Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
doi:10.5194/tc-2016-227
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
14 Oct 2016
Review status
A revision of this discussion paper was accepted for the journal The Cryosphere (TC) and is expected to appear here in due course.
Numerical modelling of convective heat transport by air flow in permafrost-affected talus slopes
Jonas Wicky and Christian Hauck Department of Geosciences, University of Fribourg, Fribourg, 1700, Switzerland
Abstract. Talus slopes are a widespread geomorphic phenomenon in the Alps. Due to their high porosity a gravity-driven internal air circulation can be established which is forced by the gradient between outside (air) and internal (talus) temperature. The thermal regime is different from the surrounding environment often leading to cold microclimates and permafrost occurrences. So far this phenomenon has mainly been analysed by field studies and only few explicit modelling studies of this phenomenon exist. Numerical simulations of permafrost sometimes use parameterizations for the effects of convection, but mostly neglect the influence of convective heat transfer in air on the thermal regime. On the contrary, in civil engineering many studies were carried out to investigate the thermal behaviour of blocky layers and to improve their passive cooling capacity. The present study further develops and applies these concepts to model heat transfer in air flow in a natural scale talus slope. Modelling results show that convective heat transfer has the potential to develop a temperature difference between the lower and the upper part from about 0.7 °C (boundary closed to the atmosphere) to 2.5 °C (boundary open to the atmosphere). A seasonally alternating chimney-effect type circulation develops. Modelling results also show that this convective heat transfer leads to a cold reservoir in the lower part of the talus slope which can be crucial for maintaining the frozen ground conditions under climate change.

Citation: Wicky, J. and Hauck, C.: Numerical modelling of convective heat transport by air flow in permafrost-affected talus slopes, The Cryosphere Discuss., doi:10.5194/tc-2016-227, in review, 2016.
Jonas Wicky and Christian Hauck
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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RC1: 'Reviewers comments', Anonymous Referee #1, 25 Nov 2016 Printer-friendly Version 
 
RC2: 'General Comments', Lukas U. Arenson, 02 Jan 2017 Printer-friendly Version Supplement 
 
AC1: 'Authors response to reviewers', Jonas Wicky, 10 Mar 2017 Printer-friendly Version Supplement 
Jonas Wicky and Christian Hauck
Jonas Wicky and Christian Hauck

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Short summary
Talus slopes are a widespread geomorphic phenomenon, which may show permafrost conditions even at low altitudes due to cold microclimates induced by a gravity-driven internal air circulation. We show for the first time a numerical simulation of this internal air circulation of a field-scale talus slope which leads to temperature differences up to 2.5 °C between the upper and the lower part of the slope, with a cold reservoir developing at the bottom.
Talus slopes are a widespread geomorphic phenomenon, which may show permafrost conditions even...
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