Sea-surface temperatures (SSTs) are easily measured by satellites and can show the locations of currents that move across the ocean's surface. The following images show examples of Earth's major currents, delineated by measured differences in sea-surface temperatures. To see a generalized diagram of surface currents, click on the Surface Currents Map (below). You may want to print a copy on your local printer.
4. The image below shows sea-surface temperatures (SSTs) for the entire world ocean in August 1995. Temperatures are in degrees Celsius.
(a.) Describe the general pattern of sea surface temperatures in the ocean.
(b.) Examine the zone of warm water along the equator.
Why does this zone widen to the west in each ocean; for example, in the Pacific Ocean? (Hint: look at the Atmospheric Circulation Diagram and the Surface Currents Map.) Perturbations to this pattern are involved with the El Niño climatic condition (see other exercise on this site).
5. The image below uses sea-surface temperature measurements to illustrate the location of the Kurishio current. The Kurishio current is called a western boundary current (it moves along the west side of an ocean). Click on the image to obtain a larger-sized version. Sea-surface temperatures are in degrees Celsius.
(a.) What is the geographical location of the Kurishio Current?
(b.) Is the Kurishio Current a warm-water or a cold-water current? [Provide a temperature range.]
(c.) Do you see any evidence for the influence of another current? If so, what is its name and its temperature? Refer to the Surface Currents Map.
6. The images below use sea-surface temperature measurements to show another western boundary current, the Gulf Stream. The two images show data collected 6 days apart, on 19 February (left side) and 25 February (right side) in 1996. Major currents such as the Gulf Stream can be compared to rivers in the ocean, although they can transport incredibly huge amounts of water from place to place. For example, the Gulf Stream transports more than 150 million cubic meters of water per second, compared to a flow of 0.6 meters per second for all of the rivers that flow into the Atlantic Ocean. On these images the Labrador Current, as well as the Gulf Stream Current, is visible. Click on the left image to obtain larger-sized versions.
(a.) What is the temperature range of the Gulf Stream current?
(b.) What is the temperature range of the Labrador current?
(c.) Describe what changes occur in the currents during the 6-day period between the two images. For example, notice what happens with the ring of Gulf Stream water enclosed in the colder water.
(d.) Describe the boundaries of the Gulf Stream. For example, are they sharp or diffuse; straight or meandering?
7. In the image below, sea-surface temperatures are used to show the Agulhas Current at the tip of Africa. Measurements were collected by satellite in 21 February 1996. Click on the image to obtain a larger version.
Explain the distribution of water temperatures visible on this image in the context of the currents that affect this part of the world. Refer to the Surface Currents Map. Because the east side and west coasts of South Africa are effected by currents of different temperatures, they have quite different climates.