5:15 PM - 6:45 PM
[ACC26-P05] Formation conditions of perennial snow patches in the northern Japanese Alps
Keywords:Perennial snow patch, Glacier, Northern Japanese Alps, Formation conditions
1. abstract
More than 100 perennial snow patches are distributed in the mountains along the Sea of Japan, one of the world's snowiest regions (Higuchi and Iozawa, 1971). Variation in the area of snow patches is an indicator of short-term climatic change (Higuchi, 1968). It is an important indicator of changes in the mountain environment in the northern Japanese Alps, where meteorological observations are scarce. However, aerial photographs are not frequently obtained, continuous monitoring of the area variation of snow-capped valleys has not been conducted, and the formation environment of snow patches is not clear. In this study, we created polygon data of snow gorges from 2016 to 2023 using satellite images acquired in October, the last month of snowmelt and investigated the changes in the number and area of snow patches. We also added environmental factors to the polygon data and conducted multivariate cluster analysis for each watershed to investigate environmental factors related to the maintenance and disappearance of snow patches.
The results of the number and area of snow patches over the eight years are shown in Figure 1. The number and area of snow patches were largest in 2017 and smallest in 2016 and 2023, with slight differences. The variation in the number and area of snow patches showed the same trend.
A multivariate cluster analysis of the watersheds on the east side of the mountain ridge showed that the greater the average elevation or the proportion of slopes above 50 degrees, the fewer the number of years of snow patch loss (Figure 2). However, there were some watersheds, such as Group 5, that were not in the first-line mountainous area but still had a small number of years of snow patch loss.
Next, the analysis of watersheds on the west side of the mountain ridge showed that watersheds in Groups 2 and 3 had higher mean elevations or a greater proportion of slopes with elevations greater than 50 degrees. Watersheds in Group 5, which are not in the First Range, had the highest number of years of snow patch loss.
More than 100 perennial snow patches are distributed in the mountains along the Sea of Japan, one of the world's snowiest regions (Higuchi and Iozawa, 1971). Variation in the area of snow patches is an indicator of short-term climatic change (Higuchi, 1968). It is an important indicator of changes in the mountain environment in the northern Japanese Alps, where meteorological observations are scarce. However, aerial photographs are not frequently obtained, continuous monitoring of the area variation of snow-capped valleys has not been conducted, and the formation environment of snow patches is not clear. In this study, we created polygon data of snow gorges from 2016 to 2023 using satellite images acquired in October, the last month of snowmelt and investigated the changes in the number and area of snow patches. We also added environmental factors to the polygon data and conducted multivariate cluster analysis for each watershed to investigate environmental factors related to the maintenance and disappearance of snow patches.
The results of the number and area of snow patches over the eight years are shown in Figure 1. The number and area of snow patches were largest in 2017 and smallest in 2016 and 2023, with slight differences. The variation in the number and area of snow patches showed the same trend.
A multivariate cluster analysis of the watersheds on the east side of the mountain ridge showed that the greater the average elevation or the proportion of slopes above 50 degrees, the fewer the number of years of snow patch loss (Figure 2). However, there were some watersheds, such as Group 5, that were not in the first-line mountainous area but still had a small number of years of snow patch loss.
Next, the analysis of watersheds on the west side of the mountain ridge showed that watersheds in Groups 2 and 3 had higher mean elevations or a greater proportion of slopes with elevations greater than 50 degrees. Watersheds in Group 5, which are not in the First Range, had the highest number of years of snow patch loss.