Assessing the transferability and robustness of an enhanced temperature-index glacier-melt model

We investigate the transferability of an enhanced temperature-index melt model that was developed and tested on Haut Glacier d'Arolla, Switzerland, in the 2001 season. The model's empirical parameters (temperature factor, TF, and shortwave radiation factor, SRF) are recalibrated for: (1) other locations on Haut Glacier d'Arolla; (2) subperiods of distinct meteorological conditions; (3) different years on Haut Glacier d'Arolla; and (4) other glaciers in different years. The model parameters are optimized against simulations of an energy-balance model validated against ablation observations. Results are compared with those obtained with the original parameters. The model works very well when applied to other sites, seasons and glaciers, with the exception of overcast conditions. Differences are due to underestimation of high melt rates. The parameter values are associated with the prevailing energy-balance conditions, showing that high SRF are obtained on clear-sky days, whereas higher TF are typical of locations where glacier winds prevail and turbulent fluxes are high. We also provide a range of parameters clearly associated with the site's location and its meteorological characteristics that could help to assign parameter values to sites where few data are available.