Ocean Currents, Circulation, and Atmospheric Forces: Key Concepts for Marine Science

Surface Currents

Wind-driven and primarily characterized by horizontal motion.

Deep Currents (Thermohaline)

Driven by differences in density caused by differences in temperature and salinity. Involve vertical and horizontal motions.

Thermohaline Circulation

Deep ocean circulation driven by temperature and density differences in water. Accounts for 90% of all ocean water.

Origin of Thermohaline Circulation

Originates in high latitude surface ocean; cooled, now dense surface water sinks and changes little.

Four Main Current Types

Equatorial Currents, Western Boundary Currents (warm waters), Northern or Southern Boundary Currents (easterly flow), and Eastern Boundary Currents (cool waters).

Equatorial Currents

Flow westward along the equator; found North or South of the equator.

Western Boundary Currents

Tend to be fast, narrow, and deep. Move warm equatorial surface water to higher latitudes.

Eastern Boundary Currents

Cool waters.

Western Intensification

The phenomenon where currents on the western sides of ocean basins are typically fast, narrow, and deep.

Current Speed (Surface)

Approximately 1/100 of the wind speed measured 10 meters above the sea surface.

Sverdrup (Sv)

Unit for Current Volume transport. $1 Sv = 1,000,000 m^3/S$.

Gyre / Sargasso Sea

A gyre that circulates around the center of the North Atlantic. Known for its unique biology, including Sargassum.

Coriolis Effect

The apparent deflection of moving air relative to Earth's surface. Caused by the variation in Earth's speed of angular rotation with latitude.

Winds on Nonrotating Earth

Air rises in the tropics and sinks at the poles. Air aloft flows toward the poles, and cooled air sinks to flow toward the equator.

Convection Cells

Created by warming and cooling air. There are three Global Circulation Cells.

Main Global Winds

Trade winds, Westerlies, and Polar easterlies.

High Pressure

Characterized by descending air, clear skies, and low precipitation.

Low Pressure

Characterized by ascending air, clouds, and heavy increased precipitation.

North America's NW Coast (Summer)

Experiences northerly winds and coastal upwelling.

North America's NW Coast (Winter)

Experiences southerly winds and coastal downwelling.

Floating Plastics

Tend to photodegrade (break into smaller pieces).

Eastern Pacific Garbage Patch

A region characterized by floating trash.