Seasonal variability of the Northwestern Pacific Marginal Seas. Part I. Physical model simulation results

In this study, we applied the 3-dimensional POLCOMS ocean circulation model for the coupling with the ERSEM biogeochemical model as an initial attempt for the coupled simulation in the northwestern Pacific marginal seas. The model domain covers the whole marginal seas in the northwestern Pacific as well as the Kuroshio and Oyashio mainstream which are the major influencing boundary currents in the area. The seasonal cycle of physical variables are extracted from the 10 year (1992-2001) simulation results discarding the first 3 years of model run. The surface temperature seasonal cycle is well simulated in all the marginal seas but the skill score of the surface salinity in the northern Okhotsk Sea and the Chinese coastal region was not good enough. And to evaluate the tide simulation performance, four tidal constituents (M2, S2, O1, K1) in the coastal tidal stations except for the Okhotsk Sea have been compared with the model results. It is shown that the general performance is reasonable. It is encouraging that the volume transports in the major straits and their seasonal variation is simulated well as well as the Kuroshio.overs the whole marginal seas in the northwestern Pacific as well as the Kuroshio and Oyashio mainstream which are the major influencing boundary currents in the area. The seasonal cycle of physical variables are extracted from the 10 year (1992-2001) simulation results discarding the first 3 years of model run. The surface temperature seasonal cycle is well simulated in all the marginal seas but the skill score of the surface salinity in the northern Okhotsk Sea and the Chinese coastal region was not good enough. And to evaluate the tide simulation performance, four tidal constituents (M2, S2, O1, K1) in the coastal tidal stations except for the Okhotsk Sea have been compared with the model results. It is shown that the general performance is reasonable. It is encouraging that the volume transports in the major straits and their seasonal variation is simulated well as well as the Kuroshio.1

Analytical models for the co-oscillating tide in the Yellow Sea with forced radiation condition

TRUETRU

Application of a coupled physic-biogeochemical model into the Northwestern Pacific

In this study, a coupled 3D physico-biogeochemical model based on the POLCOMS and theERSEM models has been applied on the Northwestern pacific. The model grid is 1/10° horizontalresolution on a regular latitude-longitude and has 40 s-coordinate levels in the vertical. The model has been completed the past 10 years simulation from 1992 to 2001 after 3years spin-up. We try to validate for physical and ecological variables. The total volume transport through the Korea Strait, the Tsugaru Strait and the Soya Strait are calculated and the correlation coefficients of tidal amplitude between the observation and simulation are also calculated. And in biogeochemical model, nutrients such as nitrate, phosphate and silicate are compared with the WOA09(World Ocean Atlas 2009) and chlorophyll-a is compared with SeaWiFS satellite data. Also, as a measure of the model capability to catch seasonal change, we calculate the square of correlation coefficient(R2) and the average Cost Function(CF) using monthly climatology data for the temperature, salinity, nutrients and chlorophylla. In addition, numerical results are compared with the in-situ data carried out by the KIOST at st. M(129.098E, 34.790N) during 6 years. According to these validations, both models generally look reasonable. However, the model still has several problems like high chlorophyll-a concentration in winter at the East China Sea and southern East Sea and high oordinate levels in the vertical. The model has been completed the past 10 years simulation from 1992 to 2001 after 3years spin-up. We try to validate for physical and ecological variables. The total volume transport through the Korea Strait, the Tsugaru Strait and the Soya Strait are calculated and the correlation coefficients of tidal amplitude between the observation and simulation are also calculated. And in biogeochemical model, nutrients such as nitrate, phosphate and silicate are compared with the WOA09(World Ocean Atlas 2009) and chlorophyll-a is compared with SeaWiFS satellite data. Also, as a measure of the model capability to catch seasonal change, we calculate the square of correlation coefficient(R2) and the average Cost Function(CF) using monthly climatology data for the temperature, salinity, nutrients and chlorophylla. In addition, numerical results are compared with the in-situ data carried out by the KIOST at st. M(129.098E, 34.790N) during 6 years. According to these validations, both models generally look reasonable. However, the model still has several problems like high chlorophyll-a concentration in winter at the East China Sea and southern East Sea and high1

Optimal sapwning area of a bivalve, Saxidomus purpuratus for resource enhansement found by a physical model (ESCORT)

2

A preliminary study on the tidal effects on the Yellow Sea Bottom Cold Water and its ecosystem using a physics-ecosystem coupled model

A physics-ecosystem coupled model was developed to study the marine ecosystem around the Korean Peninsula. The physical module of the model uses a finite difference grid in the horizontal coordinates (C-grid) and a hybrid σ-z grid in the vertical coordinate to describe realistically the shallow and mild slope topography along with the deep and steep slope topography. The ecosystem module, which is based on the Ecological Regional Ocean Model (ERGOM) of Neumann (2000), is composed of ten variables, that is, three nutrient types (nitrates, ammonia and phosphates), three phytoplankton functional groups (diatoms, flagellates and blue-green algae), two zooplankton group (micro- and meso-zooplankton), detritus and dissolved oxygen, and it also comprises bottom detrital sediment. Tidal effects on the behavior of the Yellow Sea Bottom Cold Water (YSBCW) were tested using the developed model. In the normal experiment including tide, YSBCW is located in the central area of the Yellow Sea. In the case of the circulation experiment excluding tide, however, YSBCW is moved to the east side of the Yellow Sea, and the stratification in the latter case is weaker than in the former. The responses of ecosystem variables in the YSBCW were also investigated and will be discussed for the two cases.ertical coordinate to describe realistically the shallow and mild slope topography along with the deep and steep slope topography. The ecosystem module, which is based on the Ecological Regional Ocean Model (ERGOM) of Neumann (2000), is composed of ten variables, that is, three nutrient types (nitrates, ammonia and phosphates), three phytoplankton functional groups (diatoms, flagellates and blue-green algae), two zooplankton group (micro- and meso-zooplankton), detritus and dissolved oxygen, and it also comprises bottom detrital sediment. Tidal effects on the behavior of the Yellow Sea Bottom Cold Water (YSBCW) were tested using the developed model. In the normal experiment including tide, YSBCW is located in the central area of the Yellow Sea. In the case of the circulation experiment excluding tide, however, YSBCW is moved to the east side of the Yellow Sea, and the stratification in the latter case is weaker than in the former. The responses of ecosystem variables in the YSBCW were also investigated and will be discussed for the two cases.1

천수만 방조제 건설로 인한 조석현상 변화

22othe

Spring chlorophyll changes in relation with mixed layer variability in the East Sea (Japan Sea)

Year-to-year variability of chlorouhyll-a (Chl-a) in the East Sea and its relation with mixed layer depth (MLD) changes are investigated by using Chl-a concentration data estimated from satellite (SeaWiFS and MODIS) measurement. MLD was calculated from 1/12° Global HYbrid Coordinate Ocean Model (HYCOM) for the period (2004&#8722 2010). In 2008, spring CHL-a concentration in the Ulleung Basin reaches its maximum. This anomalous bloom can be attributed to relatively deep winter mixed layer that can entrain more nutrients into the upper ocean. Comparison of MLD with surface atmospheric forcing (wind and surface heat flux) suggests that the deep MLD was probably caused by a strong wind due to a strengthened Siberian high and Aleutian low, and the associated intensified surface cooling. On the other hand, spring CHL-a concentration in 2004 was not increased although the winter MLD was considerably deep. A deeper spring MLD in 2004 than normal years appears to contribute to an unfavorable light condition for spring bloom, thus resulting in the relatively low Chl-a concentration. Our finding suggests that, in addition to winter MLD, spring MLD also plays a crucial role in interannual variability of CHL-a in the East Sea. The low correlation between Asian dust and CHL-a concentrations suggest that Asian dusts did not likely influence on the 2008 spring bloom in the East Sea.culated from 1/12° Global HYbrid Coordinate Ocean Model (HYCOM) for the period (2004&#8722 2010). In 2008, spring CHL-a concentration in the Ulleung Basin reaches its maximum. This anomalous bloom can be attributed to relatively deep winter mixed layer that can entrain more nutrients into the upper ocean. Comparison of MLD with surface atmospheric forcing (wind and surface heat flux) suggests that the deep MLD was probably caused by a strong wind due to a strengthened Siberian high and Aleutian low, and the associated intensified surface cooling. On the other hand, spring CHL-a concentration in 2004 was not increased although the winter MLD was considerably deep. A deeper spring MLD in 2004 than normal years appears to contribute to an unfavorable light condition for spring bloom, thus resulting in the relatively low Chl-a concentration. Our finding suggests that, in addition to winter MLD, spring MLD also plays a crucial role in interannual variability of CHL-a in the East Sea. The low correlation between Asian dust and CHL-a concentrations suggest that Asian dusts did not likely influence on the 2008 spring bloom in the East Sea.1

East Asian Marginal Sea modeling for the climate change projection

2007년 정부간 기후변화협의체가 발표한 \\'온실가스 배출 시나리오에 따른 4차 보고서\\'(IPCC, 2007)의 결과에 의하면, 지금까지의 기후 변화는 주로 인류 기원의 온실 가스 증가에 의해서 진행되어 왔으며, 지구 온난화는 더 이상 가설이 아닌 불편한 사실임을 강조하고 있다. 더욱이 전지구 평균 변화에 대한 지역 기후 변화 추세의 편차가 매우 크게 나타나고, 우리나라가 위치한 동아시아 지역은 상대적으로 높은 편차 지역으로 분류되기 때문에, 보다 자세한 우리 주변 해역의 장기 전망에 관한 연구가 필요하다. 본 연구에서는 우리나라 인근 해역을 포함하는 동아시아 지역해의 기후변화에 따른 변화를 고찰하기 위한 하나의 방안으로서, 전구 해양 모델과 이에 연계된 지역해 둥지 모델이 연계된 동아시아 지역해 기후 전망 방법을 소개하고, A1B 시나리오에 따른 결과를 분석하였다. 전구 해양 순환 모델 및 동아시아 지역해 해양 모델은 모두 HYbrid Coordinate Ocean Model (HYCOM)을 기반으로 하고 있으며, 전구에서 지역해로의 단방향 둥지 체계를 사용하였다. 전구 해양 모델은 북극을 포함하여 남위 80 °S 까지를 망라하고 있으며, 80 °S ～ 65 °N 까지는 경도방향으로 1.5°, 위도 방향으로는 적도해역에서 1/3°, 온대 해역에서 1° 정도로 변하는 가변 격자 체계를 사용하였다. 북위 65°N 이상에서는 북극점을 가상의 두 지점으로 옮겨 보다 고해상도의 북극해를 재현할 수 있도록 하는 Arctic bipolar patch 격자를 구성하여 추가였으며, 단순한 열역학 해빙 모델도 포함하였다. 동아시아 지역해 순환 모델의 영역은 1/4도 격자 체계로 10°N ～ 65°N, 105°E ～ 171°E 범위의 것과 1/12도 격자 체계로 이보다 작은 영역인 115°E ～ 150°E, 15°N ～ 52°N의 두 가지 버전을 수립하였다. 이러한 모델 체계를 이용하여, IPCC A1B 시나리오에 따른 GFDL CM2.1 대기 모델 결과를 외력으로 하여, 전구 해양 순환 모델을 구동하고, 이로부터 동아시아 지역해 둥지 모델의 개방 경계 조건과 표층 경계 조건을 부여하고 적분한 결과를 분석하였다.2

The relations of the nutrients and chlorophyll-a variabilities with warm eddy around Dokdo.

독도주변해역에서는 중규모 난수소용돌이가 빈번하게 출현하며 지역적인 하위생태계 환경에 영향을 미칠 수 있다. 본 연구에서는 독도주변해역에서의 난수소용돌이 영향정도에 따른 영얌염과 엽록소a의 분포 특성을 살펴보기 위해서 3차원 해양순환2

수치모형 결과로 본 제주난류 수송량의 계절 및 경년 변동성

제주난류는 제주도를 남쪽에서부터 시계방향으로 돌아 제주해협을 서에서 동으로 통과하는 해류로서 동중국해와 황해 그리고 남해의 연결통로에 있어 쿠로시오 해류의 변동성과 계절풍, 조석, 장강 유출량 및 태양복사에너지 등의 변화에 따라 그 변동성이 매우 클 것으로 예상된다. 본 연구에서는 물리-생지화학 결합 모형을 이용하여 30년 (1981∼2010) 동안 수치 적분한 결과로부터 모형에서 계산된 제주난류 수송량의 계절 및 경년 변동성을 고찰하였다. 제주난류의 30년 월평균 수송량은 0.31 ± 0.07 Sv (106 m3/s) 으로 나타났으며, 2월에 0.21 ± 0.05 Sv 으로 가장 작고, 8월에 0.45 ± 0.10 Sv 으로 가장 크게 나타났다. 여름철에 크고 겨울철에 작은 제주난류의 계절 변동성은 그 기원으로 추정되는 대만난류와 쿠로시오해류의 계절 변동성과 밀접하게 연관되어있는 것으로 사료된다. 모형에서 계산된 쿠로시오 해류의 월평균 수송량은 27.25 ± 0.56 Sv 으로 평균 수송량에 비해서 계절 변동폭은 크지 않았으나, 대만난류의 월평균 수송량은 2.04 ± 0.67 Sv 으로 계절 변동폭이 쿠로시오보다 상대적으로 크게 나타났다. 특히 대만난류에서 분기되어 중국쪽 천해 지형경사를 따라 여름철에 북상하는 지류의 영향이 겨울철에 비해서 크기 때문에 제주난류의 수송량 증가를 유발하는 것으로 분석된다. 또한 여름철의 경우 경년 변동성도 다른 계절에 비해 상대적으로 크게 나타났다, 30년 동안 8월 평균 최저 수송량은 0.28 Sv 이었으며, 최고 수송량은 0.71 Sv 으로 연평균 수송량의 크기와 비슷한 변동이 나타난다. 한편 제주난류의 경년변동성을 좌우하는 주요 원인을 알기 위해서 평년에 비해서 수송량이 작게 나타났던 해와 크게2