Will the sea ice break out?

Loading from the ship on sea ice.

Helicopter resupply Mawson 2011.

Resupply of Mawson by the resupply ship. 'Aurora Australis' is due at the station on 22 February 2012 – Will she get in?

Icebreaker 'Shirase' photo courtesy of AAD.

This is a question exercising the minds of station staff on a daily basis. Last year the resupply was done by helicopter because the fast sea ice was out to 70km off the coast and was too thick to penetrate. As a result some cargo was not unloaded and re-fuelling of the station was was not carried out.

Re-fuelling of the station is necessary in 2012 to keep the station operating. The Australian Antarctic Division have a number of possible strategies in hand to ensure refueling takes place. Resupply by helicopter and a chartered ice breaker the ‘Shirase’ to push a path through the ice for the Aurora Australis are being considered. But will the ice break out beforehand?

Satellite images show that the outer ice edge is, bit by bit, gradually breaking off but at the end of December the edge was still in excess of 40km from Mawson.

The condition of the sea ice near the station had sufficiently deteriorated to cease all ‘on foot’ sea ice travel from the 23rd December 2011. Quad travel had ceased a week earlier. 

The last trips on the sea ice ensured that Susan and Julie, two penguin biologists, were safely on Bechervaise Island with sufficient provisions to last until the ship arrives on 22nd February.

Julie and Susan haul their equipment to Bechervaise Id.

Provisions not already delivered, including personal belongings, work equipment, computers and extra water were hauled on sled across Kista Strait. Christmas and New Year were celebrated by the biologists in isolation from the rest of Mawson. Station music, available on radio, was the only link to the festive social activities happening on station.

Shore ponding on Bechervaise Island

Rotting ice in Horseshoe Harbour

A warm November and temperatures around zero degrees Celsius through December resulted in considerable melt of snow and ice around the station. Melting snow and ice in contact with the warmed rocky shores as well as melt streams from the plateau entering the sea along the coast accelerate the rotting of the ice close to the shore. This is particularly the case in Horseshoe Harbour.

From http://earthobservatory.nasa.gov/IOTD/view.php?id=76821&src=eoa-iotd

Dates of previous breakouts indicate that since 1954 the break out date has been getting later in the season and in recent years the sea ice has not blown out at all during the summer on 3 occasions. On average breakout would be expected by the third week of January. In the records available there doesn’t appear to be consecutive years when the ice has remained fast to the coast so the odds are good for a breakout this month (January).

From data provided by AAD.

A breakout means the ice sheet becomes broken and the pieces are then blown out to sea leaving only water along the coast. Three factors assist with a breakout, high tides, large swell waves generated by storms to the north and strong off shore wind all at the same time. Blizzard conditions on January 3rd and 4th provided 2 of the three. 
It would be great to see water in the harbour and Kista Strait and it would enable the launch of the rubber boats.  Seeing the Aurora Australis in the harbour would also be special as would the dramatic change in scenery around the station with the ice gone. Time will tell.