Journal
PERMAFROST AND PERIGLACIAL PROCESSES
Volume 22, Issue 4, Pages 378-389Publisher
WILEY
DOI: 10.1002/ppp.737
Keywords
bedrock; permafrost; advective heat transport; conductive heat transfer; laboratory experiment; numerical modelling; rockfall; climate change
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Funding
- Swiss Federal Office for the Environment
- SNF NCCR-MICS
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Advective heat transported by water percolating into discontinuities in frozen ground can rapidly increase temperatures at depth because it provides a thermal shortcut between the atmosphere and the subsurface. Here, we develop a conceptual model that incorporates the main heat-exchange processes in a rock cleft. Laboratory experiments and numerical simulations based on the model indicate that latent heat release due to initial ice aggradation can rapidly warm cold bedrock and precondition it for later thermal erosion of cleft ice by advected sensible heat. The timing and duration of water percolation both affect the ice-level change if initial aggradation and subsequent erosion are of the same order of magnitude. The surplus advected heat is absorbed by cleft ice loss and runoff from the cleft so that this energy is not directly detectable in ground temperature records. Our findings suggest that thawing-related rockfall is possible even in cold permafrost if meltwater production and flow characteristics change significantly. Advective warming could rapidly affect failure planes beneath large rock masses and failure events could therefore differ greatly from common magnitude reaction-time relations. Copyright (C) 2011 John Wiley & Sons, Ltd.
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