10:45 AM - 12:15 PM
[ACC25-P07] Measurement of Surface Velocity Change of Totten Glacier Ice Shelf, East Antarctica, Using Sentinel-1 Satellite Data
Keywords:Antarctica, Glacier, SAR, Pixel offset, Totten
Glacier flow has various effects on the global environment, including erosion and sedimentation of land surfaces and the effects of glacier outflow on sea level change. The development of synthetic aperture radar (SAR) and GRACE observations over the past few decades have revealed recent glacier acceleration and increased mass loss in Greenland and West Antarctica. Short-term velocity changes are interpreted to be due to changes in the basal sliding of glaciers and ice sheets, but are not necessarily "predicted" in advance because the constitutive law of basal sliding itself has not been established. A better understanding of the basal sliding law could lead to future predictions through numerical modeling. However, the details of short-term temporal changes in glacier flow velocity in Antarctica are not clear, compared to those in Greenland, the Asian High Alps, Alaska, and Patagonia. In limited areas around the Totten Glacier, GRACE data have indicated a decrease in mass, although not as much as in West Antarctica. Focusing on one such area, Totten Glacier, we processed C-band SAR images from the Sentinel-1 satellite with 12 (or 6) return days to determine whether there is a spatiotemporal change in surface velocity at the terminus.
SAR data were acquired in Interferometric Wide Swath mode (IW) on the Sentinel-1 satellite, which is publicly available at the Alaska Satellite Facility (ASF) of the University of Alaska. Data from Sentinel-1A and Sentinel-1B, each with a period of 6-12 days, were used to observe seasonal and short-term signals in summer and winter, respectively. The polarization used in the analysis was HH. The resolution of the SLC images is about 2.3 x 14.1 m (range x azimuth), and the swath width is about 250 km. Gamma Software was used for analysis. Offset tracking analysis was performed using two co-registered SLC images to obtain range and azimuth displacements. The Reference Elevation Model of Antarctica (REMA) was used to remove offset due to topography. The obtained displacements were transformed into a 3D displacement field (east-west, north-south, and up-down components) using the topographic gradient information in REMA.
At this point, we found that the downstream flow velocity on the ice shelf in the summer season is generally accelerated by ~15 cm/day (~50 m/year) compared to that in the winter season. The difference in velocity between winter and summer gradually increased downstream, but when the amount of change (%) was calculated, it was found to be ~2% at about 30 km from the ice shelf grounding line, 5-6% at about 50 km, and ~4% near the end of the ice shelf, indicating a relatively large amount of change in the middle reaches of the ice shelf. Comparisons with other ice shelves in East Antarctica will be made.
SAR data were acquired in Interferometric Wide Swath mode (IW) on the Sentinel-1 satellite, which is publicly available at the Alaska Satellite Facility (ASF) of the University of Alaska. Data from Sentinel-1A and Sentinel-1B, each with a period of 6-12 days, were used to observe seasonal and short-term signals in summer and winter, respectively. The polarization used in the analysis was HH. The resolution of the SLC images is about 2.3 x 14.1 m (range x azimuth), and the swath width is about 250 km. Gamma Software was used for analysis. Offset tracking analysis was performed using two co-registered SLC images to obtain range and azimuth displacements. The Reference Elevation Model of Antarctica (REMA) was used to remove offset due to topography. The obtained displacements were transformed into a 3D displacement field (east-west, north-south, and up-down components) using the topographic gradient information in REMA.
At this point, we found that the downstream flow velocity on the ice shelf in the summer season is generally accelerated by ~15 cm/day (~50 m/year) compared to that in the winter season. The difference in velocity between winter and summer gradually increased downstream, but when the amount of change (%) was calculated, it was found to be ~2% at about 30 km from the ice shelf grounding line, 5-6% at about 50 km, and ~4% near the end of the ice shelf, indicating a relatively large amount of change in the middle reaches of the ice shelf. Comparisons with other ice shelves in East Antarctica will be made.