A coastal upwelling and downwellings occurs when the wind blows offshore ore parallel to shore. Sometimes they occur when offshore wind creates a current that pushes the surface water out to sea.
What causes upwelling and downwelling?
In winter, winds blow from the south to the north, resulting in downwelling. During the summer, winds blow from the north to the south, and water moves offshore, resulting in upwelling along the coast.
What causes upwelling and where does it occur?
Upwelling is a process in which currents bring deep, cold water to the surface of the ocean. Upwelling is a result of winds and the rotation of the Earth. The Earth rotates on its axis from west to east. Because of this rotation, winds tend to veer right in the northern hemisphere and left in the southern hemisphere.
What is the cause of upwellings?
Upwelling is an oceanic process in which cold water from the deep rises toward the surface of the ocean. It is caused by strong winds and the rotation of the Earth which moves warmer surface waters offshore allowing the cold, nutrient rich water to rush up.
What is the main of cause of downwelling?
Question. 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.
22 related questions foundWhere do Downwellings occur?
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.
How does Ekman cause downwelling?
Coastal upwelling occurs where Ekman transport moves surface waters away from the coast; surface waters are replaced by water that wells up from below. Where Ekman transport moves surface waters toward the coast, the water piles up and sinks in the process known as downwelling.
Where does deep upwelling usually occur?
Where does deep upwelling usually occur? In the middle of the oceans.
Why is the Somali current unusual?
Upwelling behavior: One of the unique characteristics of the Somali Current is the presence of strong coastal upwelling - the only major instance of this happening at a western ocean boundary.
What are surface currents caused by?
Surface currents in the ocean are driven by global wind systems that are fueled by energy from the sun. Patterns of surface currents are determined by wind direction, Coriolis forces from the Earth's rotation, and the position of landforms that interact with the currents.
What causes upwelling at the equator?
Upwelling at the Equator
Equatorial upwelling is again due to the Coriolis force, acting on the sides of equatorial currents, that pulls the water in different directions in the two hemispheres.
How do upwellings affect productivity and food chains?
The upward movement of this deep, colder water is called upwelling. The deeper water that rises to the surface during upwelling is rich in nutrients. These nutrients “fertilize” surface waters, encouraging the growth of plant life, including phytoplankton.
What causes Western intensification quizlet?
Western intensification causes: -Steeper slope of surface water in the section of the gyre as compared to the eastern section of the gyre. -Very swift western boundary currents. -A large volume of water within western boundary currents.
Where do areas of divergence and upwelling occur?
In the equatorial Pacific, the trade winds blow the North and South Equatorial Currents towards the west, while Ekman transport causes the upper layers to move to the north and south in their respective hemispheres. This creates a divergence zone, and a region of upwelling and high productivity (Figure 9.5.
What causes downwelling quizlet?
Winds blowing from the north cause upwelling along the continents' eastern coasts in the Southern Hemisphere. Upwelling and downwelling also occur in the open ocean where winds cause surface waters to diverge (move away) from a region (causing upwelling) or to converge toward some region (causing downwelling).
How are most coastal currents formed?
Currents arise in the coastal ocean from the flow of freshwater out of rivers and estuaries. Currents result from both the difference in the height of the water between the river and the ocean and from the density difference between the fresh water and the salty ocean water.
Is the Somali Current warm or cold?
Quick Reference. A current in the northern Indian Ocean that reverses direction during the year. In the northern winter season, it is a warm current that is fed by an anticlockwise circulation in the Arabian Gulf and flows south-westwards along the coast of Somalia.
What Mascarene High?
The Mascarene High is an anticyclone located over the Southern Indian Ocean and has a vital role in weather and climate variability over Southern Africa. The warm Western Indian Ocean is a major source of moisture for the subcontinent also permitting tropical cyclone genesis.
What is Somali jet stream?
A low-level southwesterly jet over the Arabian Sea in the summer months, off the coast of Somalia. It is the northern branch of a cross-equatorial flow, giving rise to a major supply of moisture in support of the Asian summer monsoon.
Where are seamounts located?
Seamounts are commonly found near the boundaries of Earth's tectonic plates and mid-plate near hotspots. At mid-ocean ridges, plates are spreading apart and magma rises to fill the gaps.
What causes deep ocean currents?
These deep-ocean currents are driven by differences in the water's density, which is controlled by temperature (thermo) and salinity (haline). This process is known as thermohaline circulation. In the Earth's polar regions ocean water gets very cold, forming sea ice.
How do upwellings affect life in the oceans?
Upwelling brings those lost/sunk nutrients back to the surface, which creates "blooms" of algae and zooplankton, which feed on those nutrients. These blooms then become feeding grounds for plankton feeders, then fish, etc, sustaining ocean life that lives near the surface.
Where does Ekman divergence occur?
In the northern hemisphere, Ekman divergence occurs when the wind blows parallel to a coastline on its left. For example, during spring and summer the mean winds along the west coast of North America are southward. Associated with these winds is a net westward Ekman transport.
Where does Ekman transport occur?
This phenomenon would later become known as Ekman transport. As wind blows across the ocean, it moves water because of friction at the ocean surface.
Where does the Ekman spiral occur?
In the ocean, there are two places where the Ekman spiral can be observed. At the surface of the ocean, where the shear stress force needed corresponds with the wind stress force and at the bottom of the ocean, where the shear stress force is created by friction with the ocean floor.
