Mooring observations of tidal currents in Prydz Bay, East Antarctica are presented here. They were found to be mixed diurnal-semidiurnal over the continental shelf, with significant seasonality. Barotropic tides dominated the tidal currents at the calving front of the inner continental shelf of the Amery Ice Shelf (AIS), except at the western corner of the AIS where the seabed is abruptly deeper. The spatial and temporal averaged magnitude of tidal currents for all the current meter records was only 2.58 cm s-1, much weaker than in the Ross or Weddell seas. However, the observed maximum tidal current was about 13.12 cm s-1 at the AIS calving front. In addition, the ratio of the tidal heat flux standard deviation to the residual heat flux standard deviation could be up to 41% at the AIS front, implying the tides have the potential to modulate the heat content of the AIS cavity. To identify the footprints of the tidal influences on the AIS basal mass balance, we further assessed the temperature and salinity records from six boreholes drilled through the AIS. Interestingly, tide-like pulsing was identified in the ocean layer adjacent to the AIS basal surface, highlighting the potential tidal influences on the heat exchanges at the ice-ocean interface. Our assessment of the tidal currents in Prydz Bay underlines that the critical role of tides should be highlighted in investigations of interactions between the ocean and the AIS, and other ice shelves.

Time series of shipboard observations in the southern Arafura Sea near the Tiwi Islands indicated that the water column dynamics differed between the east and west sides of the islands. On the west side, the water column, characterized by temperature, salinity, and velocity, was barotropic and tidal advection dominated. On the east side, the water column was baroclinic and internal tides were present along with tidal advection. These conditions affected the distribution of the turbidity and fluorescence in the water column. Likewise, the influence of the daily solar radiation cycle reached the bottom on the western side, but was limited to the upper layer above the thermocline on the eastern side. The fluorescence peaks also differed between the east and west sides, with the eastern side dominated by the semidiurnal tides and the western side by the daily solar cycle. Fluorescence integrated over the water column was much higher on the eastern side than the western side. Also on the eastern side, fluorescence was limited to the lower layer, while on the western side, it encompassed the entire water column at times and peaked below the warmer, higher oxygenated water generated by solar radiation and surface mixing. These dynamics have distinct implications for biological productivity and also may affect a proposed tidal power system in the region.