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

A stormy sea

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• 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