10 - 16 September 2007

After extending our transect far into the Canadian Basin we turned towards the Mendeleev Ridge and then headed back towards Siberia. We focussed on finding positions for our remaining buoys. Besides oceanographic ones we had to distribute eight meteorological buoys. They measure surface air temperature and pressure and by their position they give information about the ice drift. Such meteorological measurements provide basic knowledge for understanding the sea ice decrease. Yet, the Arctic atmosphere is connected with the one of Europe and thus any regular observation here in this under-sampled area will improve the weather forecast in Europe. The meteorological buoys were deployed on the same floe as the oceanographic buoys or in hundreds kilometres distance.

A plan for an array of both buoy types was coordinated internationally early this year, but during the course of summer it crumbled away along with the ice. Almost weakly a new plan had to be collated in order to adapt to the changing ice conditions. Three oceanographic buoys were deployed at fairly good ice conditions from a Canadian icebreaker in the Beaufort Sea. Nine more buoys were scheduled for our expedition and that of the Russian ice-going ship “Academic Fedorov”. Six of them belong to the European Union programme DAMOCLES (Developing Arctic Modelling and Observing Capabilities for Long-term Environmental Studies), one is from the Japanese institute JAMSTEC and two are from AWI.

The enormous retreat of the sea ice in the East-Siberian Arctic defeated the plan to deploy these nine buoys in a region which in the past was the up-stream end of the Transpolar Drift from where the buoys would have had a long drift. But also further north the state of the ice gave us a headache. While the meteorological buoys are small and compact and could be transported by helicopter to any floe of moderate dimensions, the deployment of the heavy oceanographic buoys required finding a suitable floe in the immediate vicinity of the ship. “Suitable” means a diameter of at least some kilometres and possibly 2 meters thick. These criteria were hardly met by any floe in the Siberian Arctic this summer. Apart from compressed ridges, everything else was only a meter thick, porous and pierced with melt ponds so that there would be a considerable risk that with the next storm they would break into pieces.

At first we deployed the Japanese buoy in the central Makarov Basin. We had to go as far north as 87°N to find a suitable floe. After a couple of hours of hard work the buoy was in the ice, but unfortunately the final performance test showed some malfunction. So we had no alternative than to recover it; that meant that we had to retrieve 800 m of cable from below the ice – not very pleasant without the comfortable gear that is available on the ship but not on the ice. Since the poor ice cover made us assume that we would have to take one buoy back home anyway, we decided to rather deploy this buoy.

A few stations were conducted while crossing the Lomonosov Ridge then we headed for a region in the Amundsen Basin that looked promising on high-resolution satellite Radar images provided by the sea ice group from the University Hamburg. This time we really needed a large floe because we wanted to deploy four buoys in a certain distance of each other: a turbulence buoy for determining the fluxes of heat and salt between water and ice, an acoustic current profiler for the velocity in the upper few hundred meters, a CTD-profiler for temperature and salinity and an ice mass balance buoy measuring the seasonal variation of snow and ice thickness. This was comprehended by a webcam – even though only qualitatively, visual impressions reveal a lot about the weather and ice situation.

Indeed, we met several large ice floes, beautifully covered with snow hiding the enormous extent of melt ponds; a few drillings, however, revealed the misery. Eventually we decided for a huge floe, tried not to break the fragile beauty when going alongside and after an ice thickness survey during the night we found that there are some thick sites in the vicinity of ridges - just enough for all buoys. The next morning at Beaufort 6 and a snowstorm we started to drill holes and deploy the various buoys. One of them had a diameter three times that of the auger – and with ice twice as deep as the augers length it took some 12 hours and a thorough drilling strategy to get a suitable hole at all. But after two days each buoy was at its place and during the following days data gradually arrived from all buoys proving that they are working and transmitting data properly – great relief everywhere!

A day later two Russian ships crossed our way; “Academic Fedorov” and the nuclear ice breaker “Rossya”. They were also desperately searching for a large thick ice floe, which however was supposed to respond to even higher demands than ours because it should carry a manned drift station for one or two years. It would have been the 35th one in a long row of scientific Russian (or Sovjet) ice stations – this year cancelled for the first time due to the lack of sea ice stable enough to hold such a station.

We will leave the ice in the coming week and turn towards Laptev Sea, until then best regards in the name of all participants,

Ursula Schauer