• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.4
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• pp.295-302
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• 2007

Abnormally high waves occurring at the east coast of korea were observed at five field measurement stations and their characteristics were analyzed with the use of wind data provided by the Korean Meteorological Administration. The high waves occurred because strong Donghae twister that was developed by extratropical cyclone blew while high swell arrived at the east coast of Korea. At Sokcho, the most northern site among the five measurement stations, maximum gust speed was 63.7 m/s and significant wave height reached at its maximum of 9.69 m with the corresponding peak wave period of 12.8 s. The reason for appearance of the abnormally high waves is that high swell continued while the twister blew strongly. Moreover, the wind direction was the same as the direction of swell propagation, which maximizes the increase of wave height due to superposition of swell and wind-generated waves. On the east coast of Korea, outbreak of this type of storm waves is very probable in winter season so that it is requested to establish a countermeasure of minimizing possible damage caused by the storm waves.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.6
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• pp.539-546
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• 2002

The physicochemical properties of solid wastes generated from seven highway service areas, four branch offices, and one construction site were analyzed in concert with air pollutants including heavy metals emitted from near-by small-scale incinerators. The amount of solid wastes generated from highway areas has been increasing with recent increases in the number of highways and passengers. Twelve incinerators examined in this study generally had capacity smaller than 100 kg/hr, most of which were equipped with cyclone for dust removal. It was seen that the concentrations of the gas-phase air pollutants (e.g., SO$_2$, NO$_{x}$, HCl and H$_2$S) were above the acceptable emission standards except one or two sites. CO concentrations at all incinerators were also higher due to incomplete combustion. In addition, particulate matters showed concentration six times higher at their maximum. The results of heavy metal analysis showed that the concentrations of Cu, Cd, and Ni satisfied the emission standards. whereas Pb at one site and Zn at five sites exceeded the standards. Cr measurement results indicated that 9 of 12 incinerators had higher values than the standard; especially one branch office showed nine times higher than normal concentration. In order to satisfy more stringent emission standards in the near future, it is necessary to install air pollution control system and to develop an intensified management plan.n.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.3
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• pp.168-174
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• 2015

Characteristics of high waves occurred in winter season on the west coast of Korea were investigated by analyzing the wave data observed at five observation locations. Records of four different high waves were subjected to the analysis together with the corresponding meteorological data during those time periods. The significant wave height reached its maximum of 6.42 m on December 4th, 2005. It was clarified that the high waves occurred due to strong wind fields that were formed over the west sea of Korea when the extra-tropical cyclone was excessively developed. Characteristics of the high waves generated in the west sea seemed to be predominantly wind sea as the temporal variation of the wave height at the coast were closely related to those of the wind speed measured at neighboring weather stations.

• Atmosphere
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• v.28 no.2
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• pp.187-200
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• 2018

The heavy snowfall phenomenon with thunder and lightning occurred in Yeongdong coastal region on 20 January 2017. Amount of snow on that day was a maximum of 47 cm and was concentrated in a short time (2 hours) at the Yeongdong coastal area. The mechanism of thundersnow was investigated to describe in detail using observational data and numerical simulation (Weather Research and Forecast, WRF) applied lightning option. The results show that a convective cloud occurred at the Yeongdong coastal area. The east wind flow was generated and the pressure gradient force was maximized by the rapidly developed cyclone. The cold and dry air in the upper atmosphere has descended (so called tropopause folding) atmospheric lower layer at precipitation peak time (1200 LST). In addition, latent heat in the lower atmosphere layer and warm sea surface temperature caused thermal instability. The convective cloud caused by the strong thermal instability was developed up to 6 km at that time. And the backdoor cold front was determined by the change characteristics of meteorological elements and shear line in the east sea. Instability indexes such as Total totals Index (TT) and Lightning Potential Index (LPI) are also confirmed as one of good predictability indicates for the explosive precipitation of convective rainfall.

• Journal of the Korean Geographical Society
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• v.45 no.6
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• pp.748-765
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• 2010

This study aims to investigate the difference of synoptic characteristics over East Asia according to the persistence of rainfall in Korea during the Changma season (June and July). In the cases of consecutive rainfall which lasts four or more days, there are developed ridges in 850hPa level east of the Korean peninsula which introduce stagnation of the synoptic cyclone over Korea. An cold area in 850hPa level moves southward from the Northern China in one day before the beginning the rainfall day in Korea and it aids the development of the stationary front in East Asia. When rainfall lasts a day or two, cyclones pass over Korea in rainy day and the stationary front in East Asia is not intensified. In both cases the synoptic cyclones near the Korean peninsula shows a deep-baroclinic structure, while in the former cases over the southwestern part of Japan a subtropical frontal zone which has a shallow structure appears near Japan. In latter cases the frontal structures are same near Korea and Japan. So, this means that the Changma is not necessarily similar to the Baiu of Japan in all cases.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.4
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• pp.441-448
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• 1996

The cyclone/annular denuder system/filter pack sampling system (ADS) was used to collect the acidic air pollutants in Chongju city. The data set was collected on nine different days with 24 hour sampling period from July 27 through August 27, 1995. The chemical species measured were $HNO_3, HNO_2, SO_2 and NH_3$ in the gas phase, and $PM_{2.5}(d_P<2.5 \mum), SO_4^{2-}, NO_3^- and NH_4^+$ in the particulate phase. Mean concentrations measured from this study were: $0.90 \mug/m^3 for HNO_3, 1.27 \mug/m^3 for HNO_2, 10.9 \mug/m^3 for SO_2, 4.82 \mug/m^3 for NH_3, 27.5 \mug/m^3 for PM_{2.5}, 5.24 \mug/m^3 for SO_4^{2-}, 1.22 \mug/m^3 for NO_3^-, and 1.64 \mug/m^3 for NH_4^+$. The fine particle $(PM_{2.5})$ mass measured for the ADS samples was slightly higher than the fine particle mass measured for the corresponding dichotomous sampler. For the wind coming from Chongju industrial complex the concentrations of acidic air pollutants measured were higher when compared with other directions. Specially, $SO_2 and PM_{2.5}$ concentrations for the wind coming from Chongju industrial complex were 3.6 and about 2 times, respectively, higher than those of other wind directions. High correlations were observed between $PM_{2.5} and fine particle's ion components $(r=0.82 with SO_4^{2-}, r=0.76 with NO_3^- and r=0.89 with NH_4^+). NH_4^+ and SO_4^{2-}$ was also highly correlated (r=0.97).

• Journal of Environmental Science International
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• v.26 no.7
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• pp.827-836
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• 2017

Freezing rain is a phenomenon when precipitation falls as a liquid rain drop, but freezes when it comes into contact with surfaces or objects. In this study, we investigated the predictability of freezing rain and its characteristics, which are strongly related with the occurrence of black ice using synoptic scale meteorological observation data. Two different cases occurred at 2012 were analyzed and in the presented cases, freezing rain often occurs in the low-level low pressure with the warm front. The warm front due to the lower cyclone make suitable environment in which snow falling from the upper layer can change into supercooled water. The $0^{\circ}C$ temperature line to generate supercooling water is located at an altitude of 850 hPa in the vertical temperature distribution. And the ground temperature remained below zero, as is commonly known as a condition for black ice formation. It is confirmed that the formation rate of freezing rain is higher when the thickness after 1000-850 hPa is 1290-1310 m and the thickness of 850-700 hPa layer is larger than 1540 m in both cases. It can also be used to predict and estimate the generation of freezing rain by detecting and analyzing bright bands in radar observation.

• Journal of Environmental Science International
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• v.4 no.1
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• pp.53-62
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• 1995

To collect and evaluate an aerosol acidity ($H^+$) in ambient air, the cyclone/annular denuder/filter pack sampling system (ADS) was used. Aerosol acidity was collected in Chicago using the ADS for 81 12-hr samples divided in spring/summer/fall 1990 and winter 1991. This study illustrated that the ADS was suitable for measuring aerosol acidity. The $10^{-5}N$ $HCIO_4$ extraction solution for pH determination provided more reliable scale than $10^{-4}N$ HClO4. NH3 should be removed prior to particle collection to accurately measure $H^+$ concentration on the filter. There was seasonal variation in aerosol acidity concertrations. Aerosols were more acidic in the summer. High correlations between $SO_4^{2+} and$NH_4^+$, and between TEX>$SO_4^{2+}$H^+$ were observed during the entire sampling period.

• Journal of the Korean earth science society
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• v.29 no.7
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• pp.567-578
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• 2008

The extratropically transitioning cyclones have been shown to have a large effect on weather system in the midlatitues and cause sometimes the severe weather phenomena. However, both operational forecasting and research aspect of ET remain a significant challenge. Because it is difficult to distinguish ET stage due to obscure configuration of the cyclone itself. Furthermore, any definition of ET should not only be precise enough to satisfy the needs of the operational and research communities. Therefore, the "operational deterministic process for ET" was proposed and has been used to diagnose both structure and subsequent process of ET in 2007. In this study, it has been examined the maximum wind and SST in the 1st step, satellite image in the 2nd step, sounding in the 3rd step, surface weather chart analysis in the final step. This operational manual has allowed better monitoring and understanding of the changes in the structure as ET occurs.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.6
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• pp.481-492
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• 2009

The characteristic of cold water by upwelling in the southeast of the Korean Peninsula and the effect of sea breeze in this region are investigated. The coastal upwelling around the southeast coast of the Korea Peninsula is analyzed by using Coastal Oceanographic Data statistical analyses for 5 years were carried out. The period of an cold water event, on the average, was observed southwesterly wind events. The analysis suggests that strong and persistent southwesterly winds in period of an cold water play an important role of bring the moisture to the surface, generating persistent cyclone as jangma. In order to investigate the effect of cold water on sea breeze, we considered two case. First, Exp. 1 is not occurred coastal upwelling on sea breeze. Second, Exp. 2 is occurred cold water on sea breeze. Two experiments were completed separately to the effects of cold water by upwelling. The results show the sea breeze is stronger in Exp. 2, when the cold water occurs, and weaker in Exp. 1, when there is no cold water. In order to verify the effect of the sea breeze on the cold water by upwelling, on the intensification and change of direction of the prevailing wind, the sea breeze effectively intensify cold water condition.