2013-12-28

Into the Southern Ocean

Pos: 61°26.531 S, 162°46.472 W
Sea: 3 m
Wind: SW 14 m/s
Weather: Grey

We have crossed the 60° S latitude and are now in what is generally referred to as the Southern Ocean. It comprises all water south of 60° S which encircles the Antarctic continent.





 A quarter of the Southern Ocean. Red squares are our mooring (= underwater stationary instruments) sites, the boat is our current position. Approximately 2300 km to go still.


The Southern Ocean normally has  a depth between 4000 and 5000 m, with the greatest depth being the South Sandwich Trench at 7236 m. The continental shelf area is comparatively deep and narrow, up to 800 m deep. The Southern Ocean  is the source of most of the cold and fresh bottom water for the world´s oceans. It is stongly influenced by the perpetually eastward flowing Antarctic Circumpolar Current (ACC). This is the stongest ocean current anywhere, with 100 times the flow of all the world´s rivers combined.


Jets and eddies in the ACC (from an ocean model)


Pretty soon at around 65° S we will encounter some ice. But most of our moorings, except for one, are in more or less ice free zones, according to the Polar View sea ice map from two days ago. Data is from the Japanese satellite Shizuku



Polar View sea ice map. Moorings are red squares

Today we have been working with our MicroCATs, which will be deployed on the mooring wires measuring Salinity, Temperature and Depth. (see my earlier post "Scientific Background" for more info). The right setups must be configured and they also need a test run in a box of saltwater.




Anna reassembling a SBE 37 IMP

They are very fine (and expensive) instruments made by Sea Bird Electronics. The accuracy of the temperature sensor is +- 0.002 °C. I find it quite remarkable that the battery pack, consisting of 12 Lithium cells with total voltage of 14 V will make it run for three years, taking measurements every 15 minutes in a -2°C environment.



Battery pack (exciting isn´t it?)


Our internet connection is slowly getting weaker. It is now a matter of days until it will be all gone. Hopefully I will be able to do another post. I will end now with the obligatory albatross.



Albatross in the big grey

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