ERTH 535:
Planetary Climate Change
(Spring 2018)
Pre-class Quiz #3:
Ocean Surface Currents
Dr. Dave Dempsey
Dept. of Earth & Climate Sci.,
SFSU

This is a "preview" version of Pre-class Quiz #3. The preview version is suitable for printing and leisurely inspection before you submit your answers to the interactive or "live" version—that is, the real thing. When you feel ready to submit your answers, go to iLearn's ERTH 535 "Pre-class Quiz" section, select the interactive version, and follow its instructions.

(Responses must be submitted via iLearn by 12:00 p.m. on Monday., April 2.)

Description: The questions below address material relevant to understanding ocean surface currents. It is based on Reading Assignment #5a.

Questions:

(1) Multiple Choice. Driver of Ocean Surface Currents. What drives ocean surface currents (that is, what gets surface ocean water moving in the first place)? (Pick the one correct answer.)

  1. The rotation of the earth (and the resulting Coriolis effect).
  2. Differential heating of the ocean surface by the sun (greater at low latitudes, less at high latitudes)
  3. Differences in seawater density arising from differences in salinity and temperature.
  4. Surface winds (through frictional drag between moving air and the ocean surface).

(2) Multiple Choice. Large-Scale Ocean Surface Current Patterns. Mostly as a combined result of surface wind drag and the Coriolis effect, what is the large-scale pattern of ocean surface currents at low and middle latitudes? (Pick the one best answer.)

  1. Surface current patterns are the same as surface wind pattern, since winds drive surface ocean currents.
  2. Surface currents move in large, circular patterns (gyres), flowing counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
  3. Surface currents move in large, circular patterns (gyres), flowing clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.
  4. Surface currents circulate around the edges of continents, with little motion in the open ocean between continents.

(3) Multiple Choice. Temperature Changes of Water in Gyres. What happens to the temperature of water as it circulates around gyres? (Pick the one best answer.)

  1. Water warms in the westward-moving portions of gyres in the tropics and cools in the eastward-moving portions at midlatitudes.
  2. Water cools in the westward-moving portions of gyres in the tropics and warms in the eastward-moving portions at midlatitudes.
  3. Water that moves poleward on the western sides of gyres is warmer than polar oceans, while water moving equatorward on the eastern sides is colder than the tropical oceans.
  4. Gyres move warmer water toward the poles and colder water toward the equator, helping to redistribute heat latitudinally.

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