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We left the ice late yesterday, pushing through a band of old floes past numerous icebergs, with one last leopard seal seen off the bow just before we hit open water. The ice floes were moving up and down in a gentle 1-2 m swell, a good sign that this was indeed the last of the ice: the ice damps the swell so effectively that the ship has barely rocked at all in the last 10 days or so, despite winds often exceeding 30 knots. We completed our last two CTD stations with the bottom camera attached on the edge of the continental slope: from here on, the stations are deep and the pressures at the bottom are too high for the camera system. We also deployed the last of the Argo floats. These floats are free-drifting and rise up and down between the ocean surface and 2km depth every ten days. This particular float is a special ice float that can sample under sea ice. The float has software that allows it to 'sense' the ice above, stop rising, store the profile in memory and then rise again when the ice has cleared. When the float does reach the surface it beams temperature and salinity information back via satellite to a ground station in Hobart. With more than 3000 of these floats deployed, almost all of the global oceans are well covered except for the polar regions. The next frontier is getting more of these floats into the seasonal ice zone to measure the water column that is covered by ice in winter. With our heading now due north, we really are on our way home. We will finish the last few stations over the next two days, and start our transit home on February 1, in time for our scheduled arrival early on February 6.
REGARDS: Steve, Fred and Penny
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.