The Whole Earth Course

1. 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

2. Outline of the Class • BREAK – geostrophy • Ekman Upwelling • ENSO • Ocean Waves • Tides and Sea Level • Ocean Economy • Summary of Chapter 10

3. Review:Forces affecting seawater • Acceleration = • Pressure gradient force + • Coriolis force + • Gravity + • Friction ΣF=ΣM∙a Newton’s 2nd Law Infrared Image of Florida Current

4. 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

5. Wind-driven Circulation:Ekman SpiralCoriolis balances Friction Ekman surface current is 45º to right of wind in northern hemisphere

6. 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

7. Global SST and Ekman Upwelling What’s happening at the equator?

8. Equatorial Upwelling

9. ENSO – El Niño Southern Oscillation Enso String Quartet

10. El Niño SST anomalies La Niña SST anomalies 1997 event

11. ENSO Animation What is an SST anomaly?

12. Segue to Thermohaline Circulation

13. 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.

14. North Atlantic Deep Water (NADW) when warm salty surface water from south cools and sinks to form a deep western boundary current (DWBC).

15. Deep Western Boundary Current You’re kidding right? It flows to the south?

16. 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 = ?

17. Temperature-Salinity (T-S) Diagram

18. Waves on the Beach (segue to waves)

19. Orbital Motion in Waves http://www.srh.weather.gov/srh/jetstream/ocean/images/gullloop.gif celeritywave= wavelength ÷ period Units of celerity?

20. Global Waveheight from Satellite Waves at sea

21. Deepwater to Shallow water

22. 1755 Lisbon Tsunami travel times

23. 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 =?

24. Wave Energy (per unit area) hwave increases as Zwater decreases

25. Florida Tech students doing beach profiles at Sebastian Inlet

26. Littoral Currents Rip Current

27. Time and tide wait for no man. St. Marher, 1225 Segue to Tides tide gauge

28. Earth-Moon System

29. 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

30. Gravitation and Inertial Forces

31. Syzygy and Quadrature Sebastian Inlet, FL

32. Major Tidal Components

33. How to predict the Tide Nova Scotia, Canada

34. Tide Predictions USC&GS Tide Predicting Machine

35. Global Ocean M2 Tide Low water – The Netherlands

36. Segue to Ocean Economy http://oceanservice.noaa.gov/facts/oceaneconomy.html transportation fisheries minerals energy tourism defense

37. Sectors and the EEZ Exclusive Economic Zone

38. Summary • Average Depth ~3800 m; Deepest 10,924 m • Salinity ~35 ‰; mostly Na, Cl, SO4, Mg • Temperature range –2C to 36C • Pressure mostly hydrostatic • Currents mostly geostrophic • Waves feel bottom when Z=L/2 • Tides – semidiurnal, diurnal, fortnightly… • Economics =