Journal Search Engine
Search Advanced Search Adode Reader(link)
Download PDF Export Citaion korean bibliography PMC previewer
ISSN : 1225-6692(Print)
ISSN : 2287-4518(Online)
Journal of the Korean earth science society Vol.40 No.4 pp.414-427
DOI : https://doi.org/10.5467/JKESS.2019.40.4.41

Case Studies of Mass Concentration Variation in the Central-Southern Korean Peninsula Caused by Synoptic Scale Transport of Dust Storms

Hak-Sung Kim*, Jae-Hee Cho
Department of Earth Science Education, Korean National University of Education, Chungbuk 28173, Korea
Corresponding author: envir007@knue.ac.kr Tel: +82-43-230-3777
August 7, 2019 August 15, 2019 August 20, 2019

Abstract


In East Asia, the long-range transport of dust storms originating from Mongolia and northern China affects airborne dust loadings over downwind areas in the southern Korean Peninsula. Since 1997, dust loading cases caused by dust storms have been observed using the thresholds of total suspended particles (TSP, ≥250 μg m−3 hr−1 ) and particulate matter less than 10 μg (PM10, ≥190 μg m−3 hr−1 ) in the central-southern Korean Peninsula. There were two dust loading cases that exceeded these thresholds in 2016 and three in 2017, which reflects the downward trend of the last twenty-one years in the central-southern Korean Peninsula. Furthermore, five other dust loading cases with mass concentrations lower than the thresholds were observed from 2016 to 2017. In the moderate dust loading cases exceeding the thresholds, a descending motion of cut-off lows below 45°N and a southward trough at 500 hPa gpm isopleths intensified at the western ridge, and largely extended the surface high-pressure system over southeast China. Airborne dust loadings following pronounced north-westerlies in the forward side of the high-pressure system were transported to the surface of the central-southern Korean Peninsula. However, in slight dust loading cases lower than the thresholds, the restricted descending motion of cut-off lows over 45°N and the southwestward trough at 500 hPa gpm isopleths intensified the zonal flow over the Korean Peninsula. Surface high- and low-pressure systems moved eastward from the source compared to moderate dust loading cases. Due to the zonal movement of dust storms traversing eastern China, slight dust loading cases were observed with relatively higher ratios of PM2.5/TSP and carbon monoxide (CO) in the central-southern Korean Peninsula.



초록


    1. Introduction

    Dust storms typically occur in the arid regions of Mongolia and northern China in spring, when strong surface wind blows against the dry surface, causing an abundance of dust to float up in the air. Strong surface wind is induced by the higher pressure gradient force between high and low-pressure systems. These transient weather systems have been documented as one of the main processes causing dust storms, since their arid characteristics may trigger wind erosion across a wide area, and the associated cold frontal activities may lift dust from the surface (Chung, 1992;Gao et al., 2006). Prior studies have also indicated that the surface condition of high and low-pressure systems over arid areas plays an important role in determining the strength or transport pathway of dust storms (Laurent et al., 2005;Kim, 2008;Liang et al., 2016).

    Air-borne dust particles caused by dust storms are transported to the downwind area including eastern China, the Korean Peninsula, Japan, and occasionally as far as North America by the circulation of surface high and low-pressure systems (Seinfeld et al., 2004;Wang and Fang, 2006;Kim et al., 2016). Severe dust loading cases have mainly been analyzed on the movement of air flows at both upper and surface levels in the downwind area (Chun et al., 2001;Kim et al., 2006;Tsai and Chen, 2014;Park et al., 2016). Furthermore, the synoptic features and transport passing routes for severe dust loading cases were classified to assess air quality in the downwind area (Kim et al., 2006;Kim, 2008;Kim and Chung, 2010).

    The adverse effects of dust loadings on air quality highlight observable developments in dust storms such as the ground-based measurement of mass concentrations, satellite data analysis, lidar measurement, and the air quality model. Consequently, satellite observations have become an essential supplement to the inefficiency of ground observatory facilities in the East Asian region (Chung and Le, 1984;Kim et al., 2016). However, the ground measurement of mass concentrations has been used as a method of air quality assessment (Chung et al., 2003a;Chung et al., 2003b;Huang et al., 2013;Kim et al., 2016). In particular, the background measurement of mass concentrations in a downwind area is essential to the observation of long-range transport of air pollutants. Dust loading cases caused by dust storms have been observed by using the thresholds of TSP or PM10 in central-southern Korean Peninsula since 1997 (Chung et al., 2003a).

    Long-term observations have shown that occurrences of dust storms and dusty days in source areas in Mongolia and China are decreasing (Gao et al., 2003;Natsagdorj et al., 2003;Wang et al., 2008). It was suggested that the phenomenon is attributable to the weakened activity of high and low-pressure systems and lower surface winds induced by warming in the higher latitudes (Hulme et al., 1994;Hara et al., 2006;Kim et al., 2017). In the southern Korean Peninsula, dusty days by dust storms have reduced with a decreasing rate of −0.8±0.1 day yr−1 since 1997 (Kim et al., 2017). Therefore, average mass concentrations of TSP and PM10 have tended to decrease significantly in winter and spring at the background site as well as in large urban areas in the southern Korean Peninsula. It is necessary to analyze synoptic features at both upper and surface levels for recent dust loading cases in the downwind area.

    2. Data and Analyzing Methods

    2.1. Background measurements of TSP and PM10

    Korea Centre for Atmospheric Environment Research (KCAER) is located in Gangnae, Cheongju in central-southern Korean Peninsula (Fig. 1). The Taeahn Peninsula (TAP), located in the central western seaside in the southern Korean Peninsula, is 100 km away from KCAER. There are no large urban or industrial areas between the two sites. TAP has served as a monitoring site under the National Oceanic and Atmospheric Administration (NOAA) Greenhouse Gases Monitoring Division (GMD) corporate network since 1993. This collaboration has made it possible to measure long-range transport air pollutants including dust storms from Mongolia and northern China at KCAER.

    KCAER has been measuring the ground-based mass concentrations of TSP and PM10 since 1993. The thresholds of TSP (≥250 μgm−3 hr−1 ) or PM10 (≥190 μgm−3 hr−1 ) for observing dust loading cases caused by dust storms have been used at KCAER in central-southern Korean Peninsula since 1997 (Chung et al., 2003a). Additionally, the first PM2.5 mass concentration measurements were made in 2001 at KCAER in the southern Korean Peninsula. In prior studies, these mass concentrations were used as background measurement data in a downwind site from China (Kim et al., 2016;Kim et al., 2017).

    2.2. Satellite and meteorological data

    Since 1996, KCAER has been using satellite data received directly from the NOAA orbital satellites. The RGB-composite images have been used to detect the large-scale transport of air pollutants in the East Asian region. In this study, brightness temperature differences (BTD) were analyzed to detect the largescale transport of dust storms from their sources to the southern Korean Peninsula. The BTD method for NOAA satellite data was described in a prior study (Kim et al., 2016).

    The reanalysis data (2.5° ×2.5°) of the National Center for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) were used to analyze synoptic features for dust loading cases observed at KCAER. Synoptic features for dust loading cases were analyzed by using meteorological charts including 500 hPa gpm isopleths and surface weather maps. The sounding data at KCAER were made available courtesy of NCEP-Global Data Assimilation System (GDAS). Also, height variations for each 24 hour period at 500 hPa gpm isopleths were obtained from the Korea Meteorological Administration (KMA) to analyze the strength and movement pathways of troughs and ridges.

    3. Results and Discussions

    3.1. Observations of dust storms and associated dust loading cases

    The large-scale transport of dust storms was observed using NOAA satellite RGB-composite images and BTD analyses in the East Asian region. Figure 1 shows occurrences of dust storms in southern Mongolia and northeastern China moving toward centralsouthern Korean Peninsula during April 21-24, 2016. On April 21, a dust storm occurred in southern Mongolia and northeastern China. On April 22, the southeastward transport of the dust storm traversed Bohai Bay. However, on the RGB-composite image and BTD analysis of April 23, the distinction between dust storms and clouds is less evident. Nonetheless, it was found that the dust storm of April 23 impacted the air quality in central-southern Korean Peninsula along with airborne dust loadings (Fig. 2). Mass concentrations of TSP and PM10 sharply increased at a level higher than the thresholds on April 23 and peaked with 345 and 278 μgm−3 hr−1 , respectively, on April 24. A BTD analysis shows the distribution of dust loadings in central-southern Korean Peninsula on April 24. Compared with TSP and PM10, PM2.5 mass concentrations were low, less than 58 μgm−3 hr−1 during April 23-24. However, there was an impact of fine anthropogenic dust falls measured at a maximum of PM2.5 78 μgm−3 hr−1 on April 22.

    Table 1 shows the dust storms and associated dust loading cases observed in central-southern Korean Peninsula from 2016 to 2017. These dust storms originated from Mongolia and northern China. There were two dust loading cases higher than the thresholds in 2016 and three in 2017. In the two years of 2016 and 2017, the mass concentrations of TSP and PM10 in dust loading cases were the highest with 488 and 390 μgm−3 , respectively. Since 1997, dust loading cases higher than the thresholds caused by dust storms have decreased in central-southern Korean Peninsula (Kim et al., 2017). For the last 21 years, the yearly average number of dust loading cases and associated maximum PM10 were 6 and 796 μgm−3 , respectively. These long-term decreasing trends reflect fewer cases and reduced maximum mass concentrations in dust loadings in central-southern Korean Peninsula for 2016 and 2017.

    Among the dust loading cases exceeding the thresholds, two cases of dust loadings were observed on April 23-24, 2016 and May 6-8, 2017, marking the highest TSP mass concentrations in recent years. However, the other two cases (April 19-20, 2017 and November 22, 2017) were observed showing the lower PM10 mass concentrations less than 144 μgm−3 hr−1 , respectively. Conversely, five dust loading cases showing lower mass concentrations less than the thresholds were observed. Between April 8-10, 2016, the daily average PM10 mass concentration pointed to 120 μgm−3 . Incidentally, the daily average PM10 with 100 μgm−3 day−1 or over is the air quality standard of the southern Korean Peninsula. Even though dust loading cases were observed with lower mass concentrations less than the thresholds, airborne dust loadings adversely impacted the air quality of centralsouthern Korean Peninsula.

    3.2. Classification of synoptic features for dust loading cases

    Dust loading cases caused by dust storms in centralsouthern Korean Peninsula were classified with different synoptic features by using 500 hPa gpm isopleths and surface weather maps from 2016 to 2017. In Table 1, the first days out of six dust loading cases were selected to compare synoptic features of dust loading cases. Figure 3 shows the 500 hPa gpm isopleths and surface weather maps for three dust loading cases (April 23, 2016, May 7, 2016, and May 6, 2017) higher than TSP and PM10 thresholds. These dust loading cases were observed in central-southern Korean Peninsula in the surface weather map between a forward side of a high-pressure system and a backward side of a cold front associated with a lowpressure system. On the 500 hPa gpm isopleths, the cut-off lows descend south of 45° N to reach the Korean Peninsula. The southeastward descending of a cut-off low resulted in a deep southward trough and an intense ridge on the west side.

    Surface high (low)-pressure systems were located over the northwest (northeast) region of the Korean Peninsula. Surface high (low)-pressure systems were formed under both sides of the cut-off low and southward extension of the trough at the 500 hPa gpm isopleths. As a result of the deep trough and intensified ridges, surface high (low)-pressure systems favored a southward motion instead of a zonal motion. Due to the strong northwesterly wind in the west side of the southeastward moving trough, the surface highpressure systems extended from Mongolia of 40-50° N all the way down to southeastern China. While surface high-pressure systems were higher than 1027 hPa in the sources of dust storms, the high pressure gradually decreased to under 1025 hPa. However, surface lowpressure systems were less than 1002 hPa in the sources of dust storms and moved eastward to the north of the Korean Peninsula with small pressure variations. A surface cold front stretched southward in the low-pressure systems and traversed the Korean Peninsula from west to east. The strong descending northwesterly wind brought an abundance of airborne dust loadings to the lower troposphere in the forward side of the surface high-pressure system.

    Figure 4 shows the 500 hPa gpm isopleths and surface weather maps for dust loading cases (March 6, 2016, April 8, 2016, and November 8, 2017) with lower mass concentrations less than the threshold values. The southeastward movement of cut-off lows merely approached 45° N at 500 hPa gpm isopleths. Therefore, the cut-off lows were mostly located in the north of 45° N. On the 500 hPa gpm isopleths, the dominant synoptic feature was the location of cut-off lows over 45° N and a strong westerly wind that passed the Korean Peninsula at 30-45° N. There were surface high-pressure systems developing over Mongolia at 40-50° N rated higher than 1037 hPa, whereas the surface high-pressure systems grew weaker under 1028 hPa with a large decreasing pressure while extending to eastern China. The strength of the surface low-pressure systems was rated as weak in the source areas, compared with dust loading cases higher than the thresholds. At the same time, the pressure of the surface low-pressure systems continued with small variations from the dust loading origins. The surface high-pressure system extended from Mongolia to northeastern China covering a small area compared with the dust loading cases higher than the thresholds. A cold front stretched from northeast to southwest in the surface low-pressure system and traversed the Korean Peninsula. The smaller airborne dust loadings were accompanied by a weak descending northwesterly wind in the forward side of the surface high-pressure system.

    Dust loading cases were classified as moderate and slight, based on the different ground mass concentrations and synoptic features at 500 hPa gpm isopleths and surface weather maps (Table 2). In the slight dust loading cases with lower mass concentrations of TSP and PM10, the transport of dust loadings were not effective in the forward side of the weakened surface high-pressure system after passing a cold front. Compared with the slight dust loading cases, the descending movement of moderate dust loading cases was relatively stronger in the forward side of the surface high-pressure system. Therefore, moderate dust loading cases with higher mass concentrations occurred in central-southern Korean Peninsula. In 2005, Kim and Chung (2010) classified dust storms, and associated dust loadings with severe and moderate cases, based on the strength of descending air flows in the forward side of surface high-pressure systems. In this analysis, these both severe and moderate dust loading cases were higher than the thresholds. With dust storms and associated dust loading cases in the East Asian region decreasing, higher mass concentration cases have been noticeably decreasing in centralsouthern Korean Peninsula (Kim et al., 2017).

    Conversely, two dust loading cases (January 27, 2017 and April 12, 2017) having lower mass concentrations less than the thresholds occurred under synoptic features of moderate dust loading cases. In a dust loading case that occurred on January 1, 2017, the sources were covered with snow in eastern Mongolia and were, therefore, not in a condition to float dust into the atmosphere. Furthermore, the dust loading case of April 12, 2017 originated from dust storms in eastern Mongolia and northeastern China. This area has not been recorded as a major source of heavy dust loading cases (Natsagdorj et al., 2003;Chung et al., 2003c;Tan et al., 2012). The floating dust from the source was not serious enough to cause a dust loading case exceeding the thresholds in the downwind area of central-southern Korean Peninsula.

    3.3. Upper-level features of moderate and slight dust loading cases

    The 500 hPa height variation for the last 24 hours resulted in the movement of troughs as well as ridges. In a moderate dust loading case on May 6, 2017, a trough was located northeast of the Korean Peninsula, and a ridge intensified, increasing to a height of 238 m over eastern Mongolia (Fig. 5a). The intensified ridge at 500 hPa induced the surface high-pressure system to extend to southeast China as shown in Fig 1. However, in a slight dust loading case on November 8, 2017, 500 hPa height only increased to 91m over eastern Mongolia after an eastward movement of the trough (Fig. 5b). The strength of the surface high-pressure system showed small variations from 1037 to 1025 hPa on May 6, 2017, along with conspicuous decreases in pressure from 1042 to 1028 hPa on November 8, 2017. Table 3 presents variations in height at 500 hPa over the East Asian region on moderate and slight dust loading cases. When a trough was located over the Korean Peninsula at 500 hPa on a moderate dust loading case, the western ridge of the trough visibly intensified as the height increased, compared with that on a slight dust loading case. The relative strong descending cold airflow in the forward side of the surface high-pressure system could have been developed in moderate dust loading cases.

    Figure 6 shows the sounding plots for moderate and slight dust loading cases in central-southern Korean Peninsula. In the moderate dust loading cases, a rapid sinking motion in the forward side of the surface high-pressure system induced air masses to dry and an inversion layer to develop from 500 hPa to the surface. The intensified inversion layer developed by way of the descending air mass between 700-850 hPa. Furthermore, the prevailing winds were northwesterly in this intensified inversion layer. Along the downward strong northwesterly wind, dust loadings descended rapidly into the lower troposphere in central-southern Korean Peninsula. In contrast, the sinking motion was not pronounced in the forward side in the weakened highpressure system in the slight dust loading cases. The only shallow sinking of air masses occurred in the slight dust loading cases of March 6 and April 8, 2016.

    3.4. Backward trajectory analysis

    Backward trajectories were performed for three days from the maximum mass concentration-hour in a dust loading case. Figure 7 shows the isentropic backward trajectories of moderate and slight dust loading cases made available courtesy of the National Oceanic and Atmospheric Administration (NOAA) Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model (Rolph et al., 2017). In the moderate dust loading cases, air flows passed through sources of dust storms in eastern Mongolia from the north of Mongolia, and moved southeastward to central-southern Korean Peninsula. However, air flows passed through the sources of dust storms in southern Mongolia and northern China from western Mongolia, and moved to central-southern Korean Peninsula causing slight dust loading cases. While the southward movement of air flows prevailed for moderate dust loading cases, the easterlies were more pronounced from the sources of dust storms to central-southern Korean Peninsula for slight dust loading cases.

    Dust loadings originating from the arid regions of Mongolia and northern China were composed of coarse mineral particles. Therefore, mineral dust loadings do not cause a high PM2.5 to be emitted to the atmosphere by anthropogenic combustion. The maximum PM2.5 mass concentrations of moderate and slight dust loading cases were rated as low, measured at less than 53 μgm−3 hr−1 . If dust storms were transported from East Asian deserts to the downwind site in the southern Korean Peninsula by way of eastern China, the PM2.5 ratio in dust loadings could increase to about 32% (Kim et al., 2016). Table 4 shows the maximum PM2.5 mass concentrations, ratios of PM2.5/TSP, and CO in moderate and slight dust loading cases. The relatively high PM2.5 ratio over 20% in the slight dust loading cases was caused by dust storms traversing eastern China compared with moderate dust loading cases as shown in Fig. 7. CO concentrations were also observed with higher levels in slight dust loading cases.

    4. Conclusions

    This study classified the synoptic features of dust loading cases observed in central-southern Korean Peninsula, based on the ground measurement of mass concentrations from 2016 to 2017. During these two years, there were two dust loading cases higher than the thresholds in 2016 and three in 2017. The longterm decreasing trend of dust storms in the source areas reflect the decreasing and weakening of dust loading cases in central-southern Korean Peninsula since 1997. Dust loading cases were separated using the threshold values of TSP and PM10. Moderate (slight) dust loading cases higher than (less than) the threshold values were characterized by the synoptic feature of 500 hPa and surface levels.

    During the dust transport to the downwind area, the southward movements of cut-off lows differed from moderate to slight dust loading cases. The cut-off lows associated with the moderate dust loading cases moved southeastward beyond 45° N at 500 hPa gpm isopleths. At this time, the trough extended southward to the south of the Korean Peninsula. A surface highpressure system extended with small decreasing strength from Mongolia to southeastern China, even though the surface low-pressure system continued moderately while moving. A cold front in the surface low-pressure system stretched southward and traversed from west to east over the Korean Peninsula. Due to strong descending air flows in the forward side of the surface high-pressure system, the air mass was dried from 500 hPa to the surface, and an inversion layer developed between 700-850 hPa. The strong descending northwesterly wind in the forward side of the surface high-pressure system brought an abundance of airborne dust loadings to the lower troposphere in central-southern Korean Peninsula.

    In contrast, the southeastward movement of the cutoff lows associated with the slight dust loading cases was restricted over 45° N at 500 hPa gpm isopleths. Westerly wind was concentrated over the Korean Peninsula at 30-45° N. Despite a strong surface highpressure system in Mongolia, decreases in pressure were larger than those of the moderate dust loading cases while in transport. Therefore, a surface highpressure system extended to eastern China covering a small area, compared to the moderate dust loading cases. The surface low-pressure system was weak while in transport. A cold front in a surface lowpressure system stretched from northeast to southwest and passed the Korean Peninsula. The weak descending air flows were confirmed at a small increasing 500 hPa height and a shallow dried layer in the forward side of the surface high-pressure system. The weak descending northwesterly wind was not so effective as to bring airborne dust loadings to the lower troposphere in central-southern Korean Peninsula.

    Furthermore, a backward trajectory analysis showed that moderate dust loading cases pass eastern Mongolia and move southeastward to the southern Korean Peninsula. However, slight dust loading cases pass Mongolia and northern China, and move to the southern Korean Peninsula through eastern China. This pathway added to the fine anthropogenic dust emitted in eastern China. Even though the PM2.5 mass concentration caused by dust storms was rated as lower than 53 μgm−3 hr−1 , the ratio of PM2.5 is larger than 20 %, compared with the maximum ratio of 19% in moderate dust loading cases. Furthermore, the higher CO concentrations were observed in slight dust loading cases with the passing route of dust storms over eastern China.

    Figure

    JKESS-40-4-414_F1.gif

    RGB-composite images (left) and BTD analysis (right) showing the large-scale transport of dust storms (DS) from Mongolia and northeastern China to central South Korea in 2016. The blue rectangles are the location of KCAER and TAP in central- southern Korean Peninsula in BTD images.

    JKESS-40-4-414_F2.gif

    Hourly mass concentrations of TSP, PM10, and PM2.5 measured in central-southern Korean Peninsula during April 21-24, 2016. Thresholds of dust loading cases originating from dust storms are denoted by TSP (250 μgm−3 hr−1 ) and PM10 (190 μgm− 3 hr−1 ).

    JKESS-40-4-414_F3.gif

    500 hPa gpm isopleths (left) and surface weather maps (right) for (a)-(c) dust loading cases observed in central-southern Korean Peninsula from 2016 to 2017.

    JKESS-40-4-414_F4.gif

    500 hPa gpm isopleths (left) and surface weather maps (right) for (a)-(c) dust loading cases observed in central-southern Korean Peninsula from 2016 to 2017.

    JKESS-40-4-414_F5.gif

    Height variations for the last 24 hours at 500 hPa on (a)-(b) dust loading days in the East Asian region in 2017.

    JKESS-40-4-414_F6.gif

    Sounding plots at KCAER for (a)-(c) moderate and (d)-(f) slight dust loading cases. Solid and dashed lines represent temperatures and dew point temperatures, respectively, at 0900 LST.

    JKESS-40-4-414_F7.gif

    Three-day isentropic backward trajectories of (a) moderate and (b) slight loading cases arriving at central South Korea. The arriving height is 1,000 m and trajectories are marked every 12 hours.

    Table

    Observations of dust storms and associated airborne dust loading cases, based on the thresholds (TSP 250 μgm−3 hr−1 or PM10 190μgm−3 hr−1 ) in central-southern Korean Peninsula from 2016 to 2017

    Classification synoptic features for dust loading cases observed in central-southern Korean Peninsula from 2016 to 2017

    500 hPa height variations for the last 24 hours in both sides of the trough in the East Asian region

    Maximum PM2.5 mass concentrations, ratios of PM2.5/TSP, and CO in in moderate and slight dust loading cases observed in central-southern Korean Peninsula from 2016 to 2017

    Reference

    1. Chung, Y.S. ,1992, On the observations of yellow sand in Korea. Atmospheric Environment, 26(15), 2743-2749.
    2. Chun, Y. , Boo, K.O. , Kim, J. , Park, S.U. , and Lee, M. ,2001, Synopis, transport, and physical characteristics of Asian dust in Korea. Journal of Geophysical Research, 106(D16), 18461-18469.
    3. Chung, Y.S. , Kim, H.S. , Han, K.Y. , and Jugder. D. ,2003a, On East Asian sand and duststorms and associated significant dustfall observed from January to May 2001. Water, Air, & Soil Pollution: Focus, 3(2), 259-277.
    4. Chung, Y.S. , Kim, H.S. , Dulam, J. , and Harris, J. ,2003b, On heavy dustfall observed with explosive sandstorms in Chongwon-Chongju, Korea in 2002. Atmospheric Environment, 37(24), 3425-3433.
    5. Chung, Y.S. , Kim, H.S. , Jugder, D. , Natsagdorj, L. , and Chen, S.J. ,2003c, On sand and dust storms and associated significant dustfall observed in Cheongju- Chongwon, Korea during 1997-2000. Water, Air, & Soil Pollution: Focus, 3, 5-19.
    6. Chung, Y.S. and Le, H.V. ,1984, Detection of forest-fire smoke plumes by satellite image. Atmospheric Environment, 18(10), 2143-2151.
    7. Gao, T. , Yu, X. , Ma, Q. , Li, H. , Li, X. , and Si, Y. ,2003, Climatology and trends of the temporal and spatial distribution of sandstorms in Inner Mongolia. Water, Air, & Soil Pollution: Focus, 3(2), 51-66.
    8. Gao, T. , Xu, Y. , Bo, Y. , and Yu, X. ,2006, Synoptic characteristics of dust storms observed in Inner Mongolia and their influence on the downwind area (the Beijing-Tianjin Region). Meteorological Applications, 13(4), 393-403.
    9. Hara, Y. , Uno, I. , and Wang, Z. ,2006, Long-term variation of Asian dust and related climate factors. Atmospheric Environment, 40(35), 6730-6740.
    10. Huang, X.X. , Wang, T.J. , Jing, F. , Liao, J.B. , Cai, Y.F. , Yin, C.Q. , Zhu, J.L. , and Han, Y. ,2013, Studies on a severe dust storm in East Asian and its impact on the air quality of Nanjing, China. Aerosol and Air Quality Research, 13(1), 179-193.
    11. Hulme, M. , Zhao, Z.C. , and Jiang, T. ,1994, Recent and future climate change in East Asia. International Journal of Climatology, 14(6), 637-658.
    12. Kim, H.C. , Kim, S.T. , Son, S.W. , Lee, P. , Jin, C.S. , Kim, E.H. , Kim, B.U. , Ngan, F. , Bae, C.H. , Song, C.K. , and Stein, A. ,2016, Synoptic perspectives on pollutant transport patterns observed by satellites over East Asia: Cases studies with a conceptual model. Atmospheric chemistry and physics, Discussions, doi:10.5194/acp-2016-673.
    13. Kim, H.S. and Chung, Y.S. ,2010, Characteristics of mass concentrations depending on synoptic feature during airborne dustfall episodes observed at Cheongwon in Korea in 2005. Asia-Pacific Journal of Atmospheric Sciences, 46(2), 209-216.
    14. Kim, H.S. , Chung, Y.S. , and Cho, J.H. ,2017, Long-term variations of dust storms and associated dustfall and related climate factors in Korea during 1997-2016. Air Quality, Atmosphere & Health, 10(10), 1269-1280.
    15. Kim, H.S. , Chung, Y.S. , and Yoon, M.B. ,2016, An analysis on the impact of large-scale transports of dust pollution on air quality in East Asia as observed in central Korea in 2014. Air Quality, Atmosphere & Health, 9(1), 83-93.
    16. Kim, J. ,2008, Transport routes and source regions of Asian dust observed in Korea during the past 40 years (1965-2004). Atmospheric Environment, 42(19), 4778-4789.
    17. Kim, Y.K. , Song, S.K. , Lee, H.W. , Kim, C.H. , and Oh, I.B. ,2006, Characteristics of Asian dust transport based on synoptic meteorological analysis over Korea. Journal of the Air & Waste Management Association, 56(3), 306-316.
    18. Laurent, B. , Marticorena, B. , Bergametti, G. , Chazette, P. , Maignan, F. , and Schmechtig, C. ,2005, Simulation of the mineral dust emission frequencies from desert areas of China and Mongolia using an aerodynamic roughness length map derived from the POLDER/ADEOS 1 surface products. Journal of Geophysical Research, 110(D18), doi: 10.1029/2004JD005013.
    19. Liang, D. , Wang, Y.Q. , Ma, C. , and Wang, Y.J. ,2016, Variability in transport pathways and source areas of PM10 in Beijing during 2009-2012. Aerosol and Air Quality Research, 16(12), 3130-3141.
    20. Natsagdorj, L. , Jugder, D. , Chung, Y.S. ,2003, Analysis of duststorms observed in Mongolia during 1937-1999. Atmospheric Environment, 37(9-10), 1401-1411.
    21. Park, M.E. , Cho, J.H. , Kim, S. , Lee, S.S. , Kim, J.E. , Lee, H.C. , Cha, J.W. , and Ryoo, S.B. ,2016, Case study of the heavy Asian dust observed in late February 2015. Atmosphere, Korean Meteorological Society, 26(2), 257-275.
    22. Rolph, G. , Stein, A. , and Stunder, B. ,2017, Real-time Environmental Applications and Display sYstem: READY. Environmental Modelling & Software, 95, 210-228.
    23. Seinfeld, J.H. , Carmichael, G.R. , Arimoto, R. , Conant, W.C. , Brechtel, F.J. , Bates, T.S. , Cahill, T.A. , Clarke, A.D. , Doherty, S.J. , Flatau, P.J. , Huebert, B.J. , Kim, J. , Markowicz, K.M. , Quinn, P.K. , Russell, L.M. , Russell, P.B. , Shimizu, A. , Shinozuka, Y. , Song, C.H. , Tang, Y. , Uno, I. , Vogelmann, A.M. , Weber, R.J. , Woo, J.H. , and Zhang, X.Y. ,2004, ACE-ASIA: regional climatic and atmospheric chemical effects of Asian dust and pollution. Bulletin of the American Meteorological Society, 85(3), 367-380.
    24. Tan, S.C. , Shi, G.Y. , and Wang, H. ,2012, Long-range transport of spring dust storms in Inner Mongolia and impact on the China seas. Atmospheric Environment, 46, 299-308.
    25. Tsai, F. and Chen, W.N. ,2014, Comparison of the synoptic environments conducive to eastward versus southeastward transport of Asian dust events. Advances in Meteorology, doi:10.1155/2014/467659.
    26. Wang, W. and Fang, Z.Y. ,2006, Numerical simulation and synoptic analysis of dust emission and transport in East Asia. Global and Planetary Change, 52(1-4), 57-70.
    27. Wang, X. , Huang, J.P. , Ji, M.X. , and Higuchi, K. ,2008, Variability of East Asia dust events and their long-term trend. Atmospheric Environment, 42(13), 3156-3165.