• Atmosphere
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• v.13 no.4
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• pp.57-70
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• 2003

The National Center for Intensive Observation of Severe Weathers (NCIO) as a part of METRI's principal project "Korea Enhanced Observing Period; KEOP" was established at Haenam Weather Observatory in order to effectively monitor and observe heavy rainfall in summer, which is essential for the identification of the structure and evolution mechanism of mesoscale severe weather system. The intensive field-based experiments in 2002 within southwestern Korea toward various meteorological phenomena ranging from heavy rainfall to snowfall were conducted in collaboration with KMA(Korea Meteorological Administration) and universities. In this study, preliminary analysis results using intensive observation data obtained from these experiments are presented together with the introduction of NCIO and its operational structure.

• Journal of Korea Water Resources Association
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• v.31 no.5
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• pp.621-635
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• 1998

The feasibility of cloud seeding in Korea is presented from analyses of precipitation, cloud amount, satellite data, and upper air data. The daily mean precipitation over Dae-Kwan-Ryong is the largest(~4.5 mm/day), while the intensity of precipitation (amount of yearly rainfall divided by the frequency of rain days) over Southern area is above 14 mm/day, which shows the largest in Korea. Both the daily mean and the intensity of precipitation over Andong area are the smallest with values of ~2.7 mm/day and ~11 mm/day, respectively. In the meanwhile, the occurrence frequency of appropriate cloud top temperature (-10'~-30') for cloud seeding over the region has a large value (~130 days/year). The precipitation patterns of the region vary with wind direction and intensity calculated from 43 AWSs(Automatic Weather Station) and the additional 7 rain guages which were installed along Northern and Southern part of the Sobaek mountain. The Sc(Stratocumulus) cloud type over Andong is frequently observed, and Cirrus and Altostratus next. From the results, it is estimated that the feasibility of cloud seeding over the area would be high if a proper strategy of cloud seeding is set up. LCL (Lifting Condensation Level) and CCL (Convective Condensation Level) have the most frequency in 1000-950 hPa being occupied 4/9 of total analysis period and in 400-500 hPa, respectively, with both small variations from season to season. The correlation between vapor mixing ratio and CCL is the highest in Summer and the lowest in Winter. It means that the height of cumulus in Summer is high with an abundant water vapor but vice versa in Winter, and that the strategy of cloud seeding should be different with seasons.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.5
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• pp.522-526
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• 2006

To investigate the characteristics of rainwater in Daegu area, parameters such as pH, electrical conductivity, TOC, TIC and TC were analyzed on 34 samples from January to December 2005. Results revealed that higher values were measured in winter than in summer. Furthermore samples that originated from industrial and commercial areas had higher chemical concentrations and conductivity as compared with those from residential and reference areas. Seldom acid-rain occurrence was recorded(27.2%) as compared with non-acid precipitation(72.8%) incidence. Also higher organic carbon fraction(TOC) was detected(72.5%) than inorganic form(TIC)(27.5%) in terms of component ratio with TC. During frequent rainfalls, the concentration of chemicals was decreased to a degree. Conversely, lower rate of rainfall gave out higher chemical values. Thereby the improvement of air qualify in 2005 compare with 2003 report was influenced by the environment authorities' efforts to reduce air pollutions and various factors by the depression of the region's economy.

• Journal of Korea Water Resources Association
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• v.36 no.4
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• pp.561-573
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• 2003

This study has analyzed the drought return and duration characteristics using the monthly rainfall at Seoul, and compared them with those obtained by applying the Poisson process. The Standardized Precipitation Index (SPI) was used as the drought index along with the 10 month moving average for the rainfall smoothing. The thresholds applied for the analysis of drought were -1.00, -1.50, and -2.00. The drought return and duration characteristics derived from the analysis of observed data show that: (1) The moderate drought occurs every 2 years and lasts about 4 - 5 months. (2) The severe drought occurs every 3 - 5 years and lasts about 2 - 4 months. (3) The extreme drought occurs every 8 - 23 years and lasts about 1 - 4 months. Especially, the severe droughts (thresholds of -1.5 and -2.0) before the long dry period were found to have longer return periods but shorter durations than those after the long dry period. This seems to be because of the high variability of precipitation as well as the fact that no snowfall has been added for the winter precipitation before the long dry period. Finally, the comparison of results derived from the analysis of observed data and those derived by applying the Poisson process shows that the Poisson process well explain the return and duration characteristics of drought.

• Atmosphere
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• v.22 no.1
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• pp.57-71
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• 2012

Influences of orographic and ocean effect, which depend on the detailed geographic characteristics, upon winter time (December-February) precipitation in the Yeongdong region are investigated. Most of precipitation events in the Yeongdong region during the wintertime are associated with moist northeasterly (coming from the northeast direction) winds and also the spatial distribution of precipitation shows a great difference between Mountain area (Daegwallyeong) and Coastal area (Gangneung). The linear correlation coefficient between the meteorological variables obtained from NCEP/NCAR Reanalysis Data and precipitation amount for each precipitation type is calculated. Mountain type precipitation is dominated by northeasterly wind speed of the low level (1000 hPa and 925 hPa) and characterized with more precipitation in mountain area than coastal area. However, Coastal type precipitation is affected by temperature difference between ocean and atmosphere, and characterized with more precipitation in coastal area than mountain area. The results are summarized as follows; In the case of mountain type precipitation, the correlation coefficient between wind speed at 1000 hPa (925 hPa) and precipitation amount at Daegwallyeong is 0.60 (0.61). The correlation is statistical significant at 1% level. In the case of coastal type precipitation, the correlation coefficient of temperature difference between ocean and 925 hPa (850 hPa) over the East sea area and precipitation amount at Gangneung is 0.33 (0.34). As for the mountain type precipitation, a detailed analysis was conducted in order to verify the relationship between precipitation amount at Daegwallyeong and low level wind speed data from wind profiler in Gangneung and Buoy in the East Sea. The results also show the similar behavior. This result indicates that mountain type precipitation in the Yeongdong region is closely related with easterly wind speed. Thus, the statistical analysis of the few selected meteorological variables can be a good indicator to estimate the precipitation totals in the Yeongdong region in winter time.

• Atmosphere
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• v.20 no.3
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• pp.229-238
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• 2010

The 1,000~500 hPa thickness and the $0^{\circ}C$ isotherm at 850 hPa have been used as the traditional predictors for wintertime precipitation-type forecasts. New approaches are taking on added significance as preexistence method of determination for wintertime precipitation-type exhibits more or less prevalent false alarms. Moreover thicknesses and thermodynamic profiles from ordinary upper-air observation were not adequate to monitor the atmospheric structure. In this regard, Microwave radiometric profiler microwave radiometer is useful in wintertime precipitation-type forecasts because radiometric measurements provide soundings at high temporal resolution. In this study, the determination and the predictability of wintertime precipitation-type were examined by using the calculated thicknesses, temperature of 850 hPa (T850) from a microwave radiometer, and surface observation at National Center for Intensive Observation of severe weather (NCIO) located at Haenam, Korea. The critical values for traditional predictors (thickness of 1000~500 hPa and T850) were evaluated and adjusted to Haenam region because snow rarely occurred with a 1000-500 hPa thickness > 5,300 m and T850 > $-10^{\circ}C$. Three thicknesses (e.g., 1,000~850, 1000~700, and 850~700 hPa thickness), T850, surface air temperature, and wet-bulb temperature were also evaluated as the additional predictors. A simple nomogram and a flow chart were finally designed to determine the wintertime precipitation-type using the microwave radiometer. The skill scores for the predictability of precipitation-type determination are considerably improved and the predictors showed the temporal variations in 12 hours before precipitation. We can monitor the hit and run snowfall in winter successful by realtime watch of the predictors, especially in commutes of big cities.

• Journal of Korea Water Resources Association
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• v.39 no.10 s.171
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• pp.845-854
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• 2006

Establishment of snowmelt factors is necessary to simulate stream flow using snowmelt models during snowmelt periods. The few observed data related snowmelt was the major cause of difficulty in extracting snowmelt factors such as snow cover area, snow depth and depletion curve. The objective of this study was to extract snowmelt factors using RS, GIS technique and meteorological data. Snow cover maps were derived from NOAA/AVHRR images for the winter seasons from 1997 to 2003. Distributed snow depth was mapped by overlapping between snow cover maps and interpolated snowfall maps from 69 meteorological observation station. Depletion curves of snowmelt area were described from the linear regression equations of each year between the average temperature and snow cover area in Soyanggang-dam and chungju-dam watershed.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.3
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• pp.143-149
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• 2001

This study was conducted to analyze the propertis, acidity and chemical compositions of the snowfall in the bare land and Idlest stand. The research sites of this study are the Daegwalyung (a high hill) and Woongyori in Pyungchang-gun, Kangwon province. The results of this study are as follows: The snowfall pH showed large changes when the snowfall was small. The more snow falls, the smaller changes of the pH are narrow. According to the local conditions, it means that the acid deposition changed over adsorption ratio in suspended matters of the atmosphere. Changes of the ion concentrations for the snowfall in the forest stand showed a thendency to increase. Chemical composition of the snowfall for each sampling site showed that the ion concentrations of $Ca^{2+}$and anions had higher value than other ions.s.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.3
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• pp.779-786
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• 2008

This study was performed to evaluate the characteristics of current air quality and to examine the monthly and yearly variation of $SO_2,\;O_3,\;CO,\;NO_2$, and fine particulate matter(PM-10) concentration in Seosan for the period of 1998-2006. During the recent 3 years, from 2004 to 2006, the yearly mean concentration of $SO_2,\;NO_2$, and PM-10 remained stability but CO and $O_3$ are gradually decreased. The monthly mean concentration of $NO_2$, CO, and $SO_2$ were high in the winter season and decreased steadily to the summer season, but the maximum concentration of $O_3$ and PM-10 appeared in the springtime. The number of days exceeding 24-hour standards for PM-10 were 54 times at Dokgodri and 25 times at Dongmundong. The number of sampling days exceeding the 1-hour and 8-hour standards for $O_3$ were 68 and 210 times at Dongmundong and at Dokgotri 93 and 213 times, respectively.

• Journal of Climate Change Research
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• v.8 no.2
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• pp.109-123
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• 2017

The effects of recent climate change on hydrological systems could affect the Winter Olympic Games (WOG) because the event is dependent on suitable snow and ice conditions to support elite-level competitions. We investigate the long-term variability and change in winter total precipitation (P), snowfall water equivalent (SFE), and ratios of SFE to P during the period 1973/74~2015/16 in Gangwon province. The climatological percentages of SFE relative to winter total precipitation were 71%, 28%, and 44% in Daegwallyeong, Chuncheon, and Gangneung, respectively. The winter total P, SFE, and SFE/P has decreased (but not significantly), although significant increases of winter maximum and minimum temperature were detected at a 95% confidence level. Notably, a significant negative trend of SFE/P at Daegwallyeong in February, the month of the WOG, was attributable to a larger decrease in SFE related to the increases in maximum and minimum temperature. Winter wet-day minimum temperatures were warmer than climatological minimum temperatures averaged over the study period. The 20-year return values of daily maximum P and SFE decreased in Yongdong area. Since the SFE/P decrease with increasing temperature, the probability of rainfall rather than snowfall can increase if global warming continues.