• Journal of the Korean earth science society
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• v.34 no.7
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• pp.693-710
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• 2013

This study investigates the distribution of suspended particulates during the Asian dust period in Busan, Korea in the spring of 2009. Weather map and automatic weather system (AWS) data were used to analyze the synoptic weather conditions during the period. Particulate matter 10, laser particle counter data, satellite images and a backward trajectories model were used to analyze the aerosol particles distribution and their origins. In Case 1 (20 February 2009), when the $PM_{10}$ concentration increased, the aerosol volume distribution of small ($0.3-1.0{\mu}m$) particles decreased, while the concentration of large ($1.0-10.0{\mu}m$) particles increased. When the $PM_{10}$ concentration decreased, the aerosol volume distribution was observed to decrease as well. The prevailing winds changed from weak northerly winds to strong southwesterly winds when the concentration of the large particles increased. The correlation coefficient between the $PM_{10}$ concentration and aerosol volume distribution of large particles showed a high positive value of over 0.9. The results from the trajectory model show that the Asian dust originated in the Gobi desert and the Nei Mongol plateau. In Case 2 (25 April 2009), when the $PM_{10}$ concentration increased, the aerosol volume concentration of small ($0.3-0.5{\mu}m$) particles decreased, but the concentration of large ($0.5-10.0{\mu}m$) particles increased. The opposite was observed when the $PM_{10}$ concentration decreased. The prevailing winds changed from northeasterly winds to southwesterly and northeasterly winds. The correlation coefficient between the $PM_{10}$ concentration and aerosol volume distribution of large particles ($1.0-10.0{\mu}m$) showed a high positive value of about 0.9. The results from the trajectory model show that the Asian dust originated in Manchuria and the eastern coast of China.

• Korean Journal of Environmental Biology
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• v.34 no.1
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• pp.18-29
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• 2016

The effects of water temperature, salinity, water column nutrient contents, and phytoplankton primary productivity on pigment composition and concentration, as well as primary productivity of Pyropia yezoensis Ueda purple lavers were studied at the primary cultivation areas in the Manho (Jindo-Haenam) region on the southwestern coast of Korea in March 2014. The water temperature was $9.1{\sim}9.6^{\circ}C$, salinity was 32.5~33.1, and transparency was 0.7~1.5 m. The shallow euphotic depth resulted from the high turbidity. Water column dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and silicate concentrations were $3.59{\sim}5.73{\mu}M$, $0.16{\sim}0.41{\mu}M$, and $12.41{\sim}13.94{\mu}M$, respectively. Chlorophyll a (Chl a) concentration was $0.51{\sim}1.25{\mu}g\;L^{-1}$. Nanoplankton ($0.7{\sim}20{\mu}m$ size class) accounted for 58% of the total Chl a concentration. Fucoxanthin was the dominant photosynthetic pigment at all sites. Microplankton ($20{\sim}200{\mu}m$ size class) accounted for 64% of the total fucoxanthin concentration. The primary productivity of phytoplankton was $57.72{\pm}4.67(51.05{\sim}66.71)mg\;C\;m^{-2}d^{-1}$. The nanoplankton ($0.7{\sim}20{\mu}m$ size class) accounted for 77% of the total phytoplankton primary productivity. The calculated phytoplankton primary productivity was $11,337kg\;C\;d^{-1}$. The primary productivity of Pyropia blades was $1,926{\pm}192(1,102{\sim}2,597)mg\;C\:m^{-2}d^{-1}$, i.e., calculated as $39,295kg\;C\;d^{-1}$. The total primary productivity of phytoplankton and Pyropia blades was $50,632kg\;C\;d^{-1}$. The primary productivity of Pyropia blades was 3.5 times greater than that of phytoplankton in the Manho region on the southwestern coast of Korea.

• Korean Journal of Remote Sensing
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• v.27 no.4
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• pp.467-480
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• 2011

Spatial and temporal variabilities of NPP(Net Primary Production) retrieved from two satellite instruments, AVHRR(Advanced Very High Resolution Radiometer, 1981-2000) and MODIS(MODerate-resolution Imaging Spectroradiometer, 2000-2006), were investigated. The range of mean NPP from A VHRR and MODIS were estimated to be 894-1068 $g{\cdot}C/m^2$/yr and 610-694.90 $g{\cdot}C/m^2$/yr, respectively. The discrepancy of NPP between the two instruments is about 325 $g{\cdot}C/m^2$/yr, and MODIS product is generally closer to the ground measurement than AVHRR despite the limitation in direct comparison such as spatial resolution and vegetation classification. The higher NPP values over South Korea are related to the regions with higher biomass (e.g., mountains) and higher annual temperature. The interannual NPP trends from the two satellite products were computed, and both mean annual trends show continuous NPP increase; 2.14 $g{\cdot}C/m^2$/yr from AVHRR(1981-2000) and 6.08 $g{\cdot}C/m^2$/yr from MODIS (2000-2006) over South Korea. Specifically, the higher increasing trends over the Southwestern region are likely due to the increasing productivity of crop fields from sufficient irrigation and fertilizer use. The retrieved NPP shows a closer relationship between monthly temperature and precipitation, which results in maximum correlation during summer monsoons. The difference in the detection wavelength and model schemes during the retrieval can make a significant difference in the satellite products, and a better accuracy in the meterological and land use data and modeling applications will be necessary to improve the satellite-based NPP data.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.2
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• pp.89-105
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• 2008

Sea level and atmospheric pressure data of 1999-2005 from four stations along the Korean east coast were analyzed to understand the sea level variability and its causal mechanism. The results of the wavelet and the auto-spectrum analyses indicate that the sea level fluctuations of 3-17 day period are statistically significant at the 95% confidence level, especially in spring to early summer. In this period, the coherency between the sea levels and the atmospheric pressures in a cross-spectrum is high, implying the importance of an inverted barometric effect in generation of the sea level fluctuations. To learn about the sea level variability, the cross-spectrum analyses were applied between the sea levels of the adjacent stations. The results show a case of southward phase propagations along the coast, as in 1999, 2003 and 2005, and an another case of no progressive phase lags between the stations, as in 2000-2002, and 2004. The phase speed in the former case is 12-15 m/s, which is a commonly observed phase speed of coastal Kelvin waves. Generation of such fluctuations seems to be related to low pressure cells developed in the Asian continent in spring and summer and moving eastward over the coastal region north of the stations. The latter case of no progressive phase lag, however, occurs when the low pressure cells developed in the continent move along the region south of the stations. In this case, the northeastward phase propagation with a speed of 5-8 m/s is observed along the southwestern coast of Japan.

• Journal of the Korean Geographical Society
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• v.43 no.3
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• pp.324-336
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• 2008

This paper examines the recent changes of summer precipitation in the aspect of temporal and spatial features using long-term($1958{\sim}2007$) observed station data over South Korea. tong-term mean summer precipitation has revealed two precipitation peaks during summer(June to September); one is the Changma as the first peak, and the other is the post-Changma as the second peak. During the Changma period, the spatial distribution of the maximum precipitation areas is determined by the prevailing southwesterlies and the quasi-stationary front, which results in large amount of precipitation at the windward side of mountain regions over South Korea. However during the post-Changma period, the spatial distribution of the maximum precipitation areas is determined by the lower tropospheric circulation flows from the west and the southeast around the Korean peninsula, and the weather phenomena such as Typhoons, convective instability, and cyclones which are originated from the Yangtze river. The larger amount of precipitation is founded on the southern coastal region and mountain and coastal areas in Korea during the second peak. Time series of total summer precipitation shows a steady increase and the increasing trend is more obvious during the recent 10 years. Decadal variation in summer precipitation indicates a large increase of precipitation, especially in the recent 10 years both in the Changma and the post-Changma period. However, the magnitude of change and the period of the maximum peak presents remarkable contrasts among stations. The most distinct decadal change occurs at Seoul, Busan, and Gangnueng. The precipitation amount is increasing significantly during the post-Changma period at Gangnueng, while the precipitation increases in the period between two maximum precipitation peaks during summer at Seoul and Busan.

• Korean Journal of Plant Resources
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• v.2 no.2
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• pp.298-305
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• 1989

This study was carried out to understand the immigration period, climatic conditions for mass immigration and bionomical characters ofthe brown pLanthopper(BPH) in Hae NamThe results are as follows ; (1) The Periods of first immigraion and mass immigration of BPH , were from the late June to early JuLy and from earlyto mid JuLy in HaeNam, that were faster about 15-30days than in inland of ChonnanThe climatic factors that related closely to mass immigration wereas follows ; temp.: $20{\;}~{\;}25^{\circ}C$, humidity : 86 ~ 95 % , wind direcion : SW, wind velocity: 1.0 ~ 2.9gm/sec. (2)The population of immigranted BPH was in the field much more overthe mountain near coast than other places . Biotype composition showed that biotype I was on the decrease and biotype II, III were on the increase (3)The bionomical characters were variable, for climatic conditions,that egg stage, nymphal stage and adult stafe of immigranted BPHwere 9-12days, 13-16days and 12-36days respectively, that hatchability(%) and emergence rate ( % ) were higher than 80%. The adult Longevity in female and macropterous BPH showed Longerthan that of male and brachypterous respectively. (4) The distance of nymphs and brachypterous adults move by walking was within 16cm over the water surface, by hopping was within 20cm horizontally.

• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.3
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• pp.119-129
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• 2013

This study was conducted to predict the changes in forest biomass in different ecoprovinces and forest types under climate change scenario based on cumulative data (i.e., digital forest site and climate maps, National Forest Inventory data) and various prediction models. The results from this study showed that predicted changes over time in biomass varied according to ecoprovince and forest type in Korea. A reduction in biomass was predicted for all forest types associated with the mountain, southeastern hilly, and southwestern hilly ecoprovinces. On the other hand, the biomass was predicted to increase for the coniferous forest and mixed-forest types in the central hilly ecoprovince. Furthermore, increases in biomass are predicted for all forest types, except coniferous forests, in the coastal ecoprovince. The results from this study provide a basis for developing technology to predict forest impacts due to climate change by predicting changes in forest biomass based on the estimation of site index.

• Korean journal of applied entomology
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• v.15 no.3 s.28
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• pp.111-126
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• 1976

Regional differences in economic importance of the four species of rice leafhoppers, viz., Laodelphax striatellus, Nephotettix cincticeps, Nilaparvata Iugens and Sogatella furcifera, were analyzed and discussed based on population surveys conducted in Suweon and in southern and south-western coastal areas. The economic importance of L. striatellus and N. cincticeps, which are found throughout the year in Korea, seems to be less in middle regions. This is believed due to effective natural control through severe winter climate, cultural practices in rice and barley growing, and natural enemies such as spiders. However, the economic importance of these two species is significantly greater in southern regions with a less severe winter climate, and where cultural practices in rice and barley favour synchronization between the life cycles of insects and the seasonal succession of host plants. with regard to N. lugens and S. furcifera, which cannot overwinter in Korea, initial populations are the result of long distance migration across the East China Sea. Weather elements related to their migration result in more abundant immigrants of these two species in southern than in middle regions. Thus, different policies are needed for the integrated control of rice leafhoppers in middle and southern Korea.

• Economic and Environmental Geology
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• v.34 no.5
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• pp.485-498
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• 2001

This study was objected to identify the temporal and spatial variations oi groundwater quality and contamination using monthly groundwater monitoring data collected from 30 wells in Daejung watershed, Jeju Island. Water samples were analyzed for major cations. anions, and environmental isotopes including $^{18}0-H_2$O,$^{2}H-H_2$O and$^{15}$ N-NO$_3$The groundwater represented mostly Na(Mg)-HCO$_3$ type, with local change toward Ca-HCO$_3$ type and Na-Cl type. Groundwater quality depends upon various factors such as the local groundwater flowpaths, input of surface contaminants with recharge events, and sea-water intrusion along the coastal area. Nitrate contamination changed temporally according to recharge events and spatially. $\delta$$^{18}$ O-$\delta$$_2$H data for monthly sampled groundwaters showed distinctive clusters, implying that groundwater was originated from independent precipitation, and subsequently recharged very fash. Using$\delta$$^{15}$ N-NO$_3$ data, major sources of nitrate and its areas of influence could be identified. The areas under influence of livestock farms showed relatively high NO$_3$-N concentrations and$\delta$$^{15}$ N values higher than 5$\textperthousand$. The agricultural areas in southeastern part showed very high concentrations of NO$_3$-N with the $\delta$$^{15}$ N values of lower than 5$\textperthousand$.

• Korean Journal of Remote Sensing
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• v.29 no.4
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• pp.423-441
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• 2013

On 21 September 2010, one of Chuseok holidays in Korea, localized heavy rainfalls occurred over the midwestern region of the Korean peninsula. In this study MTSAT-2 infrared and water vapor channel imagery are examined to find out some features which are obvious in each stage of the life cycle of convective cell for this heavy rain event. Also the kinematic and thermodynamic features probably associated with them are investigated. The first clouds related with the Chuseok heavy rain are detected as low-level multicell cloud (brightness temperature: $-15{\sim}0^{\circ}C$) in the middle of the Yellow sea at 1630~1900 UTC on 20 Sept., which are probably associated with the convergence at 1000 hPa. Convective cells are initiated in the vicinity of Shantung peninsula at 1933 UTC 20, which have developed around the edge of the dark region in water vapor images. At two times of 0033 and 0433 UTC 21 the merging of two convective cells happens near midwestern coast of the peninsula and then they have developed rapidly. From 0430 to 1000 UTC 21, key features of convective cell include repeated formation of secondary cell, slow horizontal cloud motion, persistence of lower brightness temperature ($-75{\sim}-65^{\circ}C$), and relatively small cloud size (${\leq}-50^{\circ}C$) of about $30,000km^2$. Radar analysis showed that this heavy rain is featured by a narrow line-shaped rainband with locally heavy rainrate (${\geq}50$ mm/hr), which is located in the south-western edge of the convective cell. However there are no distinct features in the associated synoptic-scale dynamic forcing. After 1000 UTC 21 the convective cell grows up quickly in cloud size and then is dissipated. These satellite features may be employed for very short range forecast and nowcasting of mesoscale heavy rain system.