• Journal of Korean Society for Atmospheric Environment
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• v.32 no.3
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• pp.256-271
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• 2016

The source and transport of the severe Asian dust event (ADE) recently observed in the Korean peninsula were analyzed based on observations (surface weather charts and satellite data) and modeling study (WRF-CMAQ modeling systems). The ADE occurred on 20-21 March 2010 in South Korea with very high $PM_{10}$ concentrations (up to approximately $3,000{\mu}g/m^3$ in Daegu and Jeju). The dominant meteorological conditions affecting the dust outbreak and transport processes were found to be associated with the two synoptic features: (1) strong airflows (i.e., westerlies) induced by a strong pressure gradient resulting from a dense isobar pattern (west-high and east-low) between Tuva Republic and Mongolia and (2) a rapid movement of the strong westerlies merged with airflows generated near Gobi Desert and Inner Mongolia. The merged strong westerlies with a low pressure played a pivotal role in the huge amount of AD and its transport height of 5-8 km. The time and location of dust emissions calculated in the source regions were similar to those observed in the weather charts and satellite image. The ADE simulation mostly showed agreement in the patterns and the concentration levels of modeled dust (including $PM_{10}$) with those of the observations.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.E1
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• pp.1-14
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• 2004

Meteorological mechanisms in association with long-range transport of Asian dust in April 2001 have been investigated using weather maps, satellite images, TOMS and surface $PM_{10}$ data, backward trajectories, plus modeling output results (geopotential heights, horizontal wind vectors, potential temperatures, and streamlines). The results indicated that long -range transport of Asian dust to the west coast of North America was associated with strong westerlies between the Aleutian low and the Pacific high acting as a conveyor belt. Accelerating westerly flows due to cyclogenesis at the source regions over East Asia transported pollution from the continent to the central Pacific. When the system reached the Aleutian Islands, the intensity of troughs and the westerlies were amplified in the North Pacific. Thereafter the winds between the Aleutian Islands and the Pacific Ocean were more intensified from the air flow transport of the conveyor belt. Consequently, the strong wind in the conveyor belt enhanced the dust transport from the Pacific Ocean to the west coast of North America. This was evidenced by $PM_{10}$ concentration (maximum of about $100{\mu}g\;m^{-3}$) observed In California. Further evidence of the dust transport was found through the observation of satellite images, the distribution of TOMS aerosol index, and the analyses of streamlines and backward trajectories.

• Journal of Climate Change Research
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• v.7 no.1
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• pp.49-57
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• 2016

In the present study, the time series of the number of days on which temperatures were not higher than $-5^{\circ}C$ in winter in Seoul was analyzed. The results showed a decreasing tendency until recently. Statistical change-point analysis was conducted to examine whether climate regime shifts existed in this time series. According to the results, the number of days on which temperatures were not higher than $-5^{\circ}C$ in winter in Seoul drastically decreased since 1988. Therefore, to find out the reason for the recent decrease in the number of days, differences between the means of large-scale environments in winder during 1988~2010 and those during 1974~1987 were analyzed. In all layers of the troposphere, anomalous anticyclones developed in regions around the Korean Peninsula and thus the Korean Peninsula was affected by westerlies or south-westerlies. This was associated with the recent a little further northward development of western North Pacific subtropical high. Therefore, environments good for warm and humid air to flow into the Korean Peninsula were formed. To examine whether relatively warm and humid air actually flowed into the Korean Peninsula recently, temperatures and specific humidity in all layers in the troposphere were analyzed and according to the results the Korean Peninsula showed warm and humid anomalies. In the analyses of sensible heat net flux and maximum temperatures at a height of 2 m that can be felt by humans, the East Asia Continent including the Korean Peninsula showed positive anomalies.

• Journal of Korean Society for Atmospheric Environment
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• v.7 no.3
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• pp.203-207
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• 1991

Scientists in the National Institute of Environmental Research had carried out air and precipitation sampling. According to the data analysed, the acidity (pH) measured was in the range of 3.7 $\sim$ 5.5. Detailed analysis indicated that observed acid rain was associated with westerlies generally coming out of the mainland of China and with a cyclone formed therein. Emission of air pollution from Korea and Japan also appeared to contribute in the observed high acidity in some cases. The one of chief reasons for the occurrence of acid rain in the west coast of Korea was due to the increase in the total emission of air pollution in China. In 1990, China was the world's top producer of coal amounting in 1.05 B tons with an annual increase of 10%, and the produced 100 M tons of crude oil. $SO_2$ emission from all energy usage in China was estimated at 25 $\sim$ 50 M ton per year.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.1
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• pp.41-49
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• 1997

Status of photochemical air pollution in the Greater Seoul Area (GSA) between 1990 and 1995 was assessed in terms of frequency distributions, number of days exceeding standards, average concentration and meteorological effects. In Seoul compared with other areas in Korea, daily maximum concentration was higher but average concentration was not so high due to lower daily minimum from April to October. The top 5th percentile was high especially in summer season. Average number of days exceeding 100 ppb at monitoring stations in GSA was highest in 1994, the hottest year, but it was only 4 days a year. Mean meteorological pattern of high ozone days could be summarized as low wind speeds, high temperatures, strong solar radiation, and low precipitation. Westerlies were more frequent on high ozone days and at Pangi station located in the eastside of GSA, both number of high ozone days and average concentration were high. Effect of precursor transport on the rise of ozone concentration was, however, not consistently important on the whole in GSA.

• Journal of Korean Society for Atmospheric Environment
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• v.10 no.3
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• pp.175-182
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• 1994

Backward trajectory analysis was carried out for 41 cases at 850 hPa level and 47 cases at 700 hPa level during the period from May 1992 to August 1993 in order to understand the impact of long-range transported pollutants from the neighboring countries on the distribution pattern of acid rain in Korea. The occurrence frequencies of acid rain were also investigated using the rainwater data observed at 5 stations in the central part of Korea, Kangwha, Seoul, Yangpyong, Hongchon, and Inje. The trajectory analysis showed that westerlies were dominant on 700 hPa level and southwesterlies on 850 hPa level in Korea. The pH values were also often lower when the trajectory was stagnant in the upper air over Korea. However, pH values were normally higher in all directions of flows during the Yellow Sand Period due to the increase of Positive ion components such as $Ca^{+2}$. The pH values were also normally higher when air flows from north or northeast.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.2
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• pp.113-132
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• 2003

In May 2001, the Stockholm Convention on Persistent Organic Pollutants (POPs) for phasing out and eliminating POPs was signed by 90 countries at the Diplomatic Meeting in Stockholm. In 1998, three years before the Convention, the protocols on POPs and heavy metals were adopted by the United Nations Economic Commission for Europe under the Convention on Long-Range Transboundary Air Pollution. Growing attention on POPs and heavy metals during the past 10 years is primarily due to their toxicity in minute quantities. POPs and some metal compounds are even more toxic because of their bioaccumulation potentials associated with a high lipid solubility. Furthermore, owing to their persistence and semi - volatility, they are widely distributed in the environment, traveling great distances on wind and water currents. Recent international cooperation to address POPs and heavy metals has focused on these issues. Long -range transport of those pollutants are particularly concerned since Korea is located downwind of prevailing westerlies from China. In this paper, a review is provided to assess the properties, sources, emissions, and atmospheric concentrations on POPs and heavy metals.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.40-41
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• 2019

Fine dust, which is emerging as a global problem, attracted much attention recently in Korea. One of the reasons is that recent factory relocation and expansion in China affected the increase of domestic fine dust concentration due to the influence of the Yangtze river battalion and westerlies. Fine dust is a big problem not only in outdoor but also indoors. The room requires periodic ventilation and is also essential for improving indoor air quality. The fine dusts are designated as Group 1 carcinogens in WHO and the risk of fine dusts on the human body due to respiratory diseases is also increasing. In this study, the characteristics of the fine dust adsorption matrix are examined and the actual application direction is derived.

• Journal of the Korean association of regional geographers
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• v.4 no.1
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• pp.43-56
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• 1998

The purpose of this study is to identify distributional characteristics of climatic elements and to analyze synoptic characteristics on the pressure fields for spring droughts in Korea. In the distributions of minimum temperature during the spring droughts, positive anomalies and negative anomalies are mixed up, but in March the negative anomaly areas are widely distributed in Korea. It implies that the droughts of March have more frequent occurrences of the west-high, east-low pressure patterns. In the maximum air temperatures, the positive anomalies appear in Korea. It indicates that the spring droughts have rain days, cloud amount and humidities less than normal. As a result, the amount of evaporation is increased in Korea. In the pressure anomaly of surface pressure fields, the positive anomalies appear in the west, negative anomalies in the east in March, but in May the positive anomalies appeared zonally around the Korean peninsula. It indicates that March droughts have more frequent occurrences of the west-high. east-low patterns, but in May the Korean Peninsula has more frequent recurrences of the migratory anticyclone patterns. The height anomaly patterns of 500hPa pressure surface in spring droughts are similarly shown to those of surface fields. In March droughts, the positive height anomalies appear in the west, the negative height anomalies in the east, but in April the negative height anomaly areas are extended to the west part. In May the positive anomalies appear zonally around the Korean Peninsula, and strong positive height anomalies appear around the Kamchatka Peninsula and the sea of Okhotsk. These are the result of circulations that inhibit the eastward movement of westerlies and that has persistent anticyclone circulation patterns around the Korean Peninsula. As a result, the zonal indices of westerlies during March and April droughts are lower than normal, but higher in May. These data indicate that early spring droughts are associated with weak zonal flow, but the late spring droughts are obviously related with strong zonal flow. In addition, during early spring droughts the abnormally deep trough over the west coast of the North Pacific Ocean that accompanied the anticyclone was associated with frequent advection of air from the dry regions in the Central Asia into the Korean Peninsula. The atmospheric circulation patterns at the height of the 500hPa pressure surface in May was quite different from March and April circulation patterns. Instead of the abnormal ridge in the west and trough in the east, the circulation pattern in May was characterized by a much stronger than normal anticyclone over the Korean Peninsula. Also, the zonal indices of westerlies in May are higher than normal. The occurrences of drought in early spring, therefore, have mechanism different from those of late spring.

• Proceedings of the Korean Quaternary Association Conference
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• 2004.06a
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• pp.24-25
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• 2004

It is well known that there is an inverse relationship between the strength of Indian summer monsoon Rainfall (ISMR) and extent of Eurasian snow cover/depth in the preceding season. Tibetan snow cover/depth also affects the Asian monsoon rainy season largely. The positive correlation between Tibetan sensible heat flux and southeast Asian rainfall suggest an inverse relationship between Tibetan snow cover and southeast Asian rainfall. Developments in Regional Climate Models suggest that the effect of Tibetan snow on the ISMR can be well studied by Limited Area Models (LAMs). LAMs are used for regional climate studies and operational weather forecast of several hours to 3 days in future. The Eta model developed by the National Center for Environmental Prediction (NCEP), the Fifth-Generation NCAR/Penn State Mesoscale Model (MM5) and Regional Climate Model (RegCM) have been used for weather prediction as well as for the study of present-day climate and variability over different parts of the world. Regional Climate Model (RegCM3) has been widely . used for various mesoscale studies. However, it has not been tested to study the characteristics of circulation features and associated rainfall over India so far. In the present study, Regional Climate Model (RegCM-3) has been integrated from 1 st April to 30th September for the years 1993-1996 and monthly mean monsoon circulation features and rainfall simulated by the model at 55km resolution have been studied for the Indian summer monsoon season. Characteristics of wind at 850hPa and 200hPa, temperature at 500hPa, surface pressure and rainfall simulated by the model have been examined for two convective schemes such as Kuo and Grell with Arakawa-Schubert as the closure scheme, Model simulated monsoon circulation features have been compared with those of NCEP/NCAR reanalyzed fields and the rainfall with those of India Meteorological Department (IMD) observational rainfall datasets, Comparisons of wind and temperature fields show that Grell scheme is closer to the NCEP/NCAR reanalysis, The influence of Tibetan snowdepth in spring season on the summer monsoon circulation features and subsequent rainfall over India have been examined. For such sensitivity experiment, NIMBUS-7 SMMR snowdepth data have been used as a boundary condition in the RegCM3, Model simulation indicates that ISMR is reduced by 30% when 10cm of snow has been introduced over Tibetan region in the month of previous April. The existence of Tibetan snow in RegCM3 also indicates weak lower level monsoon westerlies and upper level easterlies.