Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

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Motion of Glaciers, Sea Ice, and Ice Shelv es in Canisteo Peninsula, West Antarctica Observed by 4-Pass Differential Interferom etric SAR Technique Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

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Motion of Glaciers, Sea Ice, and Ice Shelves in Canisteo Peninsula, West Antarctica Observed by 4-Pass Differential Interferometric SAR Technique. Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA. Contents. Introduction Study Area and Data Method - PowerPoint PPT Presentation

Transcript of Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Page 1: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Motion of Glaciers, Sea Ice, and Ice Shelves in Canisteo Peninsula, West Antarctica Observed by 4-Pass Differential

Interferometric SAR Technique

Hyangsun Han and Hoonyol Lee

Kangwon National University, KOREA

Page 2: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

ContentsIntroduction

Study Area and Data

Method

Analysis of Differential Interferogram

Conclusion

Page 3: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

IntroductionImportance of POLAR REGION

Glaciers, Sea Ice, and Ice Shelves are closely related to the Global Warming and Sea Level RisingThe motion of glaciers and the degradation of sea ice and ice shelves in the Antarctic are being acceleratedLarge changes have been observed in the West Antarctica

Usefulness of Synthetic Aperture Radar (SAR) for the polar researchSAR is not affected solar radiation or atmosphere conditionsDifferential SAR interferometry technique is useful in extracting the surface displacement of glaciers, sea ice, and ice shelves

Page 4: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

IntroductionObjective

Extraction of interferometric phases from ERS-1/2 tandem pairs of Canisteo Peninsula, West AntarcticaAnalysis of the motion of glaciers, sea ice, ice shelves, and their kinematic interactions by using 4-pass DInSAR technique

Page 5: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Study Area

Radarsat-1 mosaic image of the Antarctic

Canisteo Peninsula near Amundsen Sea in West Antarctica(100 km×100 km)

Page 6: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Study Area

Canisteo Peninsula near Amundsen Sea in West Antarctica(100 km×100 km)

Center Location :73˚ 57´ 46˝ S / 101˚ 53´ 26˝ W

Ice shelves and small islands around the peninsulaSeveral glaciers of different size on the coastal areaCrevasses between the peninsula and ice shelves

Geocoded ERS-1 SAR image of the study area (1995/10/21, 100 km×100 km)

Azimuth

Range

Amundsen Sea

Canisteo Peninsula

Ice shelfIce shelf

Page 7: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

ERS-1/2 SAR DataERS-1 SAR1995/10/21

ERS-1 SAR1996/03/09

ERS-2 SAR1995/10/22

ERS-2 SAR1996/03/10

Azimuth Range Azimuth Range

Azimuth Range Azimuth Range

Page 8: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

ERS-1/2 SAR Data

Track Orbit(ERS-1/2)

Date(ERS-1, ERS-2)

*Bperp(m) *Ha (m)

278

22310/26371995/10/21

1995/10/2240.0 243.2

24314/46411996/03/09

1996/03/10152.4 63.9

*Bperp: Perpendicular baseline*Ha: Height ambiguity

Page 9: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

MethodSAR Interferometry (InSAR)

Using the difference of phases between two or more SAR imagesWidely used to extract topography and deformation of surface

Differential SAR Interferometry (DInSAR)Extracting displacement of surface by removing topographic phases2-pass (accurate DEM is nedded), 3-pass, and 4-pass DInSARApplication: measuring displacements by earthquake and volcano, ground subsidence, motion pattern of glaciers and ice shelves, etc.

Page 10: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

4-Pass DInSARFor the 2-pass DInSAR

An accurate DEM is neededRadarsat-1 Mapping Project (RAMP) DEM is the best for the Antarctic

RAMP DEM is not accurate enough to apply 2-pass DInSARThe horizontal resolution of 400 m in the study area

Use of 4-pass DInSAR technique4-pass DInSAR can extract surface displacement without DEMUse of two interferogramsOne interferogram is used to estimate the topographic phases (topo-pair) to be subtracted from the other interferogram containing the phases of deformation (diff-pair)

Page 11: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Interferogram GenerationGeneration of SLC image

Offsets estimation

Co-registration

Generation of multi-look interferogram

Estimation of interferometric baseline

Generation of earth-flattened interferogram

Page 12: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Decision of topo-pair and diff-pairOctober 21-22, 1995

Perpendicular baseline: 40 mHeight ambiguity: 243.2 mThe springtime of the AntarcticMany changes occur over the surface

March 9-10, 1996Perpendicular baseline: 152 mHeight ambiguity: 63.9 mInterferogram well shows topographic phases

Weaknesses and limitationsMore changes occur in March than October due to the high temperatureSome phases of deformation in the topo-pair interferogramA gap of 5 months between two pairs

Diff-pair

Topo-pair

Page 13: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Erath-Flattened InterferogramThe earth-flattened interferogram extracted from diff-pair

The positive fringes on glaciers and sea ice

Many circular fringes on ice shelves

No fringes on some sea ice due to large movement of sea ice during a day

Some topographic phases

Page 14: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Erath-Flattened InterferogramThe earth-flattened interferogram extracted from topo-pair

The topographic phases are well displayed

No interferometric phases in the sea

Some fringes by surface displacement

Page 15: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Differential InterferogramThe differential interferogram

The major parts of topography were removed

Fringes by deformation were shown in the differential interferogram

One fringe (from purple to yellow, cyan, and purple again) represents the change of 2.83 cm from radar to ground

Page 16: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Analysis of Differential Interferogram

Interaction between glaciers and sea ice

The largest glacier in Canisteo Peninsula

Glacier moves toward the sea ice

The sea ice shows up rise interferometric phases

The pushing glacier gave repulsive force to sea ice which type is land-fast ice

The land-fast ice showed the structure of anticline

Page 17: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Interaction between glaciers and sea ice

Other glaciers in Canisteo Peninsula

Glacier rapidly moved to land-fast ice

The interferometic phases of the adjoining land-fast ice indicated the up rise of ice surface

Analysis of Differential Interferogram

Page 18: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Interaction between glaciers and sea ice

Glacier and sea ice indicated the interferometric phase of the same direction

Sea ice was moved by the motion of glacier in the same horizontal direction towards the sea

The sea ice is similar to the land-fast ice

The ice type is the land-fast ice weakly harnessed to sea bottom or pack ice not harnessed at all

Analysis of Differential Interferogram

Page 19: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Sea ice motion and type

Sea ice showed rapid motion by ocean tide → Pack Ice

The land-fast ice indicated a little motion

The sea ice type can be classified

Analysis of Differential Interferogram

Page 20: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Sea ice motion and type

Sea ice showed rapid motion by ocean tide → Pack Ice

The land-fast ice indicated a little motion

The sea ice type can be classified

Analysis of Differential Interferogram

Page 21: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Interferometric phases on ice shelf

Many circular interferometric phases on the ice shlef

They are observed in both the topo-pair and diff-pair interferogram

Seamounts or unidentified islands may be under the bottom of the ice shelf

→ a cause for the motion on the surface of ice shelf

Analysis of Differential Interferogram

Page 22: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

ConclusionWe revealed dynamic features of glaciers, sea ice, ice shelves and their interactions by applying 4-pass DInSAR to ERS-1/2 tandem pairs

The upwelling sea ice by repulsive force against the fast motion of glaciers is observed

Sea ice showing the motion in the same direction with the glaciers could be land-fast ice weakly connected to sea bottom or pack ice

We could classify the sea ice type and decide a clear boundary between different ice types

The circular fringes on ice shelves were caused by seamounts or unidentified islands at the bottom of the ice shelves

For more detailed analysis, it is necessary to apply numerical analysis and modeling

Page 23: Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA