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Yesterday we continued to meet dense pack ice as we attempted to head south along the CASO CTD transect west of the Mertz Glacier. Rather than spend time pushing against the ice we decided to move to the middle of the three CASO transects, to sample along longitude 147E to the north of the Mertz. We completed 2 of the sites along this transect before again meeting dense pack ice and once more moved slightly west. We have now completed 3 sites along 146 35E. Satellite imagery indicates that the sites directly to the south of our current position should be clear. The CTD data indicates that we are again positioned over an outflow of bottom water generated by the Mertz Polynya as it pours off the continental shelf, in contrast to the Ross Sea bottom water detected further east. This is the first time it has been confirmed that Mertz bottom water streams over the shelf in more than one place. Over the past few days we have collected water samples from as deep as 4000 m. At this depth the pressure is about 400 times atmospheric pressure, to put this in perspective, if you opened a full diving cylinder at this depth the pressure would force water into the cylinder and fill about a quarter of it rather than allow the air out. Our plan is to complete this phase of CASO sampling by about 1800 this evening, then to steam to the polynya moorings to take advantage of a weather window to again move the Pole Compass, before re-starting the CEAMARC sea-bed sampling. Regards, Martin and Sarah.
Map
A map showing Australia and Antarctica. The map shows the journey of one voyage that has occured in the season, with each route highlighted in a distinct colour.