Circulation and water mass transports on the East Antarctic shelf in the Mertz Glacier region

The summer circulation is strongly constrained by the DSW distribution and forms a clockwise circulation primarily transporting the fresh surface waters and the warm mCDW around the dome of DSW. Over the upper flank of the Mertz Bank, the inflow branch transports the mCDW towards the Mertz Glacier, while, over the lower part of the slope, the outflow branch returns to the sill a diluted mode of the same water mass. A total of 0.19 Sv of mCDW inflows at the sill and two-third reach the Mertz Glacier and recirculate in front of it, allowing the mCDW to penetrate into the deeper part of the depression. Possible scenarios of interaction between the mCDW and the DSW with the glacier are examined. It is shown that, despite the water mass pathways and transports suggest possible ice-ocean interaction, both lateral and basal melting were likely small in summer 2008. Finally, our results suggest that, in addition to bathymetric features, the distribution of the residual DSW which is left from the preceding winter sets up regional pressure gradients which provide a seasonal control on the shelf circulation. In particular, the spring collapse of the convective patch would contribute to setting up a deep pycnocline which strongly impacts the shelf circulation in the following summer, with possible feedback of the mCDW transports on the polynya activity and water mass formation.