November 8- Sampling ice

A lot can happen in two weeks even if it is at a slower pace than normal due to the cold and wind. Our temperatures are not that cold by Fairbanks standards, hovering around -20F. However, when you add 15-20 knots of wind you quickly arrive into the -35 to -40 range. This takes its toll on both people and equipment when working outdoors for hours on end. There have been some cold injuries but for the most part people are taking care of one another with constant questions about their well-being and making people who show any signs of cold take a break in a warmer space or return to the ship. We are not all created equal when it comes to working in the cold.

We have finished installing our fish camera and sediment trap at depths of 370 and 200 m respectively below the sea ice for our Chinese and Swedish partners.  We have drilled an inordinately large number of 12-inch holes in the sea ice to create circular blocks of ice that can then be pulled up onto the ice floe to create a working hole. We have literally removed a few tons of ice to create holes large enough to install the equipment. In addition, the is now an 8 ft by 8 ft hole beside the ship that we will use to deploy oceanographic equipment from the ship. 

The big CTD hole next to the ship. Photo by Esther Horvath/Alfred Wegener Institute

This morning was the first opportunity to test the large hole alongside the ship. Along with two others, I arrived at the gangway at 0700 to wait for the equipment to be lowered to the ice so we could begin to remove the ice that had formed in the hole overnight (-24F and 10 knots of wind). The makeshift cover was lifted from the hole and we began cutting the ice around the edges using a chainsaw and ice saws. Within a half an hour we had a serviceable hole. [I should note that a submersible pump is constantly moving water to the surface from a depth of ~10 ft. This makes it more difficult for the water to freeze except at the edges of the hole where we can cut it and remove it in blocks if necessary (the hole will be worked on several times per week).]

After the hole had been prepared the next stage of the operation involved coordinating with the crew to move the water sampler into position. The water sampling equipment is sensitive to temperature, so if possible it needs to be kept at or above freezing. Being the first exercise with this new equipment, there was much debate and consternation about who had come up with these grandiose ideas and where they were now. At any rate the large CTD rosette was encased in a larger heated frame and covered with a red vinyl shroud. Heated air was then pumped into the structure as it was wheeled out on deck and then lowered toward the newly ice-free hole. The structure was lowered towards the hole while we guided it to its landing spot, two boards that spanned the hole. Once the frame was sitting firmly on the boards, the CTD rosette was lowered into the hole through the bottom of the covering. It began its decent to ~3300 ft (1000 m) all the time recording the temperature, salinity, chlorophyll concentration, amongst other important variables. The door to the frame was opened and the covering was pulled away from the wire and set aside until the CTD returned to the surface. All told this exercise took ~3.5 hours. Under normal operating conditions during the Arctic summer this procedure would normally take right around 60-70 minutes from deployment to recovery. The lesson for many today was that sampling plans will need to be modified during the long winter nights as temperatures and extra precautions will not allow for the lofty plans of scientists conceived during meetings located far from the realities of the Arctic.

The CTD instrument. Photo by Rob Rember

The UAF team has been able to skirt around the difficulties of working with large quantities of water by concentrating most of our work on the snow, the ice and small volumes of water that we collect from directly under the ice. One of our larger responsibilities as a ‘UAF team’ (comprised of Marc Oggier and I) is to coordinate the sea ice coring work on Mondays for the sea ice, ecology and biogeochemical teams. We were tasked with building two teams of 5 people. One samples ice that had survived the summer melt season as well as newly forming ice. By the time the camp setup had ended and the cities were built, we had ~35 cm of new ice that had grown in open water since this past summer, we are calling this first year ice or FYI. The second year ice (or SYI) is highly variable in its thickness so it was more challenging to find an area that is accessible for a year.

Last Monday (October 28) we attempted coring at both sites simultaneously. It was around -20F that morning but there was little wind. This was the first time that the two teams, comprised of members from around the world, had worked together. We left the ship before 9 am arriving by 9:15 at the SYI site where we discussed where Marc would start the first of ~50 sampling weeks. Five minutes later, the second team left for the FYI site where we set up temporary camp. Camp consists of unloading the ice coring equipment and setting up an ice fishing tent to cut or ‘section’ the ice. Once up, the tent is readied by getting sampling bags and containers prepared for the ice cores. We had a small meeting to discuss where to start. Our two Russian experts (Nikolai and Egor) gladly accepted the task of physically doing the ice coring. I have to say they were fantastic to watch work. They took great effort in removing the snow from the ice and collecting the core. One requirement from some of the science teams was that no water should rush to the surface of the ice after the core was collected as frequently happens during coring. They managed this by feel and sound as each core was extracted. First you can hear the water entering the barrel as you descend into the more porous bottom of the ice pack and finally there is a slow release when you fully cut through the bottom of the ice pack. Normally ice cores will break at weak points during coring but they did not break a single core. They took their jobs very seriously and are great to work alongside. I am sure I will never hear them say it is too cold to work.

Ice coring in the dark winter night. Photo by Esther Horvath/Alfred Wegener Institute

We had a list of ice cores ~ 25 long at each site. We set up the coring schedule so that while cores requiring cutting/sectioning were worked on, other cores that could be simply bagged were collected and set aside. As we worked through our list of ice cores, for the first time I realized that we had overestimated the amount of time required. Our efficient system was working well and by 1230 we had completed 95% of the work. At that point our bear guards were replaced with others from the ship. We continued through the remainder of the 25 cores and moved on to collected sea water and snow. Both teams were back onboard by ~2:30 pm having collected all cores and all water samples. Back onboard, I discovered that not everyone thought it was possible to collect the full core list at two sites in a single day. Both groups were congratulated at the evening meeting. Marc and I certainly did not do it alone, people from many nations worked together including Germany, Russia, China, Canada, Norway and the US. Good planning and common goals always help achieve good results. We repeated the exercise this past Monday (November 4) with the same results even though it was considerably colder and windier. We are off to a great start with respect to collecting weekly ice cores for a year from our two sites. Marc and I are also going to start coring at other sites as time allows on Saturdays. This will help us to address some questions about variability of the ice within a couple kilometers of the ship.