Thermohaline circulation

Thermohaline circulation

Thermohaline circulation (THC) is a part of the large-scale <a href="/en/Ocean_current" title="Ocean current" class="wl">ocean circulation</a> that is driven by global <a href="/en/Density_gradient" title="Density gradient" class="wl">density gradients</a> created by surface heat and freshwater <a href="/en/Flux" title="Flux" class="wl">fluxes</a>.<a href="#cite_note-1" style="counter-reset: mw-Ref 1;">[1]</a><a href="#cite_note-2" style="counter-reset: mw-Ref 2;">[2]</a> The adjective thermohaline derives from <a href="https://en.wiktionary.org/wiki/thermo-" title="wikt:thermo-" class="extiw" target="_blank">thermo-</a> referring to <a href="/en/Temperature" title="Temperature" class="wl">temperature</a> and -haline referring to <a href="/en/Salinity" title="Salinity" class="wl">salt content</a>, factors which together determine the <a href="/en/Water_(molecule)#Density_of_saltwater_and_ice" title="Water (molecule)" class="mw-redirect wl">density of sea water</a>. <a href="/en/Wind" title="Wind" class="wl">Wind</a>-driven surface currents (such as the <a href="/en/Gulf_Stream" title="Gulf Stream" class="wl">Gulf Stream</a>) travel <a href="/en/Polar_regions_of_Earth" title="Polar regions of Earth" class="wl">polewards</a> from the equatorial <a href="/en/Atlantic_Ocean" title="Atlantic Ocean" class="wl">Atlantic Ocean</a>, cooling en route, and eventually sinking at high <a href="/en/Latitude" title="Latitude" class="wl">latitudes</a> (forming <a href="/en/North_Atlantic_Deep_Water" title="North Atlantic Deep Water" class="wl">North Atlantic Deep Water</a>). This dense water then flows into the <a href="/en/Ocean_basin" title="Ocean basin" class="mw-redirect wl">ocean basins</a>. While the bulk of it <a href="/en/Upwelling" title="Upwelling" class="wl">upwells</a> in the <a href="/en/Southern_Ocean" title="Southern Ocean" class="wl">Southern Ocean</a>, the oldest waters (with a transit time of about 1000 years)<a href="#cite_note-3" style="counter-reset: mw-Ref 3;">[3]</a> upwell in the North Pacific.<a href="#cite_note-4" style="counter-reset: mw-Ref 4;">[4]</a> Extensive mixing therefore takes place between the ocean basins, reducing differences between them and making the <a href="/en/World_Ocean" title="World Ocean" class="mw-redirect wl">Earth's oceans a global system</a>. The water in these circuits transport both energy (in the form of heat) and mass (dissolved solids and gases) around the globe. As such, the state of the circulation has a large impact on the <a href="/en/Climate" title="Climate" class="wl">climate</a> of the Earth.

<div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none" about="#mwt1">Part of large-scale ocean circulation</div>

<figure class="wiki-thumb"><a href="/en/File:Thermohaline_Circulation_2.png" class="mw-file-description image media-thumb" data-hash="File:Thermohaline_Circulation_2.png"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Thermohaline_Circulation_2.png/350px-Thermohaline_Circulation_2.png" decoding="async" data-file-width="1100" data-file-height="690" data-file-type="bitmap" height="220" width="350" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Thermohaline_Circulation_2.png/525px-Thermohaline_Circulation_2.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Thermohaline_Circulation_2.png/700px-Thermohaline_Circulation_2.png 2x" alt="Thermohaline_Circulation_2.png"></a><figcaption>A summary of the path of the thermohaline circulation. Blue paths represent deep-water currents, while red paths represent surface currents.</figcaption></figure>
<figure class="wiki-thumb"><a href="/en/File:Thermohaline_Circulation_using_Improved_Flow_Field.ogv" class="app_media media-thumb" data-hash="File:Thermohaline_Circulation_using_Improved_Flow_Field.ogv"><video poster="//upload.wikimedia.org/wikipedia/commons/thumb/4/4a/Thermohaline_Circulation_using_Improved_Flow_Field.ogv/350px--Thermohaline_Circulation_using_Improved_Flow_Field.ogv.jpg" preload="none" height="118" width="350" resource="./File:Thermohaline_Circulation_using_Improved_Flow_Field.ogv"><source src="//upload.wikimedia.org/wikipedia/commons/4/4a/Thermohaline_Circulation_using_Improved_Flow_Field.ogv" type="video/ogg; codecs=&quot;theora&quot;" data-file-width="640" data-file-height="216" data-title="Original Ogg file, 640 × 216 (697 kbps)" data-shorttitle="Ogg source"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/4a/Thermohaline_Circulation_using_Improved_Flow_Field.ogv/Thermohaline_Circulation_using_Improved_Flow_Field.ogv.120p.vp9.webm" type="video/webm; codecs=&quot;vp9, opus&quot;" data-width="214" data-height="72" data-title="Lowest bandwidth VP9 (120P)" data-shorttitle="VP9 120P"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/4a/Thermohaline_Circulation_using_Improved_Flow_Field.ogv/Thermohaline_Circulation_using_Improved_Flow_Field.ogv.160p.webm" type="video/webm; codecs=&quot;vp8, vorbis&quot;" data-width="288" data-height="98" data-title="Low bandwidth WebM (160P)" data-shorttitle="WebM 160P"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/4a/Thermohaline_Circulation_using_Improved_Flow_Field.ogv/Thermohaline_Circulation_using_Improved_Flow_Field.ogv.180p.vp9.webm" type="video/webm; codecs=&quot;vp9, opus&quot;" data-width="320" data-height="108" data-title="Low bandwidth VP9 (180P)" data-shorttitle="VP9 180P"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/4a/Thermohaline_Circulation_using_Improved_Flow_Field.ogv/Thermohaline_Circulation_using_Improved_Flow_Field.ogv.240p.vp9.webm" type="video/webm; codecs=&quot;vp9, opus&quot;" data-width="426" data-height="144" data-title="Small VP9 (240P)" data-shorttitle="VP9 240P"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/4a/Thermohaline_Circulation_using_Improved_Flow_Field.ogv/Thermohaline_Circulation_using_Improved_Flow_Field.ogv.240p.webm" type="video/webm; codecs=&quot;vp8, vorbis&quot;" data-width="426" data-height="144" data-title="Small WebM (240P)" data-shorttitle="WebM 240P"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/4a/Thermohaline_Circulation_using_Improved_Flow_Field.ogv/Thermohaline_Circulation_using_Improved_Flow_Field.ogv.360p.vp9.webm" type="video/webm; codecs=&quot;vp9, opus&quot;" data-width="640" data-height="216" data-title="VP9 (360P)" data-shorttitle="VP9 360P"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/4a/Thermohaline_Circulation_using_Improved_Flow_Field.ogv/Thermohaline_Circulation_using_Improved_Flow_Field.ogv.360p.webm" type="video/webm; codecs=&quot;vp8, vorbis&quot;" data-width="640" data-height="216" data-title="WebM (360P)" data-shorttitle="WebM 360P"></video></a><figcaption>Thermohaline circulation</figcaption></figure>

The thermohaline circulation is sometimes called the ocean conveyor belt, the great ocean conveyor, or the global conveyor belt, coined by climate scientist <a href="/en/Wallace_Smith_Broecker" title="Wallace Smith Broecker" class="wl">Wallace Smith Broecker</a>.<a href="#cite_note-5" style="counter-reset: mw-Ref 5;">[5]</a><a href="#cite_note-6" style="counter-reset: mw-Ref 6;">[6]</a><a href="#cite_note-7" style="counter-reset: mw-Ref 7;">[7]</a> On occasion, it is used to refer to the <a href="/en/Zonal_and_meridional" title="Zonal and meridional" class="mw-redirect wl">meridional</a> overturning circulation (often abbreviated as MOC). The term MOC is more accurate and well defined,[<a href="/en/Wikipedia:Please_clarify" title="Wikipedia:Please clarify" class="wl">clarification needed</a>] as it is difficult to separate the part of the circulation which is driven by temperature and <a href="/en/Salinity" title="Salinity" class="wl">salinity</a> alone as opposed to other factors such as the wind and <a href="/en/Tidal_force" title="Tidal force" class="wl">tidal forces</a>.<a href="#cite_note-8" style="counter-reset: mw-Ref 8;">[8]</a> 
Moreover, temperature and salinity gradients can also lead to circulation effects that are not included in the MOC itself.

The <a href="/en/Atlantic_meridional_overturning_circulation" title="Atlantic meridional overturning circulation" class="wl">Atlantic Meridional Overturning circulation</a> (AMOC) is part of a global thermohaline circulation.

Thermohaline circulation is a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes. Extensive mixing therefore takes place between the ocean basins, reducing differences between them and making the Earth's oceans a global system. The water in these circuits transport both energy and mass around the globe. As such, the state of the circulation has a large impact on the climate of the Earth. The thermohaline circulation is sometimes called the ocean conveyor belt, the great ocean conveyor, or the global conveyor belt, coined by climate scientist Wallace Smith Broecker. 
Moreover, temperature and salinity gradients can also lead to circulation effects that are not included in the MOC itself. The Atlantic Meridional Overturning circulation is part of a global thermohaline circulation. 