Dissipation of wind waves by pancake and frazil ice in the autumn Beaufort Sea

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Description:	Rogers, E Wednesday 6th September 2017 - 15:00 to 16:30


Created:	2017-09-08 13:22
Collection:	Mathematics of sea ice phenomena
Publisher:	Isaac Newton Institute
Copyright:	Rogers, E
Language:	eng (English)
Distribution:	World (downloadable)
Explicit content:	No
Aspect Ratio:	16:9
Screencast:	No
Bumper:	UCS Default
Trailer:	UCS Default


Abstract:	I will be presenting the following paper: W.E. Rogers, J. Thomson, H.H. Shen M.J. Doble, P. Wadhams and S. Cheng, 2016: Dissipation of wind waves by pancake and frazil ice in the autumn Beaufort Sea Journal of Geophysical Research: Oceans vol 121 7991-8007 doi:10.1002/2016JC012251 The full paper may be found at the link above. The abstract follows: A model for wind-generated surface gravity waves, WAVEWATCH III (R), is used to analyze and interpret buoy measurements of wave spectra. The model is applied to a hindcast of a wave event in sea ice in the western Arctic, 11–14 October 2015, for which extensive buoy and ship-borne measurements were made during a research cruise. The model, which uses a viscoelastic parameterization to represent the impact of sea ice on the waves, is found to have good skill—after calibration of the effective viscosity—for prediction of total energy, but over-predicts dissipation of high frequency energy by the sea ice. This shortcoming motivates detailed analysis of the apparent dissipation rate. A new inversion method is applied to yield, for each buoy spectrum, the inferred dissipation rate as a function of wave frequency. For 102 of the measured wave spectra, visual observations of the sea ice were available from buoy-mounted cameras,and ice categories (primarily for varying forms of pancake and frazil ice) are assigned to each based on the photographs. When comparing the inversion-derived dissipation profiles against the independently derived ice categories, there is remarkable correspondence, with clear sorting of dissipation profiles into groups of similar ice type. These profiles are largely monotonic: they do not exhibit the ‘‘roll-over’’ that has been found at high frequencies in some previous observational studies. The introduction to the seminar will include a general overview of wave forecasting for the Arctic. Public release statement: The published paper has been approved for public release. The introduction/overview slides are pulled from earlier presentations which were approved for public release.

Abstract:

I will be presenting the following paper:
W.E. Rogers, J. Thomson, H.H. Shen M.J. Doble, P. Wadhams and S. Cheng, 2016:
Dissipation of wind waves by pancake and frazil ice in the autumn Beaufort Sea
Journal of Geophysical Research: Oceans vol 121 7991-8007 doi:10.1002/2016JC012251
The full paper may be found at the link above.
The abstract follows:
A model for wind-generated surface gravity waves, WAVEWATCH III (R), is used to analyze and interpret buoy measurements of wave spectra. The model is applied to a hindcast of a wave event in sea ice in the western Arctic, 11–14 October 2015, for which extensive buoy and ship-borne measurements were made during a research cruise. The model, which uses a viscoelastic parameterization to represent the impact of sea ice on the waves, is found to have good skill—after calibration of the effective viscosity—for prediction of total energy, but over-predicts dissipation of high frequency energy by the sea ice. This shortcoming motivates detailed analysis of the apparent dissipation rate. A new inversion method is applied to yield, for each buoy spectrum, the inferred dissipation rate as a function of wave frequency. For 102 of the measured wave spectra, visual observations of the sea ice were available from buoy-mounted cameras,and ice categories (primarily for varying forms of pancake and frazil ice) are assigned to each based on the photographs. When comparing the inversion-derived dissipation profiles against the independently derived ice categories, there is remarkable correspondence, with clear sorting of dissipation profiles into groups of similar ice type. These profiles are largely monotonic: they do not exhibit the ‘‘roll-over’’ that has been found at high frequencies in some previous observational studies.

The introduction to the seminar will include a general overview of wave forecasting for the Arctic.
Public release statement: The published paper has been approved for public release. The introduction/overview slides are pulled from earlier presentations which were approved for public release.

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Dissipation of wind waves by pancake and frazil ice in the autumn Beaufort Sea