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Analysis of the Impact of Physics Representation on Permafrost Modeling

Presentation Date
Wednesday, December 15, 2021 at 2:00pm
Convention Center - Poster Hall, D-F



Permafrost degradation due to climate change is expected to affect the hydrology and ecology of the Arctic system, which will further impact human infrastructure and Arctic communities. To reduce the potential damage, better understanding and representation of Arctic physics is required for improved prediction of permafrost dynamics. Generally, incorporating full physical processes will improve modeling accuracy, while also resulting in increased runtime. Any numerical experiment must choose between representing more complex physics and computational expense. Therefore, the purpose of this work is to provide permafrost hydrology modelers important references for better choosing the right model representation for a given modeling experiment by formally studying the tradeoff between complexity and runtime under relevant physical metrics. Specifically, this work will discuss the following three common physics simplifications in permafrost modeling, as well as the corresponding hydrological responses: (1) assuming equal density of ice and liquid water in frozen soil; (2) neglecting advective heat transfer during soil freezing and thaw; (3) neglecting the cryosuction effect in unsaturated freezing soil. We will show a comparison between assuming the simplification and including full physics for the three cases using various modeling scenarios that explore different scales, distinct soil properties and meteorological conditions from different sites. The results of this comparison show the influence of the representation of these physics on active layer thickness, evaporation, discharge, and local temperature and water content, demonstrating the sensitivity of these metrics to each of the processes considered.

Funding Program Area(s)