Chasing the Buoys

An ocean current can be defined as:

Any continuous flow of water along a definite path in the ocean. 

The flow may occur where: At the surface or far below it. 

The flow may be: Vertical or parallel to the surface. 

The circulation of these water masses in motion can be categorized as either wind driven or thermohaline. 

Thermohaline currents are: Vertical and are caused by changes in temperature and salinity.  They account for the thorough mixing of the deep masses of ocean water.

Wind driven circulation is set into motion by: moving air masses,

With the motion being confined primarily to: horizontal movement in the upper waters of the oceans. 

Currents carry enormous amounts of warm water away from the equator and currents return equal amounts of cold water. 

Current flow can affect:  temperatures, biotic systems, and climate.

Surface ocean currents are deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, due to the Coriolis effect. 

The Coriolis effect holds that: because the Earth is spinning,

surface waters move in a clockwise direction in the Northern Hemisphere and in a counterclockwise direction in the Southern Hemisphere. 

Surface ocean currents are mainly wind-driven and occur in all of the world's oceans.  Examples of large surface currents that move across vast expanses of ocean are: the Gulf Stream, the North Atlantic Current, the California Current , the Atlantic South Equatorial Current, and the Westwind Drift.

The currents eventually come into contact with the continents which deflect them, creating giant oceanic current circles known as gyres.

These are the major currents that affect the North Pacific Ocean and create the North Pacific gyre.  As with all ocean currents in the Northern Hemisphere, the water is colder on the eastern side and warmer on the west. 

Why is this?

Because the flow is counterclockwise which bring the warm water up from the equator along the west side of the ocean and also brings cold water down from the North along the east side of the oceans. 

There are two important currents off the Oregon coast.

The California current is wide and slow, flowing south year-round about ten miles off shore.

The Davidson current is narrow and fast moving, flowing northward just off-shore.  It is seasonal and is generated by strong winter storms.

Why Scientists Study Currents:

It is important to know the direction and speed of ocean currents as they can influence many natural and man-made ocean conditions:

•           Predicting the direction of oil spills.

•           Aid in marine search and rescues. 

•           Finding fishing locations and studying ocean productivity.

•           Predicting storm tracks.

•           Monitoring possible iceberg locations and early warnings for ships.

What will Drifters tell us

Oceanographers use drifter data to: track major ocean currents and eddies throughout the world. 

Drifter data can be used to: verify data from satellites, such as sea surface temperatures or ocean color. 

Data from drifters can be used to: predict where pollutants, such as oil or sewage, would go if dumped  or accidentally spilled into the sea. 

Scientists also use drifter data to: build models of climate and weather patterns, such as El Niño and La Niña,  and tropical storms and hurricanes. 

Many organisms in the ocean drift along with ocean currents, especially the larvae and juveniles of many marine species.

Latitude and Longitude

A latitude or longitude is similar to an x or y coordinate on a graph or grid, except in this case, the grid overlays the spherical Earth.  Because the Earth is round, we use an angular distance, rather than a straight distance to measure from a point of origin (usually 0,0 on a graph).

Both latitude and longitude are measured in degrees, or portions of a degree.  There are 360 degrees in a circle.  Latitude is measured as the angular distance in degrees north or south of the equator, the north and south pole are located at 90 degrees north and south latitudes respectively.  East - West running circles on a globe, which connect points of equal latitude, are called parallels of latitude.

Longitude: Measured in degrees East or West of the prime meridian.

Lines drawn running North and South

Predicting Currents

Scientists use this information to make predictions as to the direction currents will take depending on the time of year.  One useful result is the ability to forecast the direction an offshore oil spill would take and where emergency efforts would be concentrated.

Emergency Response

When the New Carrissa ran aground on the Oregon shore in  February, 1999, ocean current information was analyzed to predict the path that a potential oil spill would take. 

Ocean Productivity

Another useful tool provided by this data is: a commercial fisherman’s ability to find rich ocean waters in which to fish.  The marine food web thrives best in areas where cold, nutrient rich waters rise to the surface along the coast in a process termed upwelling.  This creates great plankton blooms and many species of fish concentrate in these spots to feed.