Estimating black carbon aging time-scales with a particle-resolved aerosol model

TL;DR

This study uses a particle-resolved aerosol model to estimate black carbon particle aging time-scales in urban plumes, revealing different regimes and time-scales for daytime and nighttime aging processes.

Contribution

Introduces a novel method to estimate black carbon aging time-scales using cloud condensation nuclei activation criteria within a particle-resolved model.

Findings

Daytime aging dominated by condensation processes.

Nighttime aging dominated by coagulation processes.

Aging time-scales range from 0.06 to 10 hours during the day and 6 to 20 hours at night.

Abstract

Understanding the aging process of aerosol particles is important for assessing their chemical reactivity, cloud condensation nuclei activity, radiative properties and health impacts. In this study we investigate the aging of black carbon containing particles in an idealized urban plume using a new approach, the particle-resolved aerosol model PartMC-MOSAIC. We present a method to estimate aging time-scales using an aging criterion based on cloud condensation nuclei activation. The results show a separation into a daytime regime where condensation dominates and a nighttime regime where coagulation dominates. For the chosen urban plume scenario, depending on the supersaturation threshold, the values for the aging time-scales vary between 0.06 hours and 10 hours during the day, and between 6 hours and 20 hours during the night.