Editing Downwelling (section)

=== Eddies ===
[[File:Anti-cyclonic warm core eddy.png|thumb|Warm-core eddy in the Northern Hemisphere. Shown are the clockwise rotation of waters, depressed isopycnals, and low productivity at the eddy's center. ]]
Meso- (>10-100's km) and submesoscale (<1-10 km) [[eddies]] are ubiquitous features of the upper ocean. Eddies have either a [[Cyclonic rotation|cyclonic]] ([[Cold core ring|cold-core]]) or [[Anticyclonic rotation|anticyclonic]] ([[Warm core ring|warm-core]]) rotation.  Warm-core eddies are characterized by [[Anticyclonic rotation|anticyclonic]] rotation that directs surface waters inward, creating high sea surface temperature and height.<ref>{{Cite web |last=Hallberg |first=Robert |title=Ocean Mesoscale Eddies |url=https://www.gfdl.noaa.gov/ocean-mesoscale-eddies/ |access-date=2023-11-29 |website=www.gfdl.noaa.gov |language=en-US}}</ref> The high central hydrostatic pressure maintained by this rotation causes the downwelling of water and the depression of [[isopycnal]]s - surfaces of constant density (see [[Eddy pumping]]) at scales of hundreds of meters per year.<ref>{{Cite journal |last1=Qu |first1=Yushan |last2=Wang |first2=Shengpeng |last3=Jing |first3=Zhao |last4=Wang |first4=Hong |last5=Wu |first5=Lixin |date=October 2022 |title=Spatial Structure of Vertical Motions and Associated Heat Flux Induced by Mesoscale Eddies in the Upper Kuroshio‐Oyashio Extension |url=https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022JC018781 |journal=Journal of Geophysical Research: Oceans |language=en |volume=127 |issue=10 |doi=10.1029/2022JC018781 |bibcode=2022JGRC..12718781Q |issn=2169-9275|doi-access=free }}</ref> The typical result is a deeper surface layer of warm water often characterized by low [[primary production]].<ref>{{Cite journal |last1=Jyothibabu |first1=R. |last2=Karnan |first2=C. |last3=Arunpandi |first3=N. |last4=Santhi Krishnan |first4=S. |last5=Balachandran |first5=K.K. |last6=Sahu |first6=K.C. |date=February 2021 |title=Significantly dominant warm-core eddies: An ecological indicator of the basin-scale low biological production in the Bay of Bengal |url=https://linkinghub.elsevier.com/retrieve/pii/S1470160X20309559 |journal=Ecological Indicators |language=en |volume=121 |pages=107016 |doi=10.1016/j.ecolind.2020.107016|doi-access=free }}</ref><ref>{{Cite journal |last1=Waite |first1=Anya M. |last2=Raes |first2=Eric |last3=Beckley |first3=Lynnath E. |last4=Thompson |first4=Peter A. |last5=Griffin |first5=David |last6=Saunders |first6=Megan |last7=Säwström |first7=Christin |last8=O'Rorke |first8=Richard |last9=Wang |first9=Miao |last10=Landrum |first10=Jason P. |last11=Jeffs |first11=Andrew |date=2019-05-21 |title=Production and ecosystem structure in cold‐core vs. warm‐core eddies: Implications for the zooplankton isoscape and rock lobster larvae |url=http://dx.doi.org/10.1002/lno.11192 |journal=Limnology and Oceanography |volume=64 |issue=6 |pages=2405–2423 |doi=10.1002/lno.11192 |issn=0024-3590|doi-access=free }}</ref>

Warm-core eddies play multiple important roles in [[Biogeochemical cycle|biogeochemical cycling]] and air-sea interactions. For example, these eddies are seen to decrease ice formation in the [[Southern Ocean]] due to their high sea surface temperatures.<ref>{{Cite journal |last1=Huot |first1=P.-V. |last2=Kittel |first2=C. |last3=Fichefet |first3=T. |last4=Jourdain |first4=N. C. |last5=Fettweis |first5=X. |date=2022-01-22 |title=Effects of ocean mesoscale eddies on atmosphere–sea ice–ocean interactions off Adélie Land, East Antarctica |url=http://dx.doi.org/10.1007/s00382-021-06115-x |journal=Climate Dynamics |volume=59 |issue=1–2 |pages=41–60 |doi=10.1007/s00382-021-06115-x |bibcode=2022ClDy...59...41H |issn=0930-7575|doi-access=free }}</ref> It has also been observed that air-sea fluxes of carbon dioxide decrease at the center of these eddies and that temperature was the leading cause of this inhibited flux.<ref>{{Cite journal |last1=Kim |first1=Dongseon |last2=Lee |first2=Seon-Eun |last3=Cho |first3=Sosul |last4=Kang |first4=Dong-Jin |last5=Park |first5=Geun-Ha |last6=Kang |first6=Sok Kuh |date=2022-08-11 |title=Mesoscale eddy effects on sea-air CO2 fluxes in the northern Philippine Sea |journal=Frontiers in Marine Science |volume=9 |doi=10.3389/fmars.2022.970678 |issn=2296-7745 |doi-access=free }}</ref> Warm-core eddies transport oxygen into the ocean interior (below the photic zone) which supports [[Cellular respiration|respiration]].<ref>{{Cite web |title=Mesoscale Eddy - an overview {{!}} ScienceDirect Topics |url=https://www.sciencedirect.com/topics/earth-and-planetary-sciences/mesoscale-eddy#:~:text=Eddies%20are%20important%20because%20they,and%20momentum%20to%20the%20seafloor. |access-date=2023-12-12 |website=www.sciencedirect.com}}</ref> Although compounds such as oxygen are transported into the deep ocean, there is an observed decrease in carbon export in warm-core eddies due to intensified stratification at their center.<ref>{{Cite journal |last1=Shih |first1=Yung‐Yen |last2=Hung |first2=Chin‐Chang |last3=Tuo |first3=Sing‐how |last4=Shao |first4=Huan‐Jie |last5=Chow |first5=Chun Hoe |last6=Muller |first6=François L. L. |last7=Cai |first7=Yuan‐Hong |date=2020-12-08 |title=The Impact of Eddies on Nutrient Supply, Diatom Biomass and Carbon Export in the Northern South China Sea |journal=Frontiers in Earth Science |volume=8 |page=607 |doi=10.3389/feart.2020.537332 |bibcode=2020FrEaS...8..607S |issn=2296-6463 |doi-access=free }}</ref> Such stratification inhibits the mixing of nutrient-rich waters to the surface where they could fuel primary production. In this case, since primary production stays low, carbon export potential remains low.