@article{77d3cbbacf824424a5ac0e988f818256,
title = "Light-absorption enhancement of black carbon in the Asian outflow inferred from airborne SP2 and in-situ measurements during KORUS-AQ",
abstract = "We investigated the changes in the size distribution, coating thickness, and mass absorption cross-section (MAC) of black carbon (BC) with aging and estimated the light absorption enhancement (Eabs) in the Asian outflow from airborne in-situ measurements during 2016 KORUS-AQ campaign. The BC number concentration decreased, but mass mean diameter increased with increasing altitude in the West Coast (WC) and Seoul Metropolitan Area (SMA), reflecting the contrast between freshly emitted BC-containing particles at the surface and more aged aerosol associated with aggregation during vertical mixing and transport. Contradistinctively, BC number and mass size distributions were relatively invariant with altitude over the Yellow Sea (YS) because sufficiently aged BC from eastern China were horizontally transported to all altitudes over the YS, and there are no significant sources at the surface. The averaged inferred MAC of refractory BC in three regions reflecting differences in their size distributions increased to 9.8 ± 1.0 m2 g−1 (YS), 9.3 ± 0.9 m2 g−1 (WC), and 8.2 ± 0.9 m2 g−1 (SMA) as BC coating thickness increased from 20 nm to 120 nm. The absorption coefficient of BC calculated from the coating thickness and MAC were highly correlated with the filter-based absorption measurements with the slope of 1.16 and R2 of 0.96 at 550 nm, revealing that the thickly coated BC had a large MAC and absorption coefficient. The Eabs due to the inferred coatings was estimated as 1.0–1.6, which was about 30% lower than those from climate models and laboratory experiments, suggesting that the increase in the BC absorption by the coatings in the Asian outflow is not as large as calculated in the previous studies. Organics contributed to the largest Eabs accounting for 69% (YS), 61% (WC), and 64% (SMA). This implies that organics are largely responsible for the lensing effect of BC rather than sulfates in the Asian outflow.",
keywords = "Absorption enhancement, Aging process, Black carbon, KORUS-AQ, SP2",
author = "Chaeyoon Cho and Schwarz, {Joshua P.} and Perring, {Anne E.} and Lamb, {Kara D.} and Yutaka Kondo and Park, {Jong Uk} and Park, {Do Hyeon} and Kyuseok Shim and Park, {Jin Soo} and Park, {Rokjin J.} and Meehye Lee and Song, {Chang Keun} and Kim, {Sang Woo}",
note = "Funding Information: The authors are grateful to the NASA DC-8 pilots and crew, and to all members of the KORUS-AQ science team for their contributions during the field campaign and the agencies operating the surface networks. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education ( 2020R1A6A3A01097230 ), the Korea Meteorological Administration Research and Development Program under Grant KMI2018-01111 , and by the FRIEND (Fine Particle Research Initiative in East Asia Considering National Differences) Project through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (Grant No.: 2020M3G1A1114615 ). The NOAA SP2 data were obtained and analyzed with the support of the NASA Radiation Sciences Program, the NASA Upper Atmosphere Research Program, the NASA Tropospheric Chemistry Program, and the NOAA Atmospheric Composition and Climate Program. Funding Information: The authors are grateful to the NASA DC-8 pilots and crew, and to all members of the KORUS-AQ science team for their contributions during the field campaign and the agencies operating the surface networks. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2020R1A6A3A01097230), the Korea Meteorological Administration Research and Development Program under Grant KMI2018-01111, and by the FRIEND (Fine Particle Research Initiative in East Asia Considering National Differences) Project through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (Grant No.: 2020M3G1A1114615). The NOAA SP2 data were obtained and analyzed with the support of the NASA Radiation Sciences Program, the NASA Upper Atmosphere Research Program, the NASA Tropospheric Chemistry Program, and the NOAA Atmospheric Composition and Climate Program. Publisher Copyright: {\textcopyright} 2021 Elsevier B.V.",
year = "2021",
month = jun,
day = "15",
doi = "10.1016/j.scitotenv.2021.145531",
language = "English",
volume = "773",
journal = "Science of the Total Environment",
issn = "0048-9697",
publisher = "Elsevier",
}
