Dynamic oceanography and paleothermometry in the Mozambique Channel, upstream of the Agulhas Current
Fallet, U. (2011). Dynamic oceanography and paleothermometry in the Mozambique Channel, upstream of the Agulhas Current. PhD Thesis. [S.n.]: [s.l.]. hdl.handle.net/1871/23932
The world’s oceans are an important component of the global climate system because they convey a substantial amount of energy between the low and high latitudes by adelicately balanced network of surface and deep ocean currents. The southern tip ofAfrica is a key area with regard to ocean currents because there the exchange between warm Indian Ocean surface waters (the Agulhas Current) and cold Atlantic deep waters takes place, which acts as a valve for the global circulation system. The Agulhas Current is fed by fast-rotating, meso-scale eddies originating in the Mozambique Channel. These eddies can span the entire width of the Mozambique Channel (~400 km) and reach to the 2700 m deep channel floor. Four to six of these eddies migrate through the Mozambique Channel per year causing rapid subsurface temperature and salinity changes of up to 14 °C and 0.4 psu, respectively.In addition to these eddies, an annual cycle in sea surface temperature of 5.2 °C is observed in the Mozambique Channel that plays a dominant role in determiningtemperature proxy signals. (A temperature proxy is a variable that can be measured inmodern settings and calibrated to modern temperature variation for application in paleo-climate research.) To study the effect of temperature variation and eddy migration, an array of instruments was deployed on mooring cables across the Mozambique Channel that allow for quantifying current transport and particle fluxes.The particle fluxes were analyzed for a number of organic and inorganic temperature proxies, which were compared with satellite sea surface temperature data to establish the first temperature calibrations for the SW Indian Ocean. Additionally, temperatureproxies were coupled to in situ measured current velocities to establish the effect of eddy transport in the Mozambique Channel. These temperature calibrations are essential for future paleoceanographic studies in the area. Results are compared withHolocene bottom sediments accumulating across the channel floor to estimate how proxy signatures are transferred into the sediment. Below, I summarize my main findings and conclusions.
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