• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.3
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• pp.196-204
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• 2005

The horizontal and vertical distribution of yellowfin tuna, Thunnus albacares (Bonnaterre) and bigeye tuna, Tunnus obesus (Lowe) in relation to oceanic conditions such as thermal structure produced during El Nino/La Nina episodes were analyzed on the basis of data sets for the catches and efforts from the Korean tuna longline fishery and for the oceanographic observations from the NOAA during 1982-2002 in the tropical Pacific. The high density of fishing ground appeared in the western Pacific ($5^{\circ}N-5^{\circ}S,\;160^{\circ}E-180^{\circ}W$) for yellowfin tuna and in the eastern Pacific ($5^{\circ}N-15^{\circ}S,\;130^{\circ}W-100^{\circ}W$) for bigeye tuna. yellowfin and bigeye tunas were mainly distributed at the 110-250 m layer and 245-312 m layer, respectively, in the western Pacific. However, in the eastern Pacific, they were mostly caught at the 116-161 m and 205-276 m layer for yellowfin tuna and bigeye tuna, respectively. It can be suggested that bigeye tuna be distributed in the deepest layer among tunas and show a vertical size stratification. It was observed that during the El Nino events the main fishing ground of yellowfin tuna shifted from the western Pacific toward the eastern Pacific. In the eastern Pacific which showed a higher density of bigeye tuna, the vulnerability of bigeye tuna caught by deep longline increased during the El Nino events due to deepening of thermocline layer and a more intensively distribution of the fish schools in the lower layer of thermocline during the El Nino events.

• Proceedings of the Korea Water Resources Association Conference
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• 2003.05a
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• pp.151-158
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• 2003

Recently, there has been considerable interest in the influence of El Nino/Southern Oscillation (ENSO) on a global scale. ENSO has been measured by a simple index called Southern Oscillation Index (SOI). The statistical characteristics of SOI have been also focused to reveal the influence of ENSO. The SOI trend shows that El Nino events are generally getting stronger and more frequently occurring than La Nina events. However, the variation of SOI has varied significantly in a long-term. The SOI values are computed using the mean value and its standard deviation of the base period from 1951 to 1980. In the present study, the different base periods are applied to compute the SOI values and the influence of the different base periods is investigated in detail to reveal the long-term variation of SOI From the results, we could conclude that the present SOI should be carefully considered as a criterion to judge whether the El Nino and La Nina events are occurring.

• Journal of Korea Water Resources Association
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• v.38 no.12 s.161
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• pp.985-994
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• 2005

We examined problems of the principal component analysis(PCA), which is able to analyze at the low dimensionality as a methodologv to assess hydrologic time series, and introduced the theory and characteristics of independent component analysis(ICA) that can supplement problems of principal component analysis. We also applied the global sea surface temperature(SST) of the Nino region and assessed the correlation between El $\tilde{n}ino$-Southern Oscillation(ENSO) and SST. The results of examining separation-ability of principal components using mixed signals indicate that the independent component analysis is statistically superior compared to that of the principal component analysis. Finally, we assessed correlation between ENSO and global anomaly SST. The independent component analysis was applied to the $5^{\circ}{\times}5^{\circ}$(latitude and longitude) global anomaly SST in the Nino+3.4 region that is the El $\tilde{n}ino$ observation section. We assessed the correlation with the ENSO years. These results of the analysis show that only one independent component($86\%$) was able to represent the entire behavior and was consistent with the main ENSO years. Finally, we carried out independent component analysis for summer seasonal rainfalls at nine stations and could extract ICs to reflect geographical characteristics. The increasing trend has been shown at IC-1 and IC-2 since 1970s.

• Journal of electromagnetic engineering and science
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• v.5 no.4
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• pp.189-192
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• 2005

The measurement of unique rainfall phenomenon and rain attenuation on 38 GHz terrestrial links at South Korea in 1998 is presented. It was one of the most severe rainfall years at the measured region due to increased EI Nino signal. The rainfall rate exceeded at $0.01\%$ was 97.4 mm/h during a worst month and annual rate was 63.5 mm/h. Experimentally measured results have been compared with some models and found that the rain attenuation by system level was underestimated by the existing prediction models. As it was measured only three months, further study and measurement of rainfall and rain attenuation in this region are needed for stable millimeter-wave system operation at all times.

• Journal of the Korean Society of Marine Environment & Safety
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• v.7 no.1
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• pp.1-6
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• 2001

Recently, EI nino and La nina phenomena have known as a cause of the unusual weather and meterological disasters in the world. The meteorological disasters in Korea have mainly caused by typhoons. In this paper, we studied the relationship between EI Nino and La Nina phenomena and the number of typhoons which have affected on Korea using the long-term data for the period from 1940 to 1999 (60 years) in case of normal years, EI Nino years and La Nina years, the numbers of typhoons which have affected on Korea are 3.1/year, 2.7/year and 3.9/year respectively. The number of typhoons which have affected on Korea in La Nina years is more than those in EI Nino years and normal years The occurrence rate of typhoon in La Nina years is also higher than those in EI Nino years and normal years.

• Journal of the Korean earth science society
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• v.26 no.7
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• pp.706-713
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• 2005

Subsurface oceanic data (Z20; Depth of $20^{\circ}C$ isotherm and WWV; Warm Water Volume) from the tropical Pacific Ocean from 1980 to 2004 were utilized to examine upper ocean variations in relation to E1 Nino. Time series analysis using EOF, composite, and cross-correlation methods indicated that there are significant time delays between subsurface oceanic parameters and the Nino3.4 SST. It implied that Z20 and WWV would be more reliable predictors of El Nino events. Based on analyzed results, we also constructed neural network model to predict the Nino3.4 SST from 1996 to 2004. The forecasting skills for the model using WWV were statistically higher than that using the trade wind except for short range forecasting less than 3 months. This model greatly predicted SST than any other previous statistical model, especially at lead times of 5 to 8 months.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.695-702
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• 2009

This study includes spatial variations in the catch of billfishes in the Pacific Ocean and examines factors affecting interannual changes in the catch. Main billfish species caught by Korean tuna longline fishery were blue marlin and swordfish. A main fishing ground of the species was the tropical Pacific Ocean, while additional fishing ground of billfishes tended to be formed in the Pacific coast of Mexico in the El Nino periods. Further, the catch of billfishes was significantly related to CPUE (tons/average of the used hooks/vessel) in the entire Pacific Ocean as an index of stock abundance and equatorial SOI (EQSOI) as an index of El Nino event. Annual changes in the catch of billfishes in the Pacific Ocean could be regulated mainly by variations of stock abundance. In addition, increase of the density of billfishes in the tropical Pacific and additional formation of fishing ground by El Nino event possibly contribute to increase of the catch of billfishes in the Pacific Ocean. On the other hand, linear regression model may be more adequate in the analysis of relationships between fisheries data and indices made from using some environmental factors.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.403-411
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• 1995

The atmospheric responses to a Sea Surface Temperature Anomaly(SSTA) over the equatorial eastern Pacific Ocean have been investigated using the horizontally fine resolution model based on OSU 2-layer Atmospheric General Circulation Model(AGCM). The SSTAS daring the peak phase of 1982-83 El Nino have been applied to the model as the boundary conditions of the experiment. The model simulates the eastward movement of the rising branch of the Walker circulation. That is, the major features associated with the El Nino such as the increase of the precipitation rate over the center of the Pacific and decrease over the Indonesia, and the 500hPa geopotential height anomaly in the middle latitude are properly describes in the fine resolution model experiment. The model results indicate that this horizontally fine resolution UM can successfully simulate the ENSO anomalies and be more effectivelly used for the study of the climate and the climate changes.

• Journal of Climate Change Research
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• v.9 no.2
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• pp.171-179
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• 2018

The causal relationship between El Nino-Southern Oscillation (ENSO) and winter climate variability in Korea is tested by analyzing Korea Meteorological Administration Automatic Synoptic Observing System datasets for the past 59 years. Consistent with previous studies, positive phase of ENSO (El Nino) tends to cause warmer temperature and heavier precipitation in Korea in early winter with three-week lead time. This causality is quantified by performing Granger causality test. It turns out that ENSO explains an additional 9.25% of the variance of early-winter temperature anomalies in Korea, beyond that already provided by temperature itself. Likewise, 22.18% additional information is gained to explain early-winter precipitation variance by considering ENSO. This result, which differs from simple lead-lag correlation analysis, suggests that ENSO needs to be considered in predicting early-winter surface climate variability in Korea.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.3 s.14
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• pp.33-41
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• 2004

The purpose of this study is to analyze the relationship between El Nino phenomena and the monthly rainfall variations of Seoul city which is composed of 30 year data during $1967{\sim}1996$. In this study, the monthly rainfall data at Seoul city is analyzed by applying an intervention model. As it is unavailable to get the data of El Nino phenomena, the point of intervention have been decided from the literature survey of the data observed to be the years of 1972, 1976, 1979, 1982, 1986 and 1991. As a results the El Nino was revealed more significant to the monthly rainfall at Seoul. In addition, monthly rainfall varied between the maximum 53.41mm and the minimum 2.50mm. To prevented future natural disaster, long term water planning and management is requied in consideration El $Nin\tilde{o}$.