In summer 2018, we travelled to the Juneau Icefield, Alaska, with funds from Columbia’s Lenfest Junior Faculty Development Fund. Our aim was to use radar to measure how quickly snow turns to ice.
Snow is gradually buried and compacted under its own weight. It is difficult and time-consuming to measure, so we are developing a technique using an ice-penetrating radar that could make it much easier and quicker to monitor this process. Compaction of snow (or technically, firn, which is Arctic snow that has survived more than one full year) is important because it impacts how we measure the mass of glaciers and ice sheets.
The first stage in the expedition was a flight to Juneau, AK, where we spent three days packing, re-packing, testing a drone, swimming at an Alaskan beach, and we even had time for a meal at a restaurant overlooked by some huge cruise ships!
To measure how quickly snow compacts we needed to find some snow. In the temperate climate of Juneau, Alaska in summer, this means flying a short distance inland to the top of the Juneau Icefield by helicopter.
Why don’t we just stay in NYC and wait for the winter, you may ask? Because in the upper reaches of glaciers and ice sheets, the snow never melts away completely and lasts for hundreds of years before turning into ice. This ‘firn’ behaves differently than the snow that falls in the winter and melts in the following summer. So we needed to find some firn and Juneau Icefield is one of the most easy-to-access places to do that.
We flew up to the highest place on the ice field using a commercial helicopter company that usually runs sightseeing trips. This was all organized by the amazing Juneau Icefield Research Program (JIRP). They have been giving young people their first experience of geoscience and cold-region fieldwork for over 70 years. Every summer, they traverse the ice field on skis (75 miles!).
The helicopter ride took us up to Camp 18, perched on a rock between two beautiful glaciers flowing out from the ice field. We were met by the JIRP staff and students and eased into a few days of camp life, with chores, packing and preparing for the ski up to our field site. After three days we were ready to head to the ice divide.
On the Ice Divide
We set up camp on the ‘ice divide.’ This is where ice flows outwards in two directions: one southwards into the US and one northwards into Canada. We started by drilling several ice cores to measure the density of the snow, firn and ice. We brought up samples from up to 70 feet below the surface. This information is vital for interpreting our radar data.
For our 10 days at the divide we had incredible weather! This is not what we were expecting — it was a struggle to keep cool in a place where we usually have to work to stay warm. We had plenty of enthusiastic JIRP students to help with the drilling, and it went smoothly (mostly) until the very end, when we barely rescued one of the parts of the core.
When we weren’t drilling, we took radar measurements with plenty of help from the JIRP students. In small teams we drove around the surface of the ice on a snow machine pulling a sled, and made 182 radar measurements at 91 points over four days. As each measurement takes about two minutes, and involved a lot of standing around and talking about glaciers. Luckily, for most of the time we had incredible, sunny weather. Very unusual for this area. Eventually, the weather reverted to its usual fog and rain and treated us to a wet last day of radar. After that we were ski-towed back the Juneau Icefield Research Program Camp 18. After a few days we helicoptered back down to town.
Visit the Earth Institute’s State of the Planet blog to see more photos from Kingslake and Case’s Juneau fieldwork.
— Jonny Kingslake is an assistant professor at the Lamont-Doherty Earth Observatory. Elizabeth Case is a graduate student at Lamont. Both are studying glaciers.