Lab Activity: SurfaceOcean Currents

Background Information:

The lower atmospheric circulation and the upper oceanic circulation are closely linked, with the sun being the ultimate source of energy for both circulations. Unequal heating of the atmosphere produces atmospheric circulation and wind. The wind blowing over the surface of the water drives the ocean’s major surface currents. These currents, along with the wind, transfer heat from tropical regions, where there is a surplus, to polar regions, where there is a deficit. The ocean in turn, releases energy to the atmosphere which maintains the general atmospheric circulation.

The main features of the wind that drive surface circulation are the large roughly circular current systems, called gyres, which are found in most major ocean basins. Driven by the prevailing wind systems and deflected by continental boundaries and Earth’s rotation, the gyres help to redistribute heat from low to high latitudes. Along the western margins of ocean basins, warm ocean currents, such as the Gulf Stream, transport heat pole-ward. The meanders of these fast moving currents give rise to large rotating warm and cold water rings which are similar to high and low pressure cells observed in the atmosphere. Along eastern margins of the major ocean basins, currents, such as the California Current, transport cold water to the lower latitudes (toward the equator).

Related to the gyre circulation patterns are other surface circulation features. In the land-locked higher latitudes of the Northern Hemisphere, the prevailing winds drive smaller gyres which redistribute heat to the Polar Regions. In the higher latitudes of the Southern Hemisphere where there are no blocking continents, strong westerly winds drive the largest volume surface circulation in the world around Antarctica. Limited by land boundaries, the surface circulation in the northern Indian Ocean actually reverses itself, driven by the seasonally reversing monsoon winds.

Along with the widespread horizontal currents at the surface of the world ocean, there are limited regions where vertical circulation is set in motion by persistent winds. In some coastal and equatorial regions, the wind transports warm surface water away from the coast or equator, to be replaced by water from below. This process, called upwelling, brings to the unlit surface cool, nutrient-rich water which can lead to an increase in biological production.

Recent research is investigating the global connections between the wind-driven surface circulation and the density-driven deep circulation. This is a possible mechanism by which small changes in the surface circulation can influence not only the weather, but climate and climate change.

Materials:

•Set of Ocean Current Cards•Global OceanBasinMap

•Red and Blue colored pencils•Surface Ocean Currents Article

Objectives:

1.Be able to describe the typical gyre circulation pattern found in each major ocean basin

2.Be able to describe the location, temperatures, speeds, and directions of the ocean currents

Procedure:

  1. Read the “Background Information” above.
  2. Examine the Current Cards using the image on the front and the facts listed on the back.
  3. Start with the first category – Geographic Location.
  4. Sort the Current Cards into groups based on their Geographic Location
  5. On your data sheet, record the names of eachcurrent you have identified according to their Geographic Location and count up how many currents are in each category and record.
  6. Put your piles together and mix the Current Cards.
  7. Repeat steps #2-6 for each additional category listed on your data sheet.
  8. Using all the Current Cards, complete the Data Table with the correct information.
  9. Using the Data Table and the Current Cards, draw in each of the currents onto the Global Ocean Surface Current Map –Label and draw in the correct location and direction of each. Don’t forget to use a redcolored pencil for the warm currents and a blue colored pencil for the cold currents!

Student Lab Sheet

Lab Activity: SurfaceOcean Currents

Data:(write the NAME of the currents below!)

  1. First Category: Geographic Location

•The Northern Atlantic Ocean: •The Southern Atlantic Ocean:

How many currents? ______How many currents? ______

•The Southern Pacific Ocean:•The Northern Pacific Ocean:

How many currents? ______How many currents? ______

  1. Second Category: Temperature of Current

•Warm(ing) Water Currents:•Cool(ing) Water Currents:

How many currents? ______How many currents? ______

  1. Third Category: Speed of Current

•Slow: •Fast:

How many currents? ______How many currents? ______

  1. Fourth Category: Direction of Flow

•Toward the poles:•Toward the Equator:

How many currents? ______How many currents? ______

•From West to East:•From East to West:

How many currents? ______How many currents? ______

Data Table: Ocean Currents

Name / Ocean / Hemisphere / Location / Flow Direction / Temp / Character
California
N. Equatorial
Kuroshio
N. Pacific
Peru
S. Equatorial
E. Australian
W. Wind Drift
Benguela
S. Equatorial
Brazil
W. Wind Drift
Canary
N. Equatorial
Gulf Stream
N. Atlantic Drift

Analysis Questions:

Use the Current Cards with pages449 and 541 in your book to answer the following. Circle answer.

  1. The Trade Winds blow in a strong east to west direction. Ocean currents that are located in the same latitudes as the Trade Winds flow in the (same) or (opposite) direction.
  1. The Prevailing Westerlies blow in a strong west to east direction. Ocean currents that are located in the same latitudes as the Prevailing Westerlies flow in the(same) or (opposite) direction.
  1. Ocean currents driven by the prevailing wind systems are deflected by the continents to form the gyres. Using the map, where are there no continental boundaries? (0) (30N) (30S) (60N) (60S)
  1. Using the Ocean Current Chart

a. Which direction do gyres circulate in the Northern Hemisphere? (clockwise) (counterclockwise)

b. Which direction do gyres circulate in the Southern Hemisphere? (clockwise) (counterclockwise)

  1. a. In ocean gyres, regardless of the hemisphere, warm water is always transported poleward in which

region of the ocean basin?(eastern) (western)

b. The cold water currents from the high latitudes are found in what region of the ocean basin?

(eastern) (western)

  1. Near Peru, located on the west coast of South America, the ocean gyre current is(warm) (cold).
  1. a. In ocean gyres, regardless of the hemisphere, the faster currents are found in which region of the

ocean basin? (eastern) (western)

b. Slower currents are found in what region of the basin? (eastern) (western)

  1. Near Tokyo, Japan, the ocean gyre surface current is (fast) (slow).
  1. a. What color will you use to color in the warm currents on your map? (red) (blue)
    b. What color will you use to color in the cold currents on your map? (red) (blue)