Impact of Agulhas leakage on the Atlantic overturning circulation in the CCSM4

The impact of Agulhas leakage variability on the strength of the Atlantic meridional overturning circu- lation (AMOC) in the Community Climate System Model, version 4 (CCSM4) is investigated. In this model an advective connection exists that transports salinity anomalies from the Agulhas region into the North Atlantic on decadal (30–40 yr) time scales. However, there is no identifiable impact of Agulhas leakage on the strength of theAMOC,suggesting that the salinity variations are too weak to significantlymodify the stratification in theNorth Atlantic. It is argued that this study is inconclusive with respect to an impact ofAgulhas leakage on theAMOC.Salinity biases leave the South Atlantic and IndianOceans toohomogeneous, in particular erasing the observed salinity front in the Agulhas retroflection region. Consequently, salinity variability in the southeastern South Atlantic is found to be much weaker than observed. 1.