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Victoria University Antarctic Research Expedition Science and Logistics Reports 1984-85: VUWAE 29

Ocean Currents

Ocean Currents

Previous attempts to measure currents in the area have not revealed any currents greater than 5 cm/sec (measurement threshold of the instruments). This season an indirect method of determining currents by measuring salinity changes and suspended particulate concentrations was attempted.

(a)Salinity: 143, 250 ml aliquots have been taken from 22 sites within Granite Harbour. These were equally spaced within the water column; however, the density of the spacing was increased in strategic areas, e.g. around the Mackay Glacier Tongue and bergs within the harbour.
(b)Suspended Particulate: 79 filtrations of 2000 ml aliquots were executed in the field through 0.8 mm "Nuclepore filters". Sampling density was similar to that carried out for salinity.

The samples from these programmes have yet to be analysed; however, it is hoped that vertical water column profiles will give an indication of gross water mass movement. It is unlikely that tidal currents play a major role in redistributing sediment within the Granite Harbour system as average tidal flows are calculated to be approximately 0.1 cm sec−1. It is not known yet whether tidal flow is constant over the whole cycle or whether surges occur. Tide gauge measurements from previous years are interpreted to show that steady flow conditions are most likely.

Table 7. 1984 Sample Sites

Table 7. 1984 Sample Sites

page 16
Figure 10. Map showing the 1984 sample sites and dominant wind directions in Granite Harbour.

Figure 10. Map showing the 1984 sample sites and dominant wind directions in Granite Harbour.