https://repository.kopri.re.kr/handle/201206/9696 2026-04-26T12:39:18Z 2026-04-26T12:39:18Z Han, Hyangsun Lee, sungjae Kim, Jae-In Kim, Seung Hee Kim, Hyun-cheol https://repository.kopri.re.kr/handle/201206/10623 2022-03-24T07:14:05Z 2019-02-01T00:00:00Z

Title: Changes in a Giant Iceberg Created from the Collapse of the Larsen C Ice Shelf, Antarctic Peninsula, Derived from Sentinel-1 and CryoSat-2 Data Authors: Han, Hyangsun; Lee, sungjae; Kim, Jae-In; Kim, Seung Hee; Kim, Hyun-cheol Abstract: The giant tabular iceberg A68 broke away from the Larsen C Ice Shelf, Antarctic Peninsula, in July 2017. The evolution of A68 would have been affected by both the Larsen C Ice Shelf, the surrounding sea ice, and the nearby shallow seafloor. In this study, we analyze the initial evolution of iceberg A68A―the largest originating from A68―in terms of changes in its area, drift speed, rotation, and freeboard using Sentinel-1 synthetic aperture radar (SAR) images and CryoSat-2 SAR/Interferometric Radar Altimeter observations. The area of iceberg A68A sharply decreased in mid-August 2017 and mid-May 2018 via large calving events. In September 2018, its surface area increased, possibly due to its longitudinal stretching by melting of surrounding sea ice. The decrease in the area of A68A was only 2% over 1.5 years. A68A was relatively stationary until mid-July 2018, while it was surrounded by the Larsen C Ice Shelf front and a high concentration of sea ice, and when its movement was interrupted by the shallow seabed. The iceberg passed through a bay-shaped region in front of the Larsen C Ice Shelf after July 2018, showing a nearly circular motion with higher speed and greater rotation. Drift was mainly inherited from its rotation, because it was still located near the Bawden Ice Rise and could not pass through by the shallow seabed. The freeboard of iceberg A68A decreased at an average rate of -0.80 +- 0.29 m/year during February？November 2018, which could have been due to basal melting by warm seawater in the Antarctic summer and increasing relative velocity of iceberg and ocean currents in the winter of that year. The freeboard of the iceberg measured using CryoSat-2 could represent the returned signal from the snow surface on the iceberg. Based on this, the average rate of thickness change was estimated at -12.89 + 3.34 m/year during the study period considering an average rate of snow accumulation of 0.82 + 0.06 m/year predicted by reanalysis data from the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2). The results of this study reveal the initial evolution mechanism of iceberg A68A, which cannot yet drift freely due to the surrounding terrain and sea ice.

2019-02-01T00:00:00Z Han, Hyangsun Lee, sungjae Kim, Jae-In Kim, Seung Hee Kim, Hyun-cheol https://repository.kopri.re.kr/handle/201206/12471 2022-03-24T07:15:19Z 2019-01-01T00:00:00Z

Title: Initial Evolution of Giant Iceberg A-68 Analyzed by Satellite Observations Authors: Han, Hyangsun; Lee, sungjae; Kim, Jae-In; Kim, Seung Hee; Kim, Hyun-cheol Abstract: 빙산 A-68은 남극 반도의 라센 C 빙붕(Larsen C Ice Shelf)에서 2017년 7월 분리된 단면적 5800 km2의 초거대 빙산이다. A-68의 발생과 진화 과정은 남극 반도 주변 해양환경에 매우 큰 영향을 미칠 수 있기 때문에 지속적으로 모니터링 될 필요가 있다. 이 연구에서는 인공위성 영상레이더(Synthetic Aperture Radar, SAR)와 레이더 고도계 자료를 이용하여 A-68의 발생 직후부터 1.5년간 면적, 이동 및 회전속도, 프리보드(freeboard)의 변화를 관측함으로써 빙산의 초기 진화를 분석하였다. Sentinel-1 SAR 영상으로 관측된 A-68의 면적은 발생 이후 1년간 빙산 가장자리의 붕괴로 인해 감소하였고, 얕은 해저면과 고농도의 주변 해빙으로 인해 이동과 회전량이 매우 작았다. 그러나 2018년 8월 이후부터는 빙산의 급격한 움직임과 면적의 증가가 관측되었다. 빙산의 이동속도 및 회전량의 증가는 주변 해빙농도의 감소와 동시에 강한 활강풍의 영향으로 해저면이 얕은 곳으로부터 빙산이 탈출하였기 때문이다. 빙산 주변의 해빙이 감소하고 이동속도가 가속화되면 빙산과 해수 사이의 마찰이 증가하는데, 이는 빙산의 하부 용융(basal melting)을 촉발하여 두께를 감소시키는 원인으로 작용한다. 빙산의 두께 감소는 빙체의 longitudinal stretching을 수반하게 되며, 이 효과 때문에 인공위성 SAR 영상에서 A-68의 면적 증가가 관측된 것으로 분석되었다. CryoSat-2 레이더 고도계 관측에 의하면 A-68의 프리보드는 일정한 높이를 유지하다가 2018년 2월부터 0.80±0.29 m/a의 속도로 감소하기 시작하였다. 인공위성으로 관측된 A-68의 면적과 프리보드의 변화로부터 빙산 발생 이후 1.5년간 약 1.1×105 톤의 빙체 손실이 발생하였음을 확인할 수 있었다.

2019-01-01T00:00:00Z Han, Hyangsun Lee, sungjae Kim, Jae-In Kim, Seung Hee Kim, Hyun-cheol https://repository.kopri.re.kr/handle/201206/12477 2022-03-24T07:15:18Z 2019-01-01T00:00:00Z

Title: Monitoring iceberg A68 calved from the Larsen C IceShelf using satellite remote sensing Authors: Han, Hyangsun; Lee, sungjae; Kim, Jae-In; Kim, Seung Hee; Kim, Hyun-cheol Abstract: Iceberg A68 calved from the Larsen C Ice Shelf, Antarctic Peninsula, in July 2017. In this study, we analyze the initial evolution of iceberg A68 in terms of changes in its area, drift speed, rotation, and freeboard using Sentinel-1 synthetic aperture radar (SAR) images and CryoSat-2 SAR/Interferometric Radar Altimeter observations. The study period extends from July 2017 to end of 2018. The area of the iceberg sharply decreased in mid-August 2017 and mid-May 2018 via large calving. The area of A68 decreased only 2% over 1.5 years. A68 was relatively stationary until mid-July 2018, while it was surrounded by the Larsen C Ice Shelf front and a high concentration of sea ice, and when its movement was interrupted by the shallow seabed. The iceberg passed through the front of the Larsen C Ice Shelf after July 2018, showing a higher drift speed and greater rotation. The freeboard of A68 decreased at an average rate of 0.80± 0.29 m/a during FebruaryNovember 2018, which could have been due to basal melting. The freeboard measured from CryoSat-2 could represent the returned signal from the snow surface on the iceberg. Based on this, the average rate of freeboard change was estimated at 1.62± 0.30 m/a during the study period considering an average rate of snow accumulation of 0.82±0.06 m/a predicted by reanalysis data from the Modern-Era Retrospective analysis for Research and Applications, Version 2.

2019-01-01T00:00:00Z Han, Hyangsun Lee, sungjae Kim, Jae-In Kim, Hyun-cheol https://repository.kopri.re.kr/handle/201206/12475 2022-03-24T07:15:18Z 2019-01-01T00:00:00Z

Title: Operational iceberg A68 monitoring with remote sensing and information services Authors: Han, Hyangsun; Lee, sungjae; Kim, Jae-In; Kim, Hyun-cheol Abstract: Iceberg A68 is a supersized iceberg that calved from Larsen C Ice Shelf in July 2017. The area of Iceberg A68, when it was calved from the ice shelf, was about 5800 square kilometers which accounts approximately for 12% of the area of Larsen C Ice Shelf. Iceberg A68 is currently the largest iceberg in Antarctica. Due to the split with Iceberg A68, the flow velocity of Larsen C Ice Shelf may change, which can change the oceanic outflow of the ice sheet and cause a change to the sea level. In addition, the occurrence of a supersized iceberg can affect the surrounding marine ecosystem and the sea ice forms, so continuous and constant monitoring for the iceberg is necessary. The Korea Polar Research Institute (KOPRI) have monitored Iceberg A68 and the changes in the surrounding environment by using satellite remote sensing and provided the iceberg information from the satellites through a web-based services. High-resolution SAR image enables precise surface observation without being affected by weather conditions and sun altitudes. Changes in the area and drift of Iceberg A68 are monitored by using Sentinel-1 and KOMPSAT-5 SAR images. The split with iceberg A68 may result in a change in the ice flow velocity of Larsen C Ice Shelf. The flow velocity of Larsen C Ice Shelf is monitored by offset tracking of Sentinel-1 SAR images. Using CryoSat-2 altimetry observations, changes in the thickness of iceberg A68 is monitored. The thickness is estimated by using the freeboard height of the iceberg observed monthly through the satellite altimeter. This provides basic information that can be used in various research fields such as predicting global environmental change, sea-level change, oceanography, biology, and glaciology through the satellite observations of the iceberg A68.

2019-01-01T00:00:00Z