Horn, Myriel

Rabe, Benjamin

Schauer, Ursula

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Multi-decadal link between Arctic Ocean and subpolar North Atlantic freshwater anomaliesHorn, M., Schauer, U., and Rabe, B. (in prep.)Why do we care about freshwater?Ocean‘s salinity changes only due to the addition or removal of freshwater by• Precipitation/evaporation• Continental run-off• Sea ice melting/formationArctic OceanSubpolar North Atlanticand Nordic Seas Insulation effect of the freshsurface layer Deep water formation(Meridional OverturningCirculation)CirculationCurry and Mauritzen (2005) Rudels (2009)Arctic OceanSubpolar North Atlanticand Nordic SeasRecent freshwater changesRabe et al. (2014) Mauritzen et al. (2012)Subpolar North AtlanticArctic OceanRecent freshwater changes IICurry and Mauritzen (2005)Subpolar North Atlanticand Nordic SeasLiquid freshwater content𝐿𝐹𝑊𝐼 =  𝑧=0𝑚ℎ 𝑆𝑟𝑒𝑓−𝑆𝑆𝑟𝑒𝑓𝑑𝑧 [m]𝑆𝑟𝑒𝑓 = 35𝐿𝐹𝑊𝐶 =  𝐿𝐹𝑊𝐼 𝑑𝐴 [km³]Inventory of liquid freshwater Liquid freshwater contentSubpolar North AtlanticArctic Ocean𝑆𝑟𝑒𝑓 = 35h = depth of 34 isohalineh = 2000 mCTD section in the subpolar North AtlanticSalinityObjectiveHow do the liquid freshwater contents of the Arctic Ocean andthe North Atlantic covary over the past two decades?→Total freshwater content of the Arctic Ocean including liquid and solid freshwater contents→ Liquid freshwater content of the subpolar North AtlanticFreshwater variability The freshwater contents are significantly anti-correlated. The amount of the anomalies are of the same size.  Freshwater anomalies suggest an oscillation.Liquid andsolid freshwatercontentLiquid freshwatercontentFreshwater variability Time series hint at multidecadal oscillations.The anomalies have been normalised by twice their standard deviationPossible mechanisms underlayingThe freshwater might be redistributed as a response to frequent changes inathmospheric pressure patternsMauritzen (2012)North Atlantic and Arctic Oscillation Index The cumulative oscillation indices and the liquid freshwater content of the subpolar North Atlantic are significantly correlated.The time series have been normalised by twice their standard deviation, detrended and demeaned. ConclusionsDecadal scale changes of the freshwater content in the subpolar Seasare likely to originate in the Arctic Ocean.Freshwater changes of the Arctic Ocean and of the subpolar North Atlantic and the Nordic & Barents Seas has been anti-correlated duringthe last 20 years.Thank you for yourattentionReferencesCurry, R. & Mauritzen C. Dilution of the Northern North Atlantic Ocean in Recent Decades. Science 308, 1772-1774 (2005).Rabe, B. et al. Arctic Ocean basin liquid freshwater storage trend 1992-2012. Geophys. Res. Lett. 41, 961-968 (2014).Mauritzen, C., Melsom, A. & Sutton, R. T. Importance of density-compensated temperature change for deep North Atlantic Ocean heat uptake. Nat. Geosci. 5, 905-910 (2012).Haine, T. W. N. et al. Arctic freshwater export: Status, mechanisms and prospects. Global Planet Change125, 13-35 (2015).Mauritzen, C. Arctic freshwater. Nat. Geosci. 5, 162-164 (2012).Rudels, B. Arctic ocean circulation. Encyclopedia of Ocean Sciences. Elsevier, 211-225 (2009).Freshwater variabilityNordic & Barents SeasArctic OceanSubpolar North AtlanticCorrelation with the freshwater content of the Arctic OceanFreshwater variability of the subpolar North AtlanticFreshwater variability of the subpolar North Atlantic

Multi-decadal link between Arctic Ocean and subpolar North Atlantic freshwater anomalies

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