Air and Sea Interactions

1. Air and Sea Interactions 2012 Discuss with your partner……What is the difference between climate and weather?

2. Ocean Motion • Constant Movement, more in some places then others. • Three Factors • Winds • Coriolis Effect • Current

3. Atmosphere • Winds are named for the direction in which they blow from. • Convection Current - Moves materials around. • Cells move air in the atmosphere around.

4. Atmospheric Cells Air movement into the atmosphere and back down.

5. Atmospheric Cells • Tell me as much as you can about each cell type based on what you see on the following slide: • Hadley Cells • Ferrel Cells • Polar Cells

7. Why is it not just one large cell…. • What goes up must come down. The cycle: Warm air rises…less dense. Eventually this warm air cools off. Cool air is more dense and sinks down.

8. Connecting Air Cells Three major connections

9. Meeting Air Currents – Hadley to Hadley • Intertropical Convergence Zone • Trade winds from both hemispheres converge together. • Gentle Breeze Doldrums • Wind dies down and ships are stuck in the ITCZ

10. Meeting Air Currents – Hadley to Ferrel • Horse Latitudes – 30˚N and 30˚S • Also called Subtropical High • Winds separating in different directions. • Dry air and high pressure results in weak winds. • Desert areas Why were they called the horse latitudes?

11. Meeting Air Currents –Ferrel to Polar • Cold air masses from higher latitudes and warmer air masses from lower latitudes • Areas of storm activity

12. Wind Patterns Movement of air across the globe. Different air flow convergence and divergence gives us our general climate conditions.

13. Wind Patterns • Tell me as much as you can about each wind pattern based on what you see on the following slide: • Trade Winds – Northeasterly and Southeasterly • Westerlies • Easterlies (Polar)

16. Ocean Motion • Currents are named by the direction they flow • 2 Types: • Surface Currents • Deep Sea Circulation

17. Ocean Vertical Structure • Top Ocean Layer well mixed because of air interactions. • Pycnocline – Area between the mixed layer and deep ocean layer. • Major changes in density and salinity occur here • Increasing density. • Thermocline - Temp Changes • Halocline – Salinity Changes

18. Global Conveyor Belt • Overall circulation to transport heat and salt. • Cold salt water is more dense, then the less dense warmer waters. (More oxygen and nutrients in colder water as well) • Flows top to bottom and along the surface. • Begins near Greenland 1000 years to complete a cycle.

20. Coriolis Effect • Due to Earth’s rotation. • Shallow layer of the surface water is deflected to the right in the Northern hemisphere and to the left in the Southern hemisphere • At the equator this effect is at zero.

21. Wind bombards the surface ocean Water starts to move Coriolis deflection alters its path What happens UNDER the surface?

22. Ekman Transport (Spiral) • surface layer (1) drags on • the water underneath (2). • layer 2 starts to move. It moves more slowly than layer 1 due to friction. • (smaller yellow arrow) • Coriolis deflection • alters path of layer 2. Decreases as you move down the water column.

23. Upwelling • As surface waters are pushed offshore, water is drawn from below to replace them. • Good: Upwelling brings up cold, nutrient-rich waters to the surface, which encourage seaweed growth and support blooms of phytoplankton. • Bad: upwelling that moves surface water offshore can potentially move drifting larvae long distances away from their natural habitat • Most common on West Coast

24. About half the world's total fish catch comes from upwelling zones.

25. Downwelling • Where Ekman transport moves surface waters toward the coast, the water piles up and sinks. • The surface layer of warm, nutrient-deficient water thickens as water sinks. • Reduces biological productivity and transports heat, dissolved materials, and surface waters rich in dissolved oxygen to greater depths.

26. Returns oxygen poor water to be recycled

27. Boundary Currents Western Currents Eastern Currents • Gulf Stream, Kuroshio, • East Australia Currents • California, Canary, Peru • Currents • warm water moving from • equator to pole • cold water moving from • pole to equator • narrow: < 100 km wide • wide: ~ 1000 km wide • deep: down to 2 km • shallow: < 500 m • “fast:” 100s of km/day • “slow:” 10s of km/day • sharp boundaries defined by • water temperature • diffuse boundaries

29. Wind Tricks Making a Gyre

30. Gyres Geostrophic Flow Formed by major currents interacting with each other. Deflection is piling up water (Coriolis Effect). Gravity is pulling it down. The pile is ALWAYS THERE. These forces must be EQUAL.

31. Sargasso Sea - a mound of water in the Atlantic Ocean

32. Major Gyres (5)

33. Notice how the winds are helping the currents

34. Wind Trick #2 Western Intensification

35. What happens when you push in on a plastic container of water?

36. The container moves first, and water moves a fraction of a second later.

37. Water sloshes up again the left-hand side, creating a pile

38. Earth’s rotation As Earth rotates the continents smack into the oceans The Americas hit the Atlantic Ocean Asia, Australia hit the Pacific Ocean Sverdrup et al., Introduction to the World’s Oceans, 8th edition, McGraw Hill, Fig. xxx

39. A West to East Cross Section of the mound of water Continents crash into the mound of water. The mound is asymmetrical. This leads to Western Intensification – water piles up on the coast West East North America 1m Only ~ 1m high, but that’s enough to create BIG differences in the currents.

40. Western Intensification A West to East Cross Section of the mound of water East West North America Gravity is trying to pull this down and out to flatten the ocean. The flow is constricted on the WEST side and spread out on the EAST Think about constricting flow out of a garden hose by covering half the opening with your thumb. The constricted flow moves FASTER.

41. Gulf Stream (Flowing into screen) Narrow and fast Canary Current (Flowing OUT of screen) diffuse, slow Western Intensification East West North America Think about constricting flow out of a garden hose by covering half the opening with your thumb. The constricted flow moves FASTER. WHY? SAME AMOUNT of water forced to move through smaller opening

42. The Southern Oscillation Pattern of reversing surface air pressure between the eastern and western tropical pacific

43. El Nino • Spanish for “The Christ Child”…why? • Unusually warm ocean temperatures • Results: Major rainfall, flooding, across the southern US and in Peru. Drought in the West Pacific, can cause devastating brush fires in Australia.

44. Normal vs. Nino

45. La Nina • unusually cold ocean temperatures • Eastern Pacific is cooler than usual, and the cool water extends farther westward than is usual • Wetter than normal conditions across the Pacific Northwest • Dryer and warmer than normal conditions across much of the southern tier.

46. Normal vs. Nina

47. Characteristics • Definition • Word Made by name • Example • Picture

48. When you feel you are finished, you will switch with someone that has a different word as yourself. • You will add 1 thing to it and then write at the bottom • Checked by your name.