Surface oceanic currents are driven by wind currents, the large scale prevailing winds drive major persistent ocean currents, and seasonal or occasional winds drive currents of similar persistence to the winds that drive them, and the Coriolis effect plays a major role in their development. Surface currents are measued in units of meters per second (m/s) or in knots. Because the movement of deep water in ocean basins is caused by density-driven forces and gravity, deep waters sink into deep ocean basins at high latitudes where the temperatures are cold enough to cause the density to increase. Surface ocean currents (in contrast to subsurface ocean currents), make up only 8% of all water in the ocean, are generally restricted to the upper 400 m (1,300 ft) of ocean water, and are separated from lower regions by varying temperatures and salinity which affect the density of the water, which in turn, defines each oceanic region. ![]() Ocean currents are measured in units of sverdrup (sv), where 1 sv is equivalent to a volume flow rate of 1,000,000 m 3 (35,000,000 cu ft) per second. ![]() Ocean temperature and motion fields can be separated into three distinct layers: mixed (surface) layer, upper ocean (above the thermocline), and deep ocean. Ocean dynamics define and describe the motion of water within the oceans. The two basic types of currents – surface and deep-water currents – help define the character and flow of ocean waters across the planet.Ĭauses The bathymetry of the Kerguelen Plateau in the Southern Ocean governs the course of the Kerguelen deep western boundary current, part of the global network of ocean currents. They are primarily driven by winds and by seawater density, although many other factors – including the shape and configuration of the ocean basin they flow through – influence them. Ocean currents are patterns of water movement that influence climate zones and weather patterns around the world. Another example is Lima, Peru, whose cooler subtropical climate contrasts with that of its surrounding tropical latitudes because of the Humboldt Current. Perhaps the most striking example is the Gulf Stream, which, together with its extension the North Atlantic Drift, makes northwest Europe much more temperate for its high latitude than other areas at the same latitude. For example, warm currents traveling along more temperate coasts increase the temperature of the area by warming the sea breezes that blow over them. More specifically, ocean currents influence the temperature of the regions through which they travel. Ocean currents are primarily horizontal water movements.Īn ocean current flows for great distances and together they create the global conveyor belt, which plays a dominant role in determining the climate of many of Earth's regions. Depth contours, shoreline configurations, and interactions with other currents influence a current's direction and strength. Visualization showing global ocean currents from January 1, 2010, to December 31, 2012, at sea level, then at 2,000 m (6,600 ft) below sea level Animation of circulation around ice shelves of AntarcticaĪn ocean current is a continuous, directed movement of seawater generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Ocean surface currents Distinctive white lines trace the flow of surface currents around the world. JSTOR ( January 2014) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. extension ideas/prompting questions for teachers.This article needs additional citations for verification.offer simple explanations of how climate change may impact the oceans’ chemical and physical properties.ĭownload the Word file (see link below) for:.describe how salinity affects water density.describe how temperature affects water density.Learn more in the article Climate change, melting ice and sea level rise.īy the end of this activity, students should be able to: Melting land ice and increased rainfall – as consequences of climate change – have the potential to disrupt the oceans’ chemical and physical properties, which will impact this complex circulation system. Both types of currents work with the atmosphere to help shape the Earth’s climate. Deeper currents are driven by changes in water density. Surface currents in the top 400 m are driven mainly by wind. ![]() It moves water, heat, salt and nutrients around the world. The ocean has a complex circulation system called the Global Ocean Conveyor.
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