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NSF/McMurdo Ground Station Science Workshop, Columbus OH, March 9-11, 2004

Formation of pancake ice in a wave field Hayley Shen, Stephen Ackley Clarkson University and Mark Hopkins USACRREL. NSF OPP-9814968. NSF/McMurdo Ground Station Science Workshop, Columbus OH, March 9-11, 2004. Pancake size Rafting thickness Early ice cover development

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NSF/McMurdo Ground Station Science Workshop, Columbus OH, March 9-11, 2004

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  1. Formation of pancake ice in a wave fieldHayley Shen, Stephen AckleyClarkson UniversityandMark HopkinsUSACRREL NSF OPP-9814968 NSF/McMurdo Ground Station Science Workshop, Columbus OH, March 9-11, 2004

  2. Pancake size • Rafting thickness • Early ice cover development • Heat transfer between air/ice

  3. Result #1 Pancake Size

  4. How to determine limit size? Bending failure mode: Tensile failure mode: Shen, Ackley, Hopkins 2001

  5. 95% confidence interval

  6. CRREL-2001winter, summer, 2003 summer

  7. 95% confidence interval Example: 100m wave of 5m amplitude yields 0.9m diameter pancakes.

  8. However…. HSVA-2002winter Pancake ice formation

  9. Result #2 Equilibrium Ice Thickness from Wave Rafting

  10. Non-dimensional result Dai, Shen, Ackley 2004

  11. Wave Tank Experiment Results

  12. Computer Simulation

  13. Computer Simulation (no friction)

  14. Computer Simulation (friction)

  15. Result #3 Early Ice Cover Establishment due to Wave Rafting

  16. Some old models results Hibler and Ackley 1983

  17. Geiger 1997

  18. Effects of h0 on Ice Cover Development (Earlier Appearance) Dai, Shen, Ackley 2004, in preparation

  19. Effects of Initial Ice Thickness on Ice Cover Development

  20. Result #4 Air/Ice Heat Transfer in a Wave Field

  21. Problem Definition Air W Ice H Water

  22. Experiments Experiments

  23. Results • Calm water cases • Wave cases • The standard deviation for wave cases is high, suggesting that heat transfer coefficient may depend on wave parameters • Enhanced turbulence, increased surface area, and a thin boundary layer above water/ice may be the reasons Dai, Shen, Ackley, 2004, in preparation

  24. We have found: • Pancake ice size can be predicted from waves • Rafting thickness can also be predicted • Rafting thickness is important in early ice cover development • Waves may greatly increase the thermodynamic growth of ice • Waves may not always result in pancakes, the critical condition has not been identified

  25. Next Steps • Heat transfer between air/ice in a wave field • The critical condition for pancake formation • Incorporating Wave Effects into short and long term climate models

  26. We need….. Accurate weather data Accurate hydrographical data

  27. Why?

  28. (Wang, Shen, and Shen, Okhotsk Sea Conference, 2000) Temperature of Dec. 30, 1993. Left panel is from NCEP real-time data, right from NCEP/NCAR Reanalysis data

  29. Temperature difference between NCEP real-time and reanalysis data for 92-93 winter.

  30. Ice concentration. Date: March 5, 1993. Input data: NCEP real-time. Ice concentration. Date: March 5, 1993. Input data: NCEP Reanalysis.

  31. Observed buoy trajectories and simulated ice floe trajectories in the winter of 1993-94.

  32. A lot of work to be done!Collaborations!

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