City Scale Modeling of Ultrafine Particles in Urban Areas with Special Focus on Passenger Ferryboat Emission Impact

Abstract

Air pollution by aerosol particles is mainly monitored as mass concentrations of particulate matter, such as PM10 and PM2.5. However, mass-based measurements are hardly representative for ultrafine particles (UFP), which can only be monitored adequately by particle number (PN) concentrations and are considered particularly harmful to human health. This study examines the dispersion of UFP in Hamburg city center and, in particular, the impact of passenger ferryboats by modeling PN concentrations and compares concentrations to measured values. To this end, emissions inventories and emission size spectra for different emission sectors influencing concentrations in the city center were created, explicitly considering passenger ferryboat traffic as an additional emission source. The city-scale chemical transport model EPISODE-CityChem is applied for the first time to simulate PN concentrations and additionally, observations of total particle number counts are taken at four different sampling sites in the city. Modeled UFP concentrations are in the range of 1.5–3 × 104 cm−3 at ferryboat piers and at the road traffic locations with particle sizes predominantly below 50 nm. Urban background concentrations are at 0.4–1.2 × 104 cm−3 with a predominant particle size in the range 50100 nm. Ferryboat traffic is a significant source of emissions near the shore along the regular ferry routes. Modeled concentrations show slight differences to measured data, but the model is capable of reproducing the observed spatial variation of UFP concentrations. UFP show strong variations in both space and time, with day-to-day variations mainly controlled by differences in air temperature, wind speed and wind direction. Further model simulations should focus on longer periods of time to better understand the influence of meteorological conditions on UFP dynamics.

Measurement and Modeling of Ship-Related Ultrafine Particles and Secondary Organic Aerosols in a Mediterranean Port City

“…The P8P + 2 parametrization scheme for particle number concentration and PNSD calculation [ 30 ] calculates dry deposition and coagulation (between particles of the same size class) of each size class of particles. Ten particle size classes are defined in the P8P + 2 scheme, covering the particle diameter size range between 0.001 µm and 10 µm ( Table S1, Supplementary Materials ).…”

“…For residential heating, a particle number emission inventory was created based on the heating demand and fuel types used based on the city average in Marseille, and population density. Emission factors of particle number for different fuel types (solid, heating oil, natural gas) as given in Lauenburg et al [ 30 ] were weighted for the respective fuel shares. For road transport, annual total PN emissions for all urban line sources were estimated based on vehicular NO x emissions by applying a conversion factor of 2.15 × 10 14 per gram of emitted NO x , as given by Ketzel et al for workdays [ 73 ].…”

“…Knowledge gaps regarding the size-segregated and chemical characterization of ship-related particles currently impede the source apportionment of ambient particles in coastal cities and need to be addressed for a better assessment of health implications related to shipping [ 5 ]. While a large number of studies investigated the effect of ship-related PM 2.5 in coastal areas, currently only a few studies [ 7 , 10 , 22 , 30 ] deal with the effect of shipping on the number concentrations of UFP and its chemical composition in port cities.…”

Localizing SDG 11.6.2 via Earth Observation, Modelling Applications, and Harmonised City Definitions: Policy Implications on Addressing Air Pollution

“…EPISODE-CityChem was created to fill the gap between regional and micro-scale simulations for air quality and its output includes hourly or time-averaged concentrations of pollutants at specified locations within an urban area. The performance of EPISODE-CityChem and its compliance with quality criteria for regulatory purposes has been demonstrated in several urban-scale studies [40,[42][43][44][45][46][47].…”

“…Hamburg was chosen as a case study because the high-resolution mapping of air pollution and SDG 11.6.2 is a demanding task (as discussed in Section 4.1), which necessitates a pre-establishment of the utilized methods for any urban area of study. The proposed modelling system for the intra-urban approaches is state-of-the-art and is already applied, tested, and demonstrated for the city of Hamburg [40,[42][43][44][45][46][47]. The overarching scope of this paper is to provide a demonstration of the EO potential in addressing and localizing the SDGs and, in particular, SDG Indicator 11.6.2.…”