Abstract. The performance of two numerical models of different complexity, i.e., a Shallow Ice Approximation (SIA) and a Full-Stokes Model (FSM), is studied by analyzing glacier evolutions at various bed geometries and by applying different climatic forcings. Glacier bed geometry changes from a constant slope and a uniform width to a superimposed Gaussian bump or ice-fall on a constant slope and an exponentially varying width. Constant slopes of 0.1, 0.2 and 0.3 are chosen to study the evolution of a large, medium and small glacier, respectively. A specific mass balance serves as a climatic forcing. The steady 5 state is reached 60, 30 and 10 years, respectively faster for large, medium and small glacier, when simulations are performed using SIA instead of FSM. Glaciers time response is studied by using step and periodic changes, and by imposing natural variability in the equilibrium-line altitude. Glacier length response time is up to 14 years longer when FSM is used compared to SIA. When periodic and natural variability are enforced, glaciers simulated using SIA lag in phase compared to the forcing up to 81.2°for glacier length and up to 56.5°for volume. Contrary to that, glaciers simulated with FSM show greater lag in 10 phase compared to the forcing for glacier length and smaller lag for volume. The models differ in their treatment of glacier flow mechanics and differences in physical variables become apparent with increasing glacier bed slope and bed profile complexity.

ABSTRACT. The extensive dataset of Variegated Glacier's 1982/83 surge and antecedent quiescent phase is fragmentary and predominantly of flow line nature. Applying the raw centre line data in a flow line model to conduct research into the mechanism behind Variegated Glacier's surge behaviour inevitably entails problems. In this study, the incomplete dataset is extrapolated into the upper and lower parts of the glacier. Furthermore, the centre line data are adapted to account for differences between width-averaged and centre line surface mass balance and ice thickness change, inflow from tributaries, and changes in surface width over time. The modifications to the dataset are backed-up by observations and clear, plausible physical explanations. Moreover, the revised dataset meets the imposed constraints regarding ice volume flux, specific mass balance and net volume change. Hence, the final dataset is considered a satisfying revision that makes the dataset more valuable for future research. Subsequent application of the revised dataset corroborates the idea that glacier evolution during quiescence is basically the growth back towards steady state after the glacier was brought out of balance by the preceding surge.