After two-and-a-half years, the adopt-a-buoy project draws to a close

13 January 2020

In April 2017, sea-ice physicist Stefanie Arndt from the Alfred Wegener Institute in Bremerhaven proved once again that necessity is the mother of invention: she and her colleagues were wondering how they could present their research on sea-ice physics in a more appealing way for the ‘Open Ship’ exhibit on board our research icebreaker, RV Polarstern. The idea they ultimately came up with: inviting young visitors (schoolchildren) to draw or paint pictures that would then accompany autonomous measuring devices (buoys) as they drifted through the ice-covered Arctic and Antarctic Ocean. Children across the country joined in, and Arndt had soon received more than 60 pictures from enthusiastic young artists aged 3 to 16, from Hamburg all the way to Munich – and as stand-alone works of art or group collages (see examples here) – at her ‘polar post office’ in Bremerhaven.

Since the planned Arctic expedition, on which the pictures were meant to decorate the polar bears’ home, didn’t take place as originally planned, Arndt took all of the pictures with her when she travelled to the Antarctic – which was on an expedition that didn’t start until January 2018. “So as not to keep them waiting too long, I also gave the children the chance to share in the preparations for my upcoming expedition – and of course I always let them know where their pictures now were,” she explains.

Then the time had come: between 11 and 26 February 2018 the buoys, together with a host of colourful pictures, were deployed in the Antarctic. “At first my colleagues Marcus Huntemann and Nicolas Stoll, who helped me with the work on the ice, didn’t know exactly what it was all about – until they got a chance to see the pictures for themselves. Not only were they impressed; they also understood precisely what needed to be done: after each buoy was set up, a group of pictures were selected to accompany it – and then came the most important part: taking a photograph of the buoy in the icy landscape as proof.” Once back on board the ship, the photo was then used as part of an adopt-a-buoy certificate and, together with information on when and where their picture began its journey, was mailed off to the children. “When it came to mailing the certificates, I received a tremendous amount of positive feedback – not to mention questions from curious children. The most common one was: How cold is it where you are?” the sea-ice physicist recalls. “Of course, it’s a perfectly normal question to ask. But I never imagined it would be so exciting for the children. This also made my job easier, because I suddenly knew how to begin the life story for each buoy: with the temperature on the day it was launched with their picture.” Therefore, as soon as each respective buoy stopped transmitting, because its home ice floe disintegrated and it sank in the ocean, or because it was crushed by shifting pack ice, Arndt would sit down in her polar post office and write down its buoy biography. In these biographies, the children found answers to questions like: From where to where did the buoy (and my picture) drift? How many kilometres did they travel? What storms and snowfall did my picture get to see? How much snow gathered on my picture? “Writing these reports was a lot of fun for me – because you then look at very straightforward aspects, like the accumulated snowfall or the number of storms, and arrive at insights that are of considerable interest, and not just for the children, but also us researchers,” she explains. 

Unfortunately, the first buoy quit transmitting in mid-March, because a major storm had destroyed its ice floe. By December 2018, 11 of the 13 buoys with accompanying pictures were out of action. According to Arndt, “Unfortunately, the majority of the buoys deployed during this expedition stopped transmitting fairly early on. We suspect that the massive iceberg A23, which was in our research area, might be the culprit: thanks to its position, comparatively close to the southern ice shelf of the Weddell Sea, the sea ice tends to get jammed between the iceberg and shelf – where the mounting pressure causes it to break up.”

In Arndt’s eyes, the snow buoy (2018S59) and ice mass balance buoy (2018M11), which continued to transmit data well into 2019, are two absolute highlights. The destination area for the subsequent Polarstern expedition to the Weddell Sea in February 2019, i.e., a year after the buoys were first deployed, included the Larsen-C Ice Shelf and the iceberg A68. This meant it might actually be possible to retrieve the two buoys: both had been transported north, along the Antarctic Peninsula by the Weddell Gyre – putting them on a ‘collision course’ with Polarstern’s planned route. And lo and behold: even though the intended destination couldn’t be reached due to the ice conditions, the snow buoy (2018S59) was within helicopter range of the ship, allowing Arndt and the rest of the sea-ice team to fly to it. As she recalls: “Trying to find a white buoy in a snow-covered landscape was like trying to find the proverbial needle in a haystack. But thanks to several pairs of trained eyes, we actually found it fairly quickly.” This was anything but self-explanatory, since the ‘landscape’ looked quite different than it had a year earlier, when Arndt and her team had first installed the buoy on the ice. “The buoy was surrounded by pack ice hummocks – and was leaning to one side and crooked.” The snow data transmitted had stopped making sense in June 2018 – when the floe was compressed into these hummocks. But the other data continued to be transmitted. “This is the first time we’ve ever been able to return to a buoy deployed in the Antarctic Ocean; that was really my personal highlight.” In addition, the team gathered snow and ice readings on the floe – just as they had a year earlier, which makes the buoy’s dataset all the more valuable. After the team’s visit, the buoy continued drifting north until late April 2019, when it stopped transmitting somewhere in the marginal ice zone.

The ‘last survivor’ from the adopt-a-buoy project was the ice mass balance buoy (2018M11), which continued transmitting until 27 November 2019, when it, too, was lost in the marginal ice zone. In the course of 1 year, 9 months and 9 days, the buoy had traversed the Weddell Sea and covered a distance of more than 8200 km. To give the children a better idea of what this distance means, in the buoy biographies the sea-ice physicist described it as “the distance from Berlin to the North Pole – and back!”. And that’s not the only impressive fact: no other ice mass balance buoy has ever recorded reliable data from the Weddell Sea for so long. According to Arndt, “The thermistor chains used in the buoys are delicate, and in past years, we’ve seen them destroyed time and time again by storms on the surface, ice compression, and the like. That’s why we’re all the more excited about this long time series – and its scientific analysis.

”With the loss of 2018M11, the buoy project has now come to an end. When asked if she plans to launch any similar projects in the future, the AWI expert laughs: “A lot of people have been asking me that lately. I’d very much like to set up a comparable project, because I think it makes our research and findings much more concrete and relatable for the children, their parents and teachers when we try to make them part of our work. That’s very important, since we’re conducting research for the sake of their future – so that the next generation, too, can live in a world with a white continent, Antarctica, and an ice-covered North Pole, the Arctic.”

Dr. Stefanie Arndt
Dr. Renate Treffeisen