• Journal of Korean Society for Atmospheric Environment
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• v.28 no.6
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• pp.615-631
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• 2012

This study provides an evaluation for capability of Integrated Climate and Air quality Modeling System (ICAMS) on future regional scale climate projection. Temperature and precipitation are compared between ground-level observation data and results of regional models (MM5) for the past 30 years over the Korean peninsula. The ICAMS successfully simulates the local-scale spatial/seasonal variation of the temperature and precipitation. The probability distribution of simulated daily mean and minimum temperature agree well with the observed patterns and trends, although mean temperature shows a little cold bias about $1^{\circ}C$ compared to observations. It seems that a systematic cold bias is mostly due to an underestimation of maximum temperature. In the case of precipitation, the rainfall in winter and light rainfall are remarkably simulated well, but summer precipitation is underestimated in the heavy rainfall phenomena of exceeding 20 mm/day. The ICAMS shows a tendency to overestimate the number of washout days about 7%. Those results of this study indicate that the performance of ICAMS is reasonable regarding to air quality predication over the Korean peninsula.

• Journal of Korean Society on Water Environment
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• v.30 no.4
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• pp.441-451
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• 2014

Streamflow is typically divided into two components that are direct runoff and baseflow, it is required to analyze and estimate behaviors of those two flow components to understand watershed characteristics so that watershed management plan can be effective in pollutant reductions. Since pollutant load behaviors in a stream or river are variable by flow component behaviors, best management practices need to be applied in a watershed based on the pollutant load behaviors varying with flow components. Thus, baseflow behaviors were analyzed separating baseflow from streamflow data collected from fifteen streamflow gaging stations in the 4 major river watersheds which are the Han river, Nakdong river, Guem river, and Yeongsan Somjin river watersheds. Moreover, precipitation trends throughout the 4 River Systems were investigated, thus daily precipitation data were collected from sixty-five locations. The Hank river watershed displayed the largest precipitation (925.2 mm) in summer but the lowest precipitation (71.8 mm) in winter, indicating the watershed has the most fluctuating precipitation characteristic. While the precipitation trends in the Four River Systems varied, a distinct feature in baseflow trends was not found, moreover baseflow percentages to streamflow were typically greater than 50% in the Four River Systems. As shown in this study, it would be expected significant amount of pollutants could be contributed to the stream in the form of baseflow at the watershed.

• Journal of Soil and Groundwater Environment
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• v.26 no.6
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• pp.47-64
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• 2021

In this study, the annual and monthly groundwater recharge for the Sapgyo-cheon upstream basin in Chungnam Province was evaluated by water balance analysis utilizing WetSpass-M model. The modeling input data such as topography, climate parameters, LAI (Leaf Area Index), land use, and soil characteristics were established using ArcGIS, QGIS, and Python programs. The results showed that the annual average groundwater recharge in 2001 - 2020 was 251 mm, while the monthly groundwater recharge significantly varied over time, fluctuating between 1 and 47 mm. The variation was high in summer, and relatively low in winter. Variation in groundwater recharge was the largest in July in which precipitation was heavily concentrated, and the variation was closely associated with several factors including the total amount of precipitation, the number of days of the precipitation, and the daily average precipitation. This suggests the extent of groundwater recharge is greatly influenced not only by quantity of precipitation but also the precipitation pattern. Since climate condition has a profound effect on the monthly groundwater recharge, evaluation of monthly groundwater recharge need to be carried out by considering both seasonal and regional variability for better groundwater usage and management. In addition, the mathematical tools for groundwater recharge analysis need to be improved for more accurate prediction of groundwater recharge.

• Journal of Information Science Theory and Practice
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• v.10 no.spc
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• pp.135-142
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• 2022

Recently, with the development of data processing technology and the increase of computational power, methods to solving social problems using Artificial Intelligence (AI) are in the spotlight, and AI technologies are replacing and supplementing existing traditional methods in various fields. Meanwhile in Korea, heavy rain is one of the representative factors of natural disasters that cause enormous economic damage and casualties every year. Accurate prediction of heavy rainfall over the Korean peninsula is very difficult due to its geographical features, located between the Eurasian continent and the Pacific Ocean at mid-latitude, and the influence of the summer monsoon. In order to deal with such problems, the Korea Meteorological Administration operates various state-of-the-art observation equipment and a newly developed global atmospheric model system. Nevertheless, for precipitation nowcasting, the use of a separate system based on the extrapolation method is required due to the intrinsic characteristics associated with the operation of numerical weather prediction models. The predictability of existing precipitation nowcasting is reliable in the early stage of forecasting but decreases sharply as forecast lead time increases. At this point, AI technologies to deal with spatio-temporal features of data are expected to greatly contribute to overcoming the limitations of existing precipitation nowcasting systems. Thus, in this project the dataset required to develop, train, and verify deep learning-based precipitation nowcasting models has been constructed in a regularized form. The dataset not only provides various variables obtained from multiple sources, but also coincides with each other in spatio-temporal specifications.

• Journal of the Korean earth science society
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• v.44 no.6
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• pp.540-556
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• 2023

This study analyzed rawinsonde soundings observed during the summer and early fall seasons (June, July, August and September) on the Korean peninsula to examine the utility of the Convective Available Potential Energy (CAPE) and Convective Inhibition (CIN) in predicting the occurrence of deep moist convection and precipitation. Rawinsonde soundings are categorized into two groups based on thermodynamic criteria: high CAPE and low CIN represent a high potential for deep moist convection; low CAPE and high CIN indicate conditions unfavorable for deep convection. A statistical hypothesis test is conducted to determine whether the two groups are significantly different in terms of 12-hour cumulative precipitation, 12-hour mean cloud base, and 12-hour mean mid-level cloud cover. The results, in the case of no-precipitation, reveal statistically significant differences between the two groups, except for the 12-hour mean cloud base during the 21:01-09:00 KST time period. This suggests that the group characterized by high CAPE and low CIN is more conducive to the occurrence of deep moist convection and precipitation than the group with low CAPE and high CIN.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.28 no.4
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• pp.398-411
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• 1992

The characteristics of local climate in the vicinity of Duckyang Bay have been investigated with the analysis of the surface observation data of Gohug District and the aerological data of Kwangju. In principal features of local climate, the annual range in temperature appeared identical with the mean value(24~$25^{\circ}C$) of the south coastal area, and evaporation from April to September was likely less than precipitation. The average speed of surface wind in Summer seemed higher than in other seasons on account of wea breeze. Relative humidity was 74%, annual average. In the mean cloud cover Summer(6.4) showed greater deal of amount than Winter(4.2). Duration of sunshine was the longest in May(268.4hrs), while the shortest in February(188.4hrs). The amount of the precipitable water was the greatest in July, whereas the least in January, and in Summer the greatest, in Autumn the second greatest, and in Spring the third greatest, and in Winter the least in consideration of seasonal orders. The Summer deviation was most remarkable around all sides. The direction of vector wind appeared the most changeable on the earth surface. At an altitude of 300mb all the winds blew west around all months. Moreover, water vapor transport was measured to be the greatest in Summer; while the least in Winter. So was the deviation of water vapor transport. And lastly frequency of occurrence of days in which a little cloud appeared(less than 5/10) was high except for Summer, when northerly winds blew; while frequency of occurrence of day plenty of clouds floated was outstandingly high at the time of strong southerly winds.

• Atmosphere
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• v.31 no.3
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• pp.327-340
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• 2021

In this study, the impact of soil moisture initialization in GloSea5, the operational climate prediction system of the Korea Meteorological Administration (KMA), has been investigated for the period of 1991~2010. To overcome the large uncertainties of soil moisture in the reanalysis, JRA55 reanalysis and CMAP precipitation were used as input of JULES land surface model and produced soil moisture initial field. Overall, both mean and variability were initialized drier and smaller than before, and the changes in the surface temperature and pressure in boreal summer and winter were examined using ensemble prediction data. More realistic soil moisture had a significant impact, especially within 2 months. The decreasing (increasing) soil moisture induced increases (decreases) of temperature and decreases (increases) of sea-level pressure in boreal summer and its impacts were maintained for 3~4 months. During the boreal winter, its effect was less significant than in boreal summer and maintained for about 2 months. On the other hand, the changes of surface temperature were more noticeable in the southern hemisphere, and the relationship between temperature and soil moisture was the same as the boreal summer. It has been noted that the impact of land initialization is more evident in the summer hemispheres, and this is expected to improve the simulation of summer heat wave in the KMA's operational climate prediction system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.4
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• pp.443-463
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• 2024

This study sought to improve the accuracy of precipitation prediction by utilizing monthly precipitation data for each region over the past 30 years. Using statistical models (ARIMA, SARIMA) and deep learning models (LSTM, GBM), we learned monthly precipitation data from 1983 to 2012 in Gangneung, Gwangju, Daegu, Daejeon, Busan, Seoul, Jeju, and Chuncheon. Based on this, monthly precipitation was predicted for 10 years from 2013 to 2022. As a result of the prediction, most models accurately predicted the precipitation trend, but showed a tendency to underpredict the actual precipitation. To solve these problems, appropriate models were selected for each region and season. The LSTM model showed suitable results in Gangneung, Gwangju, Daegu, Daejeon, Busan, Seoul, Jeju, and Chuncheon. When comparing forecasting power by season, the SARIMA model showed particularly suitable forecasting performance in winter in Gangneung, Gwangju, Daegu, Daejeon, Seoul, and Chuncheon. Additionally, the LSTM model showed higher performance than other models in the summer when precipitation is concentrated. In conclusion, closely analyzing regional and seasonal precipitation patterns and selecting the optimal prediction model based on this plays a critical role in increasing the accuracy of precipitation prediction.

• Journal of Environmental Science International
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• v.11 no.12
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• pp.1235-1242
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• 2002

The purpose of this study is to estimate wet deposition flux and to investigate wet deposition characteristics by using the ADOM model. Wet deposition flux of highly reactive $SO_2$ is estimated by applying observed meteorological parameters and concentrations of chemical species to the ADOM model. Wet deposition is largely dependent on large scale precipitation and cloud thickness. Wet deposition flux of sulfate depends on $SO_2$ oxidation in clouds. When large amount of $SO_2$ is converted to sulfate, deposition flux of sulfate increases, but wet deposition flux of $SO_2$ is small. On the whole, the pattern of sulfate wet deposition flux agrees with the typical pattern of sulfate wet deposition that is high in the summer(July) and low in the winter(January).

• Journal of the Korean Geographical Society
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• v.43 no.5
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• pp.681-700
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• 2008

In this study, the spatial and temporal patterns of changes in means and extreme events of temperature and precipitation across the Republic of Korea over the last 35 years (1973-2007) are examined. Over the study period, meteorological winter (December-February) mean minimum (maximum) temperature has increased by $+0.54^{\circ}C$/decade ($+0.6^{\circ}C$/decade), while there have been no significant changes in meteorological summer (June-August) mean temperatures. According to analyses of upper or lower $10^{th}$ percentile-based extreme temperature indices, the annual frequency of cool nights (days) has decreased by -9.2 days/decade (-3.3 days/decade), while the annual frequency of warm nights (days) has increased by +4.9 days/decade (+6.8 days/decade). In contrast, the increase rates of summer warm nights (+8.0 days/$^{\circ}C$) and days (+6.6 days/$^{\circ}C$) relative to changes in summer means minimum and maximum temperatures means are greater than the decreasing rates of winter nights (-5.2 days/$^{\circ}C$) and days (-4.3 days/$^{\circ}C$) relative to changes in winter temperatures. These results demonstrate that seasonal and diurnal asymmetric changes in extreme temperature events have occurred. Moreover, annual total precipitation has increased by 85.5 mm/decade particularly in July and August, which led to the shift of a bimodal behavior of summer precipitation into a multi-modal structure. These changes have resulted from the intensification of heavy rainfall events above 40mm in recent decades, and spatially the statistically-significant increases in these heavy rainfall events are observed around the Taebaek mountain region.