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

Abstract

Abstract. Fluxes of gaseous compounds and nanoparticles were studied using micrometeorological methods at Harmaja in the Baltic Sea. The measurement site was situated beside the ship route to and from the city of Helsinki. The gradient (GR) method was used to measure fluxes of SO2, NO, NO2, O3, CO2, and Ntot (the number concentration of nanoparticles). In addition, the flux of CO2 was also measured using the eddy-covariance (EC) 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. The wind speed and the turbulent parameters at each of the established heights were then recalculated for the gradient model. The effect of waves on the boundary layer was taken into consideration, as 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 the sea–air interface were observed for SO2, NO, NO2, NOx (= NO + NO2), O3, or CO2 using the GR method. 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 −0.081 μmol m−2 s−1 with an uncertainty range of 30 %–60 % for the EC methods. Ship emissions were responsible for the 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 the SO2 and CO2 concentrations. A typical value of 0.40 ± 0.06 % was obtained for the FSC, which is in compliance with the contemporary FSC limit value of 1 % in the Baltic Sea area at the time of measurements. The method to estimate the uncertainty in the FSC was found to be accurate enough for use with the latest regulations, 0.1 % (Baltic Sea area) and 0.5 % (global oceans).

The Association between Vessel Departures and Air Pollution in Helsinki Port Area 2016–2021

“…The port terminals at the city centre however are mainly operated by passenger ferry vessels with regular traffic to Mariehamn, St Petersburg, Stockholm and Tallinn and the seasonal cruise ships. Separate measuring studies have been completed in the same areas: both prior to the SECA [28] and after coming into force [29]. Using HSY continuous measurement data, a long-term association can be established better than with short-term measuring campaigns.…”

The Role of Belgian Airborne Sniffer Measurements in the MARPOL Annex VI Enforcement Chain

“…So far, several studies have been executed comparing onboard measurements with remote measurements. However, these studies were limited to one or two OGVs and concerned only one OGV type [37,38,53,[61][62][63][64]. The third research question of this study was therefore to evaluate how airborne measurements would relate to real-world emissions for a larger amount and more diverse sample of OGVs.…”

Determination of NOx emission rates of inland ships from onshore measurements

“…Shipping emissions have been typically investigated using in situ instruments, either on board or onshore (e.g. Moldanová et al, 2009;Alföldy et al, 2013;Diesch et al, 2013;Beecken et al, 2014;Pirjola et al, 2014;Beecken et al, 2015;Kattner et al, 2015;Kurtenbach et al, 2016;Kattner, 2019;Ausmeel et al, 2019;Celik et al, 2020;Walden et al, 2021). Additionally, remote sensing techniques such as differential optical absorption spectroscopy (DOAS; e.g.…”