15 Jan 2021

15 Jan 2021

Review status: a revised version of this preprint is currently under review for the journal ACP.

Measurement report: Characterization of uncertainties of fluxes and fuel sulfur content from ship emissions at the Baltic Sea

Jari Walden1, Liisa Pirjola2,3, Tuomas Laurila1, Juha Hatakka1, Heidi Pettersson4, Tuomas Walden1, Jukka-Pekka Jalkanen1, Harri Nordlund2, Toivo Truuts5, Miika Meretoja6, and Kimmo K. Kahma4 Jari Walden et al.
  • 1Climate Research Program, Finnish Meteorological Institute, Helsinki, Finland
  • 2Department of Automotive and Mechanical Engineering, Metropolia University of Applied Sciences, Vantaa, Finland
  • 3Aerosol Physics Laboratory, Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland
  • 4Meteorological and Marine Research Program, Finnish Meteorological Institute, Helsinki, Finland
  • 5Air Quality Management Department, Estonian Environmental Research Centre, Tallinn, Estonia
  • 6City of Turku, Turku, Finland

Abstract. Deposition of gaseous compounds and nanoparticles from ship emissions was studied by micrometeorological methods at Harmaja in the Baltic Sea. The gradient method was used to measure fluxes of SO2, NO, NO2, O3, CO2, and Ntot (number concentration of nanoparticles). In addition, the fluxes of CO2 were measured by the eddy covariance method. Distortion of the flow field caused by obstacles around the measurement mast was studied by applying a computation fluid dynamic (CFD) model. This was used to establish the corresponding heights in the undisturbed stream, and the wind speed as well as the turbulent parameters at each of the established heights were recalculated for the gradient model. The effect of waves on the boundary layer was taken into consideration, because the Monin–Obukhov theory used to calculate the fluxes is not valid in the presence of swell. Uncertainty budgets for the measurement systems were constructed to judge the reliability of the results. No clear fluxes across the air-sea nor sea-air interface were observed for SO2, NO, NO2, NOx (= NO + NO2) or O3, while a negative flux was observed for Ntot with a median value of −0.23 × 109 m−2 s−1 and an uncertainty range of 31–41 %. For CO2, while both positive and negative fluxes were observed, the median value was −0.0036 mg m−2 s−1 with uncertainty ranges of 25–36 % and 30–60 % for the GR and EC methods, respectively. Ship emissions were responsible for deposition of Ntot while they had a minor effect on CO2 deposition. The fuel sulfur content (FSC) of the marine fuel used in ships passing the site was determined from the observed ratio of SO2 and CO2 concentrations. A typical value of 0.40 ± 0.06 %, was obtained for FSC, which is in compliance with the contemporary FSC limit value of 1 % in the Baltic Sea Area. The method to estimate the uncertainty of FSC was found to be accurate enough for use with the latest regulations, 0.1 % (Baltic Sea Area) and 0.5 % (Global Oceans).

Jari Walden et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2020-1086', Anonymous Referee #1, 31 Jan 2021
  • RC2: 'Comment on acp-2020-1086', Anonymous Referee #2, 29 Mar 2021

Jari Walden et al.

Data sets

Measurement report: Characterization of uncertainties of fluxes and fuel sulfur content from ship emissions at the Baltic Sea Jari Walden, Liisa Pirjola, Tuomas Laurila, Juha Hatakka, Heidi Pettersson, Tuomas Walden, Jukka-Pekka Jalkanen, Harri Nordlund, Toivo Truuts, Miika Meretoja, and Kimmo K. Kahma

Jari Walden et al.


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Short summary
Ship emissions play an important role in deposition of gaseous compounds and nanoparticles affecting climate, human health especially at coastal areas, and eutrophication. Results by micrometeorological methods showed that ship emissions were mainly responsible for deposition of Ntot, whereas they accounted a minor proportion for CO2 deposition. Uncertainty analysis applied to the results of the fluxes and fuel sulfur contents of the ships demonstrate reliability of the results.