Ship Plumes Research Articles

Origins of atmospheric nitrous acid and their contributions to OH radical from ship plumes, marine atmosphere, and continental air masses over South China Sea

Nitrous acid (HONO) is an important source of atmospheric hydroxyl radical (OH). However, HONO abundance in the marine boundary layer remain largely unknown. Here, ship-based measurements were performed to characterize the origins of HONO from ship plumes, marine atmosphere, and continental emissions over South China Sea (SCS) during September 2021. The results showed that the HONO concentrations were measured at substantial levels (1.0 ± 0.8 ppbv) in polluted plumes due to generally high NOx concentrations (52.3 ± 52.5 ppbv). Comparably, much lower HONO concentrations (0.086 ± 0.102 ppbv) were observed for marine atmosphere. During nighttime, the heterogeneous conversion of NO2 was the predominant source of HONO and occurred mainly on the sea surfaces through NO2 deposition. The HONO yield from this deposition (the proportion of NO2 that was converted to HONO) was 0.08 and 0.06 for the marine atmosphere and continental emissions, respectively. In contrast, daytime known HONO formation of marine atmospheric origins was mainly attributed to homogeneous OH + NO reaction, although the contribution of heterogeneous NO2 conversion might not be negligible. Approximately half of HONO sources during daytime are unknown, which were likely from photo-enhanced NO2 conversation on the sea surfaces. Our results showed that for marine atmosphere and ship plumes, the daily contributions of HONO photolysis to OH radical formation were about 20.8 % and 72.2 %, respectively, while the contributions from ozone photolysis were 79.2 % and 27.8 %. An average HONO concentration of 0.17 ppbv was measured in close shore regions when air masses originated from mainland China, with the contributions from HONO and ozone to OH radical of 21.4 % and 78.6 % respectively, similar to those for the marine atmosphere. This study suggests that HONO in the SCS has various sources (e.g., marine atmosphere, ship plumes, and continental emissions) and makes significant contributions to the OH abundance which affects the oxidation capacity in this area.

Measurement report: Vanadium-containing ship exhaust particles detected in and above the marine boundary layer in the remote atmosphere

Abstract. Each year, commercial ships emit over 1.67 Tg of particulate matter (PM) pollution into the atmosphere. These ships rely on the combustion of heavy fuel oil, which contains high levels of sulfur, large aromatic organic compounds, and metals. Vanadium is one of the metals most commonly associated with heavy fuel oil and is often used as a tracer for PM from ship exhaust. Previous studies have suggested that vanadium-containing PM has impacts on human health and climate due to its toxicological and cloud-formation properties, respectively; however, its distribution in the atmosphere is not fully understood, which limits our ability to quantify the environmental implications of PM emitted by ships. Here, we present data obtained from a Particle Analysis by Laser Mass Spectrometry (PALMS) instrument on the NASA DC-8 aircraft during the 2016–2018 Atmospheric Tomography Mission (ATom) and show that ∼ 1 % of the accumulation mode particles measured in the marine boundary layer of the central Pacific and Atlantic oceans contain vanadium. These measurements, which were made without targeting ship plumes, suggest that PM emitted by ships is widespread in the atmosphere. Furthermore, we observed vanadium-containing ship exhaust particles at altitudes up to 13 km, which demonstrates that not all ship exhaust particles are immediately removed via wet deposition processes. In addition, using laboratory calibrations, we determined that most vanadium-containing ship exhaust particles can contain up to a few weight percent of vanadium. This study furthers our understanding of both the chemical composition and distribution of PM emitted by ships, which will allow us to better constrain the climate, health, and air quality implications of these particle types in the future. We note that these data were collected prior to the 2020 International Maritime Organization (IMO) sulfur regulation and stand as a reference for understanding how ship emissions have evolved in light of these regulations.

Using the Multicomponent Aerosol FORmation Model (MAFOR) to Determine Improved VOC Emission Factors in Ship Plumes.

International shipping's particulate matter primary emissions have a share in global anthropogenic emissions of between 3% and 4%. Ship emissions of volatile organic compounds (VOCs) can play an important role in the formation of fine particulate matter. Using an aerosol box model for the near-plume scale, this study investigated how the changing VOC emission factor (EF) for ship engines impacts the formation of secondary PM2.5 in ship exhaust plumes that were detected during a measurement campaign. The agreement between measured and modeled particle number size distribution was improved by adjusting VOC emissions, in particular of intermediate-, low-, and extremely low-volatility compounds. The scaling of the VOC emission factor showed that the initial emission factor, based on literature data, had to be multiplied by 3.6 for all VOCs. Information obtained from the box model was integrated into a regional-scale chemistry transport model (CTM) to study the influence of changed VOC ship emissions over the Mediterranean Sea. The regional-scale CTM run with adjusted ship emissions indicated a change in PM2.5 of up to 5% at the main shipping routes and harbor cities in summer. Nevertheless, overall changes due to a change in the VOC EF were rather small, indicating that the size of grid cells in CTMs leads to a fast dilution.

Validating CFD modelling of ship plume dispersion in an urban environment with pollutant concentration measurements

Air pollution in urban areas constitutes a global environmental problem, with shipping being one major contributor to hazardous pollutants in harbour areas. This work concerns the application of a method using CFD modelling to study how ships affect the air quality of port areas at a microscale level. A steady RANS-CFD approach was applied to simulate the dispersion of shipping-emitted pollutants, and a spatial sensitivity analysis of the CFD modelling results was conducted. The port of Marseille was used as a case study, and the CFD predictions were compared with on-site observations from two monitoring stations for CO2, CO, NOx, SO2 and PM concentrations. Representative modelled and measured concentrations were considered at the location of the monitoring stations to facilitate one-by-one comparisons for all pollutants in three different test cases of departing vessels. The modelling predictions presented an 8.2% (95% CI: -9.3%, 25.7%) average deviation from the measurements. Validation metrics were included to conduct a statistical comparison between predicted and measured concentrations, with almost all metric values indicating acceptable agreement between the CFD model and measurements. From a technical perspective, this study demonstrates the reliability of the applied CFD modelling method in estimating shipping plume dispersion, while from a societal perspective, this model can serve as an advisory tool for port authorities and policy makers to reduce the impact of shipping emissions on urban air quality.

To new heights by flying low: comparison of aircraft vertical NO2 profiles to model simulations and implications for TROPOMI NO2 retrievals

Abstract. The sensitivity of satellites to air pollution close to the sea surface is decreased by the scattering of light in the atmosphere and low sea surface albedo. To reliably retrieve tropospheric nitrogen dioxide (NO2) columns using the TROPOspheric Monitoring Instrument (TROPOMI), it is therefore necessary to have good a priori knowledge of the vertical distribution of NO2. In this study, we use an aircraft of the Royal Belgian Institute of Natural Sciences equipped with a sniffer sensor system to measure NOx (= NO + NO2), CO2 and SO2. This instrumentation enabled us to evaluate vertical profile shapes from several chemical transport models and to validate TROPOMI tropospheric NO2 columns over the polluted North Sea in the summer of 2021. The aircraft sensor observes multiple clear signatures of ship plumes from seconds after emission to multiple kilometers downwind. Besides that, our results show that the chemical transport model Transport Model 5, Massively Parallel version (TM5-MP), which is used in the retrieval of the operational TROPOMI NO2 data, tends to underestimate surface level pollution – especially under conditions without land outflow – while overestimating NO2 at higher levels over the study region. The higher horizontal resolution in the regional CAMS (Copernicus Atmosphere Monitoring Service) ensemble mean and the LOTOS-EUROS (Long Term Ozone Simulation European Operational Smog) model improves the surface level pollution estimates. However, the models still systematically overestimate NO2 levels at higher altitudes, indicating exaggerated vertical mixing and overall too much NO2 in the models over the North Sea. When replacing the TM5 a priori NO2 profiles with the aircraft-measured NO2 profiles in the air mass factor (AMF) calculation, we find smaller recalculated AMFs. Subsequently, the retrieved NO2 columns increase by 20 %, indicating a significant negative bias in the operational TROPOMI NO2 data product (up to v2.3.1) over the North Sea. This negative bias has important implications for estimating emissions over the sea. While TROPOMI NO2 negative biases caused by the TM5 a priori profiles have also been reported over land, the reduced vertical mixing and smaller surface albedo over sea make this issue especially relevant over sea and coastal regions.

International maritime regulation decreases sulfur dioxide but increases nitrogen oxide emissions in the North and Baltic Sea

Sulfur dioxide and nitrogen oxide emissions from shipping have been regulated internationally for more than fifteen years. Emissions reduction from shipping provides benefits for human health and the environment, but the effectiveness of regulations in reducing ship emissions is less well understood. Here, we examine how the establishment of European Emission Control Areas and other international maritime regulations in the North and Baltic Seas affect sulfur dioxide and nitrogen oxide emissions in the region. We combine and analyze more than 110,000 ship plume measurements, inspection results, and satellite data from 2018 to 2022. We find that compliance rates for sulfur emissions are higher near ports than in open waters. However, the regulations did not affect the concentration of nitrogen oxide emissions, which increased in the past three years. These findings highlight the need for enhanced emission regulations that improve air quality.

Validation of the estimated ships' emissions through an experimental campaign in port

This paper presents a correlation between the gaseous pollutant concentration measured in port and the estimated in-port ship emissions based on AIS data for the port of Naples. With the aim of better monitoring the quality ship's plumes funnels, the concentrations of Nitrogen dioxide (NO2) and Sulphur dioxide (SO2) have been continuously measured, during an experimental campaign (May–June 2021) at a height of 20 m from ground level.An innovative bottom-up ship emission modeling system with an emission inventory was created; five principal steps were realized: acquisition and cleaning, construction of ship's database, analysis of ship routes and phases in port, calculation of fuel consumption, and emission. The updated methodology bypasses the typical fixed value of specific fuel consumption, which is obtained based on the engine type and fuels and uses a correlation with the real engine load. Several updates were adopted for the emission estimation, abandoning the constant emission factor with the use of a more detailed methodology. The correlation was obtained by taking into account the prevailing winds and the overlap between the experimental campaign and the emission inventory on particular wind sectors. As a results correlations between the pollutant flow rates estimated from the AIS data and the concentrations measured during the experimental campaign, have been find (0.97 for SO2 and 0.80 for NOX).

Anomalous NO[formula omitted] emitting ship detection with TROPOMI satellite data and machine learning

Starting from 2021, more demanding NOx emission restrictions were introduced for ships operating in the North and Baltic Sea waters. Since all methods currently used for ship compliance monitoring are financially and time demanding, it is important to prioritize the inspection of ships that have high chances of being non-compliant. The current state-of-the-art approach for a large-scale ship NO2 estimation is a supervised machine learning-based segmentation of ship plumes on TROPOMI/S5P images. However, challenging data annotation and insufficiently complex ship emission proxy used for the validation limit the applicability of the model for ship compliance monitoring. In this study, we present a methodology towards the automated and scalable selection of potentially non-compliant ships using a combination of machine learning models on TROPOMI satellite data. It is based on a proposed regression model predicting the amount of NO2 that is expected to be produced by a ship with certain properties operating in the given atmospheric conditions. The model does not require manual labeling and is validated with TROPOMI data directly. The differences between the predicted and actual amount of produced NO2 are integrated over observations of the ship in time and are used as a measure of the inspection worthiness of a ship. To add further evidence, we compare the obtained results with the results of the previously developed segmentation-based method. Ships that are also highly deviating in accordance with the segmentation method require further attention. If no other explanations can be found by checking the TROPOMI data, the respective ships are advised to be the candidates for inspection.

Impact of Ship Emissions on Air Quality in the Greater Bay Area in China under the Latest Global Marine Fuel Regulation.

As the main anthropogenic source in open seas and coastal areas, ship emissions impact the climate, air quality, and human health. The latest marine fuel regulation with a sulfur content limit of 0.5% went into effect globally on January 1, 2020. Investigations of ship emissions after fuel switching are necessary. In this study, online field measurements at an urban coastal site and modeling simulations were conducted to detect the impact of ship emissions on air quality in the Greater Bay Area (GBA) in China under new fuel regulation. By utilizing a high mass-resolution single particle mass spectrometer, the vanadium(V) signal was critically identified and was taken as a robust indicator for ship-emitted particles (with relative peak area > 0.1). The considerable number fractions of high-V particles (up to 30-40% during ship plumes) indicated that heavy fuel oils via simple desulfurization or blending processes with low-sulfur fuels were extensively used in the GBA to meet the global 0.5% sulfur cap. Our results showed that ship-emitted particulate matter and NOx contributed up to 21.4% and 39.5% to the ambient, respectively, in the summertime, significantly affecting the air quality in the GBA. The sea-land breeze circulation also played an important role in the transport pattern of ship-emitted pollutants in the GBA.

Long-term characterization of organic and elemental carbon at three different background areas in northern Europe

Elemental carbon (EC) and organic carbon (OC) are major components of atmospheric PM2.5. In this article we represent the results of long-term measurements (8–12 years) of EC and OC at three different background sites in Finland: in a rural area (Virolahti) since the summer 2010, in a marine environment (Utö) since the summer 2011, and in a clean arctic environment (Pallas/Matorova) since 2014. The concentrations of OC and EC were measured with a semi-continuous organic and elemental carbon analyser (SC-OCEC) in all the sites. The yearly average concentrations of OC varied between 0.96–3.1, 0.76–1.6 and 0.30–0.69 μg m−3 at the rural (Virolahti), marine (Utö) and arctic (Pallas/Matorova) sites, respectively. Similarly, the corresponding yearly average concentrations of EC ranged between 0.095–0.48, 0.090–0.2 and 0.010–0.086 μg m−3 at those sites. A clear seasonal variation in OC and EC concentrations was observed at each measurement site. OC concentrations were highest during summertime whereas EC concentrations were highest in wintertime. The seasonality of OC was clearest at the Arctic site that had also the largest temperature variation and shortest growing season resulting in a sharp increase in OC concentrations from June to August. At all the measurement sites, OC concentrations gradually increased when the temperature rose over sub-zero temperatures whereas the daily average EC concentrations did not show as apparent temperature dependence as OC. Based on the cluster analysis, highest OC and EC concentrations, and the highest total load for EC (23–32%), at all the sites were detected with the air mass origin of southeast. In the marine environment, the effect of black carbon from ship plumes was investigated. The limit for ship fuel sulfur content changed during the measurement period (in January 2015), but it was not observed to influence the Optical EC concentrations. Overall, long-term, continuous measurements are crucial when the time trends in air quality and the effect of emission mitigation actions are investigated. In this study, a slight decrease in OC was observed at the Marine site, however, a decrease for EC was seen both at the rural and marine sites suggesting that the emission mitigation actions like EURO limits for light vehicles or improved after-treatment systems developed for industry and energy production have already decreased the background concentrations in rural areas.

Particulate Matter (PM1, 2.5, 10) Concentration Prediction in Ship Exhaust Gas Plume through an Artificial Neural Network

In the last decade the reduction of carbon dioxide emissions in the transport sector, including the marine sector, has become the direction of its strategic development. Increased air pollution in the air is one of the main reasons for premature deaths around the globe. It was determined that while many methods provide adequate information about pollution levels, improvements could be made to avoid major errors. The traditional methods are either expensive or require a lot of data and human resources to correctly evaluate those data arrays. To avoid these problems, artificial neural networks (ANN) and other machine learning methods are widely used nowadays. Many ANN models for ship pollution evaluation in ports either included the whole port area or went even further and included cities near port areas. These studies show that ANNs can be effectively used to evaluate air pollution in a wide area. However, there is a lack of research on ANN usage for individual ship pollution or ship plume evaluation. This study attempts to fill this gap by developing an ANN model to evaluate an individual ship’s plumes by combining several data sources such as AIS data, meteorological data, and measured the ship’s plume pollutants concentration. Results show good correlation; however, additional limitations have to be overcome regarding data filtering and the overall accuracy of the model.

Assessing Shipping Induced Emissions Impact on Air Quality with Various Techniques: Initial Results of the SCIPPER project

This paper presents the methods deployed by the Horizon 2O2O SCIPPER project to characterize emission performance of vessels, mainly under the perspective of checking compliance to new emissions regulations. Various on-board and remote measurement techniques have been demonstrated within five experimental campaigns conducted at Europe's main sea areas and ports. Almost a thousand of ship plumes has been measured and crossed checked with various instrumentation, revealing the emission profile of ships during actual operation Accuracy of each measurement technique was also tested. Emission measurements are further exploited to assess the impact of shipping on air quality of coastal areas, by identifying the transformations of pollutants performed in the atmosphere as plume evolves and quantifying onshore pollutants concentrations attributed to shipping activity.

Tracking Liquefied Natural Gas Fuelled Ship’s Emissions via Formaldehyde Deposition in Marine Boundary Layer

One of the reasons that anthropogenic greenhouse gas emissions estimation is imprecise is the uncertainty of aerosol impacts on cloud properties. Maritime transportation is slowly changing fuel preferences. With the policy framework changing regulations, the shipping business is going in a direction that emits less sulfur dioxide and black carbon, which are the compounds that cause linear cloud formations known as ship tracks. Aside from their effects on the total radiative forcing of a transportation mean, this phenomenon enables the detection of ships via satellite imagery sensors. The rapidly increasing trend of shifting propulsion of maritime transportation from conventional heavy fuel oil and distillate marine fuels to liquefied natural gas causes enormous hikes in methane emissions. Therefore, oxidation of the volatile organic compound in the marine boundary layer by the hydroxyl radical in the troposphere makes significant deposition of formaldehyde which causes human effects, ecosystem damage, and climate impact. The primary triggering substance among the compounds in the ship plume is methane. This paper discusses methods to assess near real time tracking of anomalies and the deposition of the short lived substance in different seasons in one of the main occurring areas, shipping corridors. The study also employs anomaly map analysis for June and December 2010 and 2020. Several global tracking methods are available with satellites, monitoring experiments, and other satellite tracking tools. Apart from a few areas the results are not indicative since the formaldehyde formations caused by LNG fueled ships are not widespread enough alongside with overall LNG fueled fleet. On the other hand, the analysis and method are promising for the follow-up of the emissions in the future.

Parameterization of a Rising Smoke Plume for a Large Moving Ship Based on CFD

The plume rising height of a ship will directly affect the maximum ground concentration and distance from the source caused by flue gas emission. Ship movement has an important effect on plume rising, but it is often ignored in previous studies. We simulated the weakening effect caused by ship movement by considering the influence of four main parameters (wind speed, ship speed, flue gas exit velocity, and flue gas exit temperature) on the smoke plume rising height, using the computational fluid dynamics (CFD) model (PHOENICS version 6.0 CHAM, London, UK). The main parameters affecting the difference in plume rising height between stationary and moving sources for the same parameter settings are the wind speed and the ship speed. Therefore, we established two simplified calculation methods that corrected the flue gas exit velocity (Vexit′) and the flue gas exit temperature (T′) for approximately simulating the smoke plume rising height of the moving ship using the formula of a stationary ship. Verification cases indicated that the corrected Vexit′ (the average of relative error is 5.48%) and the corrected T′(the average of relative error is 60.07%) not only saved calculation time but also improved the simulation accuracy compared with the uncorrected stationary source scheme (the average of relative error is 135.38%). Of these correction methods, the scheme with corrected Vexit′ is more effective. The intention is to provide some references for the field experimentation of moving ship plume rising in different ports in the future and to further study the mechanism of moving ship plume rising.

Detection of Ship Fuel Sulfur Contents in Exhaust Plumes at the Kanmon Straits, Japan, before and after the Global Sulfur Limit 2020

The global limit on the sulfur content of ship fuel was reduced from 3.50% to 0.50% in January 2020 to reduce ship emissions of SO2 and particulate matter. We conducted observational campaigns before and after the new global limit was introduced to detect changes in coastal air quality. We measured ambient concentrations of SO2 and CO2 ship plumes on shore with the sniffing method under the Kanmon Bridge over the Kanmon Straits between Honshu and Kyusyu Islands, Japan, for several weeks in August to September in 2019 and 2020. The fuel sulfur content (FSC) estimated from our measurements mainly varied from 0.50% to 3.00% in 2019, whereas the range narrowed to 0.10% to 0.40% in 2020, showing that all the ships complied. The mean FSC in 2020 was reduced to 16% of that in 2019, which was consistent with the reduction in the ambient SO2 concentration. Sakurai et al.(2021) estimated that after the 2020 global limit was brought in, SO2 emissions from ships were reduced to 24% of their previous values by assuming that all ships have a FSC of 0.50%. Our results indicate the 2020 global limit led to much greater reductions in SO2 emissions from ships than expected.

Tracking and measuring plumes from sailing ships using an unmanned aerial vehicle

Measuring sailing ship plumes provides comprehensive and real-time emission data. However, accurately tracking and measuring ship plumes still requires research. This study describes a tracking and measurement method of ship plumes using an unmanned aerial vehicle (UAV). A UAV ship exhaust measurement system and monitoring process were developed. Data from an automatic identification system (AIS) was used to improve the Gaussian plume diffusion model to facilitate the initial location of the plume on sailing ships. Based on the real-time gas measurement values obtained by the UAV, the UAV flight method was optimized to accurately track and measure the ship's plume. The Pudong Maritime Safety Administration used this system in 2019 to effectively monitor the plumes of 27 sailing ships as part of maritime law enforcement. Consequently, four cases of excessive fuel sulphur content (FSC) were detected in situ for the first time, indicating that China's maritime authorities can use the technology to supervise and control the FSC of sailing ships.

Effects of vertical ship exhaust plume distributions on urban pollutant concentration – a sensitivity study with MITRAS v2.0 and EPISODE-CityChem v1.4

Abstract. The modeling of ship emissions in port areas involves several uncertainties and approximations. In Eulerian grid models, the vertical distribution of emissions plays a decisive role for the ground-level pollutant concentration. In this study, model results of a microscale model, which takes thermal plume rise and turbulence into account, are derived for the parameterization of vertical ship exhaust plume distributions. This is done considering various meteorological and ship-technical conditions. The influence of three different approximated parameterizations (Gaussian distribution, single-cell emission and exponential Gaussian distribution) on the ground-level concentration are then evaluated in a city-scale model. Choosing a Gaussian distribution is particularly suitable for high wind speeds (>5 m s−1) and a stable atmosphere, while at low wind speeds or unstable atmospheric conditions the plume rise can be more closely approximated by an exponential Gaussian distribution. While Gaussian and exponential Gaussian distributions lead to ground-level concentration maxima close to the source, with single-cell emission assumptions the maxima ground-level concentration occurs at a distance of about 1500 m from the source. Particularly high-resolution city-scale studies should therefore consider ship emissions with a suitable Gaussian or exponential Gaussian distribution. From a distance of around 4 km, the selected initial distribution no longer shows significant differences for the pollutant concentration near the ground; therefore, model studies with lower resolution can reasonably approximate ship plumes with a single-cell emission.

Isotopic Constraints on the Formation Mechanisms of Sulfate Aerosols in the Summer Arctic Marine Boundary Layer

AbstractSulfate is a major aerosol species offsetting the Arctic warming. Quantifying sulfate formation mechanisms is conducive to assess its climatic effects and sulfur budget. However, relevant observations are sparse over the Arctic Ocean. Here, we present observations of surface sulfate and its Δ17O (=δ17O–0.52δ18O) over the latitude of 63.3–87.7°N in the Arctic Ocean in July–September 2012 to estimate sulfate production mechanisms. Potential contamination from ship plume on the observed sulfate was corrected based on black carbon. The corrected non‐sea‐salt sulfate (nss‐SO42−cor) varied from 0.0 to 1.3 μg m−3 with the mean of 0.3 ± 0.3(1σ) μg m−3. Samples with high contributions (≥80%) from sea‐salt sulfate and anthropogenic sulfate from ship plume possess Δ17O(SO42−) at ∼0‰. Δ17O of nss‐SO42−cor ranged from 0.0 to 0.9‰ with the mean of 0.5 ± 0.3‰. The low Δ17O values directly suggest the contribution from O3 oxidation to sulfate production is minor in summer Arctic due to this mechanism resulting in Δ17O(SO42−) = 9.8‰. Further calculations constrained by Δ17O indicate sulfate production was dominated by H2O2 oxidation with the possible contribution of 37%–66%, higher than the estimated fraction of 29% from OH oxidation. The role of HOBr oxidation is related to its abundance, which can reach a maximum contribution of 24% at assumption of [HOBr] = 1 ppt in summer Arctic. Future model studies with the constraint of sulfate and Δ17O observations in this study will further improve our knowledge of global sulfur budget and sulfate formation mechanisms in the Arctic.

On the Ship Particle Number Emission Index: Size‐Resolved Microphysics and Key Controlling Parameters

AbstractShipping particle number emission is important as it can influence cloud condensation nuclei abundance and thus indirectly affect clouds and perturb the Earth's radiation budget. Here, we integrate a size‐resolved Advanced Particle Microphysics module with a photochemical BOX MOdeling eXtension to the Kinetic PreProcessor and employ the resulting model to understand the microphysical and chemical characteristics of ship plumes. Simulated concentrations of key gaseous species and particle numbers are in good agreement compared with measurements from the NOAA Intercontinental Transport and Chemical Transformation (ITCT) 2K2 field study off the California coast. Further analysis reveals that significant new particle formation can occur in the plume and the growth of these secondary particles to 5–20 nm generally dominates the total particle numbers. We show that wind speed, emission rates of SO2 and NOx, solar irradiation, ambient temperature, and background [NH3] have strong nonlinear effects on the ship particle number emission index (EIPN). Depending on the ambient air and meteorological conditions, the model simulations show that EIPN can range from ∼2.5 × 1014 no. kg−1 fuel (dominated by primary particles) to ∼3.0 × 1018 no. kg−1 fuel (dominated by secondary particles). In consideration of the current worldwide expansion of Emission Control Areas, we systematically study how the EIPN decreases with reduction of fuel sulfur content to 0.1%. Our study highlights the necessity of accounting for the nonlinear dependence of secondary particle formation on key controlling parameters in calculating shipping particle number emissions, which is important for determining aerosol indirect climate effects.

Detection of ship plumes from residual fuel operation in emission control areas using single-particle mass spectrometry

Abstract. Ships are among the main contributors to global air pollution, with substantial impacts on climate and public health. To improve air quality in densely populated coastal areas and to protect sensitive ecosystems, sulfur emission control areas (SECAs) were established in many regions of the world. Ships in SECAs operate with low-sulfur fuels, typically distillate fractions such as marine gas oil (MGO). Alternatively, exhaust gas-cleaning devices (“scrubbers”) can be implemented to remove SO2 from the exhaust, thus allowing the use of cheap high-sulfur residual fuels. Compliance monitoring is established in harbors but is difficult in open water because of high costs and technical limitations. Here we present the first experiments to detect individual ship plumes from distances of several kilometers by single-particle mass spectrometry (SPMS). In contrast to most monitoring approaches that evaluate the gaseous emissions, such as manned or unmanned surveillance flights, sniffer technologies and remote sensing, we analyze the metal content of individual particles which is conserved during atmospheric transport. We optimized SPMS technology for the evaluation of residual fuel emissions and demonstrate their detection in a SECA. Our experiments show that ships with installed scrubbers can emit PM emissions with health-relevant metals in quantities high enough to be detected from more than 10 km distance, emphasizing the importance of novel exhaust-cleaning technologies and cleaner fuels. Because of the unique and stable signatures, the method is not affected by urban background. With this study, we establish a route towards a novel monitoring protocol for ship emissions. Therefore, we present and discuss mass spectral signatures that indicate the particle age and thus the distance to the source. By matching ship transponder data, measured wind data and air mass back trajectories, we show how real-time SPMS data can be evaluated to assign distant ship passages.