Friday, March 12, 2010

Friday 12 March, Day 57

After having recovered the deepest mooring, we turned back to go and retrieve the shallowest mooring that we had redeployed for a short 24-hour time-series. The idea was to check whether tides or higher frequency signals had a significant impact on the water sample properties, since the latter were only taken weekly during the whole year, and any strong signal at frequencies higher than weekly, such as tides, would get aliased in the weekly measurements.
But half-way on the way back, we stumbled upon a huge iceberg, which had drifted over half of the mooring area while we were recovering the deeper moorings!

The ship's radar indicated that the iceberg was terminating no too far to the west, but it could not see the end of it to the east, so the captain decided to go around the iceberg to its west. We then arrived in the zone between the iceberg and the ice shelf, and were soon prevented from going further by very compact sea ice which was being squeezed between the iceberg and the ice shelf, the contours of which are visible on the radar screen below, with the cloudy white area indicating the sea ice around the ship:

It looked as a death trap, so the captain decided to back away and go around the iceberg on the other side, to the east. It took a few hours to complete the loop around the 18-mile long and 5-mile wide iceberg! It was so big it looked like an ice shelf:

I did not know penguins knew how to build pyramids!

Finally, we managed to reach the shallow mooring, which was lying just between the iceberg and the ice shelf. I was relieved to see the water sampler come back on deck, for the samples it contained, and because it costs £40,000!

During this last mooring recovery, we had two spectators watching us:

Do you remember the iceberg in front of the ice shelf in the background? There is a similar one next to it, and I called them the "gates to Antarctica" last year. I was surprised to see them again! They must be grounded for having not drifted with the coastal current.

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