EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Glacier projections sensitivity to temperature-index model and climate downscaling parameter calibration choices

Lilian Schuster1, David Rounce2, and Fabien Maussion1
Lilian Schuster et al.
  • 1Department of Atmospheric and Cryospheric Sciences, University of Innsbruck, Innsbruck, Austria (
  • 2Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA, United States

A recent large-scale glacier model intercomparison revealed a strong influence of model design choice on glacier projections. Here we examine the influence of various temperature-index mass-balance models and calibration options. With the Open Global Glacier Model (OGGM) framework, we compare the performance and projections of model options such as the use of surface-type dependent degree-day factors as well as varying temporal climate resolution (daily, monthly) and downscaling strategies (temperature lapse rates, temperature and precipitation correction). We focus on 88 glaciers with long term observations of mass-balance profiles and seasonal mass-balance, allowing us to assess the added value of using multiple mass-balance statistics in the calibration process. We find that using interannual mass-balance variability to calibrate otherwise fixed parameters generally leads to an improved representation of the mass-balance gradient, which in turn is a crucial explanatory variable for future glacier evolution. Therefore, we also find a strong influence of the calibrated temperature lapse rates on future glacier volume. Using different degree-day factors for snow, firn, and ice leads to nonlinear sensitivities, where future glacier loss depends on how the accumulation area changes compared to the calibration period. Our study illustrates the strong impact of temperature-index model choice on projected glacier volume and runoff. But it cannot clearly demonstrate the added value of additional model complexity due to the lack of independent observations.

How to cite: Schuster, L., Rounce, D., and Maussion, F.: Glacier projections sensitivity to temperature-index model and climate downscaling parameter calibration choices, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-11983,, 2023.