https://repository.kopri.re.kr/handle/201206/5384 2026-04-12T06:51:13Z 2026-04-12T06:51:13Z Han, Hyangsun https://repository.kopri.re.kr/handle/201206/12042 2022-03-24T07:14:59Z 2018-03-31T00:00:00Z

Title: Study of Sentinel-1 SAR interferometry and offset tracking for surface displacement observation of polar regions Authors: Han, Hyangsun

2018-03-31T00:00:00Z Han, Hyangsun Lee, Hoonyol https://repository.kopri.re.kr/handle/201206/5776 2022-03-24T07:12:11Z 2018-01-01T00:00:00Z

Title: Glacial and tidal strain of landfast sea ice in Terra Nova Bay, East Antarctica,observed by interferometric SAR techniques Authors: Han, Hyangsun; Lee, Hoonyol Abstract: The dynamics of landfast sea ice, also called fast ice for short, has a large influence on the variability of polynyas and marine ecosystems, and the logistics for research stations near the Antarctic coast. Therefore, it is important to accurately measure the strain of fast ice and its seasonal variations, and to identify the cause of stresses on the ice. In this paper, we separate the strains from glacial stress and tidal stress of fast ice near the Campbell Glacier Tongue (CGT) in Terra Nova Bay, East Antarctica. This was done using observations from a series of one-day tandem COSMO-SkyMed Interferometric Synthetic Aperture Radar (InSAR) images obtained from December 2010 to January 2012. Firstly, we discriminated fast ice from pack ice and open water by analyzing the interferometric coherence values. We then identified the characteristics of the strains by investigating the equidisplacement lines of fringes in weekly InSAR and double-differential InSAR (DDInSAR) images. The weekly InSAR images predominantly showed glacial shear strain of the fast ice with fringes parallel to the sides of the CGT. This was due to the cumulative flow of the CGT for a week, while oscillating tidal signals were relatively small. The DDInSAR images, which cancelled glacial strain rates in two one-day InSAR images, showed a deformation of the fast ice by tidal sea surface tilt, with the fringes parallel to the coastline. Based on the unique characteristics of these strains, we separated them from the one-day InSAR images by decomposing the fringe patterns into glacial and tidal strain. Glacial shear strain rates of fast ice attached to the east of the CGT decreased from May to August owing to ice thickening and then stabilized until December. Those to the west of the CGT increased from May to July. This was possibly due to bottom melting of the ice by the increased ocean circulation during the expansion period of the nearby polynya. The glacial strain then decreased until December because of reduced polynya activity. The fast ice near the Jang Bogo Station (JBS) only showed tidal strain as it was isolated from the CGT by cracks and leads. Tidal strain rates of the fast ice were strongly correlated with the magnitude of tidal variations in all these regions, which represents shows that the tidal strain represents tidal sea surface tilt. The tidal response of fast ice to the west of the CGT and near the JBS was stronger than that to the east of the CGT, probably owing to thinner ice thickness there.

2018-01-01T00:00:00Z Han, Soojeong Lee, Hoonyol Han, Hyangsun https://repository.kopri.re.kr/handle/201206/5918 2022-03-24T07:14:11Z 2018-01-01T00:00:00Z

Title: Grounding Line Change of Ronne Ice Shelf, West Antarctica, from 1996 to 2015 Observed by using DDInSAR Authors: Han, Soojeong; Lee, Hoonyol; Han, Hyangsun Abstract: Grounding line of a glacier or ice shelf where ice bottom meets the ocean is sensitive to changes in the polar environment. Recent rapid changes of grounding lines have been observed especially in southwestern Antarctica due to global warming. In this study, ERS-1/2 and Sentinel-1A Synthetic Aperture Radar (SAR) image were interferometrically acquired in 1996 and 2015, respectively, to monitor the movement of the grounding line in the western part of Ronne Ice Shelf near the Antarctic peninsula. Double-Differential Interferometric SAR (DDInSAR) technique was applied to remove gravitational flow signal to detect grounding line from the interferometric phase due to the vertical displacement of the tide. The result showed that ERS-1/2 grounding lines are almost consistent with those from Rignot et al. (2011) which used the similar dataset, confirming the credibility of the data processing. The comparison of ERS-1/2 and Sentinle-1A DDInSAR images showed a grounding line retreat of 1.0 ± 0.1 km from 1996 to 2015. It is also proved that the grounding lines based on the 2004 MODIS Mosaic of Antarctica (MOA) images and digital elevation model searching for ice plain near coastal area (Scambos et al., 2017), is not accurate enough especially where there is a ice plain with no tidal motion.

2018-01-01T00:00:00Z Lee, Hoonyol Han, Hyangsun Jin, Hyorim Han, Soojeong https://repository.kopri.re.kr/handle/201206/8264 2022-03-24T07:11:11Z 2017-01-01T00:00:00Z

Title: TIDAL DEFLECTION OF ROSS ICE SHELF, ANTARCTICA, OBSERVED BY SENTINEL-1A DOUBLE-DIFFERENTIAL INTERFEROMETRIC SAR Authors: Lee, Hoonyol; Han, Hyangsun; Jin, Hyorim; Han, Soojeong Abstract: This paper reports the tidal deflection of Ross Ice Shelf, Antarctica, observed from Sentinel-1A data processed by using double-differential interferometric synthetic aperture radar (DDInSAR) technique. Sentinel-1A single look complex SAR data of 2015-2016, along the east and the west coast of Ross Ice Shelf, were obtained and interferometrically processed by Sentinel Application Platform (SNAP) program. GETASSE30 digital elevation model was used to remove the topographic fringes. After the phase unwrapping using SNAPHU program, the two interferograms were subtracted to obtain DDInSAR image to highlight the tidal deflection signals under the assumption of steady gravitational glacial flow. As a result, we can identify grounding lines and hinge zones in the east and the west coast of Ross Ice Shelf. The wider hinge zone in the west indicates thicker ice shelf than the east. Comparison of the tidal deflection with tidal model remind us the importance of barometric correction.

2017-01-01T00:00:00Z