14:45 〜 15:00
[ACC32-05] UAV surveys on Qaanaaq Glacier in northwestern Greenland
キーワード：氷河、グリーンランド、ドローン
While remote sensing is an effective technique to quantify glacial changes, unmanned aerial vehicle (UAV) surveys have advantages with substantially higher spatial and temporal resolutions. For example, surface elevation, ice speed, surface albedo, streams, and lakes can be analyzed with a centimeter resolution as well as a temporal separation of several days. We have performed UAV surveys on Qaanaaq Glacier (77° 28’ N, 69° 14’ E), a land-terminating glacier in northwestern Greenland during the summers in 2022, 2023, and 2024. In this study, we report on the surface elevation change and development of supraglacial streams analyzed with images obtained by the UAV surveys.
The UAV surveys were conducted five times between July 14 and August 11, 2022, six times between July 17 and August 7, 2023, and three times between July 17 and 24, 2024. The flights covered the ablation area on Qaanaaq Glacier over an elevation range from 200 to 800 m. The surveys were performed with DJI phantom4 pro V2.0 in 2022 and 2023, and with DJI mavic3M in 2024. The UAV was operated at an altitude of 120 m above the glacier surface. The ground control points were distributed on and off the glacier to improve the accuracy of image processing for digital elevation model (DEM). Using Structure-from-Motion software, Agisoft Metashape, we generated DEMs (6.4–10.8 cm resolution) and ortho-mosaic images (3.2–5.4 cm resolution). To validate the DEMs, we measured surface elevation with kinematic GPS positioning technique.
By comparing DEMs on July 20, 2023 and July 18, 2024, the mean surface elevation change rate over the study area was obtained as −1.42 m/yr. Ice loss was most significant near the terminus (−2.04 m/yr). An ice cliff situated along the glacier margin near the terminus retreated by 7 m and the surface elevation decreased by 11 m over the year. A map of supraglacial streams generated by the UAV images suggested that glacier melt was enhanced by water streams.
Based on the initial results, we are in the process of studying the glacier surface changes over the observed periods. In the presentation, we show further results from the UAV data in 2022–2024, including the surface elevation change and the development of supraglacial streams.
The UAV surveys were conducted five times between July 14 and August 11, 2022, six times between July 17 and August 7, 2023, and three times between July 17 and 24, 2024. The flights covered the ablation area on Qaanaaq Glacier over an elevation range from 200 to 800 m. The surveys were performed with DJI phantom4 pro V2.0 in 2022 and 2023, and with DJI mavic3M in 2024. The UAV was operated at an altitude of 120 m above the glacier surface. The ground control points were distributed on and off the glacier to improve the accuracy of image processing for digital elevation model (DEM). Using Structure-from-Motion software, Agisoft Metashape, we generated DEMs (6.4–10.8 cm resolution) and ortho-mosaic images (3.2–5.4 cm resolution). To validate the DEMs, we measured surface elevation with kinematic GPS positioning technique.
By comparing DEMs on July 20, 2023 and July 18, 2024, the mean surface elevation change rate over the study area was obtained as −1.42 m/yr. Ice loss was most significant near the terminus (−2.04 m/yr). An ice cliff situated along the glacier margin near the terminus retreated by 7 m and the surface elevation decreased by 11 m over the year. A map of supraglacial streams generated by the UAV images suggested that glacier melt was enhanced by water streams.
Based on the initial results, we are in the process of studying the glacier surface changes over the observed periods. In the presentation, we show further results from the UAV data in 2022–2024, including the surface elevation change and the development of supraglacial streams.