북서태평양 태풍의 진로 및 강도 예측에서 선행 태풍과 근접 태풍의 영향

본 연구는 북서태평양에서 발생하는 태풍의 진로 및 강도 예측에서 선행 태풍과 근접 태풍이 미치는 영향에 대해 조사하였다. 이를 위해 Weather Research Forecasting(WRF) 대기모형과 Regional Ocean Model System(ROMS) 해양모형을 Message Passing Interface(MPI) II로 연결한 지역접합모형을 개발하였고, 접합모형의 민감도 연구를 통해 최적의 물리 모수화 방법을 선정한 후, 2개의 수치실험을 수행하였다. 첫 번째 실험은 태풍 빌리스(0604)의 강도 예측에서 선행 태풍 에위니아(0603)에 의한 해수면 냉각 효과가 미치는 영향을 조사하였고, 두 번째 실험은 태풍 곤파스(1007)의 진로 예측에서 근접 태풍 라이언락(1006)과 남테운(1008)의 보거싱 효과가 미치는 영향을 조사하였다. 수치실험을 분석한 결과, 첫 번째 실험에서는 선행 태풍 에위니아(0603)에 의해 상당한 표층 냉각이 발생한 지역을 통과한 태풍 빌리스(0604)가 냉각 효과를 고려하지 않은 실험에 비해 강도가 많이 줄어들어 강도 예측의 향상된 결과를 보였고, 두 번째 실험에서는 태풍 곤파스(1007)가 근접해 있던 태풍 라이언락(1006), 남테운(1008)과 함께 보거싱 효과가 고려된 대기 초기조건의 향상으로 진로 예측 오차가 감소했음을 보였다. 따라서 본 연구는 태풍 예측 향상을 위해서 선행 및 근접 태풍에 대한 고려가 필요함을 제시하였다.2

Climate changes and regional climate modeling for the seas around Korea

Regional climate model (RCM) is a vital tool for understanding changes in regional climate that is a good starting point for many socio-economic impact and adaptation considerations to climate changes. Despite their limitations including systematic errors in forcing fields given by global climate models, RCMs provide the most promising means of providing information on regional climate changes mainly through much higher resolution.In this talk, we will overview ocean climate changes in the North Pacific Ocean focusing on the seas around Korea. Then we will present biases and improvements in the ocean simulated from global climate models including CMIP5 (Coupled Model Intercomparison Project Phase 5) models. Finally regional climate modeling efforts for the seas around Korea will be discussed, focusing on added values and uncertainties of RCMs.stematic errors in forcing fields given by global climate models, RCMs provide the most promising means of providing information on regional climate changes mainly through much higher resolution.In this talk, we will overview ocean climate changes in the North Pacific Ocean focusing on the seas around Korea. Then we will present biases and improvements in the ocean simulated from global climate models including CMIP5 (Coupled Model Intercomparison Project Phase 5) models. Finally regional climate modeling efforts for the seas around Korea will be discussed, focusing on added values and uncertainties of RCMs.1

Ocean climate projection for the seas around Korea using a regional climate model

A linear trend of sea surface temperature (SST) for the seas around Korea shows different spatial distribution (Min and Kim, 2006). Most of global climate models, however, cannot resolve well the regional features of historical and future ocean climate change for the seas around Korea due to their coarse resolution. It has motivated us to develop a regional climate model for the western North Pacific including the marginal seas. We conducted a historical simulation as a baseline and a future climate projection simulation using Regional Ocean Modeling System (ROMS) with a horizontal resolution of 1/12°. For the future climate projection, the model was forced with the time-averaged difference fields of 2081-2100 RCP4.5 run and 1981-2000 historical run simulated with CanESM2 for CMIP5 and the difference fields were superimposed on the present climate represented by National Centers for Environmental Prediction (NCEP) and Simple Ocean Data Assimilation (SODA) reanalysis data. This is known as the Pseudo Global Warming (PGW) method developed by Kimura and Kitoh (2007). On the other hand, we also conducted a future climate projection simulation using an atmospheric model, Wether Research Forecasting (WRF) with a horizontal resolution of 50 km to investigate the high resolution effects of future surface forcing for the seas around Korea. The model simulated the historical time series of SST anomaly showing similar trends tcean climate change for the seas around Korea due to their coarse resolution. It has motivated us to develop a regional climate model for the western North Pacific including the marginal seas. We conducted a historical simulation as a baseline and a future climate projection simulation using Regional Ocean Modeling System (ROMS) with a horizontal resolution of 1/12°. For the future climate projection, the model was forced with the time-averaged difference fields of 2081-2100 RCP4.5 run and 1981-2000 historical run simulated with CanESM2 for CMIP5 and the difference fields were superimposed on the present climate represented by National Centers for Environmental Prediction (NCEP) and Simple Ocean Data Assimilation (SODA) reanalysis data. This is known as the Pseudo Global Warming (PGW) method developed by Kimura and Kitoh (2007). On the other hand, we also conducted a future climate projection simulation using an atmospheric model, Wether Research Forecasting (WRF) with a horizontal resolution of 50 km to investigate the high resolution effects of future surface forcing for the seas around Korea. The model simulated the historical time series of SST anomaly showing similar trends t2

접합자(Model Coupling Toolkit)를 이용한 해양-대기 접합모형 구축

해양연구에 있어 해양단독모형에 대한 개발과 적용은 활발히 진행되었으나, 접합모형은 태풍과 같은 특정현상에 국한 되었고, 단기예측에 초점이 있었다. 지역해를 모사하기 위해 해양모형을 단독으로 실행하는 경우, 경계값(바람, 표층열속, 수온, 염분, 유속 등)을 기존자료로부터 받아야 한다. 그러나 해양단독모형은 대기모형과 상호작용을 고려하지 못 하므로, 이를 고려하기 위해서는 해양-대기 접합모형을 이용하여야 한다. 본 연구에서는 해양모형(Regional Ocean Modeling System)과 대기모형(Weather Research and Forecasting Model)을 접합자인 MCT(Model Coupling Toolkit)를 이용하여 접합하였고 접합에 따른 기술적인 문제를 분석하고 개선을 시도하였다. 접합모형은 병렬 처리 시, CPU에 작업구간을 할당하기 위해 도메인을 나누는 작업을 한다. 만약 도메인이 나누어 떨어지지 않는다면, 분할 도메인의 크기가 일정하지 않으므로 크기가 다른 도메인에 대한 추가 계산이 요구된다. 개선된 접합모형에서는 분할 도메인의 크기를 일정하게 하여, 크기가 다른 도메인에 대한 불필요한 계산 줄임으로써 접합모형의 성능을 개선할 수 있었다. 또한 접합 코드에서 자료를 교환하기 전에 필요한 모든 작업을 하고, 자료 교환 후에 받은 자료를 모형에 적용하는 코드를 개발하였다. 이 코드를 적용한 결과, 접합모형에서 자료교환 시 발생하는 대기시간이 줄었다. 위 두 가지 내용을 적용한 접합모형을 실제 해양 모사연구에 적용한다면, 한정된 자원으로 효율적인 모사와 예측이 가능할 것이다. 유속 등)을 기존자료로부터 받아야 한다. 그러나 해양단독모형은 대기모형과 상호작용을 고려하지 못 하므로, 이를 고려하기 위해서는 해양-대기 접합모형을 이용하여야 한다. 본 연구에서는 해양모형(Regional Ocean Modeling System)과 대기모형(Weather Research and Forecasting Model)을 접합자인 MCT(Model Coupling Toolkit)를 이용하여 접합하였고 접합에 따른 기술적인 문제를 분석하고 개선을 시도하였다. 접합모형은 병렬 처리 시, CPU에 작업구간을 할당하기 위해 도메인을 나누는 작업을 한다. 만약 도메인이 나누어 떨어지지 않는다면, 분할 도메인의 크기가 일정하지 않으므로 크기가 다른 도메인에 대한 추가 계산이 요구된다. 개선된 접합모형에서는 분할 도메인의 크기를 일정하게 하여, 크기가 다른 도메인에 대한 불필요한 &2

Effect of preceding and adjacent typhoons on the intensity and track prediction of typhoon in the western North Pacific

This study investigates the impact of preceding and adjacent typhoons on the track and intensity prediction of a typhoon in western North Pacific. For this, we developed a regional coupled model(WRF+ROMS) using a MPI(Message Passing Interface) II coupler. After determining optimal physical parameterizations of WRF based on sensitivity tests, we conducted two numerical experiments: one is to examine the sea surface cooling effect of a preceding typhoon, Ewiniar(0603), on the intensity prediction of typhoon Bilis(0604) and the other is to examine the bogussing effect for adjacent typhoons, Namtheun(1008) and Lionrock(1006), on the track prediction of Kompasu(1007). The results show that the intensity of Bilis(0604), passed over the region where a significant surface cooling occurred by the preceding typhoon Ewiniar (0603), was greatly reduced, compared to the experiment without considering the cooling effect, resulting in the improvement of intensity prediction. For the track prediction of Kompasu(1007), additional consideration of a bogussing scheme to adjacent typhoons reduced the track errors, mainly due to an improvement of initial condition. These results suggest that for not only the targeted typhoon but also the preceding and adjunct typhoons, accurate simulations of oceanic and atmospheric conditions are required for the improvement of typhoon prediction.1

An Effect of Nutrient Transport through Korea Strait on the East Sea Ecosystem: A Biological-Physical Couple Modeling

The Tsushima Warm Current plays a role of transporting not only water mass but also materials including nutrients to the East Sea through the Korea Strait. This study aims to examine an effect of the nutrient transport through the Korea Strait on the East Sea ecosystem. For this study, we used a four-component low trophic biological model coupled with a physical model due to lack of in-situ observational data. Numerical experiments were conducted with three different open boundary conditions of nutrient flux through the Korea Strait: zero, a constant, and a seasonally varying value. When zero nutrient flux was given, both spring and fall blooms were not evident in most of southern basin. With the constant and the seasonally varying nutrient fluxes, the simulated chlorophyll-a showed the observed temporal and spatial distributions. Interestingly, the results from these two boundary conditions seemed to be similar to each other indicating that the distributions of chlorophyll-a are less sensitive to the variation of nutrient flux if the flux is non-zero. These results suggest that the nutrient flux through the Korea Strait may contribute to the primary productivity in the southern East Sea.ait on the East Sea ecosystem. For this study, we used a four-component low trophic biological model coupled with a physical model due to lack of in-situ observational data. Numerical experiments were conducted with three different open boundary conditions of nutrient flux through the Korea Strait: zero, a constant, and a seasonally varying value. When zero nutrient flux was given, both spring and fall blooms were not evident in most of southern basin. With the constant and the seasonally varying nutrient fluxes, the simulated chlorophyll-a showed the observed temporal and spatial distributions. Interestingly, the results from these two boundary conditions seemed to be similar to each other indicating that the distributions of chlorophyll-a are less sensitive to the variation of nutrient flux if the flux is non-zero. These results suggest that the nutrient flux through the Korea Strait may contribute to the primary productivity in the southern East Sea.2

A development of regional climate model for western north pacifi: Assessment of a present ocean climate simulation

Recent study based on satellite and Korea Oceanographic Data Center (KODC) observations conducted over the eastern coast of Korea shows the linear trend of 10m ocean temperature during 1961-2007 years is negative in coastal areas, in contrast with positive trend offshore (Park et al., 2010). However, simulating and predicting climate variability from GCMs is difficult due to too coarse resolution of approximately 100-200 km to resolve the complex air-sea interaction system in marginal and coastal areas. The regional climate models (RCMs) have been used to downscale the GCMs output to obtain high-resolution results. Therefore, we focused on a developed regional ocean climate model using Regional Ocean Modeling System (ROMS) to study interannual variation of ocean property of present climate for the western North Pacific marginal seas.st with positive trend offshore (Park et al., 2010). However, simulating and predicting climate variability from GCMs is difficult due to too coarse resolution of approximately 100-200 km to resolve the complex air-sea interaction system in marginal and coastal areas. The regional climate models (RCMs) have been used to downscale the GCMs output to obtain high-resolution results. Therefore, we focused on a developed regional ocean climate model using Regional Ocean Modeling System (ROMS) to study interannual variation of ocean property of present climate for the western North Pacific marginal seas.1

Development of a regional climate model for ocean climate projection in the seas around Korea

A linear trend of sea surface temperature (SST) for the seas around Korea shows different spatial distribution (Min and Kim, 2006). Most of global climate models, however, cannot resolve well the regional features of historical and future ocean climate change for the seas around Korea due to their coarse resolution. It has motivated us to develop a regional climate model for the western North Pacific including the marginal seas. We conducted a historical simulation as a baseline and a future climate projection simulation using Regional Ocean Modeling System (ROMS) with a horizontal resolution of 1/12°. For the future climate projection, the model was forced with the time-averaged difference fields of 2081-2100 RCP4.5 run and 1981-2000 historical run simulated with CanESM2 for CMIP5 and the difference fields were superimposed on the present climate represented by National Centers for Environmental Prediction (NCEP) and Simple Ocean Data Assimilation (SODA) reanalysis data. This is known as the Pseudo Global Warming (PGW) method developed by Kimura and Kitoh (2007). The model simulated the historical time series of SST anomaly showing similar trends to the observed time series for the seas around Korea. It also showed a similar pattern in the spatial distribution of mixed layer depth to the climatology of de Boyer Montegut (2004) except for the northern East Sea. The volume transport along the Korea Strait simulated wcean climate change for the seas around Korea due to their coarse resolution. It has motivated us to develop a regional climate model for the western North Pacific including the marginal seas. We conducted a historical simulation as a baseline and a future climate projection simulation using Regional Ocean Modeling System (ROMS) with a horizontal resolution of 1/12°. For the future climate projection, the model was forced with the time-averaged difference fields of 2081-2100 RCP4.5 run and 1981-2000 historical run simulated with CanESM2 for CMIP5 and the difference fields were superimposed on the present climate represented by National Centers for Environmental Prediction (NCEP) and Simple Ocean Data Assimilation (SODA) reanalysis data. This is known as the Pseudo Global Warming (PGW) method developed by Kimura and Kitoh (2007). The model simulated the historical time series of SST anomaly showing similar trends to the observed time series for the seas around Korea. It also showed a similar pattern in the spatial distribution of mixed layer depth to the climatology of de Boyer Montegut (2004) except for the northern East Sea. The volume transport along the Korea Strait simulated w2

Effects of nutrient transport through the Korea Strait on the seasonal and interannual variability in the East Sea (Japan Sea) ecosystem

The nutrients supplied through the Korea Strait (KS) have been believed to have negligible effects on the nutrient budget and biological productivity of the southern East Sea (Japan Sea). However, recent studies based on observations suggest that large amounts of dissolved inorganic nitrogen and phosphorus, comparable to the levels in the Changjiang water and the Taiwan Strait, are transported through the eastern channel of the KS, with considerable interannual variation. This study aims to examine the effects of nutrient transport through the KS on the seasonal and interannual variability of the southern East Sea ecosystem. By using a four-compartment NPZD model coupled with a 3D physical model, three numerical experiments were conducted with different lateral boundary conditions of nutrient flux through the KS. The results suggest that the nutrient flux through the KS may contribute to primary productivity in the southern East Sea. The magnitude of phytoplankton blooms is also influenced by this nutrient transport. We discuss the direct or indirect contribution of the nutrient flux through KS to the primary productivity of the southern East Sea.t that large amounts of dissolved inorganic nitrogen and phosphorus, comparable to the levels in the Changjiang water and the Taiwan Strait, are transported through the eastern channel of the KS, with considerable interannual variation. This study aims to examine the effects of nutrient transport through the KS on the seasonal and interannual variability of the southern East Sea ecosystem. By using a four-compartment NPZD model coupled with a 3D physical model, three numerical experiments were conducted with different lateral boundary conditions of nutrient flux through the KS. The results suggest that the nutrient flux through the KS may contribute to primary productivity in the southern East Sea. The magnitude of phytoplankton blooms is also influenced by this nutrient transport. We discuss the direct or indirect contribution of the nutrient flux through KS to the primary productivity of the southern East Sea.1

Simulating of East Sea (Japan Sea) Ecosystem using a three-dimensional biological-physical model

3차원 해양순환 모형인 Regional Ocean Model System (ROMS)에 4개의 생태변수 (질산염 (nitrate: N), 식물플랑크톤 (phytoplankton: P), 동물플랑크톤 (zooplankton: Z), 유기쇄설물 (detritus: D))로 구성된 하위영양단계 생태계 모형을 접합하여 동해 생태계 모사를 시도하였다. 초기 N P, Z, D는 동해 전 해역에 균일하게 주었고, 표층 및 개방경계를 통한 NPZD 유입이 없다. ROMS 단독 모형에 동해 1월 평균장을 주고 대기 기후자료를 이용하여 10년 spin-up한 결과를 접합 모형의 성분 모형인 ROMS의 초기장으로 이용하였고, 대기강제력은 대기 기후자료를 이용하였다. 접합모형을 이용하여 10년 적분한 결과, 플랑크톤 봄 번성을 비롯한 N, P, Z, D 계절 변화, Subsurface Chlorophyll Maximum (SCM) 층이 연안에서 외해로 갈수로 깊어지는 현상 등이 잘 재현되었다. 하지만 동해 남쪽 상층 해역에서 N, P, Z, D 값이 낮게 모사되었는데, 이는 접합모형의 해상도가 충분하지 않아 연안용승, 중규모 에디 등이 잘 모사되지 않아 저층에서 상층으로 영양염 공급이 원활하게 재현되지 못한 점에서 비롯된 것으로 사료된다.생태계 모사를 시도하였다. 초기 N P, Z, D는 동해 전 해역에 균일하게 주었고, 표층 및 개방경계를 통한 NPZD 유입이 없다. ROMS 단독 모형에 동해 1월 평균장을 주고 대기 기후자료를 이용하여 10년 spin-up한 결과를 접합 모형의 성분 모형인 ROMS의 초기장으로 이용하였고, 대기강제력은 대기 기후자료를 이용하였다. 접합모형을 이용하여 10년 적분한 결과, 플랑크톤 봄 번성을 비롯한 N, P, Z, D 계절 변화, Subsurface Chlorophyll Maximum (SCM) 층이 연안에서 외해로 갈수로 깊어지는 현상 등이 잘 재현되었다. 하지만 동해 남쪽 상층 해역에서 N, P, Z, D 값이 낮게 모사되었는데, 이는 접합모형의 해상도가 충분하지 않아 연안용승, 중규모 에디 등이 잘 모사되지 않아 저층에서 상층으로 영양염 공급이 원활하게 재현되지 못한 점에서 비롯된 것으로 사료된다.2