Today’s TuneToday’s Tune

““This is the Sea”This is the Sea” by The Waterboysby The Waterboys

Next Midterm Next Midterm Monday, May 16, 2011, 1:00 Monday, May 16, 2011, 1:00

Here in Gilfillan Auditorium, closed bookHere in Gilfillan Auditorium, closed bookSame format as Test 1 Same format as Test 1 Bring #2 pencilBring #2 pencilStudy Guide POSTED on main class web Study Guide POSTED on main class web

site:site: http://dusk.geo.orst.edu/oceans/103syl.htmlhttp://dusk.geo.orst.edu/oceans/103syl.html

Transformation of Wind-Driven Transformation of Wind-Driven Deep-water WavesDeep-water Waves

Transformation of Wind-Driven Transformation of Wind-Driven

Shallow-water WavesShallow-water Waves

Photography by Clark Little

Photography by Clark Little

Photography by Clark Little

Photography by Clark Little

Photography by Clark Little

Photography by Clark Little

Photography by Clark Little

Photography by Clark Little

Photography by Clark Little

TsunamisTsunamisSudden shifting of the ocean floor Sudden shifting of the ocean floor

due to earthquakes, volcanic due to earthquakes, volcanic eruptions, and submarine slumping.eruptions, and submarine slumping.– open oceanopen ocean: : shortshort heights, heights, longlong

wavelengths (>100 km), and long periods wavelengths (>100 km), and long periods -- -- 400-500 mph!!!400-500 mph!!!

– shallow watershallow water: their length shortens and : their length shortens and their height increases dramatically.their height increases dramatically.

Global Wave Propagation After Global Wave Propagation After 2004 Sumatra Event2004 Sumatra Event

Titov, V., A.B. Rabinovich, H.O. Mojfeld, R.E. Thomson, and F.I. Gonzalez, The global reach of the 26 December 2004 Sumatra tsunami, Science, 309 (5743), 2045-2048, 2005.

Oregon Coastal AtlasOregon Coastal AtlasTsunami Hazard InformationTsunami Hazard Information

http://www.coastalatlas.net http://www.coastalatlas.net oror

http://bit.ly/FG8rzhttp://bit.ly/FG8rz

Tsunami from slumpingTsunami from slumping

Driscoll et al., Geology, 28(5):407-410

North Carolina ExampleNorth Carolina Example

Back to Wind-Driven Scenarios:Back to Wind-Driven Scenarios:

Storm SurgesStorm Surgesextremely high water levels due toextremely high water levels due to

– Low pressure system - big storms Low pressure system - big storms persistent onshore windspersistent onshore windsrise in sea levelrise in sea level

Hurricanes! Hurricanes! (W. Atlantic)(W. Atlantic)

Cyclones! Cyclones! (W. Pacific)(W. Pacific)

NASA Advanced Microwave Scanning Radar

Hurricane Katrina, Saturday, Aug 27, 2005

NASA PPT Radar, Visible Infrared Scanner, Tropical Microwave Imager

GOES satellite

L

Accumulation of water driven shoreward by storm winds:Elevated sea level at shore

Hurricane Katrina, Sunday, Aug 28, 2005

ESRI.com

New Orleans, Wednesday, Aug 31, 2005

OSU Wave TankOSU Wave Tank

Back to 1998 El NiñoBack to 1998 El Niño“The Perfect Storm”“The Perfect Storm”

Condition Black in HawaiiCondition Black in Hawaii

Other Types of Progressive WavesOther Types of Progressive Waves

There is one other notable type of There is one other notable type of progressive waves. progressive waves. – Internal waves Internal waves which occur underwater which occur underwater

and move along pycnoclines.and move along pycnoclines.

Internal WavesInternal WavesSlower speeds than surface waves Slower speeds than surface waves

because the because the density difference density difference between water massesbetween water masses is less than is less than between air and water. between air and water. – They occur when water masses slip over They occur when water masses slip over

one another.one another.– They have very long periods and very They have very long periods and very

large heights.large heights.

Advection Along Internal WavesAdvection Along Internal Waves

Standing WavesStanding Waves Seas, swell, and surf are progressive Seas, swell, and surf are progressive

waves. waves. Standing waves (seiches)…Standing waves (seiches)…

– Oscillate back and forth about a Oscillate back and forth about a nodenode i.e., a fixed point.i.e., a fixed point.

– Form when winds blow in one direction Form when winds blow in one direction which causes water to pile up at one which causes water to pile up at one end of a basin.end of a basin.

Node = Fixed Point Node = Fixed Point Antinode = maximum displacementAntinode = maximum displacement

SummarySummary Waves are disturbances that are generated on Waves are disturbances that are generated on

or beneath the sea surface. or beneath the sea surface. Progressive wavesProgressive waves move along the sea surface.move along the sea surface.

The size of surface waves depends on the The size of surface waves depends on the speed and duration of the speed and duration of the windwind, and the , and the fetchfetch..

Waves affect water to a depth equal to or less Waves affect water to a depth equal to or less than one-half their than one-half their wavelengthwavelength..

A special case is a A special case is a tsunamitsunami, a deepwater wave , a deepwater wave generated by a submarine disturbance with generated by a submarine disturbance with incredibly long wavelengths, high wave incredibly long wavelengths, high wave speeds, and very short wave heights, UNTIL speeds, and very short wave heights, UNTIL they feel the bottom in shallow water!they feel the bottom in shallow water!

SummarySummary(Cont.)(Cont.)

As waves enter As waves enter shallowshallow water their water their wavelength shortens and their height wavelength shortens and their height increases. increases.

The most damaging effect of storms is The most damaging effect of storms is not necessarily the waves alone, but the not necessarily the waves alone, but the waves in combination with waves in combination with storm surgestorm surge (elevated sea level), created by the winds (elevated sea level), created by the winds which pile water up along the shore.which pile water up along the shore.