Thermohaline circulation - Revision history

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	<onlyinclude>'''Thermohaline circulation''' describes the movement of [[ocean]] currents due to differences in [[temperature]] and [[salinity]] ~~among~~ regions ~~in the~~ [[water]].</onlyinclude> Temperature and salinity change the [[density]] of water, resulting in the water to move accordingly.		[[Category: Rudi grade Ashley edit]]
			<onlyinclude>'''Thermohaline circulation''' describes the movement of [[ocean]] currents due to differences in [[temperature]] and [[salinity]] in different regions of [[water]].</onlyinclude> Temperature and salinity change the [[density]] of water, resulting in the water to move accordingly.

	Cold water is usually denser than warm water (~~down to~~ 4°C where water is densest). ~~Similarly, water~~ with a high salinity is denser than ~~water that is~~ less saline.<ref name="RE1">"Ocean on the Move: Thermohaline Circulation \| UCAR Center for Science Education", The National Center for Atmospheric Research, 2016. [Online]. Available: http://scied.ucar.edu/ocean-move-thermohaline-circulation. [Accessed: 17- May- 2016].</ref> Deep ocean currents are driven by differences in the water density, which is controlled by [[temperature]] ('''thermo''') and salinity ('''haline'''). ~~Hence the~~ process is ~~known as thermohaline circulation, often known~~ as the ocean's ~~conveyer~~ belt. <ref name="RE2">Thermohaline Circulation - Currents: NOAA's National Ocean Service Education", Oceanservice.noaa.gov, 2016. [Online]. Available: http://oceanservice.noaa.gov/education/tutorial_currents/05conveyor1.html. [Accessed: 17- May- 2016].</ref>		Cold water is usually denser than warm water (4°C is where water is densest). Water with a high salinity is also denser than less saline water.<ref name="RE1">"Ocean on the Move: Thermohaline Circulation \| UCAR Center for Science Education", The National Center for Atmospheric Research, 2016. [Online]. Available: http://scied.ucar.edu/ocean-move-thermohaline-circulation. [Accessed: 17- May- 2016].</ref> Deep ocean currents are driven by differences in the water density, which is controlled by [[temperature]] ('''thermo''') and salinity ('''haline'''), hence the name "thermohaline circulation". This process is also sometimes to referred to as the "ocean's conveyor belt system".<ref name="RE2">Thermohaline Circulation - Currents: NOAA's National Ocean Service Education", Oceanservice.noaa.gov, 2016. [Online]. Available: http://oceanservice.noaa.gov/education/tutorial_currents/05conveyor1.html. [Accessed: 17- May- 2016].</ref> See figure 1 to see how this conveyor belt moves around the world.

	Any change to ocean circulation could have damaging effects on the [[hydrologic cycle\|water cycle]] and [[weather]] patterns.<ref name="RE3">”All About Sea Ice \| Environment : Climate \| National Snow and Ice Data Center", National Snow & Ice Data Center, 2016. [Online]. Available: http://nsidc.org/cryosphere/seaice/environment/global_climate.html. [Accessed: 08- May- 2016].</ref>		Any major change to ocean circulation could have damaging effects on the [[hydrologic cycle\|water cycle]] and [[weather]] patterns.<ref name="RE3">”All About Sea Ice \| Environment : Climate \| National Snow and Ice Data Center", National Snow & Ice Data Center, 2016. [Online]. Available: http://nsidc.org/cryosphere/seaice/environment/global_climate.html. [Accessed: 08- May- 2016].</ref>

			[[File:Ocean_circulation_conveyor_belt.jpg\|800px\|thumb\|center\|Figure 1. The Thermohaline Circulation Loop.<ref>"Ocean circulation conveyor belt", Commons.wikimedia.org, 2007. [Online]. Available: https://commons.wikimedia.org/wiki/File:Ocean_circulation_conveyor_belt.jpg. [Accessed: 19- May- 2016].</ref> This loop moves water and heat around the globe and is referred to as the "ocean's conveyor belt system".<ref name="RE2"/>.]]

	==Factors influencing circulation==		==Factors influencing circulation==
	===Ice===		===Ice===
	Thermohaline circulation plays an important role in supplying heat to the polar regions. ~~Hence, it~~ influences the rate of sea ice formation near the poles, which impacts other aspects of the climate system (such as the [[albedo]]).<ref name=RE1/>		Thermohaline circulation plays an important role in supplying heat to the polar regions. It influences the rate of sea ice formation near the poles, which impacts other aspects of the climate system (such as the [[albedo]]).<ref name=RE1/>

	~~The formation of sea~~ ice~~, which~~ is mainly ~~comprised of pure~~ water~~, leaves behind~~ salt in the ~~water~~ beneath the ice, ~~resulting in higher salinity~~ and ~~colder~~ water ~~that~~ sinks ~~through the water below it~~, promoting circulation.<ref name=RE1/> When ice melts, it adds fresh water to the ocean, decreasing salinity and affecting the circulation pattern. In certain areas near the polar oceans, the colder surface water also gets more saline due to [[evaporation]] ~~or sea ice formation~~.<ref name="RE4">"The Thermohaline Circulation - The Great Ocean Conveyor Belt \| Precipitation Education", Pmm.nasa.gov, 2016. [Online]. Available: http://pmm.nasa.gov/education/videos/thermohaline-circulation-great-ocean-conveyor-belt. [Accessed: 15- May- 2016].</ref>		Sea ice is mainly formed from non- to slightly saline water. This means that the salt in ocean water is expelled back into the ocean as a salty layer beneath the ice. The ice also cools the salty layer, which means it is now highly saline and cold, making it very dense. The dense water layer sinks, promoting circulation.<ref name=RE1/> When ice melts, it adds fresh water to the ocean, decreasing salinity and affecting the circulation pattern. In certain areas near the polar oceans, the colder surface water also gets more saline due to [[evaporation]].<ref name="RE4">"The Thermohaline Circulation - The Great Ocean Conveyor Belt \| Precipitation Education", Pmm.nasa.gov, 2016. [Online]. Available: http://pmm.nasa.gov/education/videos/thermohaline-circulation-great-ocean-conveyor-belt. [Accessed: 15- May- 2016].</ref>

	===Wind===		===Wind===
	The movement of the surface layer of the ocean is driven mostly by [[wind]] currents. As the surface water ~~gets pumped~~ into the deep ocean, it forces the deep water to move horizontally until it can find a region on the globe where it can rise back to the surface and complete its ~~current~~ loop. This usually occurs in ~~the~~ equatorial ~~ocean~~, typically in the Pacific and Indian Oceans.<ref name=RE4/> The North Atlantic Ocean around Greenland, Iceland, and the North Sea are major regions where surface water pumping occurs.<ref name=RE4/>		The movement of the surface layer of the ocean is driven mostly by [[wind]] currents. As the surface water sinks into the deep ocean, it forces the deep water to move horizontally until it can find a region on the globe where it can rise back to the surface and complete its circulation loop. This usually occurs in equatorial regions of oceans, typically in the Pacific and Indian Oceans.<ref name=RE4/> The North Atlantic Ocean around Greenland, Iceland, and the North Sea are major regions where surface water pumping occurs.<ref name=RE4/>

	The surface ocean current brings new water into the ~~region~~ from the South Atlantic ~~from~~ the Gulf Stream and the water returns to the South Atlantic ~~from~~ the North Atlantic Deep Water current. The constant influx of warm water into the North Atlantic polar ocean keeps the regions around Iceland and southern Greenland mostly free of sea ice year round.<ref name=RE4/> Both surface and deep waters flow from west to east around Antarctica. This ‘circumpolar’ motion links the world's oceans and allows the deep water circulation from the Atlantic to rise in the Indian and Pacific Oceans and the surface circulation to close with the northern flow in the Atlantic.<ref name=RE4/>		The surface ocean current brings new water into the northern regions from the South Atlantic by way of the Gulf Stream and the water returns to the South Atlantic using the North Atlantic Deep Water current. The constant influx of warm water into the North Atlantic polar ocean keeps the regions around Iceland and southern Greenland mostly free of sea ice year round.<ref name=RE4/> Both surface and deep waters flow from west to east around Antarctica. This ‘circumpolar’ motion links the world's oceans and allows the deep water circulation from the Atlantic to rise in the Indian and Pacific Oceans and the surface circulation to close with the northern flow in the Atlantic.<ref name=RE4/>

	==Thermohaline Loop==		==Thermohaline Loop==

	[[File:Ocean_circulation_conveyor_belt.jpg\|400px\|thumb\|right\|Figure 1. The Thermohaline Circulation Loop.<ref>"Ocean circulation conveyor belt", Commons.wikimedia.org, 2007. [Online]. Available: https://commons.wikimedia.org/wiki/File:Ocean_circulation_conveyor_belt.jpg. [Accessed: 19- May- 2016].</ref>]]

	The thermohaline circulation loop is quite complex. The Bering Straight inhibits deep currents from flowing out of the [[Arctic sea ice \| Arctic]] Ocean and into the Pacific Ocean because of its shallow ocean floor.<ref name=RE1/> The dense North Atlantic water on the floor moves southward where it joins the sinking waters in the Southern Atlantic. Like the Bering Straight passage, a shallow portion of the ocean floor blocks the flow of water from moving into the Pacific Ocean.<ref name=RE1/> This passage is called the Drake Passage, which is between the Antarctic Peninsula and the southern tip of South America and it prevents the current from flowing westward. This causes the thermohaline circulation to move east where it splits in two directions.<ref name=RE1/>
			The thermohaline circulation loop is quite complex (Figure 1). The Bering Straight inhibits deep currents from flowing out of the [[Arctic sea ice \| Arctic]] Ocean and into the Pacific Ocean because of its shallow ocean floor.<ref name=RE1/> The dense North Atlantic water on the floor moves southward where it joins the sinking waters in the Southern Atlantic. Like the Bering Straight passage, a shallow portion of the ocean floor blocks the flow of water from moving into the Pacific Ocean.<ref name=RE1/> This passage is called the Drake Passage, which is between the Antarctic Peninsula and the southern tip of South America and it prevents the current from flowing westward. This causes the thermohaline circulation to move east where it splits in two directions.<ref name=RE1/>
	Some flows north along the east coast of Africa into the Indian Ocean, while the rest continues to move east along the southern coast of Australia where finally, moving north, making it into the Pacific basin.<ref name=RE1/>		Some flows north along the east coast of Africa into the Indian Ocean, while the rest continues to move east along the southern coast of Australia where finally, moving north, making it into the Pacific basin.<ref name=RE1/>

	==Great Salinity Anomaly==		==Great Salinity Anomaly==

	When sea ice moves south through the Fram Strait into the North Atlantic, it melts~~, creating~~ a layer of fresh water ~~over~~ the surface of the ocean. This fresh water is less dense than saline water~~, which~~ tends to stay at the top of the ocean. This lower density deters the normal process of sinking at high latitudes that supports thermohaline circulation, which makes it harder for the movement of warm water ~~north~~ from the equator.<ref name=RE3/> Climate scientists have gathered evidence which has shown that this inactive process happened over a period of several years in the late 1960s and early 1970s, when additional fresh water entered the North Atlantic Ocean and affected the climate of northern Europe. Researchers call this event the “Great Salinity Anomaly.”<ref name=RE3/>		When sea ice moves south through the Fram Strait into the North Atlantic, it melts and creates a layer of fresh water at the surface of the ocean. This fresh water is less dense than saline water and tends to stay at the top of the ocean. This lower density deters the normal process of sinking at high latitudes that supports thermohaline circulation, which makes it harder for the northern movement of warm water from the equator.<ref name=RE3/> Climate scientists have gathered evidence which has shown that this inactive process happened over a period of several years in the late 1960s and early 1970s, when additional fresh water entered the North Atlantic Ocean and affected the climate of northern Europe. Researchers call this event the “Great Salinity Anomaly.”<ref name=RE3/>

			==For Further Reading==
			*[[Salinity]]
			*[[Density]]
			*[[Temperature]]
			*[[Water cycle]]
			*Or explore a [[Special:Random\|random page]]

	==References==		==References==
	{{reflist}}		{{reflist}}
			[[Category: Uploaded]]

Jmdonev: 1 revision imported: From the summer

2016-09-17T22:29:20Z

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Jmdonev at 23:43, 30 May 2016

2016-05-30T23:43:33Z

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[[Category:Done 2016-04-30]]
<onlyinclude>'''Thermohaline circulation''' describes the movement of [[ocean]] currents due to differences in [[temperature]] and [[salinity]] among regions in the [[water]].</onlyinclude> Temperature and salinity change the [[density]] of water, resulting in the water to move accordingly.

Cold water is usually denser than warm water (down to 4°C where water is densest). Similarly, water with a high salinity is denser than water that is less saline.<ref name="RE1">"Ocean on the Move: Thermohaline Circulation | UCAR Center for Science Education", The National Center for Atmospheric Research, 2016. [Online]. Available: http://scied.ucar.edu/ocean-move-thermohaline-circulation. [Accessed: 17- May- 2016].</ref> Deep ocean currents are driven by differences in the water density, which is controlled by [[temperature]] ('''thermo''') and salinity ('''haline'''). Hence the process is known as thermohaline circulation, often known as the ocean's conveyer belt. <ref name="RE2">Thermohaline Circulation - Currents: NOAA's National Ocean Service Education", Oceanservice.noaa.gov, 2016. [Online]. Available: http://oceanservice.noaa.gov/education/tutorial_currents/05conveyor1.html. [Accessed: 17- May- 2016].</ref>

Any change to ocean circulation could have damaging effects on the [[hydrologic cycle|water cycle]] and [[weather]] patterns.<ref name="RE3">”All About Sea Ice | Environment : Climate | National Snow and Ice Data Center", National Snow & Ice Data Center, 2016. [Online]. Available: http://nsidc.org/cryosphere/seaice/environment/global_climate.html. [Accessed: 08- May- 2016].</ref>

==Factors influencing circulation==
===Ice===
Thermohaline circulation plays an important role in supplying heat to the polar regions. Hence, it influences the rate of sea ice formation near the poles, which impacts other aspects of the climate system (such as the [[albedo]]).<ref name=RE1/>

The formation of sea ice, which is mainly comprised of pure water, leaves behind salt in the water beneath the ice, resulting in higher salinity and colder water that sinks through the water below it, promoting circulation.<ref name=RE1/> When ice melts, it adds fresh water to the ocean, decreasing salinity and affecting the circulation pattern. In certain areas near the polar oceans, the colder surface water also gets more saline due to [[evaporation]] or sea ice formation.<ref name="RE4">"The Thermohaline Circulation - The Great Ocean Conveyor Belt | Precipitation Education", Pmm.nasa.gov, 2016. [Online]. Available: http://pmm.nasa.gov/education/videos/thermohaline-circulation-great-ocean-conveyor-belt. [Accessed: 15- May- 2016].</ref>

===Wind===
The movement of the surface layer of the ocean is driven mostly by [[wind]] currents. As the surface water gets pumped into the deep ocean, it forces the deep water to move horizontally until it can find a region on the globe where it can rise back to the surface and complete its current loop. This usually occurs in the equatorial ocean, typically in the Pacific and Indian Oceans.<ref name=RE4/> The North Atlantic Ocean around Greenland, Iceland, and the North Sea are major regions where surface water pumping occurs.<ref name=RE4/>

The surface ocean current brings new water into the region from the South Atlantic from the Gulf Stream and the water returns to the South Atlantic from the North Atlantic Deep Water current. The constant influx of warm water into the North Atlantic polar ocean keeps the regions around Iceland and southern Greenland mostly free of sea ice year round.<ref name=RE4/> Both surface and deep waters flow from west to east around Antarctica. This ‘circumpolar’ motion links the world's oceans and allows the deep water circulation from the Atlantic to rise in the Indian and Pacific Oceans and the surface circulation to close with the northern flow in the Atlantic.<ref name=RE4/>

==Thermohaline Loop==

[[File:Ocean_circulation_conveyor_belt.jpg|400px|thumb|right|Figure 1. The Thermohaline Circulation Loop.<ref>"Ocean circulation conveyor belt", Commons.wikimedia.org, 2007. [Online]. Available: https://commons.wikimedia.org/wiki/File:Ocean_circulation_conveyor_belt.jpg. [Accessed: 19- May- 2016].</ref>]]

The thermohaline circulation loop is quite complex. The Bering Straight inhibits deep currents from flowing out of the [[Arctic sea ice | Arctic]] Ocean and into the Pacific Ocean because of its shallow ocean floor.<ref name=RE1/> The dense North Atlantic water on the floor moves southward where it joins the sinking waters in the Southern Atlantic. Like the Bering Straight passage, a shallow portion of the ocean floor blocks the flow of water from moving into the Pacific Ocean.<ref name=RE1/> This passage is called the Drake Passage, which is between the Antarctic Peninsula and the southern tip of South America and it prevents the current from flowing westward. This causes the thermohaline circulation to move east where it splits in two directions.<ref name=RE1/>
Some flows north along the east coast of Africa into the Indian Ocean, while the rest continues to move east along the southern coast of Australia where finally, moving north, making it into the Pacific basin.<ref name=RE1/>

==Great Salinity Anomaly==

When sea ice moves south through the Fram Strait into the North Atlantic, it melts, creating a layer of fresh water over the surface of the ocean. This fresh water is less dense than saline water, which tends to stay at the top of the ocean. This lower density deters the normal process of sinking at high latitudes that supports thermohaline circulation, which makes it harder for the movement of warm water north from the equator.<ref name=RE3/> Climate scientists have gathered evidence which has shown that this inactive process happened over a period of several years in the late 1960s and early 1970s, when additional fresh water entered the North Atlantic Ocean and affected the climate of northern Europe. Researchers call this event the “Great Salinity Anomaly.”<ref name=RE3/>

==References==
{{reflist}}