Ninth International Conference on Permafrost ... - IARC Research

TSP NORWAY – Thermal Monitoring of Mountain Permafrost in Northern NorwayKetil IsaksenNorwegian Meteorological Institute, Oslo, NorwayHerman FarbrotDepartment of Geosciences, University of Oslo, NorwayBernd EtzelmüllerDepartment of Geosciences, University of Oslo, NorwayHanne H. ChristiansenThe University Centre in Svalbard, Longyearbyen, NorwayLars Harald Blikra<strong>International</strong> Centre for Geohazards, Oslo, NorwayKirsti MidttømmeGeological Survey of Norway, Trondheim, NorwayJan Steinar RønningGeological Survey of Norway, Trondheim, NorwayIntroductionPermafrost is widespread in the higher mountains ofNorway. Extensive studies in southern Norway show thatthe lower regional altitudinal limit of mountain permafrostis strongly correlated with the mean annual air temperature(MAAT) and decreases eastward with increasingcontinentality (e.g., Etzelmüller et al. 2008). However, lessinformation is available on the distribution of permafrost innorthern Norway, where most investigations have focusedon periglacial geomorphology and, in particular, palsas(Isaksen et al. 2008 and references therein).In 2002 a permafrost monitoring program was initiated inTroms and Finnmark, which are the two northernmost countiesof mainland Norway. A series of miniature temperaturedataloggers (MTDs) were installed for monitoring groundsurface and air temperatures (Isaksen et al. 2008). A griddedmean annual air temperature map indicates a altitudinalgradient for discontinuous permafrost in northern Norway,decreasing from over 1000 m a.s.l. in coastal sites down tobelow 400 m a.s.l. in the interior and more continental areas(Etzelmüller et al. 2008).In March 2007, the Norwegian-founded IPY project“Permafrost Observatory Project: A Contribution to theThermal State of Permafrost in Norway and Svalbard” (TSPNORWAY) was started. In the following, the project isbriefly described, and the first results from borehole thermalprofiles are presented.The TSP Norway ProjectThe Norwegian-funded IPY project “PermafrostObservatory Project: A Contribution to the Thermal Stateof Permafrost in Norway and Svalbard” (TSP NORWAY;Christiansen et al. 2007) is a part of the international IPYfull project “Permafrost Observatory Project: A Contributionto the Thermal State of Permafrost (TSP).” TSP will obtain a“snapshot” of the permafrost environments as a benchmarkagainst which to assess past and future changes by makingstandardized temperature measurements in existing and newboreholes throughout the World’s permafrost regions. Theultimate payoff is long-term and will serve as validationof current models and understanding of how permafrostconditions are reacting to climate change. Thawing ofpermafrost in Norway may lead to subsidence of the groundsurface, having a substantial impact, for example, oninfrastructure and on the stability of mountain slopes.The main objective of TSP NORWAY is to measure andmodel the permafrost distribution in northern Norway andSvalbard, including its thermal state, thickness, and influenceon periglacial landscape-forming processes.Establishment of High Altitude BoreholesNine 7–31 m deep boreholes were drilled in bedrock inTroms and Finnmark in August and September 2007. In twoof the boreholes, a measurement setup with 15–20 thermistorsconnected to dataloggers and snow depth sensors, with datarecording every six hours, was installed. In one of theseboreholes (Kistefjellet) the data are transferred by a modemenabling online presentation. The other seven and twoexisting boreholes were instrumented with MTDs at selecteddepths. All boreholes were cased. Periodic recalibration ofthe installed thermistors is possible, and the holes remainaccessible for other probes in the future. Furthermore, aseries of MTDs were installed for monitoring surface and airtemperatures at selected sites.ResultsThe first estimate of mean ground temperature (MGT)near the bottom of the boreholes is presented in Table 1.Permafrost is presumably present in one of the boreholes(Guolasjavri 1, Fig. 1). In the remaining boreholes, MGT isnear or slightly above 0°C. Snow cover conditions seem tobe decisive for the permafrost distribution in the investigatedaltitude ranges. In addition sediment-covered ground may insome cases experience permafrost conditions due to thermal111