• 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.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.309-313
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• 2008

본 논문의 목적은 ENSO의 영향에 의한 우리나라 강우의 특성을 분석하는 것이다. 따라서 우리나라 기상관측소의 강우량 자료를 Warm(El Nino), Cold(La Nina), Normal 에피소드에 따라 기간별로 분류하였다. 또한 이렇게 분류한 자료는 Markov Chain 모형을 이용하여 100년의 자료로 모의 발생하였고 에피소드별로 빈도분석을 실시하였다. 빈도분석 결과 에피소드에 따라 각 기상관측소별로 강우의 크기에 영향을 미치고 있음을 알 수 있었다. 또한 군집분석을 실시하여 각 에피소드의 공간적인 영향에 대해서 분석하였다. 결과적으로 Warm(El Nino), Cold(La Nina) and Normal 에피소드로 대표되는 ENSO는 우리나라의 강우특성에 크게 영향을 미치는 것으로 파악되었다.

• Atmosphere
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• v.29 no.5
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• pp.627-637
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• 2019

Severe and long-lasting heat waves over Korea and many regions in the Northern Hemisphere (NH) during the 2016 summer, have been attributed to global warming and atmospheric teleconnection coupled with tropical convective activities. Yet, what controls subseasonsal time scale of heat wave has not been well addressed. Here we show a critical role of two dominant boreal summer intraseasonal oscillation (BSISO) modes, denominated as BSISO1 and BSISO2, on modulating temporal structure of heat waves in the midst of similar climate background. The 2016 summer was characterized by La Nina development following decay of strong 2015/2016 El Nino. The NH circumglobal teleconnection pattern (CGT) and associated high temperature anomalies and heat waves were largely driven by convective activity over northwest India and Pakistan during summer associated with La Nina development. However, the heat wave event in Korea from late July to late August was accompanied by the phase 7~8 of 30~60-day BSISO1 characterized by convective activity over the South China Sea and Western North Pacific and anticyclonic circulation (AC) anomaly over East Asia. Although the 2010 summer had very similar climate anomalies as the 2016 summer with La Nina development and CGT, short-lasting but frequent heat waves were occurred during August associated with the phase 1~2 of 10~30-day BSISO2 characterized by convective activity over the Philippine and South China Sea and AC anomaly over East Asia. This study has an implication on importance of BSISO for better understanding mechanism and temporal structure of heat waves in Korea.

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.146.2-146
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• 1999

No Abstract, See Full Text

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.5
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• pp.703-715
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• 2015

One of the challenges to increase milk production in a large pasture-based herd with an automatic milking system (AMS) is to grow forages within a 1- km radius, as increases in walking distance increases milking interval and reduces yield. The main objective of this study was to explore sustainable forage option technologies that can supply high amount of grazeable forages for AMS herds using the Agricultural Production Systems Simulator (APSIM) model. Three different basic simulation scenarios (with irrigation) were carried out using forage crops (namely maize, soybean and sorghum) for the spring-summer period. Subsequent crops in the three scenarios were forage rape over-sown with ryegrass. Each individual simulation was run using actual climatic records for the period from 1900 to 2010. Simulated highest forage yields in maize, soybean and sorghum- (each followed by forage rape-ryegrass) based rotations were 28.2, 22.9, and 19.3 t dry matter/ha, respectively. The simulations suggested that the irrigation requirement could increase by up to 18%, 16%, and 17% respectively in those rotations in El-Nino years compared to neutral years. On the other hand, irrigation requirement could increase by up to 25%, 23%, and 32% in maize, soybean and sorghum based rotations in El-Nino years compared to La-Nina years. However, irrigation requirement could decrease by up to 8%, 7%, and 13% in maize, soybean and sorghum based rotations in La-Nina years compared to neutral years. The major implication of this study is that APSIM models have potentials in devising preferred forage options to maximise grazeable forage yield which may create the opportunity to grow more forage in small areas around the AMS which in turn will minimise walking distance and milking interval and thus increase milk production. Our analyses also suggest that simulation analysis may provide decision support during climatic uncertainty.

• Journal of Korea Water Resources Association
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• v.33 no.S1
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• pp.327-332
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• 2000

최근 세계 각지에서는 엘리뇨 및 라니냐에 의한 기상변동에 의하여 막대한 인적, 경제적인 직간접적인 피해를 경험하여 왔다. 우리 나라의 기상에도 엘리뇨/라니냐의 영향이 시공간적으로 유의함이 최근 밝혀지고 있으며, 그에 따르는 엘리뇨/라니냐에 의한 영향의 정량적인 고려가 전국적인 수자원 장기 정책 및 관리에 필요함이 인식되어 왔다. 기상 이변 형상은 이미 실존의 현실이며, 이 중 엘리뇨/라니냐의 영향 또한 그러하다고 할 수 있다. 특히, 21세기는 물부족 및 물에 의한 재해의 가능성이 점차 증가될 것이라는 막연한 추측속에서 우리는 살고 있으나 실제적인 대책 및 연구에의 투자는 인색한 형편이다. 막상 닥쳤을 때만의, 당장의 아우성보다는 기초적인 바탕에서부터의 성실하고 결실을 맺을 수 있는 지속적인 연구가 수행되어야 한다. 왜냐하면, 미래는 현재의 연속이기 때문이다. 또한, 이의 연구는 기상, 수문, 수자원, 농업, 경제를 비롯한 여러 분야에서 다각적이고 연계적으로 이루어져야지 일방의 짧은 지식만으로 이루어 질 수는 없다. 본 연구에서는 엘리뇨/라니냐 영향 지수 산정 기법을 개발하고, 이를 이용하여 우리 나라에의 수자원에의 영향을 시공간적으로 정의하는데, 그 목적이 있다. 엘리뇨/라니냐 영향을 정의하기 위한 기법은 물리적인 기법과 통계적인 기법으로 크게 나뉠 수 있으나, 본 연구에서는 간략한 통게적인 기법을 이용하여 지수를 개발하였다. 이 지수는 엘리뇨/라니냐의 발생 강도뿐만 아니라 빈도를 동시에 고려할 수 있도록 하였다. 개발된 엘리뇨/라니냐의 영향 지수를 우선 우리나라 전역의 강수 기상 관측망 자료에 적용하였으며, 산정된 지수들을 공간적으로 Kriging 기법을 사용하여 공간 분포도(영향 지수도)를 작성하여 지역적인 영향 정도를 가시적으로 정의하였다.

• Journal of Environmental Science International
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• v.27 no.3
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• pp.203-217
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• 2018

For this study, WRF numerical modeling was performed, using RDAPS information for input data on typhoons affecting the Korean peninsula to produce wind data of 700hPa. RAM numerical modeling was also used to calculate 3-second gusts as the extreme wind speed. After comparing wind speeds at an altitude of 10 m to evaluate the feasibility of WRF numerical modeling, modeled values were found to be similar with measured ones, reflecting change tendencies well. Therefore, the WRF numerical modeling results were verified. As a result of comparing and analyzing these wind speeds, as calculated through RAM numerical modeling, to evaluate applicability for disaster preparedness, change tendencies were observed to be similar between modeled and measured values. In particular, modeled values were slightly higher than measured ones, indicating applicability for the prevention of possible damage due to gales. Our analysis of 3-second gusts during the study period showed a high distribution of 3-second gusts in the southeast region of the Korean peninsula from 2002-2006. The frequency of 3-second gusts increased in the central north region of Korea as time progressed. Our analysis on the characteristics of 3-second gusts during years characterized by El $Ni{\tilde{n}}o$ or La Nina showed greater strength during hurricanes that affected the Korean peninsula in El $Ni{\tilde{n}}o$ years.

• 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.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.3
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• pp.170-177
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• 2007

In this study, the long-term predictability of El Nino and La Nina events of Pusan National University Coupled General Circulation Model(PNU/CME CGCM) developed from a Research and Development Grant funded by Korea Meteorology Administration(KMA) was examined in terms of the correlation coefficients of the sea surface temperature between the model and observation and skill scores at the tropical Pacific. For the purpose, long-term global climate was hindcasted using PNU/CME CGCM for 12 months starting from April, July, October and January(APR RUN, JUL RUN, OCT RUN and JAN RUN, respectively) of each and every years between 1979 and 2004. Each 12-month hindcast consisted of 5 ensemble members. Relatively high correlation was maintained throughout the 12-month lead hindcasts at the equatorial Pacific for the four RUNs starting at different months. It is found that the predictability of our CGCM in forecasting equatorial SST anomalies is more pronounced within 6-month of lead time, in particular. For the assessment of model capability in predicting El Nino and La Nina, various skill scores such as Hit rates and False Alarm rate are calculated. According to the results, PNU/CME CGCM has a good predictability in forecasting warm and cold events, in spite of relatively poor capability in predicting normal state of equatorial Pacific. The predictability of our CGCM was also compared with those of other CGCMs participating DEMETER project. The comparative analysis also illustrated that our CGCM has reasonable long-term predictability comparable to the DEMETER participating CGCMs. As a conclusion, PNU/CME CGCM can predict El Nino and La Nina events at least 12 months ahead in terms of NIino 3.4 SST anomaly, showing much better predictability within 6-month of leading time.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.1
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• pp.24-37
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• 2001

Physical and chemical properties of the northest Equatorial Pacific between 5° and 12° N along 131.5 °W wore investigated in association with changes in water column structures during the summer seasons of 1998 and 1999. Climatic disturbances such as El Nino and La Nina, should have affected this area during the study Period. In 1998, a thermocline where temperature rapidly decrease with depth, was formed at 90～110 m water depth. Nutrient depicting areas, specially for nitrate+nitrite and phosphate, or oligotrophic regions were extended down to approximately 100 m depth, which coincided with the surface mixed layer depth. However, in 1999, a very fluctuating thermocline was observed with latitudes. As a result of changes in the water column structures, nutrient concentrations also showed fluctuation parallel to the changes in other physical parameters. In the photic zone, depth integrated nitrogen and phosphorus values were 34 gN/m², 7 gP/m² in 1998 and 130 gN/m², 18 gP/m² in 1999, respectively. The results indicated that nitrogen (96 gN/m²) and phosphorus (11 gP/m²) are supported by up-welling and down-welling phenomena with convergence and divergence in the study area.