Water in motion is called a current; the direction toward which it moves is called set and its speed is called drift. Modern shipping speeds have lessened the impact of currents on a typical voyage and since electronic navigation allows continuous adjustment of course, there is less need to estimate current set and drift before setting the course to be steered. Nevertheless, a knowledge of ocean currents can be used in cruise planning to reduce transit times and currents models are an integral part of ship routing systems.
The primary causes of ocean currents are wind and differences in water density caused by variations in the heat and salinity. Currents are also modified by such factors as a depth of water, underwater topography including shape of the basin in which the current is running, extent and location on land and deflection by the rotation of the earth. Below these’re the information of the two types of ocean currents.
Surface Currents
Water on the surface of oceans moves along surface currents. The surface current consist of the first 1,300 feet of water. In total, surface currents contain about 10 percent of the total volume of water in all ocean. Surface currents tend to move in circular patterns and develop into the shape of a mound with a board base and relatively narow top.
These circular currents are found in each ocean and are known as gyres. The gyres are boundary currents, they hug the coastline of continents. Western boundary currents tend to be much stronger than Eastern boundary currents. The impacts of sea currents to the estimation and modelling of wave energy potential over an area of increased economic interest.
The Impact of Ocean Currents is quite significant in wave energy-related modelling, as well as temporally and spatially independent. These facts are revealing the necessity of the utilization of the sea surface characteristics in renewable energy studies.
Deep Water Currents
Deep water currents also called thermohaline circulation are found below 400 meters and make up about 90 percent of the ocean. Like surface currents, gravity plays a role in the creation of deep water currents. Deep water is different from surface water in two distint ways. Depp water is much colder than surface currents and deep water has higher salt continent.
When salty water from a warm region is transported to a region that is cold, it tends to a sink. These deep water sink into the deep ocean basins at high latitudes where the temperatures are cold enough to cause the density to increase.
Oceans currents are influenced by two types of forces namely :
Primary Forces
Primary forces that initiate the movement of water. The primary forces that influence the currents are :
1. Heating by solar energy
Heating by solar energy causes the water to expand. Near the equator the water is about 8 centimeters high than in middle latitudes. This cause a very slight slope and water wants to flow down the slope. There’re the information impact of solar energy. Solar energy refers to energy from the sun. The sun has produced energy for billions of years. It is the most important source of energy for life forms. It is renewable source of energy unlike non-renewable sources such as fossil fuels.
Solar energy is being recognized as the future of alternative energy sources as it is non-polluting and helps combat the Greenhouse effect on global climate created by use of fossils fuels. The fact, the water cycle is an important result of solar insulation. The earth, oceans and atmosphere absorb solar radiation and their temperature rises. Warm air rises from the oceans causing convection. When this air rises to high latitudes, clouds are created by condensation of water vapor. These clouds cause rains that bring water back to the earth surface.
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2. Winds
Winds blowing on the surface of the ocean push the water. Usually winds drive currents that are at or near the ocean’s surface. Near coastal areas winds tend to drive currents on localized scale and can result in phenomena like coastal up-welling. Winds are responsible for both magnitude and direction of the ocean currents. Example; Monsoon winds is seasonal change in the direction of the prevailing or strongest, winds of a region. Monsoons cause wet and dry seasons throughout much of the tropics.
Moonsons are most often associated with the Indian ocean. Monsoons divide into two seasons. They are Summer Monsoon and Winter Monsoon. The Summer Monsoon and Winter Monsoon determine of the climate for most India and South-east Asia, as follows:
- Summer Monsoon
Summer Monsoon usually happens between April and September. It’s associated with heavy rainfall. The summer monsoon brings a humid climate and torrential rainfall to India and Southeast Asia areas. Industry in India and Southeast Asia relies in the summer monsoon. An electricity in the region is produced by hydroelectric power plants, which are driven by water collected during the monsoons. Electricity powers hospitals, schools and businesses that help the economies of these areas develop.
- Winter Monsoon
The winter Monsoon begin which lasts from October to April. These winds start in the air above Mongolia and northwestern China. Winter monsoons are less powerful than summer monsoons in Southeast Asia, because the Himalaya Mountains prevent much of the wind and moisture of the monsoons from reaching the coast. The Himalayas also prevent much of the cool air from reaching places like southern India and Sri Lanka, keeping them warm all year. The winter monsoon brings most air from the South China Sea to areas like Indonesia and Malaysia.
3. Gravity
Gravity is one of the forces which established the direction of the ocean currents. Gravity pulls water down the slope created by solar heating. The coriolis also plays a part directing ocean currents. Its effect on gravity creates the geostrophic current, which directs water to the right in the northern hemisphere and to the lest in the southern hemisphere.Surface currents are also triggered by gravity.
The top of the sea is not flat but has broad hills and valleys. Where currents converge or run into a continent, water piles up. The major ocean gyres circle around a low mound a meter or so high.
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4. Coriolis Force
The corialis force is defined as the apparent deflection of objects (airplanes,winds,missiles and ocean currents) moving un straight path relative to the earth’s surface. Its strength is proportional to the speed of the earth’s rotation at different latitudes but it has an impact on moving objects across the globe.
Some of the most important impacts of the Coriolis effect in terms of geography are the deflection of winds and currents in the ocean. In terms of affecting the wind, as air rises off of the earth’s surface, its speed over the surface increases because there’s less drag as the air no longer has to move across the earth’s many types of land-forms. Because the Coriolis effect increases with an item’s increasing speed, it significantly deflects air flows and as a result the wind.
One of the most significant impacts of the Coriolis effect is a result of its deflecting planes and missiles. Take for an example a flight leaving from San Fransisco, California that is heading to New York city. If the earth did not rotate, there would be no Coriolist effect and thus the pilot could fly in a straight path to the east. However, due to Coriolis effect, the pilot has to constantly correct for the earth’s movement beneath plane.
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Secondary Forces
Secondary forces that influence the currents to flow. The primary forces that influence the currents are :
5. Temperature difference
Temperature and density share an inverse relationship. As temperature increases, the space between water molecules increases also known as density, which therefore decreases. The process driven by density differences in water due to temperature and salinity also known as Thermohaline circulation. It has variation in different parts of the ocean. Currents driven by thermohaline circulation occur at both deep and shallow ocean levels and move much slower than tidal or surface currents.
Thermohaline circulation drives a global scale system of currents called the “Global Conveyor Belt”. It begins on the surface of the ocean near the pole in the North Atlantic. Here, the water is chilled by artic temperatures. It also gets saltier because when sea ice forms, the salt does not freeze and is left behind in the surrounding water. The conveyor belt is also a vital component of the global ocean nutrient and carbon dioxide cycles.
Warm surface waters are depleted of nutrients and carbon dioxide, but they are enriched again as they travel through the conveyor belt as deep or bottom layers. The base of the world’s food chain depends on the cool, nutrient-rich waters that support the growth of algae and seaweed.
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6. Salinaty Difference
Salinaty and density share a positive relationship. As density increases, the amount of salts in the water also known as salinaty increase. Various events can contribute to change in the density of seawater. When the water molecules of the ocean become heated, they can hold more salt and other molecules than cold water. The impact of ocean currents, when the salinaty is high enough, the water will sink, and starting a convection current. The salt and other minerals that are in the ocean water and which affect ocean currents come from several places.
In the salinaty, some biotic groups are more tolerant of salinaty than others. Communities of adult fish and macro-invertebrates appear to tolerate increasing salinaty because they either comprise salt tolerant remnants left after salt-sensitive species have been eliminated or reflect an evolution from marine ancestor.
The conclusion about the impact of ocean currents, there are few impacts that we found above the information. That the impact can be benefits for daily life also ocean life but some impact cases would be disasters. Then, below here the 6 major benefit impacts of ocean currents refer above information:
- Fisheries
The benefits of ocean currents are widely used in the field of fisheries by fisherman who will go to sea and catch the fishes. The movements of ocean currents is usually directly to the presence of plankton. Where that there are many of plankton there will be many fishes. So, that the fisherman will brought many fishes home.
- Agriculture
Specially in agriculture, farmers who make the sea as a cultivation such as seaweed and shellfish are very important for farmers to determine the tidal water. Because the cultivation could wash away by the ocean currents. So, in here farmers must be on guard.
- Tourism
Ocean currents could be benefits for tourism, it’s to determine a suitable place in tourist destination. Many people do tours to see places that can do diving, surfing, speed boot and other sea sports. So, the ocean currents in the field of tourism useful to attract the attention of visitors.
- Sailing
The captain surely will learn the ocean currents first while sailing. Because the captain surely did not want the journey crashed with the waves and ocean currents. That’s named of good captain.
- Energy
Ocean currents are also useful in the energy field. Overseas sea currents are used for energy sources. As in the Netherlands utilizing ocean currents as power electricity. The benefits are very helpful for humans to simplify in everyday life.
- Climate
In the field of climate, ocean currents are also useful in the field of climate. Ocean currents also affect the climate in a country such as Japan and the European plains affected by the ocean currents. That ocean currents also known as Kurosyiwo currents it caused the temperature of South of Japan and West coastal Canada in winter, has cold temperature.
The spread of ocean currents is scattered throughout the world and occurs in various oceanic depths. Ocean currents spread in the Pacific Ocean, Atlantic Ocean and Indian Ocean. As for several factors that need to know the ocean currents, namely wind, sea water density, salinity, tides and temperature. These factors are related so they can’t be separated.