Ice Effect on Wave Propagation in the Marginal Ice...
Transcript of Ice Effect on Wave Propagation in the Marginal Ice...
Ice Effect on Wave Propagation in the Marginal Ice Zone
Hayley H. Shen
Xin Zhao
Sukun Cheng
Clarkson University
Collaborators: Erick Rogers (NRL)
Jim Thomson (Univ. Washington)
Sponsored by Office of Naval Research Grant #N000141310294
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Theories
• Thin elastic plate (1886)
• Mass loading (1950)
• Viscous layer (1998)
• Eddy viscosity (1988)
• Viscoelastic plate (1980)
• Viscoelastic layer (2010)
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Continuum theory
Thin elastic plate Disjointed mass points Viscous layer
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floes as mass points
Theories
Eddy viscosity
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Traditional dispersion relation
Given water depth h and wave frequency , determine wavenumber k , (thus also wave celerity C and wave group velocity Cg).
New dispersion relation
Given water depth h, wave frequency , and ice characteristics, determine wavenumber k , (thus also wave celerity C and wave group velocity Cg).
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Discrete theory
Scattering
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Theories
• ki enters the model via the dynamics: determines attenuation rate (Sice,nc) • kr enters the model via the C and Cg calculations on the left-hand side of the governing equation. • code changes non-trivial • fundamentals are straightforward
…solution methods are not straightforward
ir ikkk
igncice kCES 2/,
Complex wavenumber (new approach)
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1. Modification of open-water source functions
2. Kinematics: ice changes wave length, propagation speeds: effects analogous to refraction and shoaling by bathymetry: addressed via kr
3. Source term (non-conservative): attenuation of waves: addressed via ki
4. Source term (conservative): scattering of waves by ice floes, leads
Review: effects of ice on waves
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a) IC0, SWH (m) b) IC1, SWH (m)
c) IC2, SWH (m) d) IC3, SWH (m)
Significant Wave Height (SWH) (m), 4 different Sice treatments AMOMFW2016 14
a) Ice Fraction b) =IC1-IC0, (1b)-(1a)
c) =IC2-IC0, (1c)-(1a) d) =IC3-IC0, (1d)-(1a)
∆SWH (m), 3 different Sice treatments vs. WW3 v3.14 treatment AMOMFW2016 15
Missing link
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What are their (G,)
values?
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A test in the Southern Ocean
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= AMOMFW2016 18
SeaState Program
• The ocean
• The atmosphere
• The wave and ice interaction
All in the marginal ice zone.
AR
CT
I C S E A S T AT
E
20
15
O
FF
IC
E O
F N A V A L RE
S
EA
RC
H
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AMSR2 ice conc. on 1 Oct 2015 AMSR2 ice con. on 1 Nov 2015
Beaufort Sea Ice Growth
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Guided by forecasts onboard
Wind (Ola Persson) Wave (Eric Rogers)
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and by remote sensing
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Cruise Track
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The wave
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Ice
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Ice
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Ice observations by “ice observers”
See poster by Ackley et al., Tuesday 4pm
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Nov. 2
Oct. 11
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Oct. 4
Oct. 4
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Oct. 5
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Summary
• WAVEWATCH III now has five options to treat the Sice (four address non-conservative and one conservative)
• The fourth option IC3 is now being calibrated with field data, and will be tested with future data
• So far, it appears that IC3 is capable of capturing most of the wave spectra
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Thank you AMOMFW2016 42