Glacioclimatological Study of Perennial Ice in the Fuji Ice Cave, Japan. Part 2. Interannual Variation and Relation to Climate

Abstract

A glacioclimatological study of the interannual variation of mass of perennial ice in the Fuji Ice Cave at the foot of Mt. Fuji, in central Japan is presented. The cave is a 150-m-long lava tube located in a dense forest area at an altitude of 1120 m. It has a perennial floor ice of areas approximately 3000 m³ and mean thickness 2.8 m. Mean annual air temperature at the ground surface level is 8.4°C. Ice surface levels and air temperatures were measured 39 times from July 1984 to December 1992. Mean ice level showed a 15 cm increase from 1984 to 1989 and suddenly started to decrease from 1989 to 1992. In the increase stage, annual net balance (December to November) was similar at various points, but in the decreasing stage, the lowering of the level near the entrance was very large due to intense melting. Air temperature inside the cave at the end of the annual cycle showed a correlation to net balance of the corresponding year. Comparison of yearly net balance with meteorological indices at ground level (winter and summer, annual mean air temperature and total precipitation; and number of days with strong precipitation) showed that net balance of a given year has a high correlation with the average winter air temperature anomaly of the preceding 4 yr. This is probably due to the high heat capacity of the cave system.