HR: 08:00h
AN: C11A-01 INVITED     [PDF]
TI: European Mountain Permafrost: Recent Near Surface Thermal Responses
AU: * Harris, C
EM: harrisc@cardiff.ac.uk
AF: Cardiff University, School of Earth, Ocean and Planetary Sciences, Cardiff, CF10 3YE United Kingdom
AU: Isaksen, K
EM: ketil.isaksen@mi.no
AF: Norwegian Meteorological Institute, P.O.Box 43 Blindern, Oslo, N-0313 Norway
AU: Sollid, J L
EM: j.l.sollid@geo.uio.no
AF: University of Oslo, Department of Physical Geography, P.O. Box 1042, Blindern, Oslo, N-0316 Norway
AU: Vonder M\"{u}hll, D
EM: Daniel.VonderMuehll@UniBas.ch
AF: University of Basel, Petersgraben 35/3, Basel, CH-4051 Switzerland
AU: Gruber, S
EM: stgruber@geo.unizh.ch
AF: University of Zurich - Irchel, Department of Physical Geography, Winterthurerstrasse 190, Zurich, CH-8057 Switzerland
AB: Geothermal measurements from the European PACE borehole network are firstly briefly reviewed. The network comprises six permafrost boreholes extending to at least 100 m depth in bedrock and forming a latitudinal transect from the European Alps, through the Scandinavian mountains to Svalbard. Near surface thermal regimes are first described, and active layer depths are shown to increase significantly with decreasing latitude. All boreholes show non-linear thermal profiles with near-surface warm-side temperature deviations from the deeper thermal gradient. First approximation estimates, based on curvature within the borehole thermal profiles, indicate a maximum ground surface warming of +1$\deg$C in Svalbard, considered to relate to thermal changes in the last 100 yr. In mainland Scandinavia, surface warming decreases southwards, being +0.6$\deg$C at Tarfalaryggen, Sweden and +0.5$\deg$C at Juvassh\"{o}e, Norway. In the European Alps, the steeper topography and greater influence of aspect leads to greater variation in thermal profiles, with estimated warming ranging from +0.8$\deg$C to +0.5$\deg$C. However, three-dimensional thermal modeling is necessary, particularly in the steep Alpine terrain before these thermal profiles can be interpreted with more confidence. The northernmost PACE borehole is located at Janssonhaugen, Svalbard at an altitude of 270 m a.s.l.. Morphologically the site is a sandstone bedrock remnant in a broad valley. Precipitation is low and wind action prevents significant snow accumulation. Data since 1999 indicate rapid warming at this arctic location apparently related to atmospheric temperatures. In most of the remaining boreholes, temperatures are strongly influenced by winter snow cover. However, the thermal response of Alpine boreholes to high summer temperatures in 2003 is reported and potential environmental impacts of such extreme events briefly discussed.
DE: 1615 Biogeochemical processes (4805)
DE: 1823 Frozen ground
DE: 1863 Snow and ice (1827)
DE: 3322 Land/atmosphere interactions
DE: 3344 Paleoclimatology
SC: Cryosphere [C]
MN: 2003 Fall Meeting