Amir A. Aliabadi, Jennie L. Thomas, Andreas B. Herber, Ralf M. Staebler, W. Richard Leaitch, Hannes Schulz, Kathy S. Law, Louis Marelle, Julia Burkart, Megan D. Willis, Heiko Bozem, Peter M. Hoor, Franziska Köllner, Johannes Schneider, Maurice Levasseur, Jonathan P. D. Abbatt
4 min
Abstract
Abstract. Decreasing sea ice and increasing marine navigability in northern latitudes have changed Arctic ship traffic patterns in recent years and are predicted to increase annual ship traffic in the Arctic in the future. Development of effective regulations to manage environmental impacts of shipping requires an understanding of ship emissions and atmospheric processing in the Arctic environment. As part of the summer 2014 NETCARE (Network on Climate and Aerosols) campaign, the plume dispersion and gas and particle emission factors of effluents originating from the Canadian Coast Guard icebreaker Amundsen operating near Resolute Bay, NU, Canada, were investigated. The Amundsen burned distillate fuel with 1.5 wt % sulfur. Emissions were studied via plume intercepts using the Polar 6 aircraft measurements, an analytical plume dispersion model, and using the FLEXPART-WRF Lagrangian particle dispersion model. The first plume intercept by the research aircraft was carried out on 19 July 2014 during the operation of the Amundsen in the open water. The second and third plume intercepts were carried out on 20 and 21 July 2014 when the Amundsen had reached the ice edge and operated under ice-breaking conditions. Typical of Arctic marine navigation, the engine load was low compared to cruising conditions for all of the plume intercepts. The measured species included mixing ratios of CO2, NOx, CO, SO2, particle number concentration (CN), refractory black carbon (rBC), and cloud condensation nuclei (CCN). The results were compared to similar experimental studies in mid-latitudes. Plume expansion rates (γ) were calculated using the analytical model and found to be γ = 0.75 ± 0.81, 0.93 ± 0.37, and 1.19 ± 0.39 for plumes 1, 2, and 3, respectively. These rates were smaller than prior studies conducted at mid-latitudes, likely due to polar boundary layer dynamics, including reduced turbulent mixing compared to mid-latitudes. All emission factors were in agreement with prior observations at low engine loads in mid-latitudes. Ice-breaking increased the NOx emission factor from EFNOx = 43.1 ± 15.2 to 71.6 ± 9.68 and 71.4 ± 4.14 g kg-diesel−1 for plumes 1, 2, and 3, likely due to changes in combustion temperatures. The CO emission factor was EFCO = 137 ± 120, 12.5 ± 3.70 and 8.13 ± 1.34 g kg-diesel−1 for plumes 1, 2, and 3. The rBC emission factor was EFrBC = 0.202 ± 0.052 and 0.202 ± 0.125 g kg-diesel−1 for plumes 1 and 2. The CN emission factor was reduced while ice-breaking from EFCN = 2.41 ± 0.47 to 0.45 ± 0.082 and 0.507 ± 0.037 × 1016 kg-diesel−1 for plumes 1, 2, and 3. At 0.6 % supersaturation, the CCN emission factor was comparable to observations in mid-latitudes at low engine loads with EFCCN = 3.03 ± 0.933, 1.39 ± 0.319, and 0.650 ± 0.136 × 1014 kg-diesel−1 for plumes 1, 2, and 3.
Alex: So the harder the engine works, the more of these gases it pumps out. But you mentioned the Arctic air itself plays a role in what happens next?
Sam: This is where the behaviour of the air near the surface becomes important. Imagine the air close to the ground as a room. In most places, the sun warms the ground, which creates rising air currents that act like a giant fan — mixing everything up and diluting pollutants. But in the Arctic, the air sits in very stable, still layers and doesn't mix vertically in the same way.
Alex: Like a room with no ventilation, where smoke from a candle just hangs in a thick cloud instead of dispersing?
Sam: Precisely. Because there's very little of that churning, mixing action, the ship's exhaust stays concentrated for much longer. The researchers found that the plume expanded far more slowly than what we see in warmer climates. The pollution stays dense and potent rather than thinning out.
Alex: So it's a double effect. The ship produces more pollutants while breaking ice, and then the Arctic air holds those pollutants together instead of dispersing them.
Sam: That's the central finding. The study suggests that if we apply the same calculations to the Arctic that we use elsewhere, we'll significantly underestimate how much pollution is actually lingering in these sensitive environments.
Alex: And if the exhaust doesn't clear, it must eventually settle on the ice itself.
Sam: That's the concern. One of the things they specifically measured was soot — very fine, dark carbon particles. When that dark material lands on white ice, it absorbs sunlight rather than reflecting it, which can accelerate melting. By measuring these plumes directly, researchers can start building more accurate pictures of where that soot is actually going and how much of it is accumulating.
Alex: Was this the first time anyone had flown a plane through an icebreaker's exhaust while it was actively crushing ice?
Sam: Correct. Previous studies were done when ships were idling or moving through open water. This gives us the first direct measurements of what happens during the hardest phase of Arctic navigation — and that matters, because it's precisely the phase that produces the most pollution. It's a meaningful step toward building the kind of accurate data that could inform better rules for how ships operate in the north.
Alex: And on that note, thanks for listening to ResearchPod.