http://www.nasa.gov/mpg/126449main_katrina_fred_animation.mpg

2005 Tropical Storms

Storm tracks generally fall into three categories:

1) Atlantic U-turns2) Gulf coast strikers3) East coast skirters

1999 Tropical Storms

1999 Tropical Storms – Large Waves

Data from Cape Canaveral Buoy and Model Results

Waves •Always wind, so always waves

•Transfer of energy from a windy area to a narrow coastal band

•General topics to cover:

•(1) Generation•(2) Dispersion and Travel•(3) Shoaling Transformation•(4) Breaking

Sea, Swell, Surf

Supply the bulk of the energy to coastal processes from WIND

Depends on three factors:

Wind Speed – how “fast” the wind blows

Duration – how “long” the wind blows

Fetch – how “far” the wind blows

Wave Generation

Wave Prediction Nomogram

Wave Anatomy - Periodic Waves

•T = wave period•f = wave frequency = 1/T•L = wave length•C = L/T = phase velocity or celerity•H = wave height = water surface displacement•h = water depth

•Can think of waves w.r.t. a spatial framework, or w.r.t. a temporal framework.

•d = horizontal water particle orbital diameter•s = vertical water particle orbital diameter•u = horizontal water particle velocity•w = vertical water particle velocity

Motion of water in waves

•Red dot on the surface - sees the wave form pass, but moves in a circular orbit

•When red dot is at bottom of it’s orbital, it’s in the trough of the wave, when at the top of its orbital, it’s at the crest of the wave

•Orbital size (diameter) decreases with depth

•Waves propagate through the medium

Wave Superposition

•run animation of wave superposition

Formation of Wave Groups

two wave trains of slightly different wave lengths, superposed, can create wave groups

Wave PropertiesOscillation

GLY 2030C 13

Wave Transformation

Refraction, convergence, and divergence

Wave Refraction - La Jolla Canyon

Wave Breaking Style

Plunging breakers, spilling breakers (waves of translation)

Wave Breaking

•The release of energy derived from the wind, along a narrow coastal zone - geomorphic work done by wind, really, translated through medium of water.

Wave Breaking – When it occurs?.

Style of Breaking - Illustrated

•Plunging waves (moderate beaches)

•Spilling waves (flat beaches)

•Surging waves (steep beaches)

•First observations recognized that beach slope and wave steepness had something to do with this...

Surf Zone Wave Decay and Energy Dissipation

•Steep, reflective beaches -

•Wave breaking (and energy dissipation) is concentrated through plunging breakers.

•Broken wave surges up the beach as runup.

•Low-slope, dissipative beaches -

•Extensive, wide surf zone over which spilling breakers dissipate energy.

•At any time, several broken wave bores, and smaller unbroken waves, are visible.

•Villano Beach

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Wave Speed - Nearshore

•wave speed C = (gh)1/2

•tow-in waves: H = ~8 m

•C = (10 m/s2 * 10 m)1/2 ~ 10 m/s

•~25 mph!

•waves “surfable” by mortals:

•C = (10 m/s2 * 2 m)1/2 ~ 4.4 m/s

•~9 mph!

•How fast does a Laird Hamilton surf?