Modeling the evolution of aerosol particles in a ship plume using PartMC-MOSAIC

Abstract

Abstract. This study investigates the evolution of shipemitted aerosol particles using the stochastic particleresolved model PartMC-MOSAIC (Particle Monte Carlo model-Model for Simulating Aerosol Interactions and Chemistry). Comparisons of our results with observations from the QUANTIFY (Quantifying the Climate Impact of Global and European Transport Systems) study in 2007 in the English Channel and the Gulf of Biscay showed that the model was able to reproduce the observed evolution of total number concentration and the vanishing of the nucleation mode consisting of sulfate particles. Further process analysis revealed that during the first hour after emission, dilution reduced the total number concentration by four orders of magnitude, while coagulation reduced it by an additional order of magnitude. Neglecting coagulation resulted in an overprediction of more than one order of magnitude in the number concentration of particles smaller than 40 nm at a plume age of 100 s. Coagulation also significantly altered the mixing state of the particles, leading to a continuum of internal mixtures of sulfate and black carbon. The impact on cloud condensation nuclei (CCN) concentrations depended on the supersaturation threshold S at which CCN activity was evaluated. For the base case conditions, characterized by a low formation rate of secondary aerosol species, neglecting coagulation, but simulating condensation, led to an underestimation of CCN concentrations of about 37 % for S = 0.3 % at the end of the 14-h simulation. In contrast, for supersaturations higher than 0.7 %, neglecting coagulation resulted in an overestimation of CCN concentration, about 75 % for S = 1 %. For S lower than 0.2 % the differences between simulations including coagulation and neglecting coagulation were negligible. Neglecting condensation, but simulating coagulation did not impact the CCN concentrations below 0.2 % and resulted in an underestimation of CCN concentrations for larger supersaturations, e.g., 18 % for S = 0.6 %. We also explored the role of nucleation for the CCN concentrations in the ship plume. For the base case the impact of nucleation on CCN concentrations was limited, but for a sensitivity case with higher formation rates of secondary aerosol over several hours, the CCN concentrations increased by an order of magnitude for supersaturation thresholds above 0.3 %.

Plume-exit modeling to determine cloud condensation nuclei activity of aerosols from residential biofuel combustion

“…PartMC-MOSAIC has been used to model aerosol dynamics in urban areas (Riemer et al, 2009, CCN activation (Ching et al, 2012;Fierce et al, 2013), and ship plumes (Tian et al, 2014). Within PartMC-MOSAIC, we also implemented a module that reproduces the entrainment of background air (Jones, 2014), which allows for a variable water content in the plume.…”

The MESSy aerosol submodel MADE3 (v2.0b): description and a box model test

“…For the present study we chose N p ≈ 10 5 , as was done in previous applications of PartMC-MOSAIC (e.g. Riemer et al, 2009;Tian et al, 2014). In order to capture the large range of possible sizes and concentrations, one computational particle can represent a larger number of real particles .…”

“…The PartMC-MOSAIC version used for the present study (v. 2.2.1) corresponds to the detailed description in Tian et al (2014), so that we only give a brief summary of the relevant features here.…”

Metrics to quantify the importance of mixing state for CCN activity

“…For example, Ching et al (2012) quantified the impact of aerosol mixing state on cloud droplet formation, and Fierce et al (2013) investigated the sensitivity of CCN activity to mixing state characteristics at emission. The model was also used to explain the observed diurnal variations in aerosol hygroscopicity on the North China Plain (Liu et al, 2011) and to characterize the evolution of aerosol mixing state in a ship plume (Tian et al, 2014).…”