As part of my activities onboard the Akademik Fedorov, I installed a seasonal sea ice mass balance (SIMB) buoy. This buoy was developed at CRREL (Cold Regions Research and Engineering Lab) and is used to measure sea ice melt and sea ice growth from both top and bottom. You can check the data this buoy is collecting in real time on this website: http://imb.crrel.usace.army.mil if you search for 2013H.
As it was my first buoy deployment ever, I decided to check if everything is working properly. So during the first week of the cruise I connected all the instruments on the helo-deck and got a successful transmission. All was left to do was to wait until we reached the proposed location and deploy the buoy. Due to weather and sea ice complications, we did not get as far north as originally planned. Our vessel, the Akademik Fedorov, can only sustain sea ice less than 2m, and honestly she feels a little easier in less-packed ice. So as we headed north and the sea ice became thick enough for the buoy deployment, we decided to do an ice station on September 3rd, 2013 when our location was at latitude 80degrees 15.7min N, and longitude 155degrees 54min E. Simultaneously to the SIMB we deployed an O-buoy, an ITP (ice-tethered profiler) and a met-buoy. The O-buoy has a webcam mounted on it and as it was the first one to be deployed, it recorded the process of the SIMB installation. I wish I had internet access to see the footage!
A completed buoy looks like a pipe, standing perpendicular to the sea ice cover, with the majority of its length underwater (remember that when ice floats on the surface of the ocean the majority of its mass is underwater). Initially we drilled a 2-inch hole to measure the ice floe thickness. It was 140cm thick with a 5cm snow layer on top – an ideal thickness for our buoy deployment. We then drilled a 10inch hole for an actual buoy to be deployed in. The anchor goes in first – we held it with a metal rod while we attached the rest of the pipe to it. Without the pipe, the anchor would have sunk, but the overall density of the buoy makes it buoyant, and ensures that it floats. The SIMB has a simple design, to ensure a novice like me can deploy it in the field. However, it does help to be prepared – a set of tools, such as a flathead and a Philips screwdriver, electrical tape, a knife, and a power drill, will speed up the installation dramatically. Luckily I had our cruise technicians around and could borrow their tools and expertise. It also helps to have extra hands around – balancing a long pipe as you lower it down into the hole is rather awkward if you only have one or two people around.
A couple of days ago I got an e-mail from my mom. She went to the buoy website and was able to obtain new measurements. It turns out that it was snowing on the sea ice floe where we left the buoy – about 3cm of new snow has accumulated over the first week. At the same time, sea ice has been melting from the bottom! The bottom melt has traditionally been overlooked as it is really hard to observe. However, it is believed to be an important contributor to sea ice changes in the Arctic. Buoys like SIMB help us understand the processes important for sea ice mass balance in greater detail.
- Masha Tsukernik