Assigned Session: #AGM28: Generic Meeting Session
Initializing a glacier model for simulations of debris transport: A case study of the Oberaletsch Glacier
Abstract ID: 28.7420 | Accepted as Poster | Poster | 2025-02-28 12:45 - 14:15 | Ágnes‐Heller‐Haus/Small Lecture Room
José Manuel Muñoz Hermosilla (0)
Miles, Evan (2,3,4), Melo Velasco, Vicente (1), McCarthy, Michael (1,2), Hardmeier, Florian (3), Jouvet, Guillaume (5), Pellicciotti, Francesca (1)
José Manuel Muñoz Hermosilla ((0) Institute of Science and Technology Austria, Am Campus 1, 3400, Klosterneuburg, Lower Austria, AT)
Miles, Evan (2,3,4), Melo Velasco, Vicente (1), McCarthy, Michael (1,2), Hardmeier, Florian (3), Jouvet, Guillaume (5), Pellicciotti, Francesca (1)
(0) Institute of Science and Technology Austria, Am Campus 1, 3400, Klosterneuburg, Lower Austria, AT
(1) Institute of Science and Technology Austria, Klosterneuburg, Austria
(2) Swiss Fedreal Reserch Institute WSL, Birmensdorf, Switzerland
(3) University of Zurich, Zurich, Switzerland
(4) University of Fribourg, Fribourg, Switzerland
(5) University of Lausanne, Lausanne, Switzerland
(2) Swiss Fedreal Reserch Institute WSL, Birmensdorf, Switzerland
(3) University of Zurich, Zurich, Switzerland
(4) University of Fribourg, Fribourg, Switzerland
(5) University of Lausanne, Lausanne, Switzerland
Debris-covered glaciers are an important component of the climate system and contribute to alpine hydrology, with surface debris significantly influencing glacier processes and evolution. However, the supply and transport of debris in the glacier system are usually poorly constrained by available observations and their representation in glacier evolution models is thus challenging. Accurately modeling their dynamics and the evolution of debris extent requires numerical frameworks capable of coupling ice dynamics with surface mass balance (SMB) and debris transport processes. A fundamental challenge is the model initialization, due to the entangled processes of ice dynamics, debris transport, and mass balance. Since most glacier observations (e.g. remote sensing) cover only the very recent period, a careful model initialization is needed to avoid parameter equifinality.
This study focuses on the Oberaletsch Glacier, Switzerland, to reproduce the glacier’s state at the end of the Little Ice Age (LIA) and set the stage for future simulations of debris evolution. We take advantage of the well-constrained geometry of the glacier at the end of the LIA due to historic surveys and contemporary bed elevations to provide steady-state targets. We note that the historic observations indicate negligible debris cover at this point, allowing us to simplify the model spin-up to focus only on mass balance and ice extent.We use the Instructed Glacier Model (IGM) combined with a SMB module, which is calibrated based on historical climate data. The SMB data come from historical GSWP3_W5E5 climate data providing monthly temperature and precipitation fields, which are adjusted for topographic variations using lapse rate corrections. This dataset has daily temporal and 0.5° spatial resolution and consists of two parts, W5E5 v2.0 for the period 1979-2019 and GSWP3 v1.09 homogenized with W5E5 for the period 1901-1978. To account for historical climate trends outside the observed period, we use predefined scaling factors for temperature and precipitation.
We initialize IGM with the current geometry of the glacier free of debris with an effective date of 1400, then iteratively adjust ice flow dynamics until a steady-state geometry consistent with the LIA (approximately 1860) is achieved. The temperature gradients, precipitation factors, and calibration biases sourced from OGGM are fine-tuned to match observed glacier characteristics such as extension and SMB distribution. The resulting steady-state model provides a reliable starting point for simulations of glacier evolution, in our case including debris transport using particle-tracking techniques within the IGM.
This methodology underscores the importance of initializing glacier models with accurate geometries and climate data to ensure reliable long-term projections. This work represents the first step towards incorporating debris transport dynamics in future simulations and advancing models capable of reproducing the evolution of debris cover.
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