• Journal of Environmental Science International
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• v.16 no.10
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• pp.1157-1167
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• 2007

In an effort to interpret the characteristics of fine particle concentrations in Busan, time variations of hourly monitored concentrations $PM_{10}$ (Particulate Matter with aerodynamic Diameter ${\le}10\;{\mu}m$) in Busan are analyzed for the period from 2000 to 2005. The characteristics of aerosol second generation formation process is also interpreted qualitatively, by using the statistical analysis of the meteorological variables including temperature, wind speed, and relative humidity. The result shows some significant annual, seasonal, weekly and diurnal variations of $PM_{10}$ concentrations. In particular, seasonal(i.e., spring) variations are governed by frequency of yellow sand events even for the non-yellow sand cases where yellow-sand days are eliminated in our analysis. However, in seasonal variation, summer season predominate lower $PM_{10}$ concentrations due to the frequent precipitation, and weekly and diurnal variations are both found to be reflecting the emission rate from traffic amount. Correlation coefficients between $PM_{10}$ concentration and meterological variables for non-yellow sand days show overall negative correlation with visibility, wind speed, cloud amounts, and relative humidity. However for non-precipitation days, during non-yellow sand period positive correlation are found clearly with relative humidity, suggesting the importance of secondary aerosol formation in Busan that can be achieved by both homogeneous aerosol formation and heterogeneous transformations resulting from hygroscopic aerosol characteristics.

• Atmosphere
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• v.28 no.4
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• pp.469-477
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• 2018

We performed the comparison of observed $PM_{10}$ and $PM_{2.5}$ at both the Yonsei University and the AIRKOREA site in the same Seodaemun-gu district, Seoul from March to December 2016. Generally, the moderate correlations between two sites were found for both $PM_{10}$ and $PM_{2.5}$, but monthly difference was somewhat occurred, implying that the measurement situation is not equally maintained even in a closely located area. Particularly correlations became weaker in June and July, which seems the impact of rainy conditions. Correlations between two stations were higher for $PM_{10}$ compared to $PM_{2.5}$, probably indicating the spatially larger difference of fine mode particle. Monthly mean variation was similar between two sites showing a maximum in March and minimum in August. Diurnal variation was somewhat different: morning peak at Yonsei University but evening peak at the Seodaemun-gu AIRKOREA site, reflecting the difference of local air condition. We also compared the extent of $PM_{10}$ and $PM_{2.5}$ according to the local wind speed and direction. In general, the level of particulate matter was high when the wind is blowing from the northwestern area with low wind speed, meaning the high accumulation effect of transported air particles. Findings of this study can be usefully considered for the investigation about the discrepancy of aerosol measurement in a local scale.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.3
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• pp.1865-1877
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• 2013

Vertical variations of polycyclic aromatic hydrocarbon (PAH) concentrations in $PM_{10}$ were investigated in order to assess the factors controlling their behavior in the urban atmosphere of Bangkok City, Thailand. Air samples were collected every three hours for three days at three different levels at Bai-Yok Suit Hotel (site-1 and site-2) and Bai-Yok Sky Hotel (site-3) in February $18^{th}-21^{st}$, 2008. The B[a]P concentration showed a value 0.54 fold, lower than the United Kingdom Expert Panel on Air Quality Standard (UK-EPAQS; i.e. 250 pg $m^{-3}$) at the top level. In contrast, the B[a]P concentrations exhibited, at the ground and middle level, values 1.50 and 1.43 times higher than the UK-EPAQS standard respectively. PAHs displayed a diurnal variation with maximums at night time because of the traffic rush hour coupled with lower nocturnal mixing layer, and the decreased wind speed, which consequently stabilized nocturnal boundary layer and thus enhanced the PAH contents around midnight. By applying Nielsen's technique, the estimated traffic contributions at Site-3 were higher than those of Site-1: about 10% and 22% for Method 1 and Method 2 respectively. These results reflect the more complicated emission sources of PAHs at ground level in comparison with those of higher altitudes. The average values of incremental individual lifetime cancer risk (ILCR) for all sampling sites fell within the range of $10^{-7}-10^{-6}$, being close to the acceptable risk level ($10^{-6}$) but much lower than the priority risk level ($10^{-4}$).

• 한국해양학회지
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• v.20 no.2
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• pp.28-39
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• 1985

The driving mechanisms for low level jets(LLJ) and coastal surface maximum winds are studied with observed wind data from June, 1976 through August, 1980 at Port Aransas and Victoria, Texas, in connection with a baroclinic model. This model is developed considering the forcing functions such as the synoptic and meso-scale pressure gradient, the frictional force, and the atmospheric stability. The results show that a LLJis observed on over 95% of the occasions when a nighttime coastal wind maximum occurred. Baroclinicity generated by sloping terrain during the summertime causes the diurnal variation in the thermal field. This thermal wind component would then decrease the prevailing synoptic-scale southerly wind by day and allow it to increase at night. Nighttime atmospheric stability leads to frictional decoupling which enhances the nocturnal LLJ. At the coastal site neutral stability prevails, thus all owing downward transfer of momentum from the nocturnal LLJ and results in the nocturnal coastal surface wind maximum. The height of LLJis not uniquely related to the inversion layer, and the results of the computations using this model show a good agreement with the observations.

• Journal of Korean Society for Atmospheric Environment
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• v.7 no.3
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• pp.227-234
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• 1991

This study deals with concentration and light extinction of atmospheric aerosol in Seoul. From the measured aerosol size distribution for particle diameter ranging from 0.01 $\mum \sim 1.0 \mum$, extinction coefficient is calculated using the Mie theory. The results show that the diurnal variation of aerosol concentration, in general, reveals the lowest concentration in early morning and afternoon, while the highest at about 8 O'clock owing to the heavy traffic and accumulation of air pollution in the low atmosphere. However, aerosol concentration and extinction coefficient on April 7 give low values due to the advective wind. On the other hand, high aerosol concentration and extinction coefficenat are recorded on April 10 although solar radiation is weak. From the distribution of extinction coefficient we can find that aerosol particles of 0.1 $\mum \sim 1.0 \mum$ in diameter are highly effective on light extinction.

• Journal of Environmental Science International
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• v.8 no.3
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• pp.287-292
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• 1999

This study was performed to investigate the characteristics of nocturnal maxiumu ozone occurrence and the meteorological relevance using to hourly ozone data and meteorological data for 1995~1996 in Pusan coastal area. Kwangbokdong showed the highest occurrence of nocturnal maximum ozone as 36.9%, and Deokcheondong showed the lowest occurrence(9.2%) for research period in Pusan. The occurrence rates of nocturnal maximum ozone concentration were decreased toward land area. The low maximum temperature, high minimum temperature, low diurnal range, high relative humidity, high wind speed, high could amount, low sunshine and low radiation were closely related to the main meteorological characteristics occuring the nocturnal maximum concnetration of ozone. It was shown that normal daily variation of ozone concentration by strong photochemical reaction at the before day of nocturnal maximum ozone. The concnetration of nocturnal maximum ozone were occured by entrainment of ozone from the upper layer of developed mixing layer. There are no ozone sources near the ground at night, so that the nighttime ozone should be entrained from the upper layer by forced convection.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.1
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• pp.61-68
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• 2000

Gas-phase hydrogen peroxide(H2O2) concentrations were measured to investigate it's distribution in the ambient air in downtown Seoul(Kwanghwamum and Mullae-dong). These measurements were made during four season, from April 30, 1998 to January 29, 1999, using Cold Trap and HPLC. Measurements were also made of other photochemical oxidants and trace gases(O3, NO2, CO and SO2) and meteorological parameters(relative humidity, temperature, solar radiation and wind speed). The mean of all observations was 0.10 ppbv and the range measured was below the level of detection(>0.01 ppbv) to 0.47ppbv. The higher seasonal mean concentrations showed during the summer(0.21 ppbv) and concentrations of H2O2 showed a diurnal variation with maximum concentrations in the afternoon(12:30∼14:00). The results from the corrrelation analysis showed that the concentration of gaseous H2O2 is strongly dependent on the other air pollutants(NO2, CO and O3) and meteorological parameters(relative humidity, temperature and solar radiation.)

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.34.1-34.1
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• 2008

Cosmic ray (CR)s are energetic particles that are found in space and filter through our atmosphere. They are classified with galactic cosmic ray (GCR)s and solar cosmic ray (SCR)s from their origins. The process of a CR particle colliding with particles in our atmosphere and disintegrating into smaller pions, muons, neutrons, and the like, is called a cosmic ray shower. These particles can be measured on the Earth's surface by neutron monitor (NM)s. Regarding with the space weather, there are common types of short term variation called a Forbush decrease (FD) and a Ground Level Enhancement (GLE). In this talk, we will briefly introduce our recent studies on CRs observed by NM: (1) simultaneity of FD depending on solar wind interaction, (2) an association between GLE and solar proton events, and (3) diurnal variation of the GCR depending on geomagnetic cutoff rigidity. NM will provide a crucial information for the Korea Space Weather Prediction Center (KSWPC).

• Analytical Science and Technology
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• v.8 no.4
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• pp.731-738
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• 1995

Toxic air pollutants are investigated in a petrochemical industrial park in Taiwan by using a movable open path FTIR. The results show the qualitative and quantitative analysis of emission gases from plants, and also provide the emission rate of different compounds. More than twenty compounds under usual operation are found from this industrial park. The concentration variation with time can be correlated exactly with wind direction. It means that by changing the measuring points, the source of emission can be unambiguously identified. An EPA proved PAL model is applied to estimate the emission rate of either a point or an area source. Local atmospheric stability is determined by releasing the $SF_6$ tracer. The origins of errors come mainly from the uncertainty of source's configuration and the variation of meteorological condition. Through the continuous measurement (half an hour base in this study) of OP-FTIR sensor, the maximum value of emission rate and the annual amount of emission can be derived. The emission rate of the measured toxic gases are derived by the model technique and the results show that the emission amount are in the order of ten to hundred tons per year.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.3
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• pp.297-307
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• 2006

During January $2002{\sim}April\;2004$, hydrogen peroxide ($H_{2}O_{2}$) measurements were performed at the campus of Korea University, which is located in the northeastern part of Seoul. Gas phase hydroperoxide was collected in aqueous solution and separated by HPLC. Concentrations were determined by fluorescence using postcolumn enzyme derivatization. This measurement system was improved to be run automatically from sample collection at every 10 minutes through chemical analysis for data collection. Detection limits of $H_{2}O_{2}$ is $10{\sim}17\;pptv$, and the overall uncertainty of the measurements is better than 8%. Two-year measurements of $H_{2}O_{2}$ show typical seasonal variations. Concentrations of $H_{2}O_{2}$ were higher during $June{\sim}October$ and lower during $January{\sim}February$. Maximum concentration of 1-hour averaged $H_{2}O_{2}$ was 6.5 ppbv, which was observed in August and September. In general $H_{2}O_{2}$ concentrations were well correlated with $O_{3}$ concentrations and largely affected by meteorological factors such as temperature and wind direction.