Sensitivity of modelled mass balance and runoff to representations of debris and accumulation on the Kaskawulsh Glacier, Yukon, Canada

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Authors

Katherine M Robinson , Gwenn Elizabeth Flowers, David Robert Rounce

Abstract

Runoff contributions from glacierized catchments are changing in response to accelerating mass loss. We reconstruct the 1980-2022 mass balance, runoff and water budget of the ~70% glacierized Kaskawulsh River headwaters in Yukon, Canada, using an enhanced temperature-index model driven by downscaled and bias-corrected reanalysis data. Debris is treated using melt-scaling factors based on site-specific measurements of the critical debris thickness. Accumulation is estimated from downscaled precipitation bias corrected based on in-situ measurements. Model tuning incorporates observations of the 2007-2018 geodetic mass balance and seasonal snowline positions on the Kaskawulsh Glacier. We assess model sensitivity to the representation of supraglacial debris and accumulation, including treatments of these processes that can be applied in the absence of in-situ data. Different representations of debris produce <1% variation  in the catchment-wide runoff and water budget. In contrast, accumulation estimates that omit in-situ data produce 33-40% variations in modelled runoff relative to those that use these data. This work identifies site-specific measurements of accumulation as critical to accurate estimates of mass balance and runoff for the Kaskawulsh Glacier, in contrast to site-specific characterization of the effects of debris which influence estimated thinning rates at the glacier terminus but have little impact on the glacier-wide runoff.

DOI

https://doi.org/10.31223/X5FX3W

Subjects

Earth Sciences, Glaciology, Physical Sciences and Mathematics

Keywords

Glacier mass balance, Supraglacial debris, Accumulation bias correction, Glacier runoff

Dates

Published: 2024-07-19 15:59

Last Updated: 2024-10-30 14:50

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License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
None

Data Availability (Reason not available):
The Kaskawulsh Glacier outline was obtained from https://www.glims.org/maps/glims. The NARR data used as input to the mass balance model were obtained from https://downloads.psl.noaa.gov/Datasets/NARR. SFU Glaciology Group snow depth and density measurements can be found in Table S2 of the Supplementary Material. NASA Operation IceBridge radar data products are available at https://data.cresis.ku.edu/data/snow/2021_Alaska_SO/, and the seasonal snow thickness data were obtained from https://data.cresis.ku.edu/data/misc/Alaska_seasonal_snow/ (CReSIS, 2021). Precipitation gauge data were obtained from the Environment and Climate Change Canada Historical Climate Data website (https://climate.weather.gc.ca/historical_data/search_historic_data_e.html, last accessed 2023-11-26). Downscaling and melt-model code will be made public on github upon manuscript publication. Model inputs and outputs will be made available on Zenodo upon manuscript publication.