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.
Highlights
International shipping is responsible for approximately 3.3 % of global CO2 emissions, 5 to 8 % of global anthropogenic SO2 emissions, and 2 % of global black carbon (BC) emissions (Lack and Corbett, 2012)
In order to study the dispersion of ship emissions in the Polar boundary layer, we used the FLEXPART-Weather Research and Forecasting (WRF) model (Brioude et al, 2013, website: http://flexpart.eu/wiki/ FpLimitedareaWrf), a Lagrangian particle dispersion model based on FLEXPART (Stohl et al, 2005)
FLEXPART-WRF was driven by meteorology from the Weather Research and Forecasting (WRF) Model (Skamarock et al, 2005), with the specifics of the WRF run for NETCARE provided in Wentworth et al (2016)
Summary
International shipping is responsible for approximately 3.3 % of global CO2 emissions, 5 to 8 % of global anthropogenic SO2 emissions, and 2 % of global black carbon (BC) emissions (Lack and Corbett, 2012). Specific sensitive regions are subject to more stringent limits for Emissions Control Areas (ECAs), such as those in effect for the Baltic Sea, the Mediterranean Sea, and the Caribbean Region. In the high Arctic, including Canadian waters, there is currently no ECA established, despite the very sensitive nature of the Arctic environment and ecosystems. The decreasing sea ice and increasing marine navigability in the shipping season have already increased annual traffic in the Canadian Arctic in recent decades (Pizzolato et al, 2014). Future projections in Arctic ship traffic suggest increasing emissions by mid-century (Corbett et al, 2010a; Winther et al, 2014). Development of effective regulations requires an understanding of observed ship emissions and processing in the Arctic environment
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