• Atmosphere
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• v.23 no.1
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• pp.93-102
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• 2013

Atmospheric transport pathway of an air mass is an important constraint controlling the chemical properties of the air mass observed at a designated location. Such information could be utilized for understanding observed temporal variabilities in atmospheric concentrations of long-lived chemical compounds, of which sinks and/or sources are related particularly with natural and/or anthropogenic processes in the surface, and as well as for performing inversions to constrain the fluxes of such compounds. The Lagrangian particle dispersion model FLEXPART provides a useful tool for estimating detailed particle dispersion during atmospheric transport, a significant improvement over traditional "single-line" trajectory models that have been widely used. However, those without a modeling background seeking to create simple back-trajectory maps may find it challenging to optimize FLEXPART for their needs. In this study, we explain how to set up, operate, and optimize FLEXPART for back-trajectory analysis, and also provide automatization programs based on the open-source R language. Discussions include setting up an "AVAILABLE" file (directory of input meteorological fields stored on the computer), creating C-shell scripts for initiating FLEXPART runs and storing the output in directories designated by date, as wells as processing the FLEXPART output to create figures for a back-trajectory "footprint" (potential emission sensitivity within the boundary layer). Step by step instructions are explained for an example case of calculating back trajectories derived for Anmyeon-do, Korea for January 2011. One application is also demonstrated in interpreting observed variabilities in atmospheric $CO_2$ concentration at Anmyeon-do during this period. Back-trajectory modeling information introduced in this study should facilitate the creation and automation of most common back-trajectory calculation needs in atmospheric research.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.3
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• pp.343-355
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• 2005

Cloud/fog water was collected at Daegwallyeong, a typical clean environmental area, by using an active fog sampler during the foggy period in 2002, The pH ranged from 3,7 to 6,5 with a mean of 5,0, but the pH calculated from average concentrations of $H^+$ was 4.4. $SO_4^{2-},\;NO_3^-\;and\;NH_4^+$ were predominant ions with average concentrations of 473,3, 463,3 and $576,0\;{\mu}eq/L$, respectively, This showed that cloud/fog water was slightly acidified, but the concentrations of major pollutants were as high as those for polluted area, suggesting effect from long range transported pollutants, Samples were categorized into four groups (E, W, S, N) by applying 48-h back trajectory analysis using the Hybrid Single-Particle Largrangian Integrated Trajectory (HYSPLIT) model. Concentrations of seasalt $(Na^+\;and\;Cl^-)$ were the highest for group E, indicating large input of seasalts by air masses transported from the East Sea. The concentrations of $SO_4^{2-}$ were slightly higher in group W but the difference was not significant. However, the concentrations of $NO_3^-$ were significantly higher in group W than those in other three groups, The median values of cloud/fog water pH for group N and W were below 4,5, which is significantly lower than median values in group E and group S, This suggests that the acidifying pollutants were transported from the Asia continents and Seoul metropolitan area cause acidification of the cloud/fog water in Daegwallyeong.

• 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.1
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• pp.20-25
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• 2010

The gaseous $^{222}Rn$ concentration at the level of clouds was estimated by using the wet scavenging model of its decay products with the observed data of environmental radiation at the ground. And the origin of the $^{222}Rn$ was also discussed. The estimation was done for a precipitation event on Dec. 26-27, 2003, when a large increase of the radiation was observed in Tokai-mura in Ibaraki, Japan. From a backward trajectory analysis, the origin of $^{222}Rn$ atoms for that event was traced back to the northeastern part of China, and it was expected that the large amount of $^{222}Rn$ emitted in the northeastern part of China was transported to Tokai-mura by the Eurasian continental air mass.

• Atmosphere
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• v.24 no.2
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• pp.245-251
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• 2014

Statistical trajectory analysis has been widely used to identify potential source regions for chemically and radiatively important chemical species in the atmosphere. The most widely used method is a statistical source-receptor model developed by Stohl (1996), of which the underlying principle is that elevated concentrations at an observation site are proportionally related to both the average concentrations on a specific grid cell where the observed air mass has been passing over and the residence time staying over that grid cell. Thus, the method can compute a residence-time-weighted mean concentration for each grid cell by superimposing the back trajectory domain on the grid matrix. The concentration on a grid cell could be used as a proxy for potential source strength of corresponding species. This technical note describes the statistical trajectory approach and introduces its application to estimate potential source regions of $CO_2$ enhancements observed at Korean Global Atmosphere Watch Observatory in Anmyeon-do. Back trajectories are calculated using HYSPLIT 4 model based on wind fields provided by NCEP GDAS. The identified $CO_2$ potential source regions responsible for the pollution events observed at Anmyeon-do in 2010 were mainly Beijing area and the Northern China where Haerbin, Shenyang and Changchun mega cities are located. This is consistent with bottom-up emission information. In spite of inherent uncertainties of this method in estimating sharp spatial gradients within the vicinity of the emission hot spots, this study suggests that the statistical trajectory analysis can be a useful tool for identifying anthropogenic potential source regions for major GHGs.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.2
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• pp.162-175
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• 2008

Gyeongju, which was the central city of the ancient civilization at Silla Kingdom, has various kinds of stone cultural properties. It is significantly important to preserve historical sources of Korea. However, recent air quality data measured in Gyeongju did not show good air quality level. In order to investigate variation of the concentration of the air pollutants with meteorological condition, an air quality monitoring and an aerosol sampling were conducted during the intensive monitoring period in Gyeongju. Impacts of the meteorological factors on the air pollutants were also analyzed based on the air mass pathway categories using HYSPLIT model and the local wind patterns using MM5 model. The prevailing air mass pathways were classified into four categories as following; category I affected by easterly marine aerosols, category II affected by northwesterly continental aerosols, category III affected by southwesterly continental aerosols, and category IV affected by northerly continental aerosols. The concentrations of the air quality standards were relatively lower during the fall intensive monitoring period. At that time, the easterly marine air mass pattern was dominated. The seasonal average mass concentration of $PM_{10,Opt}$, which optically measured at the monitoring site, was the highest value of $77.6{\pm}28.3\;{\mu}g\;m^{-3}$ during the spring intensive monitoring period but the lowest value of $20.1{\pm}5.3\;{\mu}g\;m^{-3}$ during the fall intensive monitoring period. The concentrations of $SO_2$ and CO were relatively higher when the air mass came from the northwestern continent or the northern continent. The concentrations of ${SO_4}^{2-}$ and ${NO_3}^-$ increased under the northwesterly continental condition. It was estimated that the acidic aerosols were dominated in the atmosphere of Gyeongju when the air mass came from the continental regions.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.5
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• pp.584-593
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• 2008

The surface $O_3,\;CO,\;NO_x,\;and\;SO_2$ were measured at Gosan in Jeju Island from May 2004 to April 2005. Over this period, the mean concentrations $({\pm}s.d.)$ of each gas was 40.06 $({\pm}16.01)$ ppbv for $O_3,\;264.92({\pm}115.73)ppbv\;for\;CO,\;1.98({\pm}2.73)ppbv\;for\;SO)_2,\;and\;4.64 ({\pm}3.24) ppbv\;for\;NO_x$. The monthly variations and the diurnal variations of these gases show that the Gosan site is situated in a relatively clean region. However, there were episodic simultaneous peaks in CO and $SO_2$, especially in winter and early spring. Using cluster analysis with air mass back- ward trajectory analysis, we suggest that these episodes are due to the influence of transportation of polluted air mass from polluted regions. In the cluster, which was under the dominant influence of clean maritime air mass, low levels of $O_3,\;CO,\;and\;SO_2$ were observed. The levels of these species were elevated in the other two clusters which had the air mass influenced by polluted continental regions. In addition, ratios of the chemical species such as $CO/NO_x,\;SO_2/NO_x,\;and\;CO/SO_2$ revealed the somewhat different characteristics of emission sources influencing each cluster. The differences in concentration of trace gases among clusters with different origin and transport pathways imply that Gosan is under the effect of pollution transported from other regions.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.3
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• pp.297-305
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• 1996

Aerosol measurements were carried out at Kosan, Cheju Island, Korea for the period from July 20 to August 10, 1994. Total suspended particles were collected by high volume samplers and PM 2.5 particles with gaseous volatile species were collected by a filter pack sampler and their ionic composition are analyzed. The average mass concentration of PM 2.5 particles was comparable to that of PM 3 particles collected during March, 1994 at the same site but the average non sea-salt sulfate concentration was higher that that of PM 3 particles, implying the fraction of anthropogenic air apllutants during this period is higher than that during March, 1994. During the measurement period, two distincitive patterns were observed, high concentrations of mass and water soluble ions were observed between July 20 and August 1 while those during after August 2 were low. Back trajectory analysis results show that air masses arriving at Kosan during the earlier period were mainly from Korea and Japan while those during the later period were from the North Pacific Ocean. It is suggested that the particle ion concentrations during the later period are marine background concentrations at Kosan during the summertime.

• Analytical Science and Technology
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• v.25 no.1
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• pp.7-13
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• 2012

The real-time monitoring of radon ($^{222}Rn$) concentrations has been carried out to evaluate the background concentration level of atmospheric radon in Gosan site, Jeju Island. The mean concentration of radon for the recent 10 years was 2831 $mBq/m^3$ (0.077 pCi/L), which was 19.5 time lower than that of indoor radon in Korea. The seasonal concentrations were 2657, 2071, 3249, 3384 $mBq/m^3$ respectively for spring, summer, fall, and winter seasons. In monthly comparison, the radon concentrations were high in October and low in July. The hourly concentrations have increased during the nighttime, showing 3666 $mBq/m^3$ at 7 a.m., and decreased relatively during the daytime, showing 2755 $mBq/m^3$ at 2~3 p.m. From the back trajectory analysis, the radon concentrations showed higher values when the air mass was moved from the Asia continent to Jeju area, on the other hand, it showed low values when it was moved from the North Pacific Ocean.

• Analytical Science and Technology
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• v.27 no.4
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• pp.213-222
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• 2014

The atmospheric aerosols of $PM_{10}$ and $PM_{2.5}$ were collected at Gosan site of Jeju Island during 2012- 2013. Their ionic and elemental species were analyzed in order to examine the composition variation of the haze aerosols in accordance with the pathway of air mass. The concentrations of $nss-SO_4{^{2-}}$, $NO_3{^-}$, and $NH_4{^+}$ increased 2.1~3.7 times in coarse particle and 3.1~6.5 times in fine particle modes, respectively, showing especially high $NO_3{^-}$ concentrations in fine particles during the haze days. The concentrations of S, Zn, Pb and K increased 3.0~5.6 times in coarse particles and 3.2~7.7 times in fine particles during the haze days, on the other hand Al, Fe, and Ca concentrations were high only in coarse particles. Due to the back trajectory analysis, the concentrations of $nss-SO_4{^{2-}}$ and $NO_3{^-}$ for haze days were high when the inflow pathway of air mass was from China, especially a high increase of $NO_3{^-}$ as through the south of China. The $NO_3{^-}/nss-SO_4{^{2-}}$ concentration ratio was relatively high in coarse mode as air mass inflow from China, but in fine mode it was high as air mass passing through the Korean peninsula.