Simulating past and future mass balance of Place Glacier using a physically-based, distributed glacier mass balance model

Abstract

The objective of this study is to develop a physically-based distributed glacier mass balance (GMB) model for Place Glacier, British Columbia, Canada, and apply the model to develop the historic and the future mass balance. The model is forced with climate data from Regional Atmospheric Modeling System (RAMS) mesoscale atmospheric model output from 1979-2008 for developing historic mass balance on Place Glacier. The model is also run in the future (2009-2040) to develop a projection of mass balance. The model simulated the historic glacier-wide summer and winter balance on Place Glacier satisfactorily. For all years, root mean squared error (RMSE) in simulated summer and winter balance are 0.43 m water equivalent (w.e.) and 0.27 m w.e., respectively. Over the period of 29 years, the model simulated a cumulative net mass balance of -33.72 m w.e. The model outperformed both empirical temperature index (TI) and enhanced TI models in simulating summer balance on Place Glacier when forced with the same RAMS variables. A linear regression model based on Singular Value Decomposition (SVD) technique is used for downscaling future climate projections from a suite of Global Climate Models (GCMs). The cross-validation of downscaled daily air temperature showed a strong correlation with the validation dataset (r~ =0.85, p <0.05). However, the RMSE in downscaled daily air temperature is large (=2.4~C). With spatially average correlation of 0.38 and RMSE of 7.5 mm day\u207b~ , the model for daily precipitation performed less satisfactorily in downscaling large-scale precipitation. For all variables, the error statistics improved with the monthly model. Future GCM projections form CanESM2, MIROC-ESM, MPI-ESM-LR, and HadGEM2-ES, are considered for downscaling. CanESM2 predicted a large negative glacier-wide net mass balance of -2.50 m w.e. for Place Glacier in the future. For the remaining GCMs, the average of net mass balance is \u20130.96 m w.e. The average of the cumulative mass loss predicted from GCMs other than CanESM2 is -31 m w.e. From 2009-2040, CanESM2, MIROC, MPI and HadGEM2 predicted an area loss of 52%, 28% and 22%, respectively. Overall, all downscaled GCMs, except CanESM2, performed better in predicting future mass balance for Place Glacier.