17:15 〜 18:45
[ACG42-P19] アラスカ山脈におけるデブリに覆われた３氷河の変動特性
キーワード：氷河、アラスカ
The Alaska region holds ~12% of the world's glaciers, and their runoff is expected to contribute significantly to global sea-level rise (Zemp et al., 2019). In particular, Alaskan glaciers possess ~15% of debris-covered glaciers, a higher proportion than other regions, with hummocky surfaces covered by rocks and sediments (Herreid and Pellicciotti, 2020). Compared to clean glaciers, debris-covered glaciers exhibit complex melt patterns due to heterogeneous surface conditions (e.g., Sato et al., 2021); therefore, the presence of these debris-covered glaciers introduces considerable uncertainty in estimates of glacier volume changes. Some previous studies have reported that the response of debris-covered glaciers can fluctuate with different patterns even when they are located near each other and exist under similar climatic conditions (e.g., Zhao et al., 2023). However, such kind of knowledge of comparative glacier fluctuations within the same region is limited in the Alaska region. In this study, we tackled analyzing the glacier dynamics, melt, and geomorphological characteristics to evaluate the factors of different fluctuation patterns in three neighboring debris-covered glaciers in the Alaska Range.
We targeted Castner Glacier, Fels Glacier, and Canwell Glacier, which are located in the eastern Alaska Range (63.3°N, 145.5°W). These glacier areas are 53.8, 17.4, and 59.6 km2, respectively, and spanning 700-2500 m a.s.l.. We conducted a Global Navigation Satellite System (GNSS) survey in June 2023 on off–glacier stable terrain to validate/correct high-resolution satellite-based digital elevation models (Arctic DEM). Then, more than 10,000 validation points were obtained during the field campaign. We analyzed glaciers’ fluctuations from bias-corrected ArcticDEMs and published glacier thinning, velocity, and ice thickness datasets (Hugonnet et al., 2021; Millan et al., 2022). Our results show that the three neighboring glaciers have different thinning rate patterns despite being in similar elevation ranges. While Canwell Glacier showed a thinning rate decreasing along its elevation, Castner Glacier and Fels Glacier had the maximum thinning zones extending into the middle part and near the terminus, rescinding both ~4 m yr-1. These contrasting patterns of thinning rates are thought to be controlled by glacier dynamics and the morphological characteristics of glaciers’ surfaces.
We targeted Castner Glacier, Fels Glacier, and Canwell Glacier, which are located in the eastern Alaska Range (63.3°N, 145.5°W). These glacier areas are 53.8, 17.4, and 59.6 km2, respectively, and spanning 700-2500 m a.s.l.. We conducted a Global Navigation Satellite System (GNSS) survey in June 2023 on off–glacier stable terrain to validate/correct high-resolution satellite-based digital elevation models (Arctic DEM). Then, more than 10,000 validation points were obtained during the field campaign. We analyzed glaciers’ fluctuations from bias-corrected ArcticDEMs and published glacier thinning, velocity, and ice thickness datasets (Hugonnet et al., 2021; Millan et al., 2022). Our results show that the three neighboring glaciers have different thinning rate patterns despite being in similar elevation ranges. While Canwell Glacier showed a thinning rate decreasing along its elevation, Castner Glacier and Fels Glacier had the maximum thinning zones extending into the middle part and near the terminus, rescinding both ~4 m yr-1. These contrasting patterns of thinning rates are thought to be controlled by glacier dynamics and the morphological characteristics of glaciers’ surfaces.