Impacts of the closure of the Mozambique Channel on the southwest Indian Ocean circulation: A regional numerical simulation

Paleobathymetric reconstructions suggest that 35 million years ago, local uplift of the Davie Ridge could have temporarily raised a continental land-bridge between Africa and Madagascar and dramatically affected their connectivity. Numerical simulations of a regional model of the southwest Indian Ocean at mesoscale resolution are performed to investigate the consequences of such a closure of the Mozambique Channel. Compared to a reference simulation of present day circulation, blocking the Mozambique Channel results in a redistribution of the transport around Madagascar dramatically strengthening the East Madagascar Current and eddy variability south of Madagascar, broadening the Agulhas Current, and modifying water mass properties and bottom circulation. • Paleobathymetric reconstructions suggest that the Mozambique Channel was closed in the past (e.g. around 35 Ma) due to uplift of the Davie Ridge. • We investigate the consequences of this closure in a regional ocean model at 1/12°resolution and compare with present day circulation. • Blocking the Mozambique Channel dramatically strengthens the East Madagascar current and eddy variability south of Madagascar.