Discussion of the thermo-insulation effect of a seasonal snow cover on permafrost soil in Bayelva, Svalbard (1998 - 2017) with respect to current knowledge


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julia.boike [ at ] awi.de

Abstract

Bayelva is a High-Arctic research site on Spitsbergen Island in the Svalbard archipelago (78.551 ° N; 11.571 ° E) where climate, soil and snow components are recorded since 1998 by the Alfred-Wegener-Institute. This study site is underlain by permafrost with average temperatures around -2.8 °C and seasonally snow-covered from October to May. The snow pack thermally insulates the soil temperatures from air temperature signals, a connection which is not well understood yet. To gain better understanding of these thermal relationships, longterm analyses of air, radiation, soil and snow characteristics were examined in this study. Air temperature has increased by 0.14 °C per year for the period from 1998 to 2016 which is higher than the global average temperature increase in the same period. Radiation balance trend analyses are characterized by an increase in longwave radiation during winter months. Results of snow characteristic studies show that the last day in the year with a snow cover has been moving to earlier dates with 0.5 days per year from 1998 to 2016, extending the snow-free season. Thus more time for soil warming is supplied. This aligns well with warming trends of all soil temperature sensors to a depth of 9m as well as the thickening of the active layer (ALT). The ALT is estimated to have reached a depth of 2m in 2016 for the first time, following an increase of 0.05 per year. Since it is difficultly to measure the exact ALT, we used the ’Stefan-Model’. To account for different magnitudes of snow cover insulation, an effective snow depth (Sdepth,eff) was calculated for each year. High Sdepth,eff values represent high thermo-insulation, due to early snowfall and long periods with snow depths over 0.4 m, and can be linked to years in which re-freezing of the whole active layer took until early March of the next year. The results of this study support the importance of snow physical characteristics for the permafrost thermal regime, as also detailed in the Arctic Monitoring and Assessment Programme - an Arctic Council Working Group.



Item Type
Thesis (Master)
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Primary Division
Programs
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Research Networks
Peer revision
Not peer-reviewed
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Published
Eprint ID
50747
Cite as
Ebenhoch, S. (2018): Discussion of the thermo-insulation effect of a seasonal snow cover on permafrost soil in Bayelva, Svalbard (1998 - 2017) with respect to current knowledge , Master thesis, Institute of Geography.


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