Inter-ocean water exchange south of Africa is an important component of the global thermohaline circulation. Evidence exists that variability in these exchanges may significantly influence weather and climate patterns in the southern African region.
Observational estimates of the rate of mass and heat exchange south of Africa are limited and it is necessary to augment these with estimates derived from models. As an initial step in this direction, a model designed especially for the Agulhas system has been used to investigate meso- through to interannual variability in heat and volume transports between the South Indian and South Atlantic oceans south of Africa.
Volume transports of the Agulhas Current section through 35 S in the SW Indian Ocean were shown to range from 58-59 Sv in summer/autumn to 64-65 Sv in winter/spring. On average, about 0.84 PW of heat flows west into the South Atlantic across 20E with just over 1 PW flowing north into the South Atlantic across 35 S. Seasonal variations in heat transport were found at 35 S in the South Atlantic with the strongest signals through 20 E.
The substantial variability exhibited by the model in the southern Agulhas region is consistent with satellite based observations of SST patterns and eddy activity and re-inforce the significance of this region for southern African climate. |
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