About

Saewung Kim is a faculty member in the Department of Earth System Science at the University of California, Irvine. His research focuses on the biosphere-atmosphere-human interactions, specifically exploring the minor composition of atmospheric gases to understand the current status of the air we breathe, examine human impacts on the natural atmosphere, and predict future changes resulting from human activities. He works closely with the Biosphere-Atmosphere Interactions Group led by Dr. Alex Guenther. Saewung Kim is committed to advancing research in earth system science and fostering a lab culture that upholds commitments to social justice, including solidarity with Black Lives Matter and efforts to end anti-Black racism. Interested individuals are encouraged to contact him for research collaboration.

Research topics

• Chemistry
• Geography
• Environmental science
• Environmental chemistry
• Atmospheric sciences
• Political Science
• Meteorology
• Organic chemistry
• Environmental planning
• Ecology
• Inorganic chemistry
• Nuclear chemistry
• Materials science
• Business
• Photochemistry

Selected publications

• Wintertime photochemistry of acyl peroxynitrates and ozone in South Korea during the ASIA-AQ campaign

  2026-02-09

  articleOpen access

  Abstract. Wintertime photochemical air pollution in East Asia remains poorly constrained despite its impact on regional air quality. Sources and formation pathways of acyl peroxynitrates (PANs) and ozone (O3), key photochemical products, are not well understood, hindering effective mitigation strategies. We investigate PANs and O3 over South Korea using observations from the ASIA-AQ campaign (February–March 2024). PANs reached 5.5 ppbv, strongly correlating with formaldehyde and particulate matter, indicating active winter photochemistry. Median PANs were higher in the mid-southern peninsula (MS; 987 pptv) and Yellow Sea (1197 pptv) than the Seoul Metropolitan Area (842 pptv). Elevated homologue-to-acetyl peroxynitrate ratios over the MS, with enhanced acryloyl peroxynitrate, acrolein, and ethylene oxide, provided tracers for petrochemical emissions and their impacts. Acetaldehyde contributed 53–80 % of PAN production. Ethanol was a major precursor of acetaldehyde (~50 %). Strong correlations (r² > 0.8) of ethanol and halocarbons indicate industrial and solvent sources under-represented in inventories. Formaldehyde and C2+ aldehydes contributed ~30 % to ozone production. Low ozone production efficiency (< 10) and radical termination dominated by nitric acid and PANs (> 80 %) indicate VOC-limited conditions. The fractional PANs contribution to NOx loss increased with decreasing OH reactivity ratio of NO2 to aldehydes, suggesting spatial increases in ozone production following NOx reductions. These findings demonstrate that a comprehensive understanding of VOC oxidation, particularly oxygenates from industrial sources, is essential for representing winter photochemistry. PANs measurements provide critical constraints on oxidation processes and their implications for emission control.

  PublisherOA PDFDOI

• Comment on egusphere-2025-6264

  2026-03-06

  peer-reviewOpen access

  <strong class="journal-contentHeaderColor">Abstract.</strong> Wintertime photochemical air pollution in East Asia remains poorly constrained despite its impact on regional air quality. Sources and formation pathways of acyl peroxynitrates (PANs) and ozone (O₃), key photochemical products, are not well understood, hindering effective mitigation strategies. We investigate PANs and O₃ over South Korea using observations from the ASIA-AQ campaign (February&ndash;March 2024). PANs reached 5.5 ppbv, strongly correlating with formaldehyde and particulate matter, indicating active winter photochemistry. Median PANs were higher in the mid-southern peninsula (MS; 987 pptv) and Yellow Sea (1197 pptv) than the Seoul Metropolitan Area (842 pptv). Elevated homologue-to-acetyl peroxynitrate ratios over the MS, with enhanced acryloyl peroxynitrate, acrolein, and ethylene oxide, provided tracers for petrochemical emissions and their impacts. Acetaldehyde contributed 53&ndash;80 % of PAN production. Ethanol was a major precursor of acetaldehyde (~50 %). Strong correlations (r&sup2; &gt; 0.8) of ethanol and halocarbons indicate industrial and solvent sources under-represented in inventories. Formaldehyde and C₂₊ aldehydes contributed ~30 % to ozone production. Low ozone production efficiency (&lt; 10) and radical termination dominated by nitric acid and PANs (&gt; 80 %) indicate VOC-limited conditions. The fractional PANs contribution to NO_x loss increased with decreasing OH reactivity ratio of NO₂ to aldehydes, suggesting spatial increases in ozone production following NO_x reductions. These findings demonstrate that a comprehensive understanding of VOC oxidation, particularly oxygenates from industrial sources, is essential for representing winter photochemistry. PANs measurements provide critical constraints on oxidation processes and their implications for emission control.

  PublisherDOI

• Supplementary material to "Wintertime photochemistry of acyl peroxynitrates and ozone in South Korea during the ASIA-AQ campaign"

  2026-02-09 · 1 citations

  articleOpen access
  PublisherDOI

• Comment on egusphere-2025-6264

  2026-03-04

  peer-reviewOpen access

  <strong class="journal-contentHeaderColor">Abstract.</strong> Wintertime photochemical air pollution in East Asia remains poorly constrained despite its impact on regional air quality. Sources and formation pathways of acyl peroxynitrates (PANs) and ozone (O₃), key photochemical products, are not well understood, hindering effective mitigation strategies. We investigate PANs and O₃ over South Korea using observations from the ASIA-AQ campaign (February&ndash;March 2024). PANs reached 5.5 ppbv, strongly correlating with formaldehyde and particulate matter, indicating active winter photochemistry. Median PANs were higher in the mid-southern peninsula (MS; 987 pptv) and Yellow Sea (1197 pptv) than the Seoul Metropolitan Area (842 pptv). Elevated homologue-to-acetyl peroxynitrate ratios over the MS, with enhanced acryloyl peroxynitrate, acrolein, and ethylene oxide, provided tracers for petrochemical emissions and their impacts. Acetaldehyde contributed 53&ndash;80 % of PAN production. Ethanol was a major precursor of acetaldehyde (~50 %). Strong correlations (r&sup2; &gt; 0.8) of ethanol and halocarbons indicate industrial and solvent sources under-represented in inventories. Formaldehyde and C₂₊ aldehydes contributed ~30 % to ozone production. Low ozone production efficiency (&lt; 10) and radical termination dominated by nitric acid and PANs (&gt; 80 %) indicate VOC-limited conditions. The fractional PANs contribution to NO_x loss increased with decreasing OH reactivity ratio of NO₂ to aldehydes, suggesting spatial increases in ozone production following NO_x reductions. These findings demonstrate that a comprehensive understanding of VOC oxidation, particularly oxygenates from industrial sources, is essential for representing winter photochemistry. PANs measurements provide critical constraints on oxidation processes and their implications for emission control.

  PublisherDOI

• Supplementary dataset for Kim et al. (2026) Ozone Production Characteristics during the KORUS-AQ Campaign over the Seoul Metropolitan Area Deciphered by Observationally Constrained OH Reactivity.

  Zenodo (CERN European Organization for Nuclear Research) · 2026-03-04

  datasetOpen access1st authorCorresponding

  The series of mat files is associated with the F0AM simulation input and output datasets. The detailed structure is described in Read_Me.pdf.

  PublisherDOI

• Supplementary dataset for Kim et al. (2026) Ozone Production Characteristics during the KORUS-AQ Campaign over the Seoul Metropolitan Area Deciphered by Observationally Constrained OH Reactivity.

  Zenodo (CERN European Organization for Nuclear Research) · 2026-03-04

  datasetOpen access1st authorCorresponding

  The series of mat files is associated with the F0AM simulation input and output datasets. The detailed structure is described in Read_Me.pdf.

  PublisherDOI

• Aerosol, clouds and particles: general discussion

  Faraday Discussions · 2025-01-01

  article

  Christian Pfrang opened the discussion of the introductory Spiers Memorial Lecture by Thorsten Bartels-Rausch by communicating: You outlined the reduced reactivity in snow with respect to ozone (https://doi.org/10.1039/d4fd00176a). Is there evidence for slowed down ozone kinetics at low temperatures also above fr

  PublisherDOI

• Multiphase chemistry: general discussion

  Faraday Discussions · 2025-01-01

  article

  Sarah Albertin opened the discussion of the paper by Jingqiu Mao: Given the key role of formaldehyde in the formation of secondary sulfate in Fairbanks in winter, have you identified its sources of emissions? Jingqiu Mao replied: Yes, this is ongoing work. So far, the major sources include residential heating and

  PublisherDOI

• Supplementary material to "Incorporation of multi-phase halogen chemistry into Community Multiscale Air Quality (CMAQ) model"

  2025-01-21

  preprintOpen accessSenior author
  PublisherDOI

• Incorporation of multi-phase halogen chemistry into the Community Multiscale Air Quality (CMAQ) model

  Atmospheric chemistry and physics · 2025-09-10 · 1 citations

  articleOpen accessSenior author

  Abstract. Halogen radicals (Cl, Br, and I) significantly influence atmospheric oxidation capacity, affecting both O3 formation and destruction. However, understanding of halogen chemistry remains limited. To better investigate comprehensive atmospheric halogen chemistry, we incorporated halogen processes into the Community Multi-scale Air Quality (CMAQ) model: (i) emissions of Cl2, HCl, Br2, and HBr from anthropogenic sources and Br2, I2, HOI, and halocarbons from natural sources and (ii) 177 multi-phase halogen reactions. Model performance was evaluated against observed ClNO2 levels and by comparison with reported ranges of BrO and IO levels. The updated model showed significant improvements in simulating ClNO2 mixing ratios, with the index of agreement (IOA) increasing from 0.41 to 0.66 and mean bias (MB) decreasing from −159.36 to −25.07 ppt at supersites. Furthermore, simulated BrO and IO levels fell within the ranges reported in previous studies. We found that these improvements were driven by four key reactions: (i) ClO self-reaction, (ii) heterogeneous HOBr chemistry, (iii) NO2 uptake, and (iv) revised N2O5 parameterization. Based on our modeling system, we found that the presence of halogen radicals led to changes in the net Ox production rate (P(Ox)), which increased from 3.08 to 3.33 ppb h−1 on land and decreased from 0.21 to 0.07 ppb h−1 over ocean. It was noted that levels of OH, HCHO, and NOx also increased by ∼0.007 ppt (5.5 %), ∼0.03 ppb (1.6 %), and ∼0.29 ppb (2.9 %), respectively, while levels of HO2 and volatile organic compounds (VOCs) decreased by ∼0.45 ppt (5.3 %) and ∼0.71 ppb (5.9 %). These results highlight the importance of accurately representing halogen processes in regional air quality models.

  PublisherOA PDFDOI

Frequent coauthors

• Alex Guenther

  University of California, Irvine

  105 shared

• Roger Seco

  Institute of Environmental Assessment and Water Research

  79 shared

• Daun Jeong

  41 shared

• J. L. Jiménez

  37 shared

• Pedro Campuzano‐Jost

  36 shared

• Dasa Gu

  34 shared

• Dianne Sanchez

  University of California, Irvine

  31 shared

• Rodrigo Augusto Ferreira De Souza

  Escola Superior de Ciências da Saúde

  26 shared

Labs

• Dream TeamPI