Week 5

Large cracks appear on the ice floe

The ship berthed with port side against the floe © David N Thomas

The ship berthed with port side against the floe © David N Thomas

The Antarctic pack ice is an unpredictable place, and situations can change dramatically from one moment to the next. This was highlighted last week, when only 15 minutes after emailing the last journal, the message came that large cracks were appearing in our floe. One researcher who found himself on the wrong side of a crack had to be rescued by helicopter. After only a few days our floe was already breaking up!

Reflection of the ice floe in the water © David N Thomas

Reflection of the ice floe in the water © David N Thomas

By the next morning we had lost half of the floe and several of the research areas. Fortunately all the equipment could be retrieved. An ice physics group endured the hard work of installing a weather station in the late evening only for it to be dismantled the following afternoon. However, during the next day all the groups had reassembled their field stations and started measuring again. Only this time much closer to the ship.

Some of the former sites are still accessible by laying bridges to span the gaps. These cracks between floes have the tendency to open wider and close up depending on the wind direction. Therefore we have all become considerably more cautious when working away from the ship. There is in fact little danger since the ice breaks up in chunks several hundred metres in diameter, and we are in constant radio contact with the ship. The helicopters can easily get to us in a matter of minutes.

Complicated equipment measuring the carbon dioxide content of sea ice © David N Thomas

Complicated equipment measuring the carbon dioxide content of sea ice © David N Thomas

The ice is continuously moving, and where there was a gap of open water before going to bed, the next morning this can be filled with tons of ice being forced together by the wind into large pressure ridges several metres high. This can be a problem for those groups using instruments and nets deployed from the starboard side of ship to sample the water (our floe is on the port side). Several days of work have been lost because the place that they lower their sampling devices was solid with ice. Again it was a patient waiting game for them for the wind to change direction and open up the water.

The awesome power of the ice fields is striking, but it is not all strong winds and deformed boulders of ice. One of the most pleasurable times of the day is to stand on the edge of the floe, or on the ships deck, looking at the colours in the ice and the reflections of ice floes on the water. We have had some stunning weather in the past week, with at times, no wind at all. The patches of open water have been like mirrors, and it was impossible when going outside not to stand and gaze at the sheer beauty of it all. Enhanced of course by our local penguins and seals swimming close to the ship, and on one morning two minke whales paying us an inquisitive visit.

Water bottles collect water samples from the bottom of the ocean 1500 metres below © David N Thomas

Water bottles collect water samples from the bottom of the ocean 1500 metres below © David N Thomas

Of course in this good weather we have to be especially careful to protect ourselves from damaging ultraviolet radiation, under the Antarctic ozone hole. Litres of sunblock are used each day, and when we set off to work we can look like a group of ghosts so much cream has been smothered on. Anything left on the snow surface - especially if dark - quickly melts into the snow, and we are having problems keeping some experiments cold enough. In one experiment we have a series of water filled quartz bottles on the snow surface to investigate the effects of ultraviolet radiation on the chemistry of these waters. After only six hours in the harsh sunlight, the temperature of the water in the vessels was already up to five degrees celsius. Hardly what comes to mind when thinking about frozen oceans.

A strange beginning to married life - on your own and in the Antarctic © David N Thomas

A strange beginning to married life - on your own and in the Antarctic © David N Thomas

On a completely different note, we had a wedding on board. Or strictly speaking, the groom in the Antarctic married his bride who was still in Brazil. By some legal wrangling that I still do not understand, it was possible for the couple to get married long-distance. The brother of the bride actually signed the marriage certificate! Naturally this was cause for celebration on board. His colleagues hosted a reception, and there was a special wedding cake prepared. Then he was taken by skidoo to the Honeymoon Suite of the Antarctic Hotel (a decorated tent on the ice), where he was able to spend some quiet moments on his wedding night alone. He didn't stay out too long, and without a doubt it was the strangest wedding any of us had been to.

David Thomas
10th December
68°S 55°W