• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.4
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• pp.330-336
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• 2018

El $Ni{\tilde{n}}o$ would cause extreme weather conditions, which would result in a negative impact on crop production. The objective of this study was to assess the impact of El $Ni{\tilde{n}}o$ on spring kimchi cabbabe production for the period from 1981- 2016 in South Korea. In this study, years with less than 1.0 Oceanic $Ni{\tilde{n}}o$ index were classified into non El $Ni{\tilde{n}}o$ years. The other years were classified as El $Ni{\tilde{n}}o$ years. The national average production of spring kimchi cabbage in El $Ni{\tilde{n}}o$ years ($3,800kg\;10a^{-1}$) tended to be less than that in non El $Ni{\tilde{n}}o$ years ($4,016kg\;10a^{-1}$). However, there was no significant differences (p = 0.078) in the production between these groups of years. The averaged production of spring kimchi cabbage of El $Ni{\tilde{n}}o$ end years ($3,707{\pm}331kg\;10a^{-1}$) was less than those of El $Ni{\tilde{n}}o$ start years and non El $Ni{\tilde{n}}o$ years by 186 and $309kg\;10a^{-1}$, respectively. Still, such difference was not significant statistically (p=0.127), either. In contrast, there were provinces where the production of spring kimchi cabbage had significant differences by El $Ni{\tilde{n}}o$ occurrence. For example, El $Ni{\tilde{n}}o$ end years had significantly less spring kimchi cabbage production than El $Ni{\tilde{n}}o$ start years and non El $Ni{\tilde{n}}o$ years in Gangwon (p=0.038) and Gyeongbuk (p=0.053) provinces. It appeared that differences in cabbage production resulted from short sunshine duration, which merits further analysis on the impact of extreme weather condtions during El $Ni{\tilde{n}}o$ years on crop production.

• Ocean and Polar Research
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• v.33 no.spc3
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• pp.371-383
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• 2011

To investigate the physical characteristics and variations of oceanic parameters in the tropical central North Pacific, oceanographic surveys were carried out in summer of 2006 and 2007. The survey periods were classified by Oceanic Ni$\tilde{n}$o Index as a weak El Ni$\tilde{n}$o in 2006 and a medium La Ni$\tilde{n}$a in 2007. The survey instruments were used to acquire data on CTD (Conductivity Temperature and Depth), XBT (Expendable Bathythermograph), and TSG (Thermosalinograph). The dominant temporal variation of surface temperature was diurnal. The diurnal variation in 2007, when the La Ni$\tilde{n}$a weather pattern was in place, was stronger than that in 2006. Surface salinity in 2006 was affected by a northwestward branch of North Equatorial Current, which implies that the El Ni$\tilde{n}$o affects surface properties in the North Equatorial Current region. Two salinity minimum layers existed at stations east of Chuuk in both year's observations. The climatological vertical salinity section along $180^{\circ}E$ shows that the two salinity minimum layers exist in $2^{\circ}N{\sim}12^{\circ}N$ region, consistent with our observations. Analysis of isopycnal lines over the salinity section implies that the upper salinity minimum layer is from intrusion of the upper part of North Pacific Intermediate Water into the lower part of South Pacific Subtropical Surface Water and the lower salinity minimum layer is from Antarctic Intermediate Water.

• Ocean and Polar Research
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• v.37 no.3
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• pp.189-200
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• 2015

Mesozooplankton biomass including total biomass and size-fractionated biomass and the abundance of major taxonomic groups of copepods were studied in the Northwestern Subtropical Pacific Warm Pool (NSPWP) and the Northern East China Sea (NECS) from 2006 to 2014. Mesozooplankton biomass ranged from 0.69 to $3.08mgC/m^3$ (mean $1.12mgC/m^3$) in the NSPWP and from 10.60 to $69.10mgC/m^3$ (mean $30.33mgC/m^3$) in the NECS with higher values in spring than fall. Percent composition in the biomass of each size group of mesozooplankton varied interannually both in the NSPWP and in the NECS. The smallest size group (0.2~0.5 mm) contributed the least to total biomass in both regions, but significantly higher in the NSPWP than in the NECS. The percent composition in abundance of copepod taxonomic groups (i.e. Calanoida, Cyclopoida, and Poecilostomatoida) also fluctuated interannually. Mean composition of calanoid copepods was higher in the NECS than in the NSPWP, but the opposite pattern was observed for poecilostomatoid copepods. Mesozooplankton biomass both in the NSPWP and in the NECS was negatively correlated with Oceanic $Ni{\tilde{n}}o$ Index (ONI), indicating declines in biomass during El $Ni{\tilde{n}}o$ periods and vice versa during Na $Ni{\tilde{n}}a$ period. The effect of El $Ni{\tilde{n}}o$ on variation of mesozooplankton biomass was more prominent in the NSPWP than in the NECS. These results suggest that mesozooplankton biomass both in the NSPWP and in the NECS responded to El $Ni{\tilde{n}}o$ events, although the biological process that explain the reduced mesozooplankton biomass might be different in both regions.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.3
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• pp.143-150
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• 2016

In this study, we analyzed the relationship between rice yield and abnormal meteorological features for El $Ni{\tilde{n}}o$ years (with more than 1.0 Oceanic $Ni{\tilde{n}}o$ Index) since 1980 in South Korea. The national averaged rice yield of El $Ni{\tilde{n}}o$ years (n=14) was $4,663kg\;ha^{-1}$, which was less than that of non El $Ni{\tilde{n}}o$ years (n=16) by $102kg\;ha^{-1}$, but the difference was not significant statistically (t=1.215, p=0.234). The averaged rice yield of El $Ni{\tilde{n}}o$ end years ($4,558kg\;ha^{-1}$) was analyzed to be less than those of El $Ni{\tilde{n}}o$ start years and non El $Ni{\tilde{n}}o$ years by 209 and $206kg\;ha^{-1}$, respectively. But, the trend was not significant statistically (df=2, f=2.355, p=0.114). When meteorological anomalies were analyzed based on seasonal meteorological values, 18 meteorological events in total were observed for the past 30 years (1981-2010). In detail, abnormally much precipitation occurred 6 times, most often, followed by 5 times of abnormally low temperature during the past 30 years. Occurrence of meteorological anormalies of El $Ni{\tilde{n}}o$ end years was 0.71 events per year on average, which was higher than those of El $Ni{\tilde{n}}o$ start years ($0.43yr^{-1}$) and non El $Ni{\tilde{n}}o$ years ($0.63yr^{-1}$), even if the differences were not significant statistically (df=2, f=0.321, p=0.727).

• Korean Journal of Agricultural and Forest Meteorology
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• v.14 no.4
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• pp.143-154
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• 2012

As demand of water resources and attentions to changes in climate (e.g., due to ENSO) increase, long/short term prediction of precipitation is getting necessary in water planning. This research evaluated the ability of MM5 to predict precipitation in the Tampa Bay region over 23 year period from 1986 to 2008. Additionally MM5 results were statistically bias-corrected using observation data at 33 stations over the study area using CDF-mapping approach and evaluated comparing to raw results for each ENSO phase (i.e., El Ni$\tilde{n}$o and La Ni$\tilde{n}$a). The bias-corrected model results accurately reproduced the monthly mean point precipitation values. Areal average daily/monthly precipitation predictions estimated using block-kriging algorithm showed fairly high accuracy with mean error of daily precipitation, 0.8 mm and mean error of monthly precipitation, 7.1 mm. The results evaluated according to ENSO phase showed that the accuracy in model output varies with the seasons and ENSO phases. Reasons for low predictions skills and alternatives for simulation improvement are discussed. A comprehensive evaluation including sensitivity to physics schemes, boundary conditions reanalysis products and updating land use maps is suggested to enhance model performance. We believe that the outcome of this research guides to a better implementation of regional climate modeling tools in water management at regional/seasonal scale.

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.4
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• pp.279-286
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• 2020

The objective of this study was to assess the impact of El Niño on highland kimchi cabbage production for the period from 1991-2016 in South Korea. Years with less than 1.0 Oceanic Niño index (ONI) were classified into non El Niño years, while years with equal to or greater than 1.0 ONI were defined as El Niño years. The national average production (3,444 kg 10a-1) of high kimchi cabbage in El Niño years tended to be less than that in non El Niño years (3,722 kg 10a-1) with significant differences (p = 0.0042) in the production between these groups of years. The averaged production of highland kimchi cabbage of El Niño end years (3,289 kg 10a-1) was less than those of El Niño start years and non El Niño years by 310 and 433 kg 10a-1, respectively. Such difference was significant statistically (p=0.035). According to our analysis, the differences in kimchi cabbage productions resulted from low temperature, short sunshine duration, and precipitation increase during the cultivation period of highland kimchi cabbage. This study may help for further analysis on the impact of extreme weather conditions during El Niño years on crop production.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.75-83
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• 2020

This study investigated the effects of El Niño and La Niña on coastal upwelling in the East Sea of Korea using long-term (1967-2017) water temperature observation data and Oceanic Niño Index (ONI). As a result of time series analysis of water temperature, the occurrence frequency of summer coastal upwelling was the highest in the southeastern (Ulgi ~ Gimpo) coast. In 1987-1988 and 1997-1998, when the annual fluctuations of ONI plunged more than 2.5, the water temperature in whole coast areas of the East Sea (Busan ~ Goseung) rose by 4 ~ 7 ℃. The temperature structure of the East Sea coastal water was different when El Niño was strong with ONI above 1.5 and La Niña with strong ONI below -0.8. When El Niño is strong, the water temperature anomaly in coastal waters is negative. This is due to the strong baroclinic tilting and the formation of shallow temperature stratification in the coastal waters. The strong La Niña season is opposite to the strong El Niño season, whereas the water temperature anomaly is positive. In addition, the baroclinic tilting is weaker than the time of strong El Niño and the temperature stratification is formed deeper than the time of strong El Niño. The formation of temperature stratification at shallow depths when El Niño is strong can increase the probability of occurrence coastal upwelling caused by southerly winds in the summer season. On the contrary, when La Niña is strong, occurrence of coastal upwelling is less likely even if the southerly wind blows continuously. This is because the temperature stratification is formed at deeper than when El Niño is strong.