• Journal of Korea Water Resources Association
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• v.50 no.11
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• pp.735-743
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• 2017

With growing concerns about ever-increasing anthropogenic greenhouse gas emissions, it is crucial to enhance preparedness for unprecedented extreme weathers that can bring catastrophic consequences. In this study, we proposed a stochastic framework that considers uncertainty in weather forecasts for flood analyses. First, we calibrated a simple rainfall-runoff model against observed hourly hydrographs. Then, using probability density functions of rainfall depths conditioned by 6-hourly weather forecasts, we generated many stochastic rainfall depths for upcoming 48 hours. We disaggregated the stochastic 6-hour rainfalls into an hourly scale, and input them into the runoff model to quantify a probabilistic range of runoff during upcoming 48 hours. Under this framework, we assessed two rainfall events occurred in Bocheong River Basin, South Korea in 2017. It is indicated actual flood events could be greater than expectations from weather forecasts in some cases; however, the probabilistic runoff range could be intuitive information for managing flood risks before events. This study suggests combining deterministic and stochastic methods for forecast-based flood analyses to consider uncertainty in weather forecasts.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.4
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• pp.435-447
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• 2016

Anthropogenic emissions of $PM_{2.5}$ in Chuncheon are considered to be low according to the national emissions inventory; however, the atmospheric $PM_{2.5}$ concentrations have been reported to be higher than or at least similar to those measured in metropolitan (e.g. Seoul) and/or in industrial cities (e.g. Incheon, Ulsan). In this study, the concentrations of $PM_{2.5}$ and its ionic and carbonaceous compounds were measured from Jan. 2013 to Dec. 2014 in Chuncheon, Korea to identify the characteristics of high $PM_{2.5}$ concentration event. Average $PM_{2.5}$ concentration was $34.6{\mu}g/m^3$, exceeding the annual air quality standard ($25{\mu}g/m^3$). The most abundant compound was organic carbon (OC), comprising 26% of $PM_{2.5}$ mass, followed by $SO_4{^{2-}}$. Among 14 high concentration events, three events showed clearly enhanced contributions of OC, $SO_4{^{2-}}$, $NO_3{^-}$ and $NH_4{^+}$ to $PM_{2.5}$ under the fog events. One event observed in summer showed high concentration of $SO_4{^{2-}}$ while the high wind speeds and the low $PM_{2.5}/PM_{10}$ ratios were observed for the two high concentration events. These results indicate that the secondary aerosol formation under the fog events and high atmospheric temperature as well as the regional and/or the long-range transport were important on enhancing $PM_{2.5}$ concentration in Chuncheon. Cluster analysis based on back trajectories also suggested the significant impacts of regional transport from China and metropolitan areas of Korea on $PM_{2.5}$ in Chuncheon.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.1
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• pp.73-86
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• 2011

Haze phenomena were analyzed to assess the impact of long range transport process on the air quality of Seoul and Busan. We statistically classified haze days observed in both Seoul and Busan into two types of haze cases: stagnant case and long-range transport case, and analyzed the air pollutant levels comparatively for each of the two cases for the period of 2000~2007. The results showed that the long-range transport haze case occurs less frequently with the occurrence frequency of 35.5% than stagnant case with the occurrence frequency of 64.5%. During the observed all haze days, all pollutants have high concentration in comparison with those under other meteorological conditions (Rain, Mist, Dust, Clear, Rain+Mist) except for only $PM_{10}$ of Dust case where its level shows highest among total 6 categorized conditions. The long range transport haze case shows similar levels of $PM_{10}$ and $NO_2$, but higher $SO_2$ and lower $O_3$ compared with stagnant haze cases, suggesting the importance of sulfur chemistry for long range transport haze case and local photochemistry for stagnant haze case. In addition, by employing the NOAA/HYSPLIT-4 backward trajectory model, we subdivided the long range transport haze cases into two different sources: urban anthropogenic high emission areas of central China, and natural emission sources over north China and/or Mongolia. The former long range transport haze case shows higher occurrence (with Seoul 70% and Busan 85%) than the latter haze case (with Seoul 30% and Busan <10%). This is also implying that the long haze phenomena occurred over Korea have been influenced by not only the anthropogenic emissions but also the natural dust emissions. These both emission sources can be good contributors in calculating the source-receptor relationship over Korean atmospheric environment.

• Korean Journal of Ecology and Environment
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• v.53 no.2
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• pp.185-194
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• 2020

Pomacea canaliculate (channeled apple snail; CAS), which is one of the world's worst alien invasive species, is widely distributed in Korea, and raised ecological and economic problems. In this study, we surveyed the distribution and dispersal characteristics of CAS in Korea, and analyzed the effects of environmental and anthropogenic (or social) factors on their distribution and dispersal. We considered various events related to CAS such as changes of policy including promotion of agriculture using CAS and enactment of biological diversity conservation law. Our results showed that human activities strongly influenced to the distribution and dispersal of CAS in Korea. Distribution of CAS seemed to relate with environment-friendly agriculture considering environmental conditions of CAS habitats. And dispersal characteristics of CAS were significantly correlated with social factors such as cultivation area and rate of organic products, production CAS on inland fishery.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.1
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• pp.32-45
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• 2016

The anthropogenic aerosols originated from the pollutant emissions in the eastern part of China and dust emitted in northwestern China in Yellow sand regions are subsequently transported via eastward wind to the Korean peninsula and then these aerosols induce high $PM_{10}$ concentrations in Korean peninsula. In order to estimate air quality considering anthropogenic and dust emissions, Comprehensive Air-quality Model with extension (CAMx) was applied to simulate $PM_{10}$ concentration. The predicted $PM_{10}$ concentrations without/with dust emissions were compared with observations at ambient air quality monitoring sites in China and Korea for 2008. The predicted $PM_{10}$ concentrations with dust emissions could depict the variation of measured $PM_{10}$ especially during Yellow sand events in Korea. The comparisons also showed that predicted $PM_{10}$ concentrations without dust emissions were under-predicted while predictions of $PM_{10}$ concentrations with dust emission were in good agreement with observations. This implied that dust emissions from desert and barren soil in southern Mongolia and northern China minimized the discrepancies in the $PM_{10}$ predictions in East Asia. The effect of dust emission on annual $PM_{10}$ concentrations in Korea Peninsula for year 2008 was $5{\sim}10{\mu}g/m^3$, which were about 20% of observed annual $PM_{10}$ concentrations.

• Korean Journal of Remote Sensing
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• v.36 no.5_3
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• pp.1007-1011
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• 2020

Recently, natural and anthropogenic disasters have rapidly increased due to the on-going climate change and various human activities. Remote sensing (RS) technology enables the continuous monitoring and rapid detection of disastrous events thanks to its advantages covering vast areas at high temporal resolution. Moreover, RS technology has been very actively used in disaster monitoring and assessment since cluster- and micro-satellites and drones were introduced and became popular. In this special issue, nine papers were introduced, including the processing and applications of remote sensing data for monitoring, assessment, and prediction of various natural disasters. These papers are expected to serve as useful references for disaster management in the future.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.11a
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• pp.232-236
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• 2000

Multi-regression statistical analyses were applied for the water quality data of shallow alluvial ground water (n = 47) collected from the Youngdeok area, in order to quantitatively generalize the natural (non-anthropogenic) causes of regional water quality variation. Seven samples having the high contamination index ( $C_{a}$ > 3) reflect the striong effects by anthropogenic activity. Most of the alluvial groundwaters have acquired their quality primarily due to the dissolution of carbonate minerals. The results of multi-regression analysis show that chlorine is mainly derived from seawater effect. Sulfur isotopic compositions of dissolved sulfur and the S $O_4$/Cl ratio also enable us to discriminate the samples (n = 18) which are affected by atmospheric input of marine aerosol (sea-spray) and also by mixing between freshwater and seawater. Hydrogen and oxygen isotope data of the samples collected lie close to the local meteoric water line obtained from nearby Pohang city but has lower slope (5.45) on the $\delta$D-$^{18}$ O plot, indicating that alluvial groundwater was recharged from infiltrated meteoric water which has undergone some degree of kinetic evaporation. The estimated initial isotopic composition of the recharged water ($\delta$D = -74.8$^{0}$ /$_{00}$, $\delta$$^{18}$ O = -10.8$^{[-1000]}$ /$_{[-1000]}$ ) suggests that the alluvial ground water recharge largely occurs during summer storm events.s.s.

• Journal of Environmental Science International
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• v.28 no.2
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• pp.169-182
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• 2019

Temporal and spatial variations in surface ozone concentrations in Busan were investigated by using observation data from urban air quality sites during 2001-2016. The annual ozone concentrations showed a significant increasing trend of $+0.40ppb\;yr^{-1}$ in this period, with a more rapid increase of $+0.81ppb\;yr-1$ since 2010. For the monthly analysis, the increase in ozone concentration was the greatest in August ($+0.68ppb\;yr-1$). These ozone trends were due mainly to rising temperature ($+0.05^{\circ}C\;yr^{-1}$) and weak decreasing precipitation ($-6.42mm\;yr^{-1}$). However, the extreme weather events (heat wave, localized heavy rain, etc.) lead to an increase in short-term variability of ozone since 2010. The relatively low ozone concentrations in the downtown area were caused by high NOx emissions from mobile sources. The increases in ozone concentrations were observed at most of the air quality monitoring sites due to the reductions in anthropogenic emissions of NOx during 2001-2015. However, in the southern coastal area, lower rates of increase in ozone concentrations were observed by $-0.10{\sim}0.25ppb\;yr^{-1}$ due to the significant NOx emitted by ships in the Busan port and Busan new port.

• Asian Journal of Atmospheric Environment
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• v.11 no.4
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• pp.300-312
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• 2017

To improve the understanding of secondary organic aerosol (SOA) formation from the photo-oxidation of anthropogenic and biogenic precursors at the regional background station on Baengnyeong Island, Korea, gas phase and aerosol chemistries were investigated using the Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-ToF-MS) and the Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS), respectively. HR-ToF-AMS measured fine particles ($PM_1$; diameter of particle matter less than $1{\mu}m$) at a 6-minute time resolution from February to November 2012, while PTR-ToF-MS was deployed during an intensive period from September 21 to 29, 2012. The one-minute time-resolution and high mass resolution (up to $4000m{\Delta}m^{-1}$) data from the PTR-ToF-MS provided the basis for calculations of the concentrations of anthropogenic and biogenic volatile organic compounds (BVOCs) including oxygenated VOCs (OVOCs). The dominant BVOCs from the site are isoprene (0.23 ppb), dimethyl sulphide (DMS, 0.20 ppb), and monoterpenes (0.38 ppb). Toluene (0.45 ppb) and benzene (0.32 ppb) accounted for the majority of anthropogenic VOCs (AVOCs). OVOCs including acetone (3.98 ppb), acetaldehyde (2.67 ppb), acetic acid (1.68 ppb), and formic acid (2.24 ppb) were measured. The OVOCs comprise approximately 75% of total measured VOCs, suggesting the occurrence of strong oxidation processes and/or long-range transported at the site. A strong photochemical aging and oxidation of the atmospheric pollutants were also observed in aerosol measured by HR-ToF-AMS, whereby a high $f_{44}:f_{43}$ value is shown for organic aerosols (OAs); however, relatively low $f_{44}:f_{43}$ values were observed when high concentrations of BVOCs and AVOCs were available, providing evidence of the formation of SOA from VOC precursors at the site. Overall, the results of this study revealed several different SOA formation mechanisms, and new particle formation and particle growth events were identified using the powerful tools scanning mobility particle sizer (SMPS), PTR-ToF-MS, and HR-ToF-AMS.

• Atmosphere
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• v.26 no.3
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• pp.357-372
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• 2016

Northeast Asian regions have recently become the main source of anthropogenic and natural aerosols. Measurement of aerosols on the sea in these regions have been rarely conducted since the experimental campaigns such as ACE-ASIA (Asian Pacific Regional Aerosol Characterization Experiment) in 2001. Research vessel observations of aerosol mass and chemical composition were performed on the Yellow and south sea around the Korean peninsula. The ship measurements showed six representative cases such as aerosol event and non-event cases during the study periods. On non-event cases, the anthropogenic chemical and natural soil composition on the Yellow sea were greater than those on the south sea. On aerosol event cases such as haze, haze with dust, and dust, the measured mass concentrations of anthropogenic chemical and element compositions were clearly changed by the events. In particular, methanesulfonate ($MSA^-$, $CH_3SO_3^-$), a main component of natural oceanic aerosol important for sulfur circulation on Earth, was first observed by the vessel in Korea, and its concentration on the Yellow sea was three times that on the south sea during the study period. Sea salt concentration important to chemical composition on the sea is related to wind speed. Coefficients of determination ($R^2$) between wind speed and sea salt concentration were 0.68 in $PM_{10}$ and 0.82 in $PM_{2.5}$. Maximum wave height was not found to be correlated to the sea salt concentration. When sea-salt comes into contact with pollutants, the total sea-salt mass is reduced, i.e., a loss of $Cl^-$ concentration from NaCl, the main chemical composing sea salt, is estimated by reaction with $HNO_3$(gas) and $H_2SO_4$(gas). The $Cl^-$ concentration loss by $SO_4^{2-}$ and $NO_3^-$ more easily increased for $PM_{10}$ compared to $PM_{2.5}$. The results of this study will be applied to verifying a dust-haze forecasting model. In addition, continued vessel measurements of aerosol data will become important to research for climate change studies in the future.