Bottom-driven upwelling generated by eastern intensification in closed and semi-closed basins with a sloping bottom

Abstract

Cold water is observed in the eastern Great Australian Bight, and the presence of this water is inconsistent with that expected from surface Ekman-induced upwelling resulting from the imposed windfield. A numerical model is employed to investigate this situation under idealized conditions, from which the bottom slope has been identified as the most dominant factor contributing towards the presence of the cold water. A boundary current generated on the eastern side of the idealized bight is attributed to eastern intensification of a predominantly Stommel type, induced by the topographical gradient. It is proposed that the cold water observed at the eastern boundary is the result of upwelling driven by a bottom Ekman-transport convergence in this region, which is in turn the result of a large bottom stress curl maintained by the eastern intensification.