Climate in Mt. Daisetsu, as Viewed from the Year Round Meteorological Observation at Hakuun Hut in 1985

The upper part of Mt. Daisetsu has one of the most typical periglacial regions in Japan. But long term meteorological observation had not been carried out there. So the present writers carried out the year round meteorological observation at Mt. Daisetsu Hakuun hut (2, 000m above sea level) in 1985. The annual mean air temperature there was -3.8°C, and close to the value in Fairbanks, Alaska, located in discontinuous permafrost zone. Mt. Daisetsu has much more precipitation than many low latitude periglacial regions. The summit area of Mt Daisetsu also has the windward bare ground, where snow can hardly accumulate due to strong winter wind. We concider that there exists permafrost in such bare ground. Air temperature condition suggests that lower limit of permafrost in Mt. Daisetsu lies lower than 2, 000m. The existence of palsas at 1, 720m in Mt. Daisetu supports this. Summit regions of Mt. Daisetsu is under periglacial environment and many active periglacial phenomena occur there. The forest limit in Mt. Daisetsu is not dependent on WI (Warmth Index) 15.