• Atmosphere
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• v.16 no.3
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• pp.247-257
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• 2006

The Yeong-dong heavy snowfall forecast supporting system has been developed during the last several years. In order to construct the conceptual model, we have examined the characteristics of heavy snowfalls in the Yeong-dong region classified into three precipitation patterns. This system is divided into two parts: forecast and observation. The main purpose of the forecast part is to produce value-added data and to display the geography based features reprocessing the numerical model results associated with a heavy snowfall. The forecast part consists of four submenus: synoptic fields, regional fields, precipitation and snowfall, and verification. Each offers guidance tips and data related with the prediction of heavy snowfalls, which helps weather forecasters understand better their meteorological conditions. The observation portion shows data of wind profiler and snow monitoring for application to nowcasting. The heavy snowfall forecast supporting system was applied and tested to the heavy snowfall event on 28 February 2006. In the beginning stage, this event showed the characteristics of warm precipitation pattern in the wind and surface pressure fields. However, we expected later on the weak warm precipitation pattern because the center of low pressure passing through the Straits of Korea was becoming weak. It was appeared that Gangwon Short Range Prediction System simulated a small amount of precipitation in the Yeong-dong region and this result generally agrees with the observations.

• Atmosphere
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• v.17 no.4
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• pp.393-405
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• 2007

Simulation results of WRF for the case of typhoon 'Rusa' were analyzed, comparing with observed data especially forjavascript:confirm_mark('abe', '1'); the Gangneung area around to examine its ability in numerical simulation. From the hourly precipitation time series, two peaks were found at Gangneung and Daegwallyeong, while only one peak was found from those of inland regions else. Especially, for the Yeongdong region, the first peak was directly related to spiral bands generated in front of the typhoon. Convective cells that were developed within the spiral bands moved to the eastern coastal area from the sea so that local heavy rainfall occurred in the Yeongdong region. The second peak was mainly related to the accompanying rain band of typhoon itself, topographic effect and the convergence near Gangneung area. Precipitation in Gangneung was simulated as much as about 30% of observed one. The main reason of this result came from a poor representation of wind directions in Gangneung area of WRF model. Observed wind direction was northwesterly but simulated one was nearly easterly in the area. This might shift a local heavy rainfall area downstream to the mountain area rather than the coastal area.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• v.26 no.1
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• pp.31-41
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• 1998

The climatic characteristics of summer in 1998 are analyzed with the weather observational data and the upper air observational data. The temperature of that period is lower than that of normal years and the precipitation is larger. Due to the heavy rainfall which started at July 31, rain pured down compared to normal years and the maximum precipitation recorded at the many observational stations, particularly in Seoul, Kyunggi-Do region and mountanious districts like Taegwallyong, Mt. Sokri and Mt. Chiri. The patterns of general circulations in 1982/98 and 1997/98 are compared each other and are analyzed. The anomaly patterns of stream functions on winter in two El Nio years are simialr. The counterclockwise circulation occurred near the date line and the clockwise circulation was appeared near the Hwanam region and Alaska. These patterns are opposite to those of La Nia year, 1988/89. And the anomaly patterns of 500hPa geopotential height in summer are similar, too. The low temperature and much rain were dominated in summer of 1997/98. These phenomena is similar to the existing results of research, that temperature is low and precipitation is large in summer of El Nio years.

• The Korean Journal of Quaternary Research
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• v.15 no.1
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• pp.47-52
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• 2001

April∼August precipitation (141 years : A.D. 1858∼1998) of Mt. Sorak region (East-central Korea) was reconstructed using a tree-ring chronology of Pinus densiflora sampled from Beakdam Shelter area. During the reconstructed Periods, dry periods were 1880∼1887, 1893∼1901 and 1922∼1938, and wet one 1906∼1918. In the long-term variation, the late 19th and early 20th century were drier than the late 20th century. Major wet/dry periodicities in April∼August precipitation series reconstructed were 3.16 and 4.14 years, indicating that short-term variation were more prominent than long-term one.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.1
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• pp.37-43
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• 2011

In this study, we analyzed the meteorological elements, when large forest fires were occurred, The rate of precipitation was 13% of annual average precipitation. Especially, the stronger wind speed, lower humidity and rainfall than average annual record were the distinct feathers on the year when large forest fire occurred in east coast area in Kangwon region. The average, maximum and maximum instantaneous wind speed was 5.9 m/s, 11.3 m/s and 20.9 m/s when large forest fires occurred. The average, maximum and maximum instantaneous wind speed on large fire occurred were 1.8 m/s, 3.0 m/s and 6.9 m/s faster than and average wind speed when whole forest fires occurred. The results indicated that the large forest fire occurrence had a close correlation with meteorological elements.

• Journal of Korea Water Resources Association
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• v.44 no.8
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• pp.683-694
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• 2011

To analyze the regional impact of air temperature increase and precipitation variation on water resources, the variability of precipitation-effectiveness (P-E) ratio which is estimated using precipitation and air temperature data of 59 weather stations operated by the Korean Meteorological Administration (KMA) during 1973~2009 was analyzed. Also runoff data resulting from the Precipitation-Runoff Modelling System (PRMS) modelling were analyzed during 1966~2007. The overall spatio-temporal variability of P-E ratio and runoff data in South Korea is corresponding to the variability of precipitation amount. However some region shows that the P-E ratio decreases even though the trend of precipitation amount increases which may be caused by the air temperature increase. Runoff trend is similar to that of P-E ratio. Precipitation and P-E ratio have decreased all seasons except summer season and it means the reduction of available water resources during those seasons. These variability should be reflected in the spring, fall, and winter water supply strategy.

• Atmosphere
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• v.28 no.1
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• pp.85-97
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• 2018

This study evaluates the performance of the Weather Research and Forecasting (WRF) model in reproducing the present-day (1981~2005) precipitation over Far East Asia and South Korea. The WRF model is configured with 25-km horizontal resolution within the context of the COordinated Regional climate Downscaling Experiment (CORDEX) - East Asia Phase 2. The initial and lateral boundary forcing for the WRF simulation are derived from European Centre for Medium-Range Weather Forecast Interim reanalysis. According to our results, WRF model shows a reasonable performance to reproduce the features of precipitation, such as seasonal climatology, annual and inter-annual variabilities, seasonal march of monsoon rainfall and extreme precipitation. In spite of such model's ability to simulate major features of precipitation, systematic biases are found in the downscaled simulation in some sub-regions and seasons. In particular, the WRF model systematically tends to overestimate (underestimate) precipitation over Far East Asia (South Korea), and relatively large biases are evident during the summer season. In terms of inter-annual variability, WRF shows an overall smaller (larger) standard deviation in the Far East Asia (South Korea) compared to observation. In addition, WRF overestimates the frequency and amount of weak precipitation, but underestimates those of heavy precipitation. Also, the number of wet days, the precipitation intensity above the 95 percentile, and consecutive wet days (consecutive dry days) are overestimated (underestimated) over eastern (western) part of South Korea. The results of this study can be used as reference data when providing information about projections of fine-scale climate change over East Asia.

• 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 The Korean Society of Agricultural Engineers
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• v.66 no.4
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• pp.41-50
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• 2024

Precipitation is an important component of the hydrological cycle and a key input parameter for many applications in hydrology, climatology, meteorology, and weather forecasting research. Grid-based satellite rainfall products with wide spatial coverage and easy accessibility are well recognized as a supplement to ground-based observations for various hydrological applications. The error properties of satellite rainfall products vary as a function of rainfall intensity, climate region, altitude, and land surface conditions. Therefore, this study aims to evaluate the commonly used new global grid-based satellite rainfall product, Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS), using data collected at different spatial and temporal scales. Additionally, in this study, grid-based CHIRPS satellite precipitation data were used to evaluate the 2022 extreme drought. CHIRPS provides high-resolution precipitation data at 5 km and offers reliable global data through the correction of ground-based observations. A frequency analysis was performed to determine the precipitation deficit in 2022. As a result of comparing droughts in 2015, 2017, and 2022, it was found that May 2022 had a drought frequency of more than 500 years. The 1-month SPI in May 2022 indicated a severe drought with an average value of -1.8, while the 3-month SPI showed a moderate drought with an average value of 0.6. The extreme drought experienced in South Korea in 2022 was evident in the 1-month SPI. Both CHIRPS precipitation data and observations from weather stations depicted similar trends. Based on these results, it is concluded that CHIRPS can be used as fundamental data for drought evaluation and monitoring in unmeasured areas of precipitation.

• Journal of the Korean earth science society
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• v.27 no.4
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• pp.433-449
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• 2006

Temporal and spatial variations of precipitation in South Korea are investigated using 60 observation data of the recent 30-years from 1976 to 2005. The area averaged annual precipitation amount is about 1310 mm and shows a strong spatial variation, maximum at the southern and Kyoungki province (>1300 mm) and minimum at the Kyungpook province(<1100 mm). The precipitation days show a strong spatial variation with maximum at the Sobaik mountain region(>100 days) and minimum at the Kyungpook province (<90 days). The interannual variations (IAV) of precipitation amount and days are more significant at the southern and eastern part of Sobaik and Taebaik mountain, and along the Sobaik mountain, respectively. So, the difference of annual precipitation amount reaches to about 800mm between wet and dry years at the southern part of Korean peninsula. Whereas, the IAV of precipitation intensity is strong at the southern and middle part of South Korea with a minimum between two maxima. Also, seasonal variations are closely linked with the geographic environments (elevation, distance from ocean, location relative to the Taebaik mountain). Therefore, maximum and minimum of seasonal variations of precipitation are occurred at the northern inland region (ratio of summer to the annual precipitation (RSAP) is greater than 60%), eastern and southern coastal regions (RSAP is less than 53%),respectively. And the RSAP is slightly increased from 50% to 55% comparing the Ho and Kang (1988). The consistent and strong positive relation between the heavy rainfalls, the ratio of heavy rainfalls to annual precipitation and the annual precipitation indicates that heavy rainfall is more frequent and strong at the maximum annual precipitation region.