Climate sensitivity of Storglaciären, Sweden: an intercomparison of mass-balance models using ERA-40 re-analysis and regional climate model data

Abstract

Estimates of glacier contributions to future sea-level rise are often computed from massbalance sensitivities derived for a set of representative glaciers. Our purpose is to investigate how mass-balance projections and sensitivities vary when using different approaches to compute the glacier mass balance. We choose Storglaciären, Sweden, as a test site and apply five different models including temperature-index and energy-balance approaches further varying in spatial discretization. The models are calibrated using daily European Centre for Medium-Range Weather Forecasts re-analysis (ERA-40) data. We compute static mass-balance sensitivities and cumulative mass balances until 2100 based on daily temperatures predicted by a regional climate model. Net mass-balance sensitivities to a +1 K perturbation and a 10% increase in precipitation spanned from -0.41 to -0.61 and from 0.19 to 0.22 m a -1 , respectively. The cumulative mass balance for the period 2002-2100 in response to the climate-model predicted temperature changes varied between -81 and -92 m for four models, but was -121 m for the fully distributed detailed energy-balance model. This indicates that mass losses may be underestimated if temperature-index methods are used instead of detailed energy-balance approaches that account for the effects of temperature changes on all energy-balance components individually. Our results suggest that future glacier predictions are sensitive to the choice of the mass-balance model broadening the spectrum in uncertainties.

The influence of changes in glacier extent and surface elevation on modeled mass balance

“…Oerlemans, 2001). Such simplified calculations provided rather good results compared to measurements or more complex modeling approaches (Machguth et al, 2006b(Machguth et al, , 2009Hock et al, 2007). Details of the model used here were described by and a validation of model performance can be found in Machguth et al (2006b) and Paul et al (2009).…”

Simulating melt, runoff and refreezing on Nordenskiöldbreen, Svalbard, using a coupled snow and energy balance model

“…Numerical models capable of simulating the surface mass balance have proved useful in analysing the temporal evolution and spatial distribution of the mass budget of ice masses in more detail than provided by observations only (Greuell, 1992;Hock, 1999). Additionally, mass balance models have been used as predictive tools to study the sensitivity of glaciers to climate change Braithwaite and Zhang, 1999;De Woul and Hock, 2005;Raper and Braithwaite, 2006;Hock et al, 2007). Distributed mass balance models that solve the energy balance to compute melt have been shown to be capable of simulating spatial melt patterns and their variability (Arnold et al, 1996;Klok and Oerlemans, 2002;Hock and Holmgren, 2005).…”

Modeling and Hindcasting of the Mass Balance of Werenskioldbreen (Southern Svalbard)

“…Accumulation is mostly computed from precipitation using a threshold temperature to distinguish between rainfall and snowfall (e.g. Hock et al, 2007;Schuler et al, 2007). There are two popular methods of ablation process modeling:…”

“…The data from the ERA-40 re-analysis were successfully applied to mass balance models of Storglaciären in northern Sweden (Radić and Hock, 2006;Hock et al, 2007), as well as Midre Lovènbreen on NW Svalbard (Rye et al, 2010). The data of the ERA-40 re-analysis consist of a three-dimensional database which was produced from a digital climatic model, meteorological observations, and satellite data (Uppala et al, 2005).…”

“…(based on GLOBE, 1999). In order to adjust the re-analysis data to local conditions, we scaled temperature based on a lapse rate of 0.8 K/100 m. The lapse rate factor comprises temperature variations depending on elevation, horizontal distance, and model bias (Hock et al, 2007).…”