• Asian Journal of Atmospheric Environment
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• v.3 no.1
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• pp.42-51
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• 2009

Saturated n-dicarboxylic acids ($C_2-C_7$, $C_9$), unsaturated dicarboxylic acids (maleic, fumaric, phthalic acid), ketocarboxylic acids (pyruvic, glyoxylic acid), and dicarbonyls (glyoxal, methylglyoxal) were determined in size-segregated samples with a high-volume Andersen air sampler at a suburban site in Saitama, Japan, May 12-17 and July 24-27, 2007 and January 22-31, 2008. The seasonal average concentrations of these detected organic acids were 670 $ng/m^3$, accounting for about 4.4-5.7% (C/C) of water-soluble organic carbon (WSOC) and 2.3-3.6% (C/C) of organic carbon (OC). The most abundant species of dicarboxylic acids was oxalic acid, followed by malonic, phthalic, or succinic acids. Glyoxylic acid and methyglyoxal were most abundant ketocarboxylic acid and dicarbonyl, respectively. Seasonal differences, size-segregated concentrations, and the correlations of these acids with ambient temperatures, oxidants, elemental carbon (EC), OC, WSOC, and ionic components were also discussed in terms of their corresponding sources and possible secondary formation pathways. The results suggested that photochemical reactions contributed more to the formation of particulate organic acids in Saitama suburban areas than did direct emissions from anthropogenic and natural sources. However, direct emissions of vehicles were also important sources of several organic acids in particles, such as phthalic and adipic acids, especially in winter.

• Korean Journal of Remote Sensing
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• v.29 no.5
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• pp.581-588
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• 2013

We developed the three channel lidar system to measure stratospheric aerosols at the Gwangju Institute for Science and Technology (GIST), a suburban site in Republic of Korea. The system provides backscatter coefficient (${\beta}$) at 532 and 1064 nm as well as depolarization ratios (${\delta}$) at 532 nm ($2{\beta}+1{\delta}$) using the doubled Nd:YAG laser wavelength at 532 and 1064 nm. The lidar system is optimized to measure stratospheric aerosols such as volcanic ashes. This paper describes the details of the optical setup, data acquisition system, and analysis method. This study shows an example of measuring stratospheric aerosols emitted by the volcanic eruption which occurred in Mt. Nabro ($13.37^{\circ}$ N, $41.70^{\circ}$ E).

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.5
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• pp.472-481
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• 2015

Black carbon (BC) aerosols were monitored at the KIST site ($37.603^{\circ}N$, $127.046^{\circ}E$) and Cheonan-KOREATECH site ($36.766^{\circ}N$, $127.281^{\circ}E$) during the pre KORea-US Air Quality Study (KORUS-AQ) campaign using a couple of Muliti Angle Absorption Photometers (MAAP). BC mass concentrations were presented as $2.14{\pm}1.06{\mu}g/m^3$ and $0.94{\pm}0.60{\mu}g/m^3$ at KIST site (Seoul) and KOREATECH site (Cheonan), respectively. BC mass concentrations measured at KIST and KOREATECH sites from 22:00 on May 22 to 12:00 on May 23, 2015 showed 80% and 72% higher than average BC mass concentrations measured during campaign period, respectively. It indicates both sites could be influenced by a remote source. Similar patterns of BC concentrations between two sites from 20:00 to 24:00 on June 6, 2015 implies that the BC could be transported into both sites and then be stagnant inside the Korean Peninsula. Diurnal variation of BC in weekdays and weekends were also presented for the KIST and KOREATECH sites. Morning rush hour peak was observed at KIST site located in metropolitan area though no distinct morning rush hour peak was not observed at KOREATECH site located in a suburban area. This study revealed transport pathways of BC near the Korean Peninsula using back-trajectory analysis of BC measured both in a metropolitan area and in a suburban area.

• Asian Journal of Atmospheric Environment
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• v.4 no.3
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• pp.150-156
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• 2010

Inter-comparison of chemical transport models (CTMs) was conducted among four modeling research groups. Model performance of the ensemble approach to $O_3$ and $PM_{2.5}$ simulation was evaluated by using observational data with a time resolution of 1 or 6 hours at four sites in the Kanto area, Japan, in summer 2007. All groups applied the Community Multiscale Air Quality model. The ensemble average of the four CTMs reproduced well the temporal variation of $O_3$ (r=0.65-0.85) and the daily maximum $O_3$ concentration within a factor of 1.3. By contrast, it underestimated $PM_{2.5}$ concentrations by a factor of 1.4-2, and did not reproduce the $PM_{2.5}$ temporal variation at two suburban sites (r=~0.2). The ensemble average improved the simulation of ${SO_4}^{2-}$, ${NO_3}^-$, and ${NH_4}^+$, whose production pathways are well known. In particular, the ensemble approach effectively simulated ${NO_3}^-$, despite the large variability among CTMs (up to a factor of 10). However, the ensemble average did not improve the simulation of organic aerosols (OAs), underestimating their concentrations by a factor of 5. The contribution of OAs to $PM_{2.5}$ (36-39%) was large, so improvement of the OA simulation model is essential to improve the $PM_{2.5}$ simulation.