Variability of Antarctic Bottom Water formation and export from the Weddell Sea

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The Atlantic sector of the Southern Ocean (i.e., the Weddell Sea) is the main supplier for Antarctic Bottom Water (AABW) to the World Ocean. Changes in the formation rate – caused by environmental changes – could modify the strength and variability of the Meridional Overturning Circulation (MOC) and, thus, affect climate and climate change. Changes in the AABW formation process and in the amount of AABW formed might also influence the anthropogenic carbon uptake of the deep ocean. The proposal contributes to the International Polar Year (IPY) in the framework of CASO (Climate in Antarctica and the Southern Ocean). CASO aims to understand, interpret and predict climate variability and change in the southern polar region and its impact on Antarctic and global processes. The aims of this proposal are: • To determine the AABW formation in the Weddell Sea, especially to assess the variability of deep and bottom water formation. This time series is needed to understand links between the variability of bottom water formation and changing environmental conditions (i.e., degradation of ice shelves, enhanced melting, warming, freshening) • To determine the export of Weddell Sea Deep and Bottom Water (subsequently AABW) through the South Scotia Ridge and across the Greenwich Meridian and the import of deep water from easterly sources and their variability. • To determine the pathways and volume of AABW and its variability leaking into Drake Passage towards the west. • To determine the transport and variability of the Southeast Pacific Deep Slope Water (SPDSW) in the Antarctic Circumpolar Current and its supply of 3-helium to the South Atlantic and Weddell Sea.