB climate relationship evolution using 36 years of North American Regional Reanalysis (NARR) data. Testing the temperature, specific humidity, wind speed, incoming shortwave radiation, and glacier surface albedo perturbation runs showed the Haig’s summer melt energy has the strongest sensitivity to interannual variations in incoming shortwave radiation, albedo, and temperature, respectively. To test more realistic perturbations, meteorological forcing from NARR was used to reconstruct the long-term EB from perturbing the NARR anomalies. Results indicated a ~10% increase in summer melting over the historical period, with increases in most of the energy fluxes on Haig Glacier. In the third and last part of this dissertation, the EB analysis was extended to future scenarios using the CM3 climate model of the U.S. Geophysical Fluid Dynamics Laboratory (GFDL). Daily meteorological variables from both historical runs and future projections were used to estimate Haig’s EB under four radiative forcing pathways: RCP2.6, RCP4.5, RCP6.0 and RCP8.6. The interannual, decadal and century-scale variations in the glacier energy budget were assessed. Future projections suggest that net radiation and temperature remain the key controls of melt energy, and all EB terms are expected to increase this century. The model suggests that this will lead to a 75-156% increase in melt rates on the glacier by the end of the century – should Haig Glacier survive this long.
Description
Keywords
Physical Geography
Citation
Ebrahimi, S. (2016). Modelling Sensitivity of Surface Energy Balance and Melt on an Alpine Glacier: Its Past and Future Under a Changing Climate (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/26963