Editing Agulhas Current (section)

===Agulhas leakage and rings===
[[File:Agulhas Current NLOM .png|thumb|Agulhas rings are peeled off the Agulhas Current in the [[Agulhas Basin]] where it retroflects back into the Indian Ocean.]]{{Main|Agulhas Leakage}}
It is estimated that as much as 15 Sv of [[Indian Ocean]] water is leaked directly into the [[South Atlantic]].  10 Sv of this is relatively warm, salty [[thermocline]] water, with the remaining 5 Sv being cold, low salinity [[Antarctic Intermediate Water]].  Since Indian Ocean water is significantly warmer (24-26&nbsp;°C) and saltier than South Atlantic water, the Agulhas Leakage is a significant source of salt and heat for the South Atlantic Gyre.  This heat flux is believed to contribute to the high rate of evaporation in the South Atlantic, a key mechanism in the [[Thermohaline circulation|Meridional Overturning Circulation]]. A small amount of the Agulhas Leakage joins the [[North Brazil Current]], carrying Indian Ocean water into the [[North Atlantic Subtropical Gyre]].<ref name="Siedler" />  Before reaching the [[Caribbean Sea]], this leakage gets heated up by the sun around the equator, and, when finally joining the [[Gulf Stream]], this warm and salty water contributes to the formation of deep water in the North Atlantic.<ref>{{Harvnb|Schiele|2014}}</ref>

Surface water filaments are estimated to account for up to 13% of the total salt transport from the Agulhas Current into the [[Benguela Current]] and South Atlantic Gyre.  Due to surface dissipation, these filaments are not believed to significantly contribute to inter-basin heat flux.<ref name="Siedler" />

Where the Agulhas turns back on itself the loop of the retroflection pinches off periodically, releasing an [[eddy (fluid dynamics)|eddy]] into the South Atlantic Gyre. These [[warm core ring|"Agulhas Rings"]] enter the flow of the Benguela Current or are advected northwestward across the South Atlantic where they join the [[South Equatorial Current]], where they dissipate into the larger background currents.  These [[anticyclonic]] [[warm core ring]]s are estimated to have a transport of 3-9 Sv each, in total injecting salt at a rate of 2.5<math>\cdot</math>10<sup>6</sup> kg/s and heat at a rate of 45 [[terawatt|TW]].<ref name="Siedler" />

====Paleoclimate====
Since the [[Pleistocene]], the buoyancy of the South Atlantic [[thermocline]] and the strength of the Atlantic [[meridional overturning circulation]] has been regulated by the shedding of warm, saline Agulhas Rings.  The Agulhas leakage affects the Atlantic thermocline on a decadal timescale and over centuries it can change the buoyancy of the Atlantic thermocline and therefore the formation rates of [[North Atlantic Deep Water]] (NADW).<ref>{{Harvnb|Simon|Arthur|Hall|Peeters|2013|loc=Introduction, pp. 101-103}}</ref>

The provenance of ocean sediments can be determined by analysing [[Terrigenous sediment|terrigenous]] [[strontium]] isotope ratios in deep ocean cores.  Sediments underlying the Agulhas Current and Return Current have significantly higher ratios than surrounding sediments.  Franzese et al. 2009 analysed cores in the South Atlantic deposited during the [[Last Glacial Maximum]] (LGM, 20&nbsp;000 years ago), and concluded that the Agulhas leakage was significantly reduced.<ref>{{Cite journal|last1=Franzese|first1=A|last2=Hemming|first2=S|author-link2=Sidney Hemming|last3=Goldstein|first3=S|last4=Anderson|first4=R|date=2006-10-15|title=Reduced Agulhas Leakage during the Last Glacial Maximum inferred from an integrated provenance and flux study|journal=Earth and Planetary Science Letters|language=en|volume=250|issue=1–2|pages=72–88|doi=10.1016/j.epsl.2006.07.002|bibcode=2006E&PSL.250...72F}}</ref>  The trajectory of the current was the same during the LGM and that the reduced leakage must be explained by a weaker current.<ref>{{Cite journal|last1=Franzese|first1=Allison M.|last2=Hemming|first2=Sidney R.|author-link2=Sidney Hemming|last3=Goldstein|first3=Steven L.|date=2009|title=Use of strontium isotopes in detrital sediments to constrain the glacial position of the Agulhas Retroflection|journal=Paleoceanography|language=en|volume=24|issue=2|pages=n/a|doi=10.1029/2008PA001706|bibcode=2009PalOc..24.2217F|doi-access=free}}</ref>  Furthermore, it can be predicted that a stronger Agulhas Current will result in a more eastward retroflection and an increased Agulhas leakage.  {{Harvnb|Simon|Arthur|Hall|Peeters|2013}}, however, noted that changes in temperature and salinity in the Agulhas leakage is at least partly the result of variability in the composition in the current itself and can be a poor indicator of the strength of the leakage.<ref>{{Harvnb|Simon|Arthur|Hall|Peeters|2013|loc=Conclusions, p. 110}}</ref>