3:00 PM - 3:15 PM
[ACC32-06] Observing relative altitude changes of very small glaciers from optical satellite images
Keywords:Glacier, Remote sensing, Mass balance, SfM
1. Introduction
Glaciers with an area of 0.5 km² or less are referred to as very small glaciers (VSGs), and they account for more than 70% of the approximately 270,000 glaciers identified on Earth (RGI 7.0 Consortium, 2023). VSGs are particularly sensitive to climate change, exhibiting a short response time to such changes. As a result, most VSGs, characterized by their large numbers, are expected to disappear by 2100, and concerns regarding significant impacts on regional water resources and sea level rise (Rounce et al., 2023).
The accumulation of satellite data has enabled global monitoring of glacier mass balance. However, the relatively low spatial resolution of this data introduces considerable uncertainty when assessing the mass balance of VSGs (Hugonnet et al., 2021). Monitoring the mass balance of VSGs is crucial for predicting future impacts on water resources and sea levels due to glacier shrinkage from global warming.
In this study, we tergeted on Shakushizawa VSG, which was recently confirmed as a glacier (Arie et al., 2025), and used high-resolution optical images (SkySat: ground resolution 0.86 m) and photogrammetry (SfM-MVS technology) to create digital surface models (DSMs) and calculate relative altitude changes and their errors.
2. Methods
We created DSMs for the two periods from SkySat images taken of the Shakusawa VSGs on October 17, 2023, and October 21, 2024, using SfM-MVS software (Agisoft-Metashape). By comparing the two DSMs created, we calculated the altitude change of the Shakusawa VSG between 2023 and 2024. We also calculated the root mean square error (RMSE) from the relative altitude change in the stable bedrock around the glacier (altitude change = error) and obtained the error in calculating the relative altitude change of the Shakusawa VSG.
3. Results
The results of the SfM-MVS analysis using the SkySat images confirmed that, although there were many missing points on the steep cliffs, high-density point cloud data could be created in the glacier area. In addition, in the 2023-2024 fiscal year, the average altitude change of the Shakushizawa VSG was -1.23 m, and the snow surface altitude was decreasing in the wide area of the this VSG. The RMSE calculated in the stable area was 0.99 m.
Glaciers with an area of 0.5 km² or less are referred to as very small glaciers (VSGs), and they account for more than 70% of the approximately 270,000 glaciers identified on Earth (RGI 7.0 Consortium, 2023). VSGs are particularly sensitive to climate change, exhibiting a short response time to such changes. As a result, most VSGs, characterized by their large numbers, are expected to disappear by 2100, and concerns regarding significant impacts on regional water resources and sea level rise (Rounce et al., 2023).
The accumulation of satellite data has enabled global monitoring of glacier mass balance. However, the relatively low spatial resolution of this data introduces considerable uncertainty when assessing the mass balance of VSGs (Hugonnet et al., 2021). Monitoring the mass balance of VSGs is crucial for predicting future impacts on water resources and sea levels due to glacier shrinkage from global warming.
In this study, we tergeted on Shakushizawa VSG, which was recently confirmed as a glacier (Arie et al., 2025), and used high-resolution optical images (SkySat: ground resolution 0.86 m) and photogrammetry (SfM-MVS technology) to create digital surface models (DSMs) and calculate relative altitude changes and their errors.
2. Methods
We created DSMs for the two periods from SkySat images taken of the Shakusawa VSGs on October 17, 2023, and October 21, 2024, using SfM-MVS software (Agisoft-Metashape). By comparing the two DSMs created, we calculated the altitude change of the Shakusawa VSG between 2023 and 2024. We also calculated the root mean square error (RMSE) from the relative altitude change in the stable bedrock around the glacier (altitude change = error) and obtained the error in calculating the relative altitude change of the Shakusawa VSG.
3. Results
The results of the SfM-MVS analysis using the SkySat images confirmed that, although there were many missing points on the steep cliffs, high-density point cloud data could be created in the glacier area. In addition, in the 2023-2024 fiscal year, the average altitude change of the Shakushizawa VSG was -1.23 m, and the snow surface altitude was decreasing in the wide area of the this VSG. The RMSE calculated in the stable area was 0.99 m.