Introduction to Oceanic Circulation

Transcription

1 Introduction to Oceanic Circulation

2 Start rotating table

3 Wind Driven Circulation Cold Upwelling Warm Western Boundary Currents

4 Sea Surface Temperature

5 Sea Surface Temperature upwelling

6 Sea Surface Temperature western boundary current upwelling

7 Trade Winds and Upwelling

8 Wind Drags Ocean Surface Equatorward wind stress California EQ Peru

9 Conservation of Angular Momentum If no torque (force in direction of rotation), then angular momentum is conserved R 1 V 1 = R 2 V 2 V 2 R 2 V 1 R 1 R 1 < R 2 V 1 > V 2

10 Ocean Surface Moves Westward Ekman transport wind stress California EQ ocean surface rotates more slowly than the Earth moves westward relative to the Earth Peru

11 Upwelling Replaces Surface Water Ekman transport upwelling warm cold, nutrients west east

12 What Happens at the Equator?

13 Equatorial Bulge from Rotation non-rotating earth is spherical outward centrifugal acceleration rotating earth is oblate

14 Wind Drags Ocean Surface Westward EQ ocean surface rotates more slowly than the Earth

15 Equatorial Bulge from Rotation faster rotation is more oblate slower rotation is less oblate water moves poleward when rotation slows

16 Wind Drags Ocean Surface Westward EQ ocean surface moves poleward

17 Upwelling Replaces Surface Water Ekman transport upwelling warm warm cold, nutrients south equator cold, nutrients north

18 western boundary currents Sea Surface Temperature

19 Wind Stress over Subtropical Gyre

20 Surface Ocean Movement

21 Convergence of Ocean Surface Convergence

22 Ekman Pumping and Sverdrup Transport surface layer thermocline deep ocean convergence Ekman pumping divergence middle latitudes subtropical gyre equator

23 Why is Sverdrup Transport Equatorward? NP Ekman pumping pushes water into deep ocean fluid columns can be taller if they move closer to the equator EQ

24 Sverdrup transport below surface layer Deep Ocean Movement

25 How Does Water Return Poleward? Sverdrup transport below surface layer

26 How Does Water Return Poleward? Intense western boundary current

27 examine rotating table

28 Depth of Ocean Circulation Surface layer and Ekman transport: m Sverdrup transport and western boundary current: m Thermohaline circulation: Below wind-driven circulation

29 Temperature, Salinity, and Density Cold salty water is more dense than warm fresh water If surface water becomes cold enough and salty enough, it can sink down to the bottom of ocean surface cooling brine exclusion from sea ice thermocline warm, fresh cold, salty less dense more dense very cold very salty

30 How Does Water Come Back Up? In atmosphere, warm air that rises comes back down by In ocean, cold & salty water that sinks comes back up by warm, fresh less dense cold, salty more dense very cold, very salty very dense

31 How Does Water Come Back Up? In atmosphere, warm air that rises comes back down by cooling through thermal emission In ocean, cold & salty water that sinks comes back up by warming and freshening through very slow mixing warm, fresh less dense cold, salty very slow mixing more dense very cold, very salty very dense

32 Sverdrup Transport in Very Deep Ocean upper ocean convergence high latitudes equator

33 Very Deep Ocean Movement Sverdrup transport in very deep layer

34 How Does Water Return Equatorward? Sverdrup transport in very deep layer

35 How Does Water Return Equatorward? relatively intense deep western boundary current Sverdrup transport in very deep layer

36 Thermohaline Circulation cold sinking water rising water rising water rising water cold sinking water

37 A large fraction of anthropogenic CO 2 emitted every year is taken up by land plants or dissolved into the ocean. The remainder accumulates in the atmosphere.

38 current amount of anthropogenic carbon in the ocean

39 current amount of anthropogenic carbon in the ocean sinking water rising water

40 increase in oceanic CO 2 decrease in oceanic ph (ocean becomes more acidic)