09-25-05: Ruben's Report from Lomonosov Ridge Options

[Ruben_Fritzon]

Report from USCGC Healy
Sunday the 11th of September 2005

Weather: Cloudy with fog, ±0ºC, 20 knots of wind from northeast
Longitude: 161 15.969 W Latitude: 89 31.524 N
Heading: 323º
Speed: 3.9 knots

We are now in the area of the Lomonosov ridge, only 75 nautical miles from the North Pole. This area is one of the major sites for this expedition. The ice conditions are very hard which have delayed us a couple of days and also forced us to leave the planned route. The last few days we have been able to keep up good speed, about 7 knots, but not with the right heading. Crossing back and forth between the ice floes makes our effective speed to only 2.5 knots. Right before we came here both the Oden and the Healy had problems getting through the ice. This made us go round in circles. Strong wind and fog also made it impossible to use the helicopter to find a good route. Rather than getting stuck in the ice the captains of the Oden and the Healy decided to stop and wait for better conditions. During this 7 hours stop we drifted nearly 4 miles to the south!



This area is of great interest for the scientists. The Lomonosov ridge is a true water divider which prevents the deep water in Makarov basin from mixing with Amundsen basin. Previous models showed that there should be a 2400 m deep gap in the Lomonosov ridge where water could flow in between the basins. Bathymetric data from this trip showed this was almost true. The gap was only 2000 m deep but a lot wider than expected.

The water column has several layers of water with specific temperature and salinity. The instrument used for measuring these parameters is a conductivity, temperature and depth- probe, CTD (se pic). These are all factors that affect the density of the water. Colder and saltier water is denser than warmer and fresher water which makes the cold and salt water to place it self under the warmer and fresher water. The CTD makes it possible to get a ‘finger print’ of a specific water mass and therefore also possible to track where it comes from. For example, the deep water of the Makarov basin is almost half a centigrade warmer than the deep water of the Amundsen basin. Finding the ‘fingerprint’ of a certain water layer from Makarov basin in the Amundsen basin would indicate that water is moving between the basins.

During the survey around this area both Oden and Healy has been making several CTD-cast at different depths which shows interesting data about how the water is moving through this area. We have also collected sediments from the bottom using JPC and multicore, to find out more about the history of the water flows. Hopefully this data can increase the understanding about the history of the Arctic Ocean!




-Ruben