Four Major Oceans plus Arctic Ocean and nine or so Seas

1. Oceans and Coastal Processes Four Major Oceans plus Arctic Ocean and nine or so Seas Flashlight Globe

2. Recall Ocean Depths depend on the Plate Tectonic Province: (0-150 meters) (less than 3 km) ~4 km 7 to 11 km (4-7 miles)

3. Sea Level Changes • Rapid seafloor spreading expands the mid-ocean ridge displacing water and raising sea level. • Sea level slowly drops during Ice Ages when substantial volumes of ocean water are locked up in ice sheets. • Sea Level rises "suddenly" when glaciers melt

4. Ocean Salinity • Dissolved “Salts” are ions from weathering • Salinity in surface water averages ~35 parts per thousand. • Salinity variation more extreme in coastal waters. River input, evaporation in lagoons • Salinity and temperature change with depth - rapid change salinity (saltiness) at the halocline. • Salt water is more dense than fresh water • Ice is less dense than liquid water (so it floats) • Ice is freshwater, recall most fw in ice caps

5. Ocean Temperatures • Ocean temperatures of 27oC are typical of tropical surface • Waters and temperatures of 2oC are typical for deep ocean waters. • Cold water is more dense than warm water. It will move under less dense water.

6. Salinity varies w/ temperature and ocean current mixing low salinity of arctic – isolated low evap cold, freshwater rivers and snow 40 ppt Red Sea ocean: 33-37 ppt high 36-37 at +/- 30o, high evap, low eq 34 trop rain

7. Salinity shown in cross-section of ocean in ppt Southern Hemisphere Summer Saltiest at 23.5S South Latitude Sun overhead, more evaporation

8. Solar Heating • The equator receives 2.5 times more sunlight (insolation[photons / m2 ]), incoming solar radiation, than the poles. • Highest average annual ocean surface temperatures (~27oC) at equator • Lowest 0oC at high latitudes Demo, Flashlight Globe 23.5

10. Heat versus Temperature • When heat something, its temperature rises. • Heat is the total energy of molecular motion in a substance. Heat energy depends on the speed of the particles, the number of particles (the size or mass), and the type of particles in an object. • Temperature is a measure of the average energy of molecular motion in a substance. Temperature does not depend on the size or type of object. • For example, the temperature of a small cup of water might be the same as the temperature of a large bathtub of water, but the tub of water has more heat because it has more water and thus more total thermal energy.

11. Water thermal properties 1 • 1. Heat capacity Cp water very high. Water can store huge amounts of heat without raising temperature. The bonds vibrate faster, but the water molecules H2O need not speed up. • Cp water = 4.2 x Cp air Heat Capacity: heat to raise 1 cm3 substance 1oC • Ocean heat storage plays a crucial role in controlling global climate patterns. http://hendrix.uoregon.edu/~stanm/phys162s2003/PHYS162/Heat_Capacity.html

12. Water thermal properties 2 • Density r is mass/unit volume • Salt water is denser than fresh water • Cold water denser than warm water. • Freshwater Ice forms at -2oC from saltwater. Less dense than Saltwater, floats • Remaining Seawater is saltier, denser

13. Average Annual Sea-Surface Temperature ~30C Equator, 0C Poles, average temp for a latitude maintained by currents Poles should be much colder, but currents carry warm equatorial water poleward

14. Temperature and Currents • Surface waters (<300 m) warmed by Sun • Currents cause thermal mixing: results in relatively uniform surface temperature by latitude. • The impact of current activity on climate diminishes with depth

15. Temperature and Depth • Temperatures exceed 20oC over tropical ocean's surface, 2oC below 2,000 m. • The depth zone in which temperature decreases rapidly is called the thermocline 1000 m 2000 m

16. Continents and Climate • Over two-thirds of Earth’s surface is ocean. • Currents started by prevailing winds • Currents deflected by continent positions and Earth’s rotation • Climates caused by current and wind circulation

17. Ocean Currents • Again, ocean currents started by winds. • Winds are ultimately caused by equator to poles insolation (heat from Sun) differences • Winds drag surface waters as surface currents • Winds and currents are influenced by Earth's rotation (Coriolis effect). • Currents influenced by distribution of continents

18. Coriolis Effect Air masses at rest above the equator are moving much faster than air masses at rest over us in NJ. Both must rotate once per day, but the equatorial air goes much further.

19. Equatorial Air has faster spin as it moves toward poles it still has it , so it is faster than land below Coriolis Effect Air in Northern Hemisphere deflects to the right, reverse in Southern H. DEMO: Coriolis Clip

20. Winds Start Currents • Air molecules in wind push water molecules 3-4% of wind speed. • Wind moving nearly parallel to latitude as a result of Coriolis deflection. • West-pushed ocean currents form near equator, east-pushed ocean currents form about 50o Latitude • Continents deflect or prevent current flow • Results in circular current called a gyre.

21. Example: Generation of North Pacific Gyre The major wind cells Convection Maximum heat from Sun Define “Insolation” = radiation from sunlight DEMO: globe, flashlight if not done previously

22. Winds push currents Surface Currents (Influence Climate) East pushed flow near 50 degrees Gyre CW West pushed flow near equator West pushed flow near equator Gyre CCW East pushed flow near 50 degrees Note Warm Currents not past S 60o Latitudes

23. Western Boundary Currents • Winds cause water to pile up along the western subtropical sides of major oceans. • Generate fast-flowing currentsthat redistribute warm tropical waters toward the poles. • Gulf Stream, Kuroshio, Brazil currents are “West Side” marine rivers, relatively narrow (less than 100 km across) but deep water masses. • Flow at speeds of 100 to 200 km/day for thousands of kilometers, from equator to high latitudes

24. Eastern Boundary Current • Eastern boundary currents (Canary, California, Peru) complete the eastern leg of each gyre • Wider, carry less water, and move more slowly. • The Canary current, nearly 1,000 km (625 miles) wide but very shallow • 1/3 water of Gulf Stream and travels at 30 km/day • 2/3 continues as cold deep salty current

25. WIND North Atlantic Deep Water (NADW) down here

26. Evaporation and Ice formation increases saltiness and density. Dense water sinks forms NADW Arc shallowing lifts cold deep water Winds blow surface waters west, forcing deep water up to surface where it warms ThermoHaline Conveyer Belt AKA Global Ocean Conveyer Belt Wallace Broecker Columbia University

27. Shores and Coastal Processes • Shorelines are places where bodies of water meet dry land • Coasts are landward of ocean shorelines • Beach: a narrow strip of land, washed by waves or tides . • Ordinary Waves are caused by WIND • Waves are produced when wind drag causes the surface water of oceans/lakes to rise and fall - Waves get refracted on approaching shoreline

28. Typical Coast

29. Waves are caused by _____________? Parts of A Wave Fetch – length of unobstructed wind Southern Ocean inc. Straits of Magellan Dana ‘Two Years Before the Mast’

30. Oscillatory and Translatory Motion

31. Wave Refraction Still a small ‘longshore component

32. Longshore Currents (Swash and Backwash) Longshore current is produced as waves reflect from coastline. Swash and backwash

33. Rip Currents Cut inBar Sand Bar Rip Currents are produced when storms cut holes in sandbars just offshore.

34. Tides • Daily rise/fall of surfaces of oceans/lakes due to gravitational pull of the Moon/Sun on the Earth– also due to force created as Earth spins on its axis • Flood tides- elevate sea surface that cause shoreline to move inland • Ebb Tides- low sea surface that cause shoreline to move seaward

35. Tidal Bulges A mass in circular motion accelerates toward the axis of rotation. This centripetal acceleration is exerted on the mass by some other object,say a string held in my hand. The mass exerts an equal and opposite force on the object, the centrifugal force. Tides mostly caused by the Moon Affect of the Sun Much less Why?

36. The Effect of Tides On Shorelines – River Hebert in Nova Scotia Tidal Bore flows upstream Source:Clyde H. Smith/Peter Arnold, Inc.

37. Large Tidal Extremes • Bay of Fundy tides reach16 m (about 53 ft) at the head of the bay. The 12.4 hour period of the twice daily lunar tides is close to the natural back and forth sloshing period of the bay. Source:William E. Ferguson

38. Rising Tide at Bay of Fundy Maximum Source:William E. Ferguson

39. Coastal Erosion (Crashing Surf) Wave erosion occurs when deep water waves hit the shore with full force. Air and water are forced into cracks at high pressure

40. Crashing Surf, Oregon Coast Fast Erosion Source: Criag Tuttle/The Stock Market

41. Erosional Coastal Landforms Submerged Shallow Area Bends Waves

42. Erosional Coastal Landforms

43. Sea Caves on Cape Kildare, Prince Edward Island, Canada) Source:John Elk/Bruce Coleman

44. Deposition of A Tombolo

45. A Tombolo Landward of A Sea Stack – Big Sur, California Source:Cliff Wassmann

46. Coastal Protection • Riprap/Seawall- protects shore lines • Breakwaters – Stabilize beaches • Jettys – Keep inlets clear

47. Beach-Protection Structures - Riprap Source:Jack Dermid /Photo Researchers, Inc.

48. Beach-Protection Structures –Seawall Along the Gulf Coast of Louisiana Source:Martin Miller

49. Breakwaters

50. Breakwaters off Cape May, New Jersey Source:John S. Shelton