Sunday January 5, 2016
Posición 74° 52’ S, 34º 02’ W
Temperatura del agua -1,9°C
Temperatura del aire -8,0°C
Breaking ice.
This year the characteristics of sea ice are being especially harsh. The maps of ice coverage obtained via satellite indicate that sea ice and icebergs almost cover completely the way to the west of the Filchner Depression. During the last days we already start navigating breaking ice which has dramatically reduce our average speed from 10 to 3 knots, i.e., 10 nautical miles per hour (18 km / h) to only 3. These conditions of navigation force Polarstern to increase daily fuel consumption from 30 tons of fuel to almost 60. This situation means that the Captain is constantly adjusting the route to save fuel as we still have mañ miles to navigate and perhaps more difficult conditions. The spatial distribution of sea ice changes every hour because of the wind and sea currents. To choose the best way across sea ice there are two main tools, the satellite images, which are received every day at different times of the day and helicopter flights to observe the conditions of the route ahead along Polarstern plans to navigate. The team of meteorologists on board provide interpretations of satellite images every morning and they explain them to us during the meeting that we have every morning at 09:30. Previously, they have met with the Captain and the Chief Scientist at the bridge of the ship. The two helicopter pilots also attend to these meetings to learn the ongoing conditions and decide whether flying is possible to guide the Polarstern if necessary. Now we navigate towards the latitude of the British, Halley Research Station, which is also anchored to the ice on the Brunt ice shelf, on the eastern flank of the Filchner Depression. The Captain wants to learn about the conditions at a docking station there because in case we cannot reach the western flank of the Depression this will be a disembarking spot of the equipment we are supposed to leave at a deposit that the Alfred Wegener’s Institute and the British Antarctic Survey share on the Ronne Ice Shelf. Here, both Institutions, among others, conduct an investigation on the flux of water under the Filchner-Ronne Ice Shelf. This area is particularly important because here circulation of water generates super-cold water (having temperatures up to -2.1 ° C), which due to its low temperature has relatively high density and sinks activating the global thermohaline circulation. This circulation of deep water carries cold water towards the Ecuador and heat toward the poles, thus regulating global climate. It is the largest circulation belt across the planet and has a duration of about 1000 years. Currently, it is especially important to know in detail the temperature variation that this water may have to calculate its rate and consequently its impact on the potential disintegration of the Filchner-Ronne Ice Shelf, circulation and global climate. So far this Antarctica is showing us her most white face and Polarstern her more powerful side. An impressive combination that let us see how small we are against nature but also how well we can do things to know it better.
Best regards,
Enrique
Polarstern’s path after ice breaking.
White Antarctica.
Frozen sea ahead Polarstern.