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Summary of Proposal OCE1107

TitleInvestigation of sea ice breakup and freeze-up processes using high-resolution SAR and autonomous observation platforms
Investigator Hwang, Byongjun - The Scottish Association for Marine Science, Sea ice
Team Member
Dr. Richter-Menge, Jacqueline A - Cold Regions Research and Engineering Laboratory, Snow and Ice Division
Dr. Krishfield, Richard - Woods Hole Oceanographic Institution, Woods Hole Oceanographic Institution
Dr. Wilkinson, Jeremy - Scottish Association for Marine Science, Sea ice
Prof. Kim, Duk-Jin - Seoul National University, School of Earth and Environmental Sciences (SEES)
Dr. Schweiger, Axel - Applied Physics Laboratory University of Washington, Polar Science Center
SummaryThe goal of this project is to investigate the impact of external forcings (e.g. storms) on Arctic sea icebreakup and freeze-up processes by using a combination of satellite data and in-situ data from autonomous observing platforms. Time series of ocean temperature and salinity profiles, together with both sea- ice temperature and growth/melt rates, will be obtained in near real time from collocated ice tethered platforms (ITPs), deployed by the Woods Hole Oceanographic Institution (WHOI), and sea ice mass balance buoys(IMBs), deployed by the US Army Cold Regions Research and EngineeringLab (CRREL). These data will allow isolated, single-point estimates ofthe vertical fluxes of oceanic heat (during ice melt) and salt (duringice growth). High-resolution (1-18 m) TerraSAR-X (TSX) satellite SAR(Synthetic Aperture Radar) data will be used to derive the horizontal scales of sea ice concentration (SIC), floe size distribution (FSD) and lead features.These data will allow us to quantify sea ice floe breakup and freeze-up in the areas surrounding the IMB/ITP pairs, and thus to exptrapolate the point measurements of IMB/ITP data sets to larger areas. To capture the impacts of storms, we propose to conduct three case studies during spring/summer months and three case studies during autumn/winter months. Each case study will require a sequence of 10 daily TSX images, for a total of 60 TSX images for the six cases. Funding for 60 TSX images has been sucessfully secured from the Royal Society Research Grants awarded to Hwang ("Hwang_RS").
Final ReportFor the detailed final report, please refer to the final report uploaded report in PDF file. The most of the content in the report was presented at the 2013 AGU meeting, and journal publication is underway. Below is the summary of the works done through this project. The work of this project was proposed to investigate the impact of the external forcings (e.g. winds, waves) on Arctic sea ice spring-to-summer floe breakup processes by using a combination of satellite data and in-situ data from autonomous observing platforms. Single point measurement of continuous ocean temperature and salinity profiles and oceanic heat fluxes, sea- ice temperature and growth/melt rates, and atmospheric pressure and temperature can be obtained from ice tethered platforms (ITPs) by the Woods Hole Oceanographic Institution (WHOI), sea ice mass balance buoys (IMBs) by the US Army Cold Regions Research and Engineering Lab (CRREL), and Arctic Ocean Flux Buoy (AOFB) by the Naval Postgraduate School (NPS). TerraSAR-X/TanDEM-X (TSX) Synthetic Aperture Radar (SAR) data can be used to derive the horizontal scales of sea ice concentration (SIC), floe size distribution (FSD) and lead opening. These data can allow us to quantify sea ice floe breakup in the areas surrounding the autonomous buoys, and thus to extrapolate the point measurements from the buoy data to larger areas. Through this project we successfully acquired TSX SAR imagery for three buoy clusters, namely 2011J, 2012L and 2012H (see the details in the report). Some of collected SAR imagery were analysed to derive SIC and FSD, and some of physical data from the buoys were also analysed, and then the results were compared each other. Six selected SAR imagery at buoy cluster 2011J showed some notable changes in SIC and FSD even during May to June in 2012, while more dramatic changes occurred in July 2012. The results suggest that the ice floes were very much broken up in 2012 (almost 50% of floes were less than 200 m in size) even before the coming of the 2012 August Storm. In contrast SAR imagery acquired at buoy clusters 2012L/H show much less active and retarded floe breakup in 2013 spring and summer, especially relative to the 2011J case. As shown in this report, the difference is contributed to the difference in ice thickness (type) and dynamic forcing (e.g. winds and waves). Relevant to the TSX project, this study clearly shows the importance of combining TSX SAR imagery with the buoy data in understanding the marginal ice zone processes.

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