[M-IS20] Global climate change driven by the Southern Ocean and the Antarctic Ice Sheet

[MIS20-P03] Estimation of flow velocity of Shirase Glacier using Sentinel-1 SAR data

*Shotaro Ohkawa¹, Koichiro Doi^2,1, Kazuki Nakamura³, Yuichi Aoyama^2,1, Hiroto Nagai⁴ (1.The Graduate University for Advanced Studies, SOKENDAI, 2.National Institute of Polar Research, 3.College of Engineering, Nihon University, 4.School of Education, Waseda University)

Keywords:Shirase Glacier, Sentinel-1, Flow velocity

The Shirase Glacier is known for one of the fastest stream glaciers in East Antarctica. According to previous studies, the flow velocity of the Shirase Glacier was shown seasonal variations at the adjacent terminus of the Shirase Glacier. This is because the seasonal variation is considered to be affected by the buttress effect of landfast ice surrounding the glacier terminus, but the mechanism of the seasonl velocity changes is still not clear due to few research. Therefore, this study aims to clarify the relationship between the flow velocity variation of the glacier and the landfast ice in front of the Shirase Glacier.

We obtained radar images acquired from July 2018 to December 2021 by the Synthetic Aperture Radar (SAR) onboard the Sentinel-1A satellite, which has a repeat cycle of 12 days. The flow velocity of the Shirase Glacier was estimated by the offset tracking technique.

Here the seasonal variation of flow velocity is defined as the flow velocity difference in summertime and wintertime. The flow velocity of Shirase Glacier showed a seasonal variation from around 40 km downstream of the grounding line to terminus of glacier. The seasonal variation which was shown every year from 2018 to 2021 was approximately 10 m 12-day^–1.

In order to clarify why the flow velocity changes seasonally, we will calculate the momentum of the Shirase Glacier and the landfast ice using the flow rate, the area of landfast ice, and the surface altitude (ice thickness) for estimating the area of the Shirase Glacier that the landfast ice can dam.


Acknowledgment
This study was partially supported by JSPS KAKENHI Grant No. 17H06321 and 21K12214.