Sensitivity of the Greenland surface mass and energy balance to uncertainties in key model parameters

We investigate the sensitivity of a distributed glacier surface mass and energy balance model using a variance-based analysis, for two distinct periods of the last glacial cycle: the present day (PD) and the Last Glacial Maximum (LGM). The results can be summarized in three major findings: the sensi...

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Bibliographic Details
Published in:The Cryosphere
Main Authors: T. Zolles, A. Born
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2021
Subjects:
geo
Online Access:https://doi.org/10.5194/tc-15-2917-2021
https://tc.copernicus.org/articles/15/2917/2021/tc-15-2917-2021.pdf
https://doaj.org/article/cee4b7c8a6ae4c3d8d925f89387b87a1
Description
Summary:We investigate the sensitivity of a distributed glacier surface mass and energy balance model using a variance-based analysis, for two distinct periods of the last glacial cycle: the present day (PD) and the Last Glacial Maximum (LGM). The results can be summarized in three major findings: the sensitivity towards individual model parameters and parameterizations is as variable in space as it is in time. The model is most sensitive to uncertainty related to atmospheric emissivity and the down-welling longwave radiation. While the turbulent latent heat flux has a sizable contribution to the surface mass balance uncertainty in central Greenland today, it dominates over the entire ice sheet during the cold climate of the LGM, in spite of its low impact on the overall surface mass balance of the Greenland ice sheet in the modern climate. We conclude that quantifying the model sensitivity is very helpful for tuning free model parameters because it clarifies the relative importance of individual parameters and highlights interactions between them that need to be considered.