Peter Brandt Marcus Dengler Rebecca Hummels Josefine Herrford Large Scale Thermohaline Circulation 2 Kuhlbrodt et al 2007 RACE Contribution to AMOC Observing System Denmark Strait Overflow ID: 1024421
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1. Causes of Tropical Circulation VariabilityPeter Brandt, Marcus Dengler, Rebecca Hummels, Josefine Herrford
2. Large Scale Thermohaline Circulation2Kuhlbrodt et al. 2007
3. RACE Contribution to AMOC Observing SystemDenmark Strait OverflowDeep Water Export from the Labrador SeaExchange between Subtropical and Subpolar GyresWest-East Exchange, North Atlantic CurrentAMOC variability in the tropics and impact on tropical circulation and climate
4. MOC Estimates at Different LatitudesIPCC, Climate Change 2013
5. AMOC variabilityHeat flux and wind stress associated with the North Atlantic Oscillation (NAO) responsible for AMOC changesAMOC changes in the subpolar gyre reverberate in the subtropical North Atlantic.Böning et al. 2006AMOC Transport 36°N53°N
6. Collapse of the Atlantic Thermohaline CirculationCollapse was forced in the model by applying a strong initial freshening to the top layers of the North AtlanticImmediate reduction of the northward heat transport and cooling of the northern hemisphereSlower warming of the southern hemisphereprecipitation evaporation[m/yr] Vellinga and Wood 2002°CTemperature anomaly 20-30 yr after the collapse
7. Tropical ResponseStronger cross-equatorial anomalous Hadley circulation in responseto AMOCcollapseTropical response due toair-seainteractionZhang and Delworth 2005
8. Chang et al., 2008Change of Tropical ClimateSouthern hemisphere warming was found to be the results of modified STC pathways due to a substantially weakened AMOC (Chang et al. 2008)When the AMOC is substantially weakened, the northern STC becomes a closed cell and transports warmer NACW toward the equator.
9. ModelStudyOAME: AMOC collapse (no northward mass transport) and heat flux from climate model water hosing runsOME: only AMOC collapseAME: only heat flux Wen et al., 2011
10. Change of Tropical ClimateWarming of the tropical thermocline and weakened stratification south of the equator.Result is a weaker seasonal cycle and weaker interannual variability in the cold tongue region.Chang et al., 2008
11. From J.-Y. ParkFuture Sahel DraughtsLarge uncertainty in the projections of Sahel rainfallPark et al. (2015) shows the importance of the differential warming of extratropics and tropics
12. Role of Agulhas leakageHigh correlation between MOC andNBC transportBiastoch et al. 2009Biastoch et al. 2008MOCNBCIncreased Agulhas leakage: salinity increase within the NBC
13. Lübbecke et al. 2015Heat Content change due to Agulhas Leakage DynamicsIncreased Agulhas leakage contributes to tropical Atlantic (20°S-10°N) warming trend during recent decadesHindcast: 1.27Sv/decadeObservationsIdealized simulations with different Agulhas leakageREF: 16.8 SvLOCAL 19.2 Sv
14. Two pathways of the upper limp of the MOC:1) Supply of EUC and NECC/NEUC mainly from the southern hemisphere2) NBC rings South of the equator, the DWBC eddies are a major component of the cold water branch of the Meridional Overturning Circulation RecifeWestern Boundary Circulation Dengler et al. 2004
15. Hummels et al. 2015& updateWestern Boundary Mooring Array at 11°SMooring array installed from 2000 to 2004 and from 2013 ongoing
16. Hummels et al. 2015NBUC Transport AnomalyGeostrophic calculation (Zhang et al. 2011) and 1/10° model simulation show multidecadal variabilityMooring data in general agreement with model results Using additional eastern boundary transport measurements, bottom pressure measurements and interior hydrographic and satellite data, an AMOC time series will be estimated at 11°S.
17. Hummels et al. 2015Water Mass Changes at 11°SDecadal salinity trend with increasing salinities in the central water range and salinity decrease in NADWIncrease in oxgen albeit higher variability
18. Large Scale Advection of North Atlantic Deep WaterRhein et al. 2013
19. Herrford et al. 2016, submittedAABW Temperature Trends
20. SummaryRACE provides an important contribution to the Atlantic Ocean observing systemDecadal variability impact tropical Atlantic circulation and climate: long-term effect on rainfall, seasonal cycle and interannual variabilityObserved decadal NBUC water mass variability associated with Agulhas leakageDecadal deep and bottom water changesContinuous observing systems are required to address long-term climate changes