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The Whole Earth Course. Chapter 10 Hydrosphere 4 The World Ocean Instructor: Dr. George A. Maul gmaul@fit.edu / X 7453. http://www.youtube.com/watch?v=mJorZMT6W3M. Outline of the Class. BREAK – geostrophy Ekman Upwelling ENSO Ocean Waves Tides and Sea Level Ocean Economy
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The Whole Earth Course Chapter 10 Hydrosphere 4 The World Ocean Instructor: Dr. George A. Maul gmaul@fit.edu / X 7453 http://www.youtube.com/watch?v=mJorZMT6W3M
Outline of the Class • BREAK – geostrophy • Ekman Upwelling • ENSO • Ocean Waves • Tides and Sea Level • Ocean Economy • Summary of Chapter 10
Review:Forces affecting seawater • Acceleration = • Pressure gradient force + • Coriolis force + • Gravity + • Friction ΣF=ΣM∙a Newton’s 2nd Law Infrared Image of Florida Current
Break Review Questions about geostrophic currents? If Δh = 1 m in Δx = 100 km, and ø= 43.28934 °N, what is the geostrophic velocity vg (speed and direction)? w - upward Units? v - northward Direction? u - eastward
Wind-driven Circulation:Ekman SpiralCoriolis balances Friction Ekman surface current is 45º to right of wind in northern hemisphere
Ekman Mass Transport (Mx)and coastal upwelling Wind stress = +τy Wind stress = -τy y x f · Mx = τy Mass transport is 90º to right of wind in northern hemisphere
Global SST and Ekman Upwelling What’s happening at the equator?
ENSO – El Niño Southern Oscillation Enso String Quartet
El Niño SST anomalies La Niña SST anomalies 1997 event
ENSO Animation What is an SST anomaly?
The major thermohaline circulation cells that make up the global conveyer system are driven by exchange of heat and moisture between the atmosphere and the ocean.
North Atlantic Deep Water (NADW) when warm salty surface water from south cools and sinks to form a deep western boundary current (DWBC).
Deep Western Boundary Current You’re kidding right? It flows to the south?
Residence Time: How long to replace all deep water? NADW = 15 x 106 m3/s; AABW = 30 x 106 m3/s; Volume = 1350 x 106 km3; time = Volume/rate = ?
Waves on the Beach (segue to waves)
Orbital Motion in Waves http://www.srh.weather.gov/srh/jetstream/ocean/images/gullloop.gif celeritywave= wavelength ÷ period Units of celerity?
Global Waveheight from Satellite Waves at sea
Celerity of a tsunami wave Zaverage = 4,000 m Ctsunami = √gZ http://www.youtube.com/watch?v=feBtPsJH25c Units? Celerity in knots m/s ÷ 0.51 =?
Wave Energy (per unit area) hwave increases as Zwater decreases
Florida Tech students doing beach profiles at Sebastian Inlet
Littoral Currents Rip Current
Time and tide wait for no man. St. Marher, 1225 Segue to Tides tide gauge
Where is the Barycenter Located? MassEarth=5.97x1024 kg, MassMoon=7.35x1022 kg, DistanceEarth-Moon=384,400 km What’s this? r D - r) Units? rEarth=6378 km
Syzygy and Quadrature Sebastian Inlet, FL
How to predict the Tide Nova Scotia, Canada
Tide Predictions USC&GS Tide Predicting Machine
Global Ocean M2 Tide Low water – The Netherlands
Segue to Ocean Economy http://oceanservice.noaa.gov/facts/oceaneconomy.html transportation fisheries minerals energy tourism defense
Sectors and the EEZ Exclusive Economic Zone
Summary • Average Depth ~3800 m; Deepest 10,924 m • Salinity ~35 ‰; mostly Na, Cl, SO4, Mg • Temperature range –2C to 36C • Pressure mostly hydrostatic • Currents mostly geostrophic • Waves feel bottom when Z=L/2 • Tides – semidiurnal, diurnal, fortnightly… • Economics =