Chapter 9 Waves Instructor: Dr. George A. Maul gmaul@fit.edu / X 7453 OCN 5401 Chapter 9 Waves Instructor: Dr. George A. Maul gmaul@fit.edu / X 7453

Largest wave at sea ever observed 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

Hurricane wind-wave generation 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 and surfbeat

where the hyperbolic tangent Linear wave celerity CWAVE where the hyperbolic tangent Hyperbolic functions

Deepwater to Shallow water (Z>L/2) (Z<L/20)

Orbital Motion in Waves http://www.srh.weather.gov/srh/jetstream/ocean/images/gullloop.gif h

Wave Energy & Refraction Energy per unit area

Distribution of wave power, kW/m Power from Ocean Waves 𝑃 𝑤𝑎𝑣𝑒 = 𝐸 𝑤𝑎𝑣𝑒 ∙ 𝑐 𝑔𝑟𝑜𝑢𝑝 Distribution of wave power, kW/m

Wave Diffraction Slit (d) must be wider than incident wave’s wavelength L. 𝐼= 𝐼 0 𝑠𝑖𝑛𝑐 2 ( 𝜋𝑑 𝐿 sinθ)

Littoral Currents Rip Current

Capillary Waves Surface tension ( ) restoring force

Stokes Waves and Drift

Ocean surface current RADAR

Inverted Barometer Effect ∆ 𝜂 𝐼𝐵𝐸 = Δ𝑝 𝜌𝑔 Δ 𝜂 𝐼𝐵𝐸 ≅ 𝑐𝑚 𝑚𝑏 ≈ 𝑓𝑜𝑜𝑡 𝑖𝑛 𝐻𝑔

Storm Surge ∆ 𝜂 𝑠𝑠 ≅ 𝜌 𝑎𝑖𝑟 𝐶 𝐷 𝑣 𝑎𝑖𝑟 2 𝜌 𝑤𝑎𝑡𝑒𝑟 𝑔𝐻 ∆𝑥 ∆ 𝜂 𝑠𝑠 ≅ 𝜌 𝑎𝑖𝑟 𝐶 𝐷 𝑣 𝑎𝑖𝑟 2 𝜌 𝑤𝑎𝑡𝑒𝑟 𝑔𝐻 ∆𝑥 Type equation here.

Standing Waves ℓ Period T=L/C 𝑇= 2ℓ 𝑛 𝑔𝐻 n=1,2,3…

Seiche

Quarter Wave Seiche n=2 n=1 ℓ Bay of Fundy Tides: 𝑇= 4ℓ 𝑔𝐻 ℓ = 111 km; H = 10 m; T=12.4h Resonant with the M2 lunar tide

Photograph by Irene Watts, Cape Cod, MA; 2011 Sea and Swell Directional Spectrum Photograph by Irene Watts, Cape Cod, MA; 2011 Waves at sea

1755 Lisbon Tsunami travel times

Kelvin Waves

Rossby Waves

Internal Waves

Rogue Waves

OCN 5401 Chapter 9 Questions?