Thermal regime of openwork block fields on the mountains Elgahogna and Solen, central-eastern Norway

Ground temperatures in openwork blocky debris are frequently lower than in bedrock or regolith with a matrix of fine sediment, creating a negative temperature anomaly. Two years of temperature measurements in seven 1-m-deep profiles located in central-eastern Norway showed that mean annual ground temperatures were 1.3-2.0 degrees C lower in block fields (felsenmeer) compared with till and bedrock. These data suggest that mountain permafrost can be present in block fields several hundred metres lower than in bedrock and till, providing other conditions remain the same. Better thermal coupling of the ground and the air in winter was responsible for the observed anomaly, probably caused by enhanced conduction through blocks protruding into and through the snow and thereby acting as efficient heat bridges. Convection in the blocky debris, which has been used previously as an explanation of the negative thermal anomaly, was less important than initially presumed. Copyright (C) 2008 John Wiley & Sons, Ltd.