Currents Where are the Oceans? Identify the Oceans Tides Waves The Ocean Floor Ocean Storms

Where are the Oceans?

Ocean Currents

What percent of the earth’s surface is covered in water? ______________ What percent is land? ___________

What percent of the earth’s water is salt. What percent is fresh What percent of the earth’s water is salt? What percent is fresh? Drop in the Bucket

World Ocean Facts Area (1,000,000 km²) Volume (1,000,000 km³) Average Depth (m) Maximum Depth (m) Atlantic Ocean 82.4 323.6 3926 9200 Pacific Ocean 165.2 707.6 4282 11,022 Indian Ocean 73.4 291.0 3963 7460 Arctic Ocean 14.1 17.0 1205 4300

Currents

There are two principle ways to measure currents: Eulerian method employs current meters fixed to the sea bottom. Two Impeller Meters

Langrangian method employs drifters, drogues, or floats that are set loose at the sea surface or at predetermined depths and tracked acoustically. The Lagrangian Method

Ben Franklin and the Gulf Stream In the 1750s when Postmaster for the American Colonies, Ben Franklin and Capt. Timothy Folger created the first map of the Gulf Stream to help speed up delivery of mail to and from GB

Types of currents: Wind-driven currents (surface currents) occur in the uppermost 100 m or less Density currents (vertical currents) caused by salinity and temperature produce very slow flows in deeper waters.

Surface Currents Wind blowing over the ocean can move it due to frictional drag. Waves create necessary roughness for wind to couple with water. One “rule of thumb” holds that wind blowing for 12 hrs at 100 cm per sec will produce a 2 cm per sec current (about 2-3% of the wind speed)

Top-down drag Wind acts only on the surface water layer. This layer will also drag the underlying water, but with less force. Consequently, there is a diminution of speed downward. Direction of movement is also influenced by the Coriolis Effect and Ekman Spiral

Coriolis Effect The French scientist, Gaspard Coriolis, first explained the deflection of objects moving over the surface due to Earth’s rotation. coriolis experiment Pete Bethune Whale Wars (26 min)

                                                                                                                  Ekman Spiral Nansen and others exploring the Arctic noticed that ice and surface currents move at an angle to the wind direction. Ekman first explained the mathematics of this phenomena, and why it decreases with depth to produce the spiral pattern.

Vertical Ocean Currents Driven by temperature and salinity differences as water reaches the poles, it cools resulting in evaporation or freezing, leaving remaining water saltier and more dense. In addition, cold water is denser than warm water, causing it to sink (thermohaline circulation).

The Great Ocean Conveyer Why is this important? VIDEO

WHY ARE THESE CURRENTS IMPORTANT?? General Surface Current Patterns Temperature Distribution Shape coastlines Oxygen / Carbon Dioxide Exchange Distribution of Nutrients (Upwelling and Downwelling) Pollution Dispersal Plastic Plague Video WHY ARE THESE CURRENTS IMPORTANT?? http://earth.usc.edu/~stott/Catalina/Oceans.html

Gyres Circular surface currents patterns Prevailing Westerlies and Trade Winds strongly influence these flows Clockwise rotation in the Northern Hemisphere, counterclockwise in the Southern http://earth.usc.edu/~stott/Catalina/Oceans.html

Upwelling Large amounts of nutrient rich water moves up to the surface from the below Occurs most frequently in areas that experience monsoons and steady winds upwelling demo seamounts

Research 1 ocean current! Choose 1 of the ocean currents Is this a warm or cold ocean current? Name and provide a picture for one ocean organism that relies on the movement of that current Describe why this current is important for that organism’s survival (diet, migratory patterns, etc) Be descriptive! 6-7 sentences Provide a map of the location you are describing and describe the pattern of its movement

Create an ocean mural Use the internet to find 3 fish (from 3 of the 5 ocean zones) Epipelagic, mesopelagic, bathypelagic, abyssopelagic, hadopelagic Cut and paste a picture of each fish as well as its common name and adaptation for survival in its zone! Print out, color, cut and add to the mural! TUNA(epipelagic) – Countershaded color to camouflage with sunlight in order to hide from predators/ stalk prey

Review Questions What are 3 properties of ocean water that vary in different parts of the ocean? temperature, salinity, pressure, gases, density How does the direction of ocean currents differ north and south of the equator? north-clockwise, south-counterclockwise What current does the Gulf stream form as it travels north? North Atlantic Drift