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29 results on '"Han, Kyung Man"'

5. An investigation into atmospheric nitrous acid (HONO) processes in South Korea.

Author

Kim, Kiyeon, Han, Kyung Man, Song, Chul Han, Lee, Hyojun, Beardsley, Ross, Yu, Jinhyeok, Yarwood, Greg, Koo, Bonyoung, Madalipay, Jasper, Woo, Jung-Hun, and Cho, Seogju

Subjects
NITROUS acid, AIR pollutants, ATMOSPHERIC chemistry, AIR quality, GAS phase reactions
Abstract

Nitrous acid (HONO) is a main precursor of hydroxyl radicals (OH), which contribute to the formation of numerous secondary air pollutants in the troposphere. Despite its importance in atmospheric chemistry, HONO chemistry has not been fully incorporated into many chemical transport models (CTMs). Due to the lack of atmospheric HONO processes, CTM simulations often tend to underestimate atmospheric mixing ratios of HONO. This study was undertaken because simulations with the current Community Multiscale Air Quality (CMAQ) model have a strong tendency to underestimate the HONO mixing ratio. In search of missing sources of atmospheric HONO, we attempted to sequentially incorporate the following potential HONO sources and processes into the CMAQ modeling framework: (i) gas-phase HONO reactions, (ii) traffic HONO emissions, (iii) soil HONO emissions, (iv) heterogeneous HONO production on the surfaces of aerosols, (v) heterogeneous HONO formation on tree leaf and building surfaces, and (vi) photolysis reactions of particulates and deposited HNO3 /nitrates called "renoxification". The simulation performances of the modified CMAQ models were then evaluated by comparing the modeled HONO mixing ratios with the HONO mixing ratios observed at the Olympic Park station in Seoul, South Korea. When HONO processes were fully added to the CMAQ model, average daily HONO mixing ratios increased from 0.06 to 1.18 ppb. The daytime HONO mixing ratios produced from the CMAQ model run with a full account of atmospheric HONO processes were found to be in better agreement with observations than those from the original CMAQ model (CMAQv5.2.1) runs with improved statistical metrics (e.g., the index of agreement (IOA) increased from 0.59 to 0.68, while the mean bias (MB) decreased dramatically from -0.57 to -0.34 ppb). In addition, we investigated the contributions of individual atmospheric HONO processes to HONO mixing ratios, as well as the impacts of HONO atmospheric processes on the concentrations of other atmospheric species in South Korea. All these issues are also discussed in this paper. [ABSTRACT FROM AUTHOR]

Published
2024
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6. High-resolution mapping of SO2 using airborne observations from the GeoTASO instrument during the KORUS-AQ field study: PCA-based vertical column retrievals

Author

Chong, Heesung, Lee, Seoyoung, Kim, Jhoon, Jeong, Ukkyo, Li, Can, Krotkov, Nickolay A., Nowlan, Caroline R., Al-Saadi, Jassim A., Janz, Scott J., Kowalewski, Matthew G., Ahn, Myoung-Hwan, Kang, Mina, Joiner, Joanna, Haffner, David P., Hu, Lu, Castellanos, Patricia, Huey, L. Gregory, Choi, Myungje, Song, Chul H., Han, Kyung Man, and Koo, Ja-Ho

Published
2020
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9. New Era of Air Quality Monitoring from Space : Geostationary Environment Monitoring Spectrometer (GEMS)

Author

Kim, Jhoon, Jeong, Ukkyo, Ahn, Myoung-Hwan, Kim, Jae H., Park, Rokjin J., Lee, Hanlim, Song, Chul Han, Choi, Yong-Sang, Lee, Kwon-Ho, Yoo, Jung-Moon, Jeong, Myeong-Jae, Park, Seon Ki, Lee, Kwang-Mog, Song, Chang-Keun, Kim, Sang-Woo, Kim, Young Joon, Kim, Si-Wan, Kim, Mijin, Go, Sujung, Liu, Xiong, Chance, Kelly, Miller, Christopher Chan, Al-Saadi, Jay, Veihelmann, Ben, Bhartia, Pawan K., Torres, Omar, Abad, Gonzalo González, Haffner, David P., Ko, Dai Ho, Lee, Seung Hoon, Woo, Jung-Hun, Chong, Heesung, Park, Sang Seo, Nicks, Dennis, Choi, Won Jun, Moon, Kyung-Jung, Cho, Ara, Yoon, Jongmin, Kim, Sang-kyun, Hong, Hyunkee, Lee, Kyunghwa, Lee, Hana, Lee, Seoyoung, Choi, Myungje, Veefkind, Pepijn, Levelt, Pieternel F., Edwards, David P., Kang, Mina, Eo, Mijin, Bak, Juseon, Baek, Kanghyun, Kwon, Hyeong-Ahn, Yang, Jiwon, Park, Junsung, Han, Kyung Man, Kim, Bo-Ram, Shin, Hee-Woo, Choi, Haklim, Lee, Ebony, Chong, Jihyo, Cha, Yesol, Koo, Ja-Ho, Irie, Hitoshi, Hayashida, Sachiko, Kasai, Yasko, Kanaya, Yugo, Liu, Cheng, Lin, Jintai, Crawford, James H., Carmichael, Gregory R., Newchurch, Michael J., Lefer, Barry L., Herman, Jay R., Swap, Robert J., Lau, Alexis K. H., Kurosu, Thomas P., Jaross, Glen, Ahlers, Berit, Dobber, Marcel, McElroy, C. Thomas, and Choi, Yunsoo

Published
2020

12. Parameterization of polydisperse aerosol optical properties during hygroscopic growth

Author

Jung, Chang H., Han, Kyung Man, Yoon, Young Jun, Kim, Dongchul, Lee, Ji Yi, Lee, Hyung-Min, Um, J., Lee, S. S., and Kim, Yong Pyo

Subjects
Environmental Chemistry, General Materials Science, Pollution
Abstract

Aerosol water uptake and the related influence on its optical properties owing to the hygroscopic growth of polydisperse aerosols have a significant effect on air quality and climate. This study develops an analytical parameterization for a single hygroscopic optical parameter and the scattering enhancement factor for polydisperse aerosol sizes. Polydisperse lognormal size distributions for geometric mean diameters of 0.05–1 µm and geometric standard deviations of 1.3–2.5 are considered with real refractive indices between 1.35 and 1.6. The analytical expression obtained for the optical parameter is compared to Mie theory and reasonable agreements within the size range investigated in this study are observed. Further, our results show that the analytical expression could express polydispersed aerosol optical properties as a function of geometric mean diameter and geometric standard deviation of a lognormal distribution and the refractive index. The obtained analytical expression can be efficiently used for 3D models with a reduced computational burden. Copyright © 2023 American Association for Aerosol Research

Published
2023
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22. The impacts of uncertainties in emissions on aerosol data assimilation and short-term PM2.5 predictions in CMAQ v5.2.1 over East Asia

Author

Lee, Sojin, Song, Chul Han, Han, Kyung Man, Henze, Daven K., Lee, Kyunghwa, Yu, Jinhyeok, Woo, Jung-Hun, Jung, Jia, Choi, Yunsoo, Saide, Pablo E., and Carmichael, Gregory R.

Abstract

For the purpose of improving PM prediction skills in East Asia, we estimated a new background error covariance matrix (BEC) for aerosol data assimilation using surface PM2.5 observations that accounts for the uncertainties in anthropogenic emissions. In contrast to the conventional method to estimate the BEC that uses perturbations in meteorological data, this method additionally considered the perturbations using two different emission inventories. The impacts of the new BEC were then tested for the prediction of surface PM2.5 over East Asia using Community Multi-scale Air Quality (CMAQ) initialized by three-dimensional variational method (3D-VAR). The surface PM2.5 data measured at 154 sites in South Korea and 1,535 sites in China were assimilated every six hours during the Korea-United States Air Quality Study (KORUS-AQ) campaign period (1 May–14 June 2016). Data assimilation with our new BEC showed better agreement with the surface PM2.5 observations than that with the conventional method. Our method also showed closer agreement with the observations in 24-hour PM2.5 predictions with ~ 44 % fewer negative biases than the conventional method. We conclude that increased standard deviations, together with horizontal and vertical length scales in the new BEC, tend to improve the data assimilation and short-term predictions for the surface PM2.5. This paper also suggests further research efforts devoted to estimating the BEC to improve PM2.5 predictions.

Published
2020

24. Supplementary material to "The impacts of uncertainties in emissions on aerosol data assimilation and short-term PM<sub>2.5</sub> predictions in CMAQ v5.2.1 over East Asia"

Author

Lee, Sojin, primary, Song, Chul Han, additional, Han, Kyung Man, additional, Henze, Daven K., additional, Lee, Kyunghwa, additional, Yu, Jinhyeok, additional, Woo, Jung-Hun, additional, Jung, Jia, additional, Choi, Yunsoo, additional, Saide, Pablo E., additional, and Carmichael, Gregory R., additional

Published
2020
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