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Dynamics of landfast sea ice near Jangbogo Antarctic Research Station observed by SAR interferometry Hoonyol Lee 1 and Hyangsun Han 2 1 Division of Geology.

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Presentation on theme: "Dynamics of landfast sea ice near Jangbogo Antarctic Research Station observed by SAR interferometry Hoonyol Lee 1 and Hyangsun Han 2 1 Division of Geology."— Presentation transcript:

1 Dynamics of landfast sea ice near Jangbogo Antarctic Research Station observed by SAR interferometry Hoonyol Lee 1 and Hyangsun Han 2 1 Division of Geology and Geophysics, Kangwon National University, Republic of Korea (hoonyol@kangwon.ac.kr) 2 Department of Polar Remote Sensing, Korea Polar Research Institute, Republic of Korea (hyangsun@kopri.re.kr ) Hoonyol Lee 1 and Hyangsun Han 2 1 Division of Geology and Geophysics, Kangwon National University, Republic of Korea (hoonyol@kangwon.ac.kr) 2 Department of Polar Remote Sensing, Korea Polar Research Institute, Republic of Korea (hyangsun@kopri.re.kr ) Landfast sea ice is a type of sea ice adjacent to the coast and immobile for a certain period of time. It is important to analyze the temporal and spatial variation of landfast ice because it has significant influences on marine ecosystem and the safe operation of icebreaker vessels. However, it has been a difficult task for both remote sensing and in situ observation to discriminate landfast ice from other types of sea ice, such as pack ice, and also to understand the dynamics and internal strss-strain of fast ice. In this study, we identify landfast ice and its annual variation in Terra Nova Bay (74° 37′ 4"S, 164° 13′ 7"E), East Antarctica, where Jangbogo Antarctic Research Station has recently been constructed in 2014, by using Interferometric Synthetic Aperture Radar (InSAR) technology. We generated 38 interferograms having temporal baselines of 1-9 days out of 62 COSMO–SkyMed SAR images over Terra Nova Bay obtained from December 2010 to January 2012. Landfast ice began to melt in November 2011 when air temperature raised above freezing point but lasted more than two month to the end of the study period in January 2012. No meaningful relationship was found between sea ice extent and wind and current. Glacial strain (~67cm/day) is similar to tidal strain (~40 cm) so that they appear similar in one-day InSAR. As glacial stress is cumulative while tidal stress is oscillatory, InSAR images with weekly temporal baseline (7~9 days) revealed that a consistent motion of Campbell Glacier Tongue (CGT) is pushing the sea ice continuously to make interferometric fringes parallel to the glacier-sea ice contacts. Glacial interferometric fringe is parallel to the glacier-sea ice contact lines while tidal strain should be parallel to the coastlines defined by sea shore and glacier tongue. DDInSAR operation removed the consistent glacial strain leaving tidal strain alone so that the response of fast ice to tide can be used to deduce physical properties of sea ice in various ice stages. One-day InSAR images revealed that fast ice is not attached to CGT in the early ice formation stages while they began to couple with each other so that the entire glacial motion of up to 67cm/day is transferred directly to fast ice. In the final thawing stage just before ice breakage, ocean wave travelling through the fast ice is also observed by one-day InSAR. [1] Han and Lee, 2015, Tide-corrected flow velocity and mass balance of Campbell Glacier Tongue, East Antarctica, derived from interferometric SAR, Remote Sensing of Environment, 160:180~192. [2] Han H., and H. Lee, 2014. Tide deflection of Campbell Glacier Tongue, Antarctica, analyzed by double- differential SAR interferometry and finite element method, Remote Sensing of Environment, 141:201-213. Mario Zucchelli Station An example of InSAR image for classification of ice types  One day and weekly based InSAR observation enabled the observation of annual variation of landfast sea ice and its dynamics.  Fast ice lags air temperature by two months in Terra Nova Bay.  Fast ice fringes in this study area are mainly from glacial stress and tidal stress.  Weekly InSAR highlights consistent glacial strain (~469 cm/week).  DDInSAR highlights oscillatory tidal strain (~ 40 cm). Weekly InSAR verifies cumulative glacial strain with equi-strain line (fringes) parallel to the glacial contact. Fast ice to the east side of CGT(Campbell Glacier Tongue) is strongly affected by glacial stress. Some section of fast ice to the west of CGT, in contact with CGT, is also affected by glacial stress with fringes parallel to the ice contact line. Fast ice near the shoreline, isolated from CGT by cracks and leads, shows tidal strain only. DDInSAR (Double Differential InSAR) is a technique to remove constant fringes between two InSAR images It is valid only when ice surface is stable between two InSAR pairs It can remove fringes from consistent glacial stress, if any. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2013R1A1A2008062) and also by Big Science Research and Development Project (NRF-2013M1A3A3A02041853). The COSMO-SkyMed SAR dataset was provided by the Italian Space Agency through the AO Project (ID: 2215). Sea Ice Extent One-day InSARWeekly InSAR DDInSAR Study Area in a COSMO-SkyMed SAR image Study Area near TNB (After Nihash and Ohshima, J. Climate, 2015) Dates of InSAR pair (yyyy/mm/dd) Temporal baseline (day) Dates of InSAR pair (yyyy/mm/dd) Temporal baseline (day) 2010/12/01, 2010/12/0982011/06/19, 2011/06/278 2010/12/09, 2010/12/1012011/07/05, 2011/07/061 2010/12/25, 2010/12/2612011/07/22, 2011/07/297 2011/01/02, 2011/01/1082011/08/06, 2011/08/071 2011/01/10, 2011/01/1882011/08/22, 2011/08/231 2011/01/26, 2011/01/2712011/08/30, 2011/09/078 2011/02/11, 2011/02/1982011/09/07, 2011/09/081 2011/02/27, 2011/02/2812011/09/15, 2011/09/249 2011/03/15, 2011/03/1612011/10/01, 2011/10/098 2011/03/23, 2011/03/3182011/10/09, 2011/10/101 2011/03/31, 2011/04/0112011/10/25, 2011/10/261 2011/04/01, 2011/04/0872011/11/02, 2011/11/108 2011/04/08, 2011/04/1682011/11/10, 2011/11/111 2011/04/16, 2011/04/2482011/11/18, 2011/11/268 2011/05/02, 2011/05/0312011/11/26, 2011/11/271 2011/05/18, 2011/05/1912011/12/28, 2011/12/291 2011/06/03, 2011/06/0412012/01/05, 2012/01/138 2011/06/03, 2011/06/1182012/01/13, 2012/01/141 2011/06/19, 2011/06/2012012/01/13, 2012/01/218 List of COSMO-SkyMed Dataset C53B-0776 Friday, 18 December 2015 13:40 - 18:00


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