http://cwx.prenhall.com/bookbind/pubbooks/tarbuck3/chapter13/deluxe.html

Currents flow in complex patterns and are also affected by bottom topography, and the earth's rotation.

 Warm surface currents invariably flow from the tropics to the higher latitudes, driven mainly by atmospheric winds, as well as the earth's rotation.

Western boundary currents are good examples of warm surface currents: they are warm and fast, and they move from tropical to temperate latitudes .

Cold surface currents come from polar and temperate latitudes, and they tend to flow towards the equator. Like the warm surface currents, they are driven mainly by atmospheric forces . Gyres form when the major ocean currents connect.

Water flows in a circular pattern--clockwise in the Northern Hemisphere, and counterclockwise in the Southern Hemisphere .

Ocean Circulation near Florida from Princeton University

http://www.aos.princeton.edu/WWWPUBLIC/htdocs.pom/FTPbackup/Animations/GOManim.gif

Try this: You will need an orange (or other round object), a felt marking pen, and a friend to spin the orange while you draw.  Draw and equator around the orange. Have your friend spin it from west to east. As the orange spins, try to draw a line from the equator to the North Pole. Did the marker move clockwise or counterclockwise? Now as the orange spins, draw a line from the equator to the South Pole. Which way did the marker move. You have just simulated the Coriolis Effect.

Primary Forces--start the water moving

The primary forces are:

1. Solar Heating

2. Winds

3. Gravity

4. Coriolis Effect

Solar heating causes water to expand. Near the equator the water is about 8 centimeters higher than in middle latitudes. This cause a very slight slope and water flows down the slope. 

 Eastern and Western Boundary Currents  

The Gulf Stream surface current is a western boundary current, one of the strongest--warm, deep, fast, and relatively salty. It separates open-ocean water from coastal water.

The figure above shows a profile view of the Gulf Stream as it moves north along the Eastern coast. The picture below shows the discharge rates of the Gulfstream Current.

The California current is an eastern boundary current. It's broad, slow, cool, and shallow. Eastern boundary currents are often associated with upwelling.

• Discuss the importance of surface ocean currents.

http://geosci.sfsu.edu/courses/geol103/labs/currents/part2a.html

Ocean waters are constantly on the move. How they move influences climate and living conditions for plants and animals, even on land.

1) Upwelling stirs the soup and serves up a stew of nutrients that have settled into deep water. The ocean is layered: warmer on top, cold at the bottom. Organisms move from one layer to another, and plant and animal remains containing nutrients "rain" down, but the layers stay fairly separate in all but a few places.

Coastal upwelling occurs against the western sides of continents in the Atlantic, Indian, and Pacific. There, colder water rises to replace warm surface water blown out to sea by strong offshore winds. Upwelling supports about half of the world's fisheries, although these cool waters account for only 10 percent of the surface area of the global ocean .

http://www.columbia.edu/cu/record/23/11/13.html

 2) A complex of globally interconnected ocean currents, collectively known as the Conveyor, governs our climate by transporting heat and moisture around the planet. But the Conveyor is delicately balanced and vulnerable, and it has shut down or changed direction many times in Earth's history. Each time the Conveyor has shifted gears, it has caused significant global temperature changes within decades, as well as large-scale wind shifts, dramatic fluctuations in atmospheric dust levels, glacial advances or retreats and other changes over many regions of the Earth.

• Describe deep-ocean circulation.

Surface currents are confined to the top 10% of the ocean. The other 90% of the ocean is affected by deep-ocean circulation.

These waters move around the ocean basins by density driven forces and gravity.

The density difference is a function of different temperatures and salinity

These deep waters sink into the deep ocean basins at high latitudes where the temperatures are cold enough to cause the density to increase.

The global climatic flip-flops may have been set in motion by sudden switches in the operation of the deep-ocean circulation.

The driving force of deep-ocean circulation is the cold, salty water of the North Atlantic Ocean. Such water is more dense than warm, fresh water and hence sinks to the ocean bottom, pushing water through the world's oceans like a great plunger.

The volume of this deep undersea current is 16 times greater than the flow of all the world's rivers combined and it runs southward all the way to the southern tip of Africa, where it joins a watery raceway that circles Antarctica. Here the Conveyor is recharged by cold, salty water created by the formation of sea ice, which leaves salt behind when it freezes. This renewed sinking shoves water back northward, where it gradually warms again and rises to the surface in the Pacific and Indian oceans.

  In the Indian Ocean, surface waters are too warm to sink. Northern Pacific waters are cold, but not salty enough to sink into the deep. This is primarily because prevailing winds that whip around the planet hit the great mountains of the western United States and Canada and drop their moisture. The resulting snow and rain runs into the Pacific, adding a dose of fresh water that dilutes the Pacific's saltiness

• Discuss the factors that influence tides.

The word "tides" is a generic term used to define the alternating rise and fall in sea level with respect to the land, produced by the gravitational attraction of the moon and the sun. Therefore, the positions of the sun and the moon relative to earth are the major factors that influence tides. To a much smaller extent, tides also occur in large lakes, the atmosphere, and within the solid crust of the earth, acted upon by these same gravitational forces of the moon and sun.

Tides are a direct result of the gravitational influence of the Moon and the Sun or Earth.  

http://csep10.phys.utk.edu/astr161/lect/history/newtongrav.html

Bonus Question (2 points)

The constant G appearing in Newton's law of gravitation, also known as the universal gravitational constant,

where F is the force between two masses m and M a distance r apart. The numerical value of G is

G

Strength of the gravitational force depends on:

1)     distance separating any two objects

2)     mass of the two objects

In figure 1 above, the water closest to the moon is the most affected by the moon's gravitational attraction.  The massive earth is also affected but to a lesser degree. On the opposite side, the ocean water is left behind, due to its low mass and great distance from the moon.

Figure 2 shows the net motion of the water relative to the earth.

Spring and Neap Tides are caused by the combined gravitational effects of the sun and the moon on the earth. The moon's effects are greater than the sun's effects because the moon is so much closer to the earth.

During Spring tides, the moon and the sun are aligned resulting in a stronger than normal tidal force. During Neap tides the sun and the moon are opposed to each other, resulting in a weaker than normal tidal force.

Additional non-astronomical factors such as configuration of the coastline, local depth of the water, ocean-floor topography, and other hydrographic and meteorological influences may play an important role in altering the range, interval between high and low water, and times of arrival of the tides.

The most familiar evidence of the tides along our seashores is the observed recurrence of high and low water - usually, but not always, twice daily. The term tide correctly refers only to such a relatively short-period, astronomically induced vertical change in the height of the sea surface (exclusive of wind-actuated waves and swell); the expression tidal current relates to accompanying periodic horizontal movement of the ocean water, both near the coast and offshore.

• Describe wave characteristics and types.

Modified from

http://www.oceansatlas.org/

• What are the causes and effects of sea level rise.

 Sea Level Change

caused by:

1.     tides dues to the gravitational pull of the sun and the moon.

2.     land rising and falling due to erosion and isostatic adjustment.

3.     storm surges due to wind and a drop in barometric pressure  which can cover large areas to rise by 30 cm or more (Cat. 3 storm=~3 meter rise)

4.    global temperature rise due to melting glaciers and thermal expansion

Effects are

1. flooding

2. beach erosion

3. soil damage

4. change in coastal ecosystems

Most vulnerable areas are

1. Pacific Islands

2. Mississippi Delta (lose up to 100 km /yr of wetlands)

3. South Florida

Find out how rising sea levels will affect your home.

http://flood.firetree.net/

 Hydrometer Chart

http://ourworld.compuserve.com/homepages/BMLSS/sg.htm