#mosaicclouds

The German research icebreaker Polarstern has been drifting through the frozen waters of the Arctic Ocean since September last year. Julia Schmale, an atmospheric scientist from EPFL, joined the crew two months ago to study cloud formations and their role in local and global climate change.

More than two months ago, EPFL researcher Julia Schmale joined the crew of the Polarstern, a German research icebreaker that has been drifting slowly through the frozen waters starting north of Siberia towards Svalbard since September last year. The vessel is carrying an international team of scientists on a year-long research expedition, working in unusual and often challenging conditions: changeable weather, temperatures plummeting as low as –40°C, interminable darkness giving way to endless daylight, and ice as far as the eye can see.

The crew is carrying out research as part of a major expedition titled Multidisciplinary drifting Observatory for the Study of Arctic Climate, or MOSAiC for short, which aims to gain fundamental insights into conditions in the Arctic, the impact of climate change on the region and vice versa the region’s influence on global climate change.

Schmale, an atmospheric scientist, is leading the observatory’s atmospheric research team. She had planned a mid-April return to Switzerland, where she was recently appointed head of the brand-new Extreme Environments Research Laboratory at EPFL, but the COVID-19 crisis means she will remain on board until early June. Schmale is no stranger to polar environments, having taken part in the Antarctic Circumnavigation Expedition (ACE) in 2017. Her role in this latest expedition is to study how airborne molecules and particles influence cloud formations in the Arctic. In this interview, she talks to us from the front line about living and working in this extreme environment, what it’s like to head out onto the ice floe, and the aims and methods of her research.

- What’s it like living and working on the ice?

“Unpredictable. The icescape changes frequently and new cracks, leads and ridges form overnight, often preventing us from reaching our research sites on the ice. Depending on how severe the changes are, we might need to go scouting for a new route or reschedule whatever activities we had planned. Sometimes the ice becomes dynamic during the day while we’re out. When that happens, we either have to keep a close eye on our path back to the ship or we get called back by the bridge, where the on-board team coordinates and monitors activities out on the ice. Before we head out, we always complete a trip log detailing who’s going where, what gear they’re carrying and – importantly – who’s acting as the polar bear guard. Most of us are qualified polar bear guards, a role that involves keeping a permanent lookout while our colleagues are working. We carry a flare gun to scare any bears away, as well as a rifle to use if an animal approaches us too quickly. On 23 April, we saw the first bear on our floe since we arrived in early March.

The environment is just beautiful. It was still dark when we arrived, with only a slither of daylight on the horizon. The research sites on the floe looked far away, but they were easy to reach across flat ice. Now, with the sun up 24 hours a day, everything seems much closer. But moving about is much harder because many leads and cracks have formed, especially between the ship and our team’s main research site. With temperatures at around –20°C, open leads freeze over relatively quickly – about 6 cm in one day. Sometimes, ridges form when open leads close and we can end up surrounded by ice rising up to 6 meters high in just a couple of hours. On occasion, we can hear the ice moving and, if it happens fast, we can also see it. It’s also fascinating to watch frost flowers grow. We sample them to learn about their biogeochemistry.

We haven’t seen much wildlife, although we were visited by two snow buntings and a polar bear just this week. We also spotted a seal several times in a lead. We called her Lucy. There are some amphipods and copepods in the water, but we haven’t observed any fish yet.

- And what about the weather?

We’ve experienced the full range of Arctic weather conditions in our time here. We’ve had persistent low temperatures of –40°C, which makes working outdoors very challenging and renders some of ship’s equipment unusable. March was particularly stormy, with strong winds and a few complete whiteouts. Conditions have settled down recently, though. We have clear skies, sunshine and light winds – very much like winter in the Alps. Now that we’ve drifted below 84°N, warm air mass intrusions from the Atlantic are pushing temperatures as high as 0°C, bringing surface melt and rain.

- What’s daily life like on board?

It’s a very structured life. Ice conditions are the only thing that really changes our day-to-day routine. We eat three meals a day, at specific times, and we have two daily weather briefings so we can update our work plan depending on the conditions outside. There’s also a general meeting each evening where we discuss the day’s activities, achievements and challenges, look at pictures of the day, get a weather update, and talk about more general matters like the COVID-19 pandemic.

My personal schedule always involves routine checks and calibrations in my aerosol container. Sometimes I carry out repairs and do outdoor work because I have samplers in various locations on the floe. I also try to support other projects where I can.

As leader of the MOSAiC atmosphere team, my role also involves a fair amount of coordination work. At our twice-weekly team meetings, we discuss recent observations and logistical aspects of our work, among other things. For instance, we might need to figure out how to install new power lines if a lead has opened between the ship and the on-ice instrumentation. I also attend regular crew leadership group meetings where we have to make bigger-picture decisions, like whether to reposition the ship because of ice movement, how to deal with scheduling conflicts, or how long we should keep working on the floe amid crew changeover delays because of the current crisis.

We also have regular free time in our schedules. On Wednesdays and Sundays we can go out on the ice for an evening walk, or for a game of soccer or frisbee. There are also occasional camping trips. Of course, we need bear guards for any off-board activities like these. On other days we play water ball, listen to classical music or have a bar night in Zillertal, the on-board pub. We also arrange BBQs to celebrate special occasions like Easter or the return of the sun.

- How often do you go out and how dangerous is it?

I go out daily to check my instruments on the floe, or to help other members of the team, including bear guarding. All the research sites are less than one kilometer from the ship, so we can reach them on foot. Occasionally, we’ll take a skidoo if we have heavy equipment to transport.

Of course, being out on the ice can be dangerous. But we’re trained to keep ourselves safe. We wear full expedition gear to keep us warm, even at –40°C, to prevent frostbite and hypothermia, and to help us float if we fall into the water. Because the ice is dynamic, there’s always a chance that the route back to the ship could be cut off. If that happened, we’d have to stay put until we could be rescued by helicopter, or until some other solution could be found. There are also emergency kits out on the floe. We always carry VHF radios, so the bridge can let us know if there’s been a polar bear sighting, for instance. We can also keep the on-board team informed if anything significant happens out on the ice. So if we need to make a decision, that support is always there.

- What samples are you collecting and why?

I’m studying the extent to which natural and human emissions modify low-level Arctic clouds. These clouds play a vital role in maintaining the Arctic’s energy and mass balances because they reflect and absorb radiation, and because they contribute to snow cover through precipitation. In general, clouds only form in the presence of cloud condensation nuclei or ice nucleating particles. These are a subset of aerosol particles that can originate from natural sources such as sea spray, phytoplankton emissions or blowing snow, but also from human activities such as fossil-fuel combustion, other industrial emissions and agriculture.

We can use our on-board instrumentation to characterize aerosol particles in terms of their microphysical and chemical properties. Variables such as number concentration, particle size distribution, hygroscopicity, chemical composition and fluorescence help us to understand their origin – natural or human – and their potential effects on clouds. Our end goal is to understand how far natural versus human-made processes contribute to cloud formation and to the energy balance in the Arctic, and how this might change as the so-called “New Arctic” evolves and human emissions change in the future. Ultimately, this information can be used in Arctic climate change scenarios.

- What equipment do you use to collect your samples and data?

The main equipment is heavy and power-hungry, so it’s housed in the container on board. But my colleagues and I have also placed some lighter and more robust instrumentation in various locations on the floe to capture small-scale variability. These instruments mostly measure number concentration and particle-size distribution, as well as collecting particles on filters for analysis in the laboratory. I also collect fresh snow samples to understand the wet deposition of aerosol particles.

Almost all our instruments – more than 15 pieces of equipment in total – capture data in real time with a resolution of a few seconds to a few minutes, so we can understand both fast and slow processes. The instrumentation, which comes from EPFL’s Extreme Environments Research Laboratory, the Paul Scherrer Institute and the University of Helsinki, is housed in a laboratory container on the bow of the ship. It includes several mass spectrometers, cloud condensation nuclei counters, and bioaerosol sensors. Our container is just one of several atmospheric science laboratories on board. Together, we collect comprehensive information – not just about aerosols, but also trace gases, atmospheric-state variables, clouds, boundary layer dynamics, and so on.

- What have you learned about the Arctic air so far?

By looking at the data, I get an almost real-time picture of the composition of the atmosphere. When air masses come from the north – from the High Arctic – the aerosol population is aged, meaning several days to weeks old, and consists mainly of sulfuric acid. This is a common winter phenomenon known as Arctic haze, when sulfur dioxide emissions – mostly from human activity in the mid and high latitudes – accumulate over the wintertime. The haze began forming back in November. Initially, the concentration was about 50 particles per cubic centimeter. Now it’s risen to 200.

During stormy conditions, salty snow is lifted into the air where it forms aerosol particles. The number of particles depends on several factors, including the microstructure of the snow, how wind-pressed it was, and its surface roughness. Because these particles make up a significant share of the overall aerosol population, they likely play an important role in cloud formation.

When air masses arrive from the south, however, all these variables are different. The particles have been processed by clouds, and differ in origin, size and chemical composition. Mid-April is the time when phytoplankton blooms happen in the Atlantic. These blooms emit dimethyl sulfide, which is transformed to methanesulfonic acid – a tracer that we’re now seeing in the aerosol particles. We’ve also found halogens – iodic acid and bromine – in the aerosol population. These are more local in origin, and are connected to snow chemistry and UV radiation. And, of course, we also see exhaust particles from the ship, skidoos and helicopters. They carry a distinctive signature that sets them apart from other aerosol types.

- Are there noticeable differences between the Arctic and Antarctica?

The two polar regions are very different. The Arctic is an ocean surrounded by land, whereas Antarctica is a continent surrounded by an ocean, so meteorological patterns, particle-emission processes and atmospheric changes aren’t really comparable. While the fundamental processes behind aerosol chemistry and microphysics are the same, these differences in environmental conditions lead to different outcomes – not least in terms of how aerosol particles affect the polar energy budget.

- Have you personally observed changes in the Arctic climate?

That’s a difficult question. I don’t have a reliable benchmark because this is the first time that I, like many other members of the team, have been this far north at this time of year. Generally speaking, we didn’t anticipate observing so much mobile ice so early in the year. We expected to see a much more consolidated ice pack. But this might not necessarily be a sign of climate change. What was striking, however, was that precipitation fell as rain instead of snow when Atlantic air masses arrived in mid-April.

- Is the COVID-19 crisis affecting life on an Arctic research vessel?

Yes, definitely. It’s affecting us in two main ways. First, we’re all hearing news from home about how the world has changed and what it means for our families, friends and colleagues. It’s a real cause for concern and we talk about the pandemic a lot. Second, the outbreak has disrupted the crew changeover schedule. It’s taken us several weeks to figure out our options, given the travel restrictions in force around the world. Despite the delays and uncertainty around when we’ll return home, I’m happy to report that crew morale is high. We’ve grown together as a fantastic team of scientists who communicate openly and look out for each other. It’s also made my job much easier, as one of the five science team leaders on board.

- As someone who’s used to spending long periods on boats, how are you coping with living under lockdown?