• Journal of the Korean earth science society
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• v.38 no.3
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• pp.182-193
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• 2017

A typical snowfall pattern occurs over the east coastal region of the Korean Peninsula, known as the Yeongdong region. The precipitation over the Yeongdong region is influenced by the cold and dry northeasterly wind which advects over warm and moist sea surface of the East Sea of Korea. This study reveals the influence of large-scale factors, affecting local to remote areas, on the mesoscale snowfall system over the Yeongdong region. The National Centers for Environmental Prediction-Department of Energy reanalysis dataset, Extended Reconstructed sea surface temperature, and observed snowfall data are analyzed to reveal the relationship between February snowfall and large-scale factors from 1981 to 2014. The Yeongdong snowfall is associated with the sea level pressure patterns over the Gaema Plateau and North Pacific near the Bering Sea, which is remotely associated to the sea surface temperature (SST) variability over the North Pacific. It is presented that the relationship between the Yeongdong snowfall and large-scale factors is strengthened after 1999 when the central north Pacific has warm anomalous SST. These enhanced relationships explain the atmospheric patterns of recent strong snowfall years (2010, 2011, and 2014). It is suggested that the newly defined index in this study based on related SST variability can be used for a seasonal predictor of the Yeongdong snowfall with 2-month leading.

• Asian Journal of Atmospheric Environment
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• v.12 no.2
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• pp.109-126
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• 2018

This paper presents seasonal variation of $PM_{10}$ over five urban sites in Sabah, Malaysia for the period of January through December 2012. The variability of $PM_{10}$ along with the diurnal and weekly cycles of CO, $NO_2$, $SO_2$, and $O_3$ at Kota Kinabalu site were also discussed to investigate the possible sources for increased $PM_{10}$ concentration at the site. This work is crucial to understand the behaviour and possible sources of $PM_{10}$ in the urban atmosphere of Sabah region. In Malaysia, many air pollution studies in the past focused in west Peninsular, but very few local studies were dedicated for Sabah region. This work aims to fill the gap by presenting the descriptive statistics on the variability of $PM_{10}$ concentration in the urban atmosphere of Sabah. To further examine its diurnal and weekly cycle pattern, its responses towards the variations of CO, $NO_2$, $SO_2$, and ozone were also investigated. The highest mean value of $PM_{10}$ for the whole study period is seen from Tawau ($35.7{\pm}17.8{\mu}g\;m^{-3}$), while the lowest is from Keningau ($31.9{\pm}18.6{\mu}g\;m^{-3}$). The concentrations of $PM_{10}$ in all cities exhibited seasonal variations with the peak values occurred during the south-west monsoons. The $PM_{10}$ data consistently exhibited strong correlations with traffic related gaseous pollutants ($NO_2$, and CO), except for $SO_2$ and $O_3$. The analysis of diurnal cycles of $PM_{10}$ levels indicated that two peaks were associated during the morning and evening rush hours. The bimodal distribution of $PM_{10}$, CO, and $NO_2$ in the front and at the back of ozone peak is a representation of urban air pollution pattern. In the weekly cycle, higher $PM_{10}$, CO, and $NO_2$ concentrations were observed during the weekday when compared to weekend. The characteristics of $NO_2$ concentration rationed to CO and $SO_2$ suggests that mobile sources is the dominant factor for the air pollution in Kota Kinabalu; particularly during weekdays.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.1
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• pp.45-57
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• 2015

Soil moisture is critical for understanding the spatial-temporal variability of hydrologic processes. The distributions of soil moisture have been explored along transect line in hillslope hydrology. In this study, we measured several soil moistures along transect lines during ten-month period at a hillslope located the Cheong-mi catchment. The soil moisture properties were expressed by simple statistical methods (average, standard deviation, and recession slope) and analyzed in terms of soil depths and transects from the seasonal context. Supplementary studies were also performed about the effect of location, topography and soil texture to the soil moisture responses. The spatial distributions of average soil moisture at deep soil layer were distinguished from those at near surface due to the possibility of expected factors such as subsurface lateral flow from upslope, preferential flow and existence of bedrock. The soil moistures in combined line affected from significant contribution of upper transect line were relatively higher(wetter), low variability compared to those in other transect lines and seemed to be under stabilization process. There are confirmed heterogeneity of soil moisture variation related with preferential flow and significant influence of soil texture for soil moisture properties in upslope.

• Journal of Korea Water Resources Association
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• v.46 no.2
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• pp.123-137
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• 2013

This study investigated impacts of the two different types of El Ni$\tilde{n}$o on summer rainfall (June-September) in the Han River and its sub-basins. The patterns of rainfall anomalies show a remarkable difference between conventional El Ni$\tilde{n}$o and El Ni$\tilde{n}$o Modoki years. During conventional El Ni$\tilde{n}$o years, it was found that the Han River basins show decreases in the seasonal rainfall totals with high variations (CV=0.4). In contrast, during El Ni$\tilde{n}$o Modoki years, distinct positive anomalies appear in the Han River basin with a relatively small variation (CV=0.23). In addition, 11 out of 30 sub-basins show significant above-normal rainfall in southern part of the Han River Basin. For El Ni$\tilde{n}$o Modoki years, the number of heavy rainy days exceeding 30 mm/day and 50 mm/day were 9.9-day and 5.4-day, respectively. Consequently, this diagnostic study confirmed that El Ni$\tilde{n}$o Modoki has significant impacts on the variability of summer rainfall over the Han River Basin. We expect the results presented here provide useful information for the stability of the regional water supply system, especially for basins like the Han River Basin showing relatively high variability in seasonal rainfall.

• Proceedings of the KSRS Conference
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• v.2
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• pp.529-532
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• 2006

The oceanic currents in the South China Sea (SCS) are strongly influenced by monsoon winds. A review on the SCS currents has indicated that previous studies have pointed out an anticyclonic circulation in the area between the southern Vietnam coast and the Spratly Islands. However, its detail is not understood because of less information of in situ observations. The physical-biological interaction is quite new research area, which has been established and promoted by means of the ocean color remote sensing. Temporal/spatial variability of the phytoplankton activities are well captured by ocean color (OC) -derived Chlorophyll-a images. Combining the OC-Chl-a and the other high-resolution satellite data (e.g., SST images), the biological aspects of oceanographic variation is well described. The blooming phenomena in the area between the southern Vietnam coast and the Spratly islands are further investigated. Change in the wind-system related to the El Nino generates upwelling/SST-cooling in the sea south of the Spratly Islands through the air-sea-land interaction was studied. The seasonal upwelling is also associated with the harmful algal bloom (HAB) off two side of Indochina Peninsula have investigated. The seasonal variation of SCS phytoplankton blooming and related oceanic conditions in Vietnam coast was observed. Ocean color satellite data has effective contribute to study the oceanic condition and phytoplankton blooming in South China Sea.

• Ocean and Polar Research
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• v.35 no.4
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• pp.281-290
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• 2013

The vertical structure of sediment temperatures in the tidal flats of Geunso Bay and Seonyu Island in western Korea were measured for more than a year and analyzed. Mean temperature decreased with depth in spring and summer. On the contrary, it increased with depth in fall and winter, faithfully reflecting the seasonal variation resulting from the heating and cooling of the surface sediment. The surface sediment temperatures are shown to be strongly dependent on solar radiation, M2, and M4 tidal components. They are also weakly affected by precipitation. Thermal diffusivity of sediment is estimated at each depth and in each of the four seasons by applying the amplitude equation method. In Geunso Bay, the estimated seasonal-mean values decreased with depth, while they showed little change in Seonyu Island. Depth-averaged thermal diffusivity in Geunso Bay ($1.94 {\times}10^{-7}m^2/s$) was smaller than Seonyu Island ($2.20 {\times}10^{-7}m^2/s$). The variability of thermal diffusivity is shown to corelate with sediment composition and sorting from the grain-size analysis of intertidal sediments in Geunso Bay and Seonyu-do.

• Atmosphere
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• v.18 no.4
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• pp.475-483
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• 2008

The hourly precipitation data from 1973 to 2007 observed at 60 weather stations over Korea are used to characterize the diurnal and semidiurnal cycles of total precipitation amount, intensity and frequency and examine their spatial patterns and interannual variations. The results show that the diurnal cycle peaks in the morning (03-09LST) and the semidiurnal cycle peaks in the late afternoon (16-20LST). It is found that the spatial variations of the peak phase of diurnal or semidiurnal cycle relative to their corresponding seasonal mean cycle are considerably small (large) for total precipitation amount and intensity (frequency, respectively) in both winter and summer seasons. Also, the diurnal phase variations for individual years relative to the seasonal mean precipitation show the significant interannual variability with dominant periods of 2-5 years for all three elements of precipitation and the slightly decreasing trend in total precipitation amount and intensity. To compare the relative contributions of frequency and intensity to the diurnal and semidiurnal cycles (and their sum) of total precipitation amount, the percentage variance of each cycle of precipitation amount explained by frequency is estimated. The fractional variance accounted for by precipitation intensity is greater than that of frequency for these three cycles. All above analyses suggest that intensity plays a more important role than frequency in the diurnal variations of total precipitation amount.

• Atmosphere
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• v.28 no.2
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• pp.153-162
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• 2018

The statistical prediction model for wintertime surface air temperature, that is based on snow cover extent and Arctic sea ice concentration, is updated by considering $El-Ni{\tilde{n}}o$ Southern Oscillation (ENSO) and Quasi-Biennial Oscillation (QBO). These additional factors, representing leading modes of interannual variability in the troposphere and stratosphere, enhance the seasonal prediction over the Northern Hemispheric surface air temperature, even though their impacts are dependent on the predicted month and region. In particular, the prediction of Korean surface air temperature in midwinter is substantially improved. In December, ENSO improved about 10% of prediction skill compared without it. In January, ENSO and QBO jointly helped to enhance prediction skill up to 36%. These results suggest that wintertime surface air temperature in Korea can be better predicted by considering not only high-latitude surface conditions (i.e., Eurasian snow cover extent and Arctic sea ice concentration) but also equatorial sea surface temperature and stratospheric circulation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.5
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• pp.571-578
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• 2018

Seasonal variability in algal community structure of the subtidal zone was examined at four study sites on the southeastern coast of Korea from February to November 2016. A total of 81 species of algae (8 green, 12 brown, and 61 red) were indentified. During the study period, the greatest number of species was observed at Sinamri (57 species) followed by Daesongri (50 species), Dongbaekri (47 species) and Gangyangri (42 species). Of the six functional seaweed forms, the coarsely-branched form was the most dominant, accounting for about 43% of the total species at Daesongri. The annual average biomass in wet weight varied from $700.59g/m^2$ at Sinamri to $1,712.45g/m^2$ at Daesongri. The parameters of seaweed community structures were as follows: dominance index (DI), 0.30-0.54; richness index (R), 4.92-7.05; evenness index (J'), 0.54-0.72; and diversity index (H'), 2.05-2.91.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.3
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• pp.163-172
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• 2015

This study examined the potential effects of urban growth on streamflow in the Gyungan River watershed, Korea, using urban containment scenarios. First, two scenarios (conservation and development) were established, and SLEUTH model was adapted to predict urban growth into the year 2060 with 20 years interval under two scenarios in the study area. Urban growth was larger under scenario 2, focusing on development, than under scenario 1, focusing on conservation. Most urban growth was predicted to involve the conversion of farmland, forest, and grasslands to urban areas. Streamflow in future periods under these scenarios was simulated by the Soil and Water Assessment Tool (SWAT) model. Each scenario showed distinct seasonal variations in streamflow. Although urban growth had a small effect on streamflow, urban growth may heighten the problems of increased seasonal variability in streamflow caused by other factor, such as climate change. This results obtained in this study provide further insight into the availability of future water resource and can aid in urban containment planning to mitigate the negative effects of urban growth in the study area.