Presentation Information
[AAS08-P34]Evaluation of wet removal efficiency of black carbon over the Yellow Sea from aircraft measurements
*Hyeongmo Kang1, Sunran Lee2, Hee-Jung Yoo2, Sumin Kim2, Saehee Lim3, Yongjoo Choi1 (1.Hankuk University of Foreign Studies, 2.Global Atmospheric Watch and Research Division, National Institute of Meteorological Sciences, 3.Chungnam National University)
Keywords:
Black Carbon (BC),Aircraft measuerment,Wet deposition,Wet removal,Transport Efficiency (TE),Accumulated Precipitation along Trajectory (APT)
Black carbon (BC) is widely recognized as a contributor to global warming due to its strong light absorption. Freshly emitted BC particles are initially hydrophobic but gradually become hydrophilic through atmospheric aging as water-soluble materials accumulate on their surfaces during transport. This transition enhances the removal of BC-containing particles by wet deposition, which is the primary mechanism of BC removal. Nevertheless, evaluation of wet removal rates of BC is still challenging due to a lack of understanding of BC behavior during atmospheric transport. In this study, a total of 24 research flights were carried out over the Yellow Sea (YS) between February 2021 and May 2022 using the research aircraft NARA, a modified Beechcraft King Air 350HW aircraft operated by the National Institute of Meteorological Sciences (NIMS). Single Particle Soot Photometer (SP2, Droplet Measurement Technologies Inc.) was deployed to analyze BC microphysical properties, including mass concentration, mass median diameter (MMD) of BC cores, shell-to-core diameter ratio (Rshell/core), and the occurrence frequency of thickly coated BC particles (Fthick). Carbon monoxide (CO), used as a tracer for combustion emission sources, was measured by cavity ring-down spectroscopy (CRDS, G-2401m, Picarro Inc.). 5 d (120 h) backward trajectories were calculated using Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) to identify the origins of air masses arriving at the YS. The accumulated precipitation along trajectory (APT) was derived by integrating the total amount of precipitation encountered over the 72 h and the impact of wet removal was evaluated using transport efficiency (TE; (ΔBC/ΔCO)APT>0/(ΔBC/ΔCO)APT=0), defined as the ratio of ΔBC/ΔCO under wet conditions to that under dry conditions. The resulting overall half-life and e-folding lifetime of BC (2.7 d and 3.6 d, respectively) are consistent with those of previous studies. Based on these results, we further investigate TE as a function of particle size, coating thickness, and emission sources.