where does downwelling occur


Where Does Downwelling Occur?

Downwelling occurs when the water on the surface of the sea becomes denser than the water beneath it and so it sinks. Seawater gets denser when it gets colder or saltier. Where does most downwelling occur? Most downwelling happens at the poles.

Where does upwelling and downwelling occur?

Upwelling occurs in the open ocean and along coastlines. The reverse process, called downwelling, also occurs when wind causes surface water to build up along a coastline.

What causes downwelling on continental shelves?

The reverse process, called “downwelling,” also occurs when wind causes surface water to build up along a coastline and the surface water eventually sinks toward the bottom. … These nutrients “fertilize” surface waters, meaning that these surface waters often have high biological productivity.

Where does upwelling mainly occur?

Upwelling is most common along the west coast of continents (eastern sides of ocean basins). In the Northern Hemisphere, upwelling occurs along west coasts (e.g., coasts of California, Northwest Africa) when winds blow from the north (causing Ekman transport of surface water away from the shore).

How does coastal downwelling occur?

Downwelling occurs when surface waters converge (come together), pushing the surface water downwards. … In these coastal upwelling regions, surface winds push water away from the shore and create a divergence at the coast, which is replaced by water from depth.

Which region would you expect to find downwelling occurring?

Locations. Downwelling occurs in areas such as in the subpolar gyre of the North Atlantic where several surface currents meet, where cold waters meet warmer waters, such as along the outermost boundary of the Southern Ocean where cold Antarctic water sinks below warmer South Pacific and South Atlantic waters.

What is downwelling caused by?

What causes downwelling? Downwelling occurs when the water on the surface of the sea becomes denser than the water beneath it and so it sinks. Seawater gets denser when it gets colder or saltier. … And once it gets to high latitudes, the water becomes even more saline as ice forms and further concentrates sea salts.

Where around Antarctica does downwelling occur?

Surface water can be forced downward by the pressure of the pile of water that forms where currents converge or wind drives the sea against a coastline. But for bottom dwellers, the sinking of water caused by density changes is especially noteworthy.

How does downwelling affect productivity?

Downwelling is where surface water is forced downwards, where it may deliver oxygen to deeper water. Downwelling leads to reduced productivity, as it extends the depth of the nutrient-limited layer. … As the surface waters diverge, deeper water must be brought to the surface to replace it, creating upwelling zones.

What is the meaning of downwelling?

a downward current of surface water in the ocean, usually caused by differences in the density of seawater.

What is the global conveyor belt?

The global conveyor belt is a system of ocean currents that transport water around the world. While wind primarily propels surface currents, deep currents are driven by differences in water densities in a process called thermohaline circulation.

Where are the trade winds?

The trade winds can be found about 30 degrees north and south of the equator. Right at the equator there is almost no wind at all—an area sometimes called the doldrums.

What causes upwelling at the equator?

Upwelling is a result of winds and the rotation of the Earth. The Earth rotates on its axis from west to east. … The Coriolis effect also causes upwelling in the open ocean near the Equator. Trade winds at the Equator blow surface water both north and south, allowing upwelling of deeper water.

What causes downwelling quizlet?

What does downwelling cause? Causes water to be forced down. … Surface water is transported off-shore and replaced by deeper water, that moves inshore and is upwelled. Reverse occurs when the wind is oriented in the opposite direction.

What causes density?

Some density currents occur because they contain higher amounts of suspended sediments than the surrounding water. Such density currents, called turbidity currents, are believed to form when the accumulation of sediments on continental shelves becomes unstable as a result of an underwater landslide or earthquake.

Does El Nino cause downwelling?

Upwelling: the transport of deeper water to shallow levels. One oceanic process altered during an El Niño year is upwelling, which is the rising of deeper colder water to shallower depths.

Is the Pacific West coast currently experiencing upwelling?

The California current is the eastern boundary current of the North Pacific Gyre, running southward from British Columbia, Canada to Baja California, Mexico. This current draws cool, nutrient rich waters from the Alaska current down along the western coast of North America.

Why does the West coast of South Africa have high biological productivity?

Why does the west coast of South Africa have high biological productivity? … Surface waters move northward, causing a strong coastal current. Surface waters move onshore.

What are the two major sources of cold ocean water in the global conveyor belt?

This motion is caused by a combination of thermohaline currents (thermo = temperature; haline = salinity) in the deep ocean and wind-driven currents on the surface. Cold, salty water is dense and sinks to the bottom of the ocean while warm water is less dense and remains on the surface.

What is the role of the thermohaline circulation?

Thermohaline circulation plays an important role in supplying heat to the polar regions. Therefore, it influences the rate of sea ice formation near the poles, which in turn affects other aspects of the climate system (such as the albedo, and thus solar heating, at high latitudes).

How do upwelling and downwelling affect ocean life?

Currents also are a major factor in ocean ecosystems. Two types of current motion, upwelling and downwelling, strongly influence the distribution and abundance of marine life. … When currents upwell, or flow up to the surface from beneath, they sweep vital nutrients back to where they’re needed most.

How are density currents formed?

When waters of two different densities meet, the dense water will slide below the less dense water. The differing densities cause water to move relative to one-another, forming a density current. This is one of the primary mechanisms by which ocean currents are formed.

Does upwelling or downwelling happen around Antarctica?

The upwelling of deep waters in the Southern Ocean is a critical component of the climate system. The time and zonal mean dynamics of this circulation describe the upwelling of Circumpolar Deep Water and the downwelling of Antarctic Intermediate Water.

What is the thermohaline conveyor?

thermohaline circulation, also called Global Ocean Conveyor or Great Ocean Conveyor Belt, the component of general oceanic circulation controlled by horizontal differences in temperature and salinity. … The general circulation of the oceans consists primarily of wind-driven ocean currents.

What is equatorial divergence?

The divergent flows of near-surface water create a parting along the equator, like one combed on the head. … The consequent upwelling from depths where temperatures are low produces a line of cooler sea surface at the equator.

Where does deep bottom water come from?

Deep waters are “formed” where the air temperatures are cold and where the salinity of the surface waters are relatively high. The combinations of salinity and cold temperatures make the water denser and cause it to sink to the bottom. Places where the water is cold enough and salty enough to form bottom water.

How does thermohaline circulation differ from surface wind driven circulation?

thermohaline circulation

Wind-driven circulation, which is strongest in the surface layer of the ocean, is the more vigorous of the two and is configured as large gyres that dominate an ocean region. In contrast, thermohaline circulation is much slower, with a typical speed of 1 centimetre (0.4…

What causes the Ekman spiral?

The Ekman spiral, named after Swedish scientist Vagn Walfrid Ekman (1874-1954) who first theorized it in 1902, is a consequence of the Coriolis effect. … As a result, each successively deeper layer of water moves more slowly to the right or left, creating a spiral effect.

What is downwelling radiation?

Downwelling short-wave radiation at the surface has a component due to the direct solar beam, and a diffuse component scattered from atmospheric constituents and reflected from clouds. Upwelling short-wave radiation comes from reflection at the surface.

How are gyres formed?

An ocean gyre is a large system of circular ocean currents formed by global wind patterns and forces created by Earth’s rotation. The movement of the world’s major ocean gyres helps drive the “ocean conveyor belt.” The ocean conveyor belt circulates ocean water around the entire planet.

How many oceans do we have?

Historically, there are four named oceans: the Atlantic, Pacific, Indian, and Arctic. However, most countries – including the United States – now recognize the Southern (Antarctic) as the fifth ocean. The Pacific, Atlantic, and Indian are the most commonly known. The Southern Ocean is the ‘newest’ named ocean.

Does ocean water move?

Ocean water is constantly moving, and not only in the form of waves and tides. Ocean currents flow like vast rivers, sweeping along predictable paths. Some ocean currents flow at the surface; others flow deep within water. … Ocean currents are also critically important to sea life.

How is the ocean floor like a giant conveyor belt?

In sea-floor spreading, the sea floor spreads apart along both sides of a mid-ocean ridge as new crust is added. As a result, the ocean floors move like conveyor belts, carrying the continents along with them.

What would happen if the ocean conveyor belt stopped?

The ocean currents carry warmth from the tropics up to these places, which would no longer happen. If the currents were to stop completely, the average temperature of Europe would cool 5 to 10 degrees Celsius. There would also be impacts on fisheries and hurricanes in the region.

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