This document discusses several key properties and concepts related to oceans and seawater. It covers the chemical composition of seawater, how salinity varies in different ocean regions and affects density. It also describes the layering of the ocean into surface, thermocline and bottom layers based on temperature differences with depth. Deep water masses like Antarctic Bottom Water and North Atlantic Deep Water are formed in polar regions due to cold, salty conditions and sink before migrating toward the equator. Ocean currents are driven by both density currents of deep water and surface winds, which cause gyres and upwelling in various ocean regions.

1. Oceans Chapters 15.2 – 15.3

2. Goal 1 Discuss the chemical and physical properties of seawater

3. Gases Nutrients Salts (see table 15-1 page 392) Salinity 35 ppt = 3.5% Salt ions Chloride Sodium Sulfate Magnesium Calcium

4. Salinity Varies (figure 15-10 page 393) High salinity (up to 37 ppt) Evaporation Hot Low precipitation

5. Low salinity (down to 32 ppt) Low Evaporation High precipitation Freshwater influx Glacier melt River mouth

6. Image credit: PD-gov http://en.wikipedia.org/wiki/Image:Winkel-tripel-projection.jpg

7. Salinity affects Physical Properties More dense than freshwater Freshwater = 1.00 g /mL Seawater = 1.02 g/mL to 1.03 g/mL Lower freezing point Fresh water = 0° C Seawater = -2° C

8. Seawater absorbs light (see figure 15-14 page 396) RYO (Long wavelengths) 50 m Green to 100 m Average depth of oceans 3720 m Photosynthesis occurs where??

9. Goal 2 Explain ocean layering (See page 397)

10. Basis of ocean layering: Warm water  less dense  floats Cold water  more dense  sinks

11. Ocean is divided into 3 layers Surface layer Thermocline Bottom layer Layers determined by temperature characteristics

12. Temperature decrease with depth Surface layer (top layer) Warm ~ 100 m depth Equator Nonexistent at poles

13. Thermocline (middle layer) Temperature rapidly decreases Depth location varies Nonexistent at poles

14. Bottom layer (bottom layer) Very cold <4° C Near freezing temps Depth varies

15. Image credit: PD-personal http://en.wikipedia.org/wiki/Image:Thermocline.jpg Surface layer Thermocline Bottom layer

16. Goal 3 Explain deep water masses

17. Deep water mass formation Polar areas Cold Salty water = very dense Salts do not freeze out of water Sinks Migrates toward equator

18. Three major water masses Antarctic Bottom Water Antarctic winter Freezing , salt concentration Coldest Most dense

19. Image credit: PD-gov http://en.wikipedia.org/wiki/Image:Winkel-tripel-projection.jpg Antarctic Bottom Water

20. North Atlantic Deepwater Greenland Winter Freezing, salt concentration 2 nd Coldest 2 nd most dense

21. Image credit: PD-gov http://en.wikipedia.org/wiki/Image:Winkel-tripel-projection.jpg North Atlantic Deep Water

22. Antarctic Intermediate Water Antarctic winter Temperature decrease Least cold deep water mass Least dense deep water mass

23. Image credit: PD-gov http://en.wikipedia.org/wiki/Image:Winkel-tripel-projection.jpg Antarctic Intermediate Water

24. Atlantic ocean Affected by all 3 deep water masses Pacific Ocean Affected by only 2 Which one does not ???

25. Goal 4 Understand movement of water via ocean currents

26. Density currents Driven by Cold, salty deep water currents Great Ocean Conveyor Belt

27. Image credit: PD-gov http://en.wikipedia.org/wiki/Image:Thermohaline_Circulation_2.png

28. Surface currents Driven by global wind systems

29. Image credit: PD-gov http://en.wikipedia.org/wiki/Image:Ocean_surface_currents.jpg

30. Gyres Continents deflect surface currents Northern Hemi = Clockwise Southern Hemi = Counterclockwise

31. Image credit: PD-gov http://en.wikipedia.org/wiki/Image:Oceanic_gyres.png

32. Upwelling Cold bottom water deflects up continents Pushed out by winds West coasts & trade winds Nutrient rich = fish

33. Image credit: PD-gov http://cordellbank.noaa.gov/images/environment/upwelling_470.jpg