1. NC STANDARD COURSE OF STUDY E/EN SCIENCE Oceans and Beaches

2. 4.02 Analyze mechanisms for generating ocean currents and upwelling Temp (Ch. 15, Sec 1) Coriolis Effect (Ch. 16, Sec 1) Climatic influence (Ch. 16, Sec 1)

3. Chapter 15, Section 1 The Composition of Seawater Our own body fluid chemistry is similar to the chem. of seawater. Seawater consists of ~3.5% dissolved mineral substances (NaCl, other salts, metals, & gases), collectively called “salts.” The salt content of seawater makes it unsuitable for drinking or irrigating most crops and causes it to be highly corrosive to many materials.

4. Salinity (salinus = salt) is the total amt. of solid material dissolved in H 2 O Oceanographers express salinity in parts per thousand (o/oo). The avg. salinity of seawater is 3.5% or 35 o/oo. Most of the salt in seawater is sodium chloride, common table salt.

5. Sources of Sea Salts 1. Chemical weathering of rocks on the continents reaching oceans through runoff from rivers and streams 2. Earth’s interior through volcanic eruptions (Cl- chlorine, Bromine, Sulfur, Boron)

6. Processes Affecting Salinity (surface salinity variation range; 33 o/oo-38 o/oo) salinity Some processes add lg. amts. of fresh H 2 O to seawater, decreasing salinity; precipitation, runoff, icebergs and sea ice melting. salinity Other processes remove lg. amts. of fresh H 2 O from seawater, increasing salinity; evaporation, and formation of sea ice. Answer Applying Concepts?, Figure 2, pg. 423.

7. Ocean Temp Variation The ocean’s surface H 2 O temp varies w/amt. of solar radiation received, which is primarily a function of latitude. Answer Interpreting Diagrams?, Figure 3, pg. 424.

8. Temp Variation w/Depth Surface waters are warmed by the sun, so they are generally higher than deeper waters. The low-latitude curve begins w/high temp at the surface. The temp decreases rapidly w/depth because of the inability of the sun’s rays to penetrate very far into the ocean. At a depth of ~1000m, the temp remains just a few degrees above freezing and is relatively const. from this level down to the ocean floor.

9. thermocline The thermocline (thermo=heat, cline=slope) is the layer of ocean H 2 O between ~300m-1000m, where there is a rapid change of temp w/depth. The thermocline is a very important structure in the ocean because it creates a vertical barrier to many types of marine life.

10. Answer Applying Concepts?, Figure 4, pg. 425 isothermal Surface H 2 O temps in high latitudes are much cooler, and the deeper temp is similar to that at the surface, so the curve remains vertical. There is no rapid change of temp w/depth. Instead, the water column is isothermal (iso=same).

11. Ocean Density Variation Density is defined as mass per unit volume (D=m/v). An object that has low density is lightweight for its size, and an object that has high density is heavy for its size. Density is an important property of ocean H 2 O because it determines the H 2 O’s vertical position in the ocean. Density differences cause lg. areas of ocean H 2 O to sink or float.

12. Factors Affecting Seawater Density Seawater density is influenced by 2 main factors: salinity 1. An increase in salinity adds dissolved substances and results in an increase in seawater density (direct relationship). Only in extreme polar areas of the ocean does salinity significantly affect density. temperature 2. An increase in temperature results in a decrease in seawater density (inverse relationship). Temp has the greatest influence on surface seawater density.

13. Density Variation w/Depth By sampling ocean waters, oceanographers have learned that temp and salinity—and the water’s resulting density—vary w/depth. Temperature is the most important factor affecting seawater density. Temp is inversely proportional to density (D x T = constant). When H 2 O temp increases, its density decreases.

14. pycnocline The pycnocline (pycno=density) is the layer of ocean H2O between ~300m-1000m where there is a rapid change of density w/depth. A pycnocline presents a significant barrier to mixing between low-density H 2 O above and high-density H 2 O below. A pycnocline is not present in high latitudes. Answer Interpreting Diagrams ?s, Figure 5, pg. 426.

15. Ocean Layering Oceanographers generally recognize a 3-layered structure in most parts of the ocean: 1. Surface Zone-warmest H 2 O temps mixed zone This mixed zone is the area of the surface created by the mixing of water by waves, currents, and tides. It has nearly uniform temps, and usually extends to ~300m(-450m), and accounts for only ~2% of ocean H 2 O.

16. 2. Transition Zone surfacedeep zone Below the sun-warmed zone of mixing, temp falls abruptly w/depth. This distinct layer exists between the warm surface layer above and the deep zone of cold water below. It includes a thermocline and associated pycnocline, and accounts for ~18% of ocean H 2 O.

17. 3. Deep Zone Sunlight never reaches this zone, and H 2 O temps are just a few degrees above freezing. As a result, water density remains const. and high. The deep zone accts for ~80% of ocean H 2 O. In high latitudes, the 3-layered structure does not exist. Therefore, good vertical mixing between surface and deep waters can occur. Cold high- density H 2 O forms at the surface, sinks, and initiates deep-ocean currents.

18. Answer the Key Concepts ?s, Reading Focus, on top of pg. 422 Answer the Reading Checkpoint ?s on pgs. 425 & 426.

19. Chapter 16, Section 1 Ocean Circulation Ocean H 2 O is in constant motion. Winds generate surface currents, which influence coastal climate. Density differences create deep-ocean circulation, important for ocean mixing and recycling nutrients.

20. Surface Circulation Ocean currents Ocean currents are masses of ocean H 2 O that flow from 1 place to another. Surface currents are movements of H 2 O that flow horizontally in the upper part of the ocean’s surface, which develop from friction between the ocean and wind that blows across its surface. Some of these currents affect only small areas, responses to local and seasonal influences. Major horizontal movements of surface waters are closely related to the general circulation pattern of the atmosphere.

21. Gyres (gyros=a circle)-lg. whirls of H 2 O w/in an ocean basin Huge circular-moving current systems dominate the surface of the oceans. Coriolis effect The Coriolis effect is the deflection of currents away from their original course as a result of the Earth’s rotation. Currents are deflected to the right in the Northern Hemisphere, and to the left in the Southern Hemisphere. As a consequence, gyres flow in opposite directions in the 2 different hemispheres. 4 main currents exist w/in ea. gyre.

22. Answer Locate ?, Map Master Skills Activity Movement, pg. 449 Ocean Currents and Climate When currents from low-latitude regions move into higher latitudes, they transfer heat from warmer to cooler areas on Earth. The Gulf Stream brings warm H 2 O from the equator up to the N Atlantic Current, which allows Great Britain and much of NW Europe to be warmer during the winter. As cold water currents travel toward the equator, they help moderate the warm temps of adjacent land areas. Ocean currents play a major role in maintaining the Earth’s heat balance, transferring heat from the tropics to the polar regions (accts for ~1/4).

23. Upwelling is the rising of cold H 2 O from deeper layers to replace warmer surface H 2 O. Coastal upwelling (along California, western S Am, and W Africa) occurs when winds blow toward the equator and parallel to the coast. Coastal winds combined w/the Coriolis effect cause surface H 2 O to move away from shore. It is replaced by H 2 O that “upwells” from below, resulting in lower surface H 2 O temps near the shore. Upwelling Upwelling brings greater conc. of dissolved nutrients (NO 3 and PO 4 ) to the ocean surface, which promote the growth of microscopic plankton, which support extensive fish populations and other marine organisms.

24. Deep-Ocean Circulation Most H 2 O involved in deep-ocean density currents begins in high latitudes at the surface. In these regions, surface water becomes cold, and its salinity increases as sea ice forms. When dense enough, it sinks, initiating deep-ocean density currents. Because its density and salinity remain largely unchanged during its time in the deep ocean, oceanographers can track the movements of density currents. By knowing the temp, salinity, and density of a H 2 O mass, scientists can map its slow circulation through the ocean.

25. Answer Drawing Conclusions?, Figure 5, pg. 452 Also read 1 st paragraph. How long does it take for density currents originating from Antarctica to reappear at the surface after sinking?

26. 4.03 Analyze the mechanisms that produce the various types of shorelines and their resultant landforms. Nature of underlying geology Long and short term sea-level history Formation and breaking of waves on adjacent topography Human Impact Chapter 16, Section 3

27. 4.05 Investigate and analyze environmental issues and solutions for NC’s river basins, wetlands, and tidal environments. Water quality Shoreline changes Habitat preservation Chapter 11A, Section ES 18-ES 21