• Journal of Korean Society for Atmospheric Environment
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• v.20 no.4
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• pp.503-514
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• 2004

In Seoul metropolitan area, nocturnal variation of surface ozone concentrations observed at 27 monitoring sites from 1998 to 2002 showed that high ozone levels occurred frequently during the spring. Frequency distributions for nighttime ozone indicated that elevated concentrations in spring were influenced by advection of different air mass compared to other seasons. Surface wind analysis during the spring revealed that relatively strong southwesterly winds were associated with nocturnal ozone enhancement, which can be attributed to the regional transport of ozone. In order to identify the origin of nocturnal ozone enhancement in spring, 3-day backward trajectories were calculated by HYSPLIT 4 for the episode days and then classified. The results showed that NW, W, and SW flows, indicating influence of polluted air masses from the China continent, have 51% in a]1 the episode days, which suggest that the nocturnal ozone enhancement can occur under the effect of long-range transport of ozone-laden air mass on a regional scale. Case study of nocturnal ozone maxima associated with long-range transport was discussed in more detail in the light of meteorological conditions. Southwesterly synoptic flow along the outer edge of moving high-pressure system was found to be the important cause of nocturnal ozone maxima in Seoul. This flow could lead to be long-range transport of ozone that had effectively accumulated in the stagnating portion of the system located eastern coast of China. Low atmosphere soundings, backward trajectories, and elevated ozone and CO levels at the back-ground tiles gave evidence for regional effects on nocturnal ozone enhancement In Seoul.

• Atmosphere
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• v.30 no.1
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• pp.91-102
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• 2020

MERRA-2 ozone and atmospheric data are utilized to test the usefulness of reanalysis-based tracer transport analysis for ozone in the tropical tropopause layer (TTL). Transport and mixing processes related to the seasonal variation of TTL ozone are examined using the tracer transport equation based on the transformed Eulerian mean, and the results are compared to previously proposed values from model analyses. The analysis shows that the seasonal variability of TTL ozone is mainly determined by two processes: vertical mean transport and horizontal eddy mixing of ozone, with different contributions in the Northern and Southern Hemispheres. The horizontal eddy mixing process explains the major portion of the seasonal cycle in the northern TTL, while the vertical mean transport dominates in the southern TTL. The Asian summer monsoon likely contributes to this observed difference. The ozone variability and related processes in MERRA-2 reanalysis show qualitatively similar features with satellite- and model-based analyses, and it provides advantages of fine-scale analyses. However, it still shows significant quantitative biases in ozone budget analysis.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.86-88
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• 2002

The mathematical model was proposed to simulate ozone transport and remediation in unsaturated soils contaminated with phenanthrene. Soil column experiments were also carried out to calibrate the mathematical model. The experimental results successfully matched with the modeling results in various soil conditions. The model proposed nondimensional fraction factor to reveal reactivity between phenanthrene and gas phase ozone and liquid phase ozone. From sensitivity analysis, the fraction factor and stoichiometric coefficient decreased as water content increased. Simulation results showed increased SOM content retarded the ozone transport and the phenanthrene removal due to increased ozone consumption.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.3
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• pp.271-285
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• 2006

A two-dimensional photochemical transport model (2D PTM) is simulated to describe the transport and chemical reaction of ozone related to aerosols in the troposphere and stratosphere. The vertical profiles and total amounts of ozone, which are advected by both residual Eulerian circulation and the adiabatic circulation under certain circumstance, have been compared with the observation data such as ozonesondes, Brewer spectrometer, the Upper Atmosphere Research Satellite (UARS), and the Total Ozone Mapping Spectrophotometer (TOMS). As a result, we find that the observed distribution of ozone Is adequately reproduced in the model at middle and high latitude in the Northern Hemisphere as well as at Phang ($36^{\circ}\;02'N,\;129^{\circ}\;23'E$) in South Korea. In particular, the 2D PTM is well simulated in the ozone decrease due to the Pinatubo volcanic eruption in 1991. However, ozone mixing ratio are more underestimated than those of UARS and ozonesondes, because are very sensitive to the latitude of transport across the tropopause associated with both Rummukainen errors and off-line model. Relative mean bias errors and relative root mean square errors of ozone calculations using the 2D PTM are shown within${\pm}10%$, respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.124-127
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• 2003

Laboratory scale experiments on in-situ ozonation were carried out to delineate the effects of liquid phases, such as soil water and nonaqeous phase liquid (NAPL) on the transport of gaseous ozone in unsaturated soil. Soil water enhanced the transport of ozone due to water film effect, which prevent direct reaction between soil particles and gaseous ozone, and increased water content reduced the breakthrough time of ozone because of increased average linear velocity of ozone and decreased air-water interface area. Diesel fuel as NAPL also played a similar role with water film, so the breakthrough time of ozone in diesel-contaminated soil was significantly reduced compared with uncontaminated soil. However, ozone breakthrough time was retarded with increased diesel concentration, because of high reactivity of diesel fuel with ozone. In multiphase liquid system of unsaturated soil, the ozone transport was mainly Influenced by nonwetting fluid, diesel fuel in this study.

• Asian Journal of Atmospheric Environment
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• v.9 no.1
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• pp.48-56
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• 2015

The trajectory analysis of boundary layer ozone data at four regional sites in the East Asian outflow regions in Japan was carried out together with boundary layer ozone data observed at Mt. Tai and Mt. Huang in the source region of central eastern China during the monsoon onset in May-June 2003 and 2004. At all sites, the influences of anthropogenic emissions from East Asia have been found. During May and June 2004, the evidences of direct pollution transport from central eastern China to Hedo, an outflow site in Okinawa Island were observed. Ozone mixing ratios associated with air masses from central eastern China averaged 45 ppb while those associated with clean air masses from the Pacific were only 14 ppb, which resulted in averaged 31 ppb increase of ozone mixing ratios during the pollution episodes from central eastern China at Cape Hedo. Using transport time analysis and averaging all ozone episodes transported from central eastern China, the ozone dilution rate of 5.4 ppb per day was roughly estimated during air masses transported from source to outflow regions at Hedo. In the regions nearby Japanese mainland, however ozone increases by long-range transports were more related to both domestic and East Asian sources as a whole.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.2
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• pp.135-151
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• 2013

This study has been carried out to analyze the sensitivity of ozone concentrations by employing different options of cumulus parameterization schemes (CPSs) and microphysics schemes in MM5 models. These sensitivity tests were applied to long-range transport case of higher ozone over Northeast Asia. Employed CPS schemes are Betts-Miller (BM), Grell (GR), Kain-Fritsch2 (KF2), Anthes-Kuo (AK), None scheme (grid scale physics only), and four microphysics used here are Simple ice, Reisner1, Reisner2, Schultz scheme in MM5. We chose two cases of high ozone long range transport case by employing both concentrations ozone level and backward trajectory model. The results showed that modeled ozone concentrations indicated about 10% differences among CPSs. Of the all options, GR and KF2 (for CPS), and Rersiner-1 and Resiner-2 (for microphysics) showed relatively good and stable variations against ensemble mean values. For both CPS and microphysics schemes, the difference of precipitation arising from different parameterization schemes was significant by itself, but the resultant ozone variations showed only marginal. But the cloud fraction differences arising from different parameterization schemes showed better correlation with ozone variations than precipitation differences, indicating that the photochemical ozone generation variations is more dominant by cloud fraction than wet removal process for high and long-ranged transported ozone cases over Northeast Asia.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.111-114
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• 2003

A new monitoring system has been developed for in-situ and realtime measurement of ozone transport in unsaturated porous media using a fiber optic sensor. The calibration of the fiber optic transflection dip probe (FOTDP) system was successfully carried out at various ozone concentrations using a column with length of 30 cm and diameter of 5 cm packed with glass beads, which don't react with gaseous ozone. The breakthrough curves (BTCs) of ozone was obtained by converting the normalized intensity into ozone concentration. The FOTDP system reflected the ideal transport phenomena of gas phase ozone at various flow rates. The FOTDP system worked well for in-situ monitoring of gas phase ozone at various water saturations and in presence of SOM. However, the FOTDP system did not measure the ozone concentration at more than 70% water saturation.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.59-60
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• 2003

In this study, we present the analysis of vertical ozone sounding data observed over Pohang, Korea, and investigate to understand the governing mechanisms for seasonal ozone maximum in June. The vertical ozone profiles in June show that the ozone enhancement is clearly shown in the middle and upper troposphere. We have found that the June maximum is associated with the transport of ozone rich air from the stratosphere and polluted continental air mass. This is different from the previous studies shown that the regionally polluted continental air mass, influenced by the intense anthropogenic activities m northeast Asia during transport, is responsible for the ozone maximum in spring.

• Environmental Engineering Research
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• v.10 no.2
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• pp.71-78
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• 2005

A series of column experiments was conducted to develop a monitoring system for in-situ and realtime measurement of ozone transport in unsaturated porous media using a fiber optic sensor. The calibration of the fiber optic transflection dip probe (FOTDP) system was successfully carried out at various ozone concentrations using a column with length of 30 cm and diameter of 5 cm packed with glass beads, which don't react with gaseous ozone. The breakthrough curves (BTCs) of ozone were obtained by converting the normalized intensity into ozone concentration. The FOTDP system worked well for in-situ monitoring of gas phase ozone at various water saturations and in presence of soil organic matter (SOM). However, the FOTDP system did not measure the ozone concentration at more than 70% water saturation.