August 8, 2015: Juggling

Now that all the teams are working and producing fabulous results, there are lots of things to juggle. Thankfully the weather is cooperating. It is sunny, although a little colder. It was below freezing in the morning but it warmed up a bit this afternoon (remember, there isn’t really a morning – the sun is up 24 hours a day, so we have arbitrarily set our clocks to Greenwich Mean Time). The wind shifted a bit and is now out of the north, and that is helping the sea ice break up and head down Nares Strait (thankfully away from us). The mouth of Petermann Fjord still has quite a bit of ice, and the big tabular berg that broke off the ice shelf as we entered Petermann Fjord is out there now; it is starting to break into ship-sized pieces and a few have rolled onto their sides. So we are still dodging traffic of the icy kind.

Amazing results are coming in faster than we can assimilate.

The ice shelf team has completed its first borehole, using hot water to melt their way through the thick (100-200 meter) floating ice, near a central meltwater channel. They dropped a coring device through the borehole, lowered it several hundred meters through the seawater cavity under the ice, and took a two-meter sediment core. They are boxing the core up tonight and it should be on the ship tomorrow. Then we will move their camp to their next site near the glacier’s grounding line – far inland from where we are now.

We are all on the edge of our seats waiting to see the sub-ice core and send it through the instruments brought from Oregon State (OK really we don’t have time to sit down, but we are still excited). Before we even cut it open the core we will shoot gamma radiation through the core, and from that we can tell the density and porosity of the sediment. At the same time we measure the magnetic properties of the core – this tells us about the source of the sediments. Next we extract some of the pore water – water trapped in the sediment between grains, and we will take that home to measure its isotope chemistry. This will tell us whether fresh water from glacier melting is moving through the sediments, or if the bottom water under the ice shelf has changed in the past few hundred years – it is a tricky measurement. Finally we will cut open the core and use high-resolution digital photography, and both visual and microscopic descriptions of the sediment, to see what is going on. We’ve already done this on most of the nine cores we’ve taken in the fjord, which range from the current (i.e., since 2012) ice front, to the outer fjord near the shallow sill that separates Petermann Fjord from Hall Basin (which is a wide spot in Nares Strait between Greenland and Nunavut, Canada).

Our results are preliminary, but they already showed that the Petermann system has experienced some big changes in the past. We think the sediment accumulates quite rapidly here, and that means we will have a very detailed record.

Other highlights – Our physical oceanographers have great new data on water temperature in the deep fjord. They are mulling this over and comparing to past data. Smiles on their faces but also very serious looks as they ponder what is happening since the first measurements were made in the region about 14 years ago.
Physical Ocean

 

The boulder team is visiting the ship from their camp tonight; it saves fuel to have them stay onboard for a shorter helicopter flight to their next study area. They are sampling granite boulders carried by Petermann Glacier from Greenland’s interior. The team is buzzing with excitement, and also is thankful for a good meal and a hot shower after a week in the field. They will head back to camp tomorrow night. The beach team started in a new and fascinating area in Hall Land.

Beach Site

This is where Charles Hall, the leader of the 19th century Polaris Expedition that sought the North Pole, is buried – some say murdered by his crew.  We looked around for his grave; didn’t find it, but did find an archeological site with evidence of people living here.  We are not here to study archeology, so we were careful not to disturb anything, and we took no samples – it is very important that such sites not be damaged by untrained observers.   Back to the beach, we found very recent polar bear tracks and a less recent musk ox skeleton.  And plenty of evidence for marine shells now above sealevel, recording rebound of the land when the big glaciers retreated.

Beach Crew

The beach team also can’t wait to get back in the field tomorrow morning. We visited (and delivered freshly baked bread, still warm) to the Swedish biology team working higher up in Hall Land. They too are getting great data. Tonight we have succeeded in getting Icebreaker Oden past the ice still choking the entrance to Petermann Fjord, and all night we will spend mapping the sea floor in Hall Basin. As I write (about 1:00 AM) the ship is still in Greenland’s waters, but I can see Ellesmere Island, Nunavut, Canada, in the distance.Alan on the Beach

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