13. April 2008
measurements at Iskoras, Finnmark
Contact person for additional information: Herman Farbrot
Text and photos by Herman Farbrot
Summit of Iskoras early March 4, 2008, looking east. Large areas of the mountain ridge is bare-blown.
March 2008 Karianne Staalesen Lille°ren and Herman Farbrot (both
BTS method measures the ground surface temperatures beneath a thick snow cover
(>80-100 cm) before the onset of melting. Due to the low thermal conductivity
of snow, the ground surface temperatures reflect the thermal regime of the
subsurface. Hence, low temperatures (below c. -3oC) indicate
permafrost whereas temperatures close to 0░C indicate
measurements were conducted at Iskoras, an east-west aligned mountain ridge, 20
km to the south of the city Karasjok. Iskoras is the highest mountain in
Finnmarksvidda, south of the river Karasjohka. Close to the summit (597 m
a.s.l.) the telecompany Telenor has established a antenna station (see photo
above), where we kindly were allowed to stay overnight.
our investigation, we focussed on the north and the south side of the mountain
ridge. It was difficult to find sites with thick snow cover suitable for BTS
measurements. However, a consistent picture of lower BTS values in the
northfacing slope of the mountain compared to the southfacing slope emerged.
results indicate no permafrost at snow covered sites in the southern slope,
while permafrost may be present down to about 500 m a.s.l. at snow covered sites
in the northern slope. The top plateau was mainly bare-blown with snow cover
thicknesses of just a few cm. Here, a 10,7 m deep borehole was drilled September
2007 as part of the TSP Norway drilling campaign in
Permafrost distribution in the region will be further investigated by geophysical investigations (electrical resistivity tomography and seismics) the coming summer.
Lille°ren dressed up for BTS measurements and snowmobile ride in air
temperatures close to -30oC.