Major Ocean Currents and Their Effects

An Ocean Current is a large volume of water flowing in a certain direction. Both Vertical and horizontal movement of both surface and deep water masses happen in the world’s oceans. Currents are caused by wind, the Earth's rotation, and differences in water density within oceans. Currents are large-scale water movements occurring everywhere in the world. They normally move in certain specific directions. It is due to this circulation the atmospheric moisture is replenished in the atmosphere of Earth. Because ocean currents circulate water worldwide, they have a significant impact on the movement of energy and moisture between the oceans and the atmosphere. As a result, they are important to the world’s weather.

Today, ocean currents are also gaining importance due to the possibility of harnessing alternative energy sources. Because the ocean water is dense, it carries enormous amount of energy that could possibly be captured and converted into a usable form through the use of turbine generators.

Major Ocean Currents

Warm and Cold Currents

Those currents which flow from equatorial regions towards poles which have a higher surface temperature and are called warm current. They bring warm waters to the cold regions. (Warm water less dense) Solar energy strikes the oceans at the equator directly and therefore more intensely, heating the water. Those currents which flow from polar regions towards equator have a lower surface temperature and are called cold currents. They bring cold waters into warm areas. (Cold water more dense)

Major ocean currents Currents are of two general categories as surface water currents and deep water currents. There are several factors and processes involved in the generation and movement of these two kinds of ocean currents.

Surface Currents

A surface current is an ocean current that moves along the top part of an ocean. Surface currents are moved by prevailing winds and follow global wind patterns. Prevailing winds are winds that blow in regular directions almost all the time. Surface currents extend to about 400 m below the surface, and they move as fast as 100 km/day. These winds and surface currents move in circular patterns in ocean basins. Surface currents affect water to a depth of several hundred meters. Surface currents can be cold or warm. Those that flow from the poles toward the equator are cold. Those that flow from the equator towards the poles are warm.

Coriolis effect

The effect of Earth’s rotation on the direction of winds and currents. It causes winds and currents to move in a curved path.

The Coriolis Effect is the movement of wind and water to the right or left that is caused by Earth’s rotation.

It causes air and water to curve to the right in the Northern hemisphere, in a clockwise direction and also air and water to curve to the left in the southern hemisphere, in a counterclockwise direction. Currents form small or large loops and move at different speeds, depending on the land masses they contact.

How Surface Currents Affect Climate

A surface current warms or cools the air above it, influencing the climate of the land near the coast or around the globe. Climate is the pattern of temperature and precipitation typical of an area over a long period of time. Example: The Gulf Stream is a warm-water current that affects coastal areas of the southwestern United States by transferring lots of thermal energy and moisture to the surrounding air.

The California current is a surface current that carries cold water from the North Pole, southward along California’s coast. This current causes the climate in California to be cooler than it would be without the current.

What are deep ocean currents? Deep currents are caused by differences in density rather than surface winds. Density depends on temperature and salinity. The more salty and cold ocean water is the denser it is. More dense water drops to the bottom of the ocean and separates from less dense water, and that movement creates a current Cold waters at the bottom of the ocean creep slowly across the ocean floor. Deep currents move and mix water around the world. They move much slower than surface currents. Density currents circulate thermal energy, nutrients and gases.

Upwelling

Upwelling is the upward movement of cold water from the ocean depths. As wind blows away the warm surface water, cold water rises to replace it. Upwelling often occurs along coastlines. Upwelling brings up tiny ocean organisms, minerals, and other nutrients from the deeper layers of the water.

Example: Great Ocean Conveyor Belt

The Great Ocean conveyor Belt is the name for a model of the large system of ocean currents that affects weather and climate by circulating thermal energy around Earth. In this model, high salinity water cools and sinks in the North Atlantic, and deep water returns to the surface in the Indian and Pacific Oceans through upwelling Scientists estimate that the Great Ocean Conveyor Belt model takes about 1,000 years to complete a cycle.

Climate Effect

Wind pattern significantly affect climate. Examples El Niño- an abnormal climate event that occurs every 2 to 7 years in the Pacific Ocean. This causes a sheet of warm water to move eastward toward the South American coast. El Niño can last for one to two years before the usual winds and currents return.

This damage in Southern California was the result of excessive rain caused by El Niño in 1997

Other Oceanic Currents 1. Tidal Currents: generated by tides. caused by flooding of water,flowing from one location to another. the flow speed of these tidal currents is small (typically less than 0.5 m/s). flow closer to the coasts. differ from the regular oceanic currents in that they don't flow as a continuous stream. also switch directions every time when there is tide transitions between the high tide and the low tide.

2. Gyres Gyres are yet another types of currents in the oceans. These are "circular", large-scale, ocean flow patterns. They result from wind forcing, buoyancy forcing, and the Coriolis acceleration.

3. Rip Currents Rip Currents are currents seen closer to the beaches when the waves tend to carry water towards the coasts. People trying to bath in this zone will be caught by a rip current. They will be rapidly carried away from the coasts. They should not try to swim back toward the beach, because the current will be too strong.

Effects of Ocean Current

Ocean currents are very important for human beings. Climate and Trade or Economy both are deeply affected by ocean currents. Major influences made by ocean currents are:

Effects on Climate Modification of Temperature Modification of Rainfall Formation of Fog Formation of thunderous cyclones

Effects on Trade & Economy On Port’s Trade Fish Trade Trade of Perishable Goods Fishing Banks Currents are also important for marine life because they transport creatures around the world and affect the water temperature in marine ecosystems. Currents play an important role in the navigation of ships. Knowledge of ocean currents is essential to carry out the movement of ships, reduction in their shipping costs and fuel consumption.