Estimation of ice flow velocity of Shirase Glacier and its surrounding landfast ice in East Antarctica using synthetic aperture radar imagery

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K11627
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 63010:Environmental dynamic analysis-related
• Research Institution: Nihon University
• Principal Investigator: NAKAMURA Kazuki 日本大学, 工学部, 准教授 (60435500)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 氷河 / 定着氷 / 控え壁 / 相互作用 / 合成開口レーダ

Outline of Final Research Achievements

This study presents that temporal variations in ice flow velocities for Shirase Glacier and its surrounding landfast ice in Lutzow-Holm Bay, East Antarctica were estimated using synthetic aperture radar (SAR) images acquired by the Phased Array L-band SAR-2 (PALSAR-2) onboard Advanced Land Observing Satellite-2 (ALOS-2) in 2015～2018. The images were analyzed using image correlation. The flow velocity at the 10 km downstream from the grounding line of Shirase Glacier shows that flow velocity is considered to be less related to the landfast ice stability. However, the flow velocity around 40 km downstream from the GL show changes related to landfast ice condition. The flow velocity is more increasable of 0.20～0.38 km a-1 under the unstable landfast ice condition than the stable landfast ice condition. Therefore, our results show the velocity of Shirase Glacier are associated with the condition of landfast ice stability or instability.

Free Research Field

衛星雪氷学

Academic Significance and Societal Importance of the Research Achievements

海水位の上昇は氷床融解の寄与が最大の不確実性の原因となっているが、過去の海水位の変化は氷床の消長にほぼ依存しており、氷床融解による水位の上昇が懸念される。南極における雪氷の消耗の加速は西南極において顕著であるが、東南極は質量収支（積雪による涵養と海洋へ流出する消耗の和）が均衡していると考えられてきた。しかし、東南極の白瀬氷河を排出口とする氷床の流出量については消耗傾向にあり、白瀬氷河と氷河を取り囲む定着氷の動態の相互作用の理解が喫緊の課題であることを示した。このことから、本研究で明らかとなった氷河を取り囲む定着氷が控え壁の役割を果たすことは、今後、氷河の質量収支を考える上での重要な示唆である。