Abstract
In Japan, there is a strong correlation between latitude and air temperature at meteorological observation points at low altitudes. In contrast, at high altitudes, the air temperature decreases with altitude, and a corresponding vegetation distribution is formed, which is unique to mountains. Snow present in large quantities in mountainous areas, is an important water resource and its abundance depends on winter air temperatures. Assessment of winter air temperature fluctuation trends in high-altitude mountainous regions is crucial for understanding future changes in water resources and vegetation distribution dynamics. Therefore, we examine the trends in winter air temperature fluctuations in the central mountainous region, where several high-altitude meteorological observation points of the Japan Meteorological Agency are located. The latitude of the meteorological observation points and the seasonal average air temperature showed a linear relationship, except in summer, and the north-south difference in the seasonal average air temperature was the greatest in winter. Through the examination of the trends in annual minimum air temperature fluctuations at nine meteorological station locations in the central mountainous region, we noted a statistically significant upward trend at eight locations, except for Mt. Fuji. The trends in annual minimum air temperature fluctuations for each altitude of the meteorological stations were examined for over 78 years since 1945, where a clear upward trend was observed at lower altitudes but not at higher altitudes. Since 1989, the average winter air temperature and coldest month average air temperature at the central mountainous region meteorological stations did not show statistically significant fluctuation trends. Winter air temperatures in the central mountainous region, excluding Mt. Fuji, showed a long-term upward trend; however, in 34 years since 1989, winter air temperatures did not show a statistically significant upward trend at any location.
