We found permafrost at the lower end of a block slope on Mt. Nishi-Nupukaushinupuri, Hokkaido Island. The distribution of the bottom temperature of snow cover (BTS), warm funnels at the top of the slope, and ground temperature changes on the block slope indicate continuous air circulation during the winter. In the spring, snowmelt water flows to the valley bottom, and refreezes on the perennial ice that fills the voids between coarse blocks. Simultaneously, ground temperatures abruptly increase at all depths in the active layer. These results strongly suggest that air circulation in winter, as well as the ice formation processes in spring control the thermal regime of the active layer of the block slope with a mean annual air temperature (MAAT) above 0°C.
