ocn 5401 chapter 9 waves instructor: dr. george a. maul [email protected] / x 7453
TRANSCRIPT
Wave Terminology
spilling
plunging
collapsing
surging
Breaker types Largest wave at sea ever observed
Wind Waves
Wave Spectrum
Wind speed Wind duration
Internal waves, SAR Scatterometer waves Capillary waves
Wave Height Nomogram
Hurricane wind-wave generation
Wave Information – the Pilot Chart
Probability of waves exceeding 8 feet
Global Waveheight from Satellite Altimetry
Shallow water wave equations
0
x
hg
t
u 0
x
uH
t
hand
surfbeat
)tanh(kzk
gCwave
xx
xx
ee
eex
)tanh(
Linear wave celerity CWAVE
where the hyperbolic tangent
Hyperbolic functions
Deepwater to Shallow water (Z>L/2) (Z<L/20)
gZgL
CWAVE 2
Orbital Motion in Waves
http://www.srh.weather.gov/srh/jetstream/ocean/images/gullloop.gif
h
Wave Energy & Refraction
2
8
1ghE SEAWATERWAVE
Energy per unit area
Power from Ocean Waves𝑃𝑤𝑎𝑣𝑒=𝐸𝑤𝑎𝑣𝑒 ∙𝑐𝑔𝑟𝑜𝑢𝑝
Distribution of wave power, kW/m
Wave Diffraction
Slit (d) must be wider than incident wave’s wavelength L.
𝐼=𝐼 0𝑠𝑖𝑛𝑐2(𝜋 𝑑𝐿
sin θ)
Littoral Currents
Rip Current
Capillary Waves
Surface tension ( ) restoring force
Stokes Waves and Drift
Ocean surface current RADAR
Inverted Barometer Effect
∆𝜂 𝐼𝐵𝐸=Δ𝑝𝜌𝑔
Δ𝜂 𝐼𝐵𝐸≅𝑐𝑚𝑚𝑏
≈𝑓𝑜𝑜𝑡𝑖𝑛𝐻𝑔
Storm Surge∆𝜂𝑠𝑠≅
𝜌𝑎𝑖𝑟𝐶𝐷𝑣𝑎𝑖𝑟2
𝜌𝑤𝑎𝑡𝑒𝑟𝑔𝐻∆𝑥
Standing Waves
ℓ
𝑇=2ℓ
𝑛√𝑔𝐻
Period T=L/C
n=1,2,3…
Seiche
Quarter Wave Seiche
Bay of Fundy Tides: ℓ = 111 km; H = 10 m; T=12.4h
n=1n=2
Resonant with the M2 lunar tide
ℓ
Sea and Swell
Photograph by Irene Watts, Cape Cod, MA; 2011
Waves at sea
Directional Spectrum
Kelvin Waves
Rossby Waves
Internal Waves
Rogue Waves
OCN 5401
Questions?
Chapter 9