초록 ▼

- 한반도 근해의 해양환경에 직접적 영향을 주는 북태평양의 쿠로시오-오야시오 확장역은 지구온난화에 대한 민감하게 반응함.
- 다양한 시공간 규모로 변동하는 쿠로시로확장역을 연구하기 위해서 계류시스템을 설치하여 자료를 얻고 관측의 시공간 제약을 극복하기 위하여 고도계 수치모형 결과 등을 분석함.
- 하위생태계 구조･생산성 및 생지화학 물질(C, N) 순환 특성을 규명함.
- 용존 영양염, 부유물질, 입자성유기탄소 등 생태계 구조와 변동성 파악을 위한 생지화학적 기초자료를 획득 자료를 획득함.
- 침강입자와 탄소,

- 한반도 근해의 해양환경에 직접적 영향을 주는 북태평양의 쿠로시오-오야시오 확장역은 지구온난화에 대한 민감하게 반응함.
- 다양한 시공간 규모로 변동하는 쿠로시로확장역을 연구하기 위해서 계류시스템을 설치하여 자료를 얻고 관측의 시공간 제약을 극복하기 위하여 고도계 수치모형 결과 등을 분석함.
- 하위생태계 구조･생산성 및 생지화학 물질(C, N) 순환 특성을 규명함.
- 용존 영양염, 부유물질, 입자성유기탄소 등 생태계 구조와 변동성 파악을 위한 생지화학적 기초자료를 획득 자료를 획득함.
- 침강입자와 탄소, 질소의 순환 특성과 변동성을 연구 조사함
- 탄성파 해양학(Seismic Oceanography)을 이용하면 광역에서 고해상도로 수층구조를 측정함.
- 장기적 기후변화의 결과로서 발생할 쿠로시오확장역의 변화양상을 보다 명확히 예측하기 위해 지질학적 과거에 일어난 대규모 기후변화에 따른 반응을 이해하기 위하여 심해 퇴적물 코어를 획득하고 분석함.

(출처 : 초록 5p)

Abstract ▼

Ⅳ. Results of the Study
○ Variability of Kuroshio Extension
- Variability from altimeters and numerical model outputs
· Near the Shatsky Rise meridional gradients of temperature and salinity weaker that those to the upstream resulting in weaker Kuroshio jets.
· The jet show meridionally

Ⅳ. Results of the Study
○ Variability of Kuroshio Extension
- Variability from altimeters and numerical model outputs
· Near the Shatsky Rise meridional gradients of temperature and salinity weaker that those to the upstream resulting in weaker Kuroshio jets.
· The jet show meridionally bifurcated structure possibly affected by the bathymetry.
· Upper-ocean heat content variability over the Kuroshio Extension are induced by changes in the Kuroshio Extension jet and Subarctic Frontal Zone.
- Results of a tall current mooring and PIES
· Currents speed at the mooring site depend on the location of Kuroshio Extension jet.
· Variability of current at the mooring site includes semidiurnal tide (about 12 hours), inertial wave (about 21 hour), and meso-scale eddy(about 3~10 days).
· Measured time series of temperature and salinity for the full depth in the mooring site using an acoustic travel time form the PIES.
○ Survey and quantification of ecosystem structure and C-export
- Aquisition and analysis of biogeochemical data including nutrients
· In 2017, the ammonium concentration was 0.140 μM in the depth of 65 m at 38°N and the concentrations of ammonium, nitrite, nitrate and phosphate in the euphotic zone (upper 200 m of the water column) were depleted, and those of silicate was below 2 μM at all other stations.
· In 2018, ammonium, nitrite, nitrate exist between 0 to 50 m depth and the concentrations of phosphate and silicate were below 1.2 μM and 3 μM respectively, at Oyashio Current region (44°N).
· From 42°N to 32°N, the concentrations of ammonium, nitrite, nitrate and phosphate in the upper 30~70 m of the water column were depleted, and those of silicate was below 3 μM at all other stations.
- Ecosystem structure and functional properties
· The cruise in 2018 showed a greater spatio-temporal change in the lower trophic level compared to 2017 mainly due to expansion of study area to Oyashio Current region (44°N).
· Biomass of prokaryotes, phytoplankton and zooplankton showed a decreasing trend in lower latitude. with an exception of higher biomass and productivity at the stations with upwelling In the eutrophic region of the Oyashio Current.
· Primary productivity was also high in the Oyashio Current region and low in the Kuroshio waters, and that the primary production depend on the biomass of the phytoplankton.
· The ratio of bacterial production to primary productivity tended to largely increase in lower latitude, showing that energy flow via microbial loop is important in the oligotrophic subtropical area.
- Temporal variation of particle flux using time-series sediment traps
· Time series sediment traps were operated at water depth of 800 m (upper trap) and 4,000 m (lower trap) in the Kuroshio extension from November 2017 to August 2018.
· In the upper trap, total particle fluxes ranged 0.5 to 248 mg m^-2day^-1 with an average of 88 mg m^-2day^-1.
· In the lower trap, total particle fluxes varied between 0.02 and 125 mg m^-2day^-1 with an average of 44 mg m^-2day^-1.
○ Water column structure and ocean mixing
- Operated the direct/indirect observations to figure out the quantity of vertical mixing.
- Calculated dissipation rate from the directly measuring the micro structure has 10^-7 kg/m³ in the upper layer, keep decreasing at 80~120 m and stable at the deeper layer about 10^-10~10^-9 kg/m³.
- Using Thorpe scale and GM model for the indirect method to calculate dissipation rate.
- Shih method has better quantity and trend than Osborn method at calculate vertical diffusion.
- Analyzed the influences of the surrounding environments of the exploration area on the water column reflection data acquisition.
- Performed the seismic exploration along a line approximately 132 km long at the Kuroshio extension to obtain the water column reflection data, and obtained the oceanographic data directly from the oceanographic instruments along the line.
- Applied the seismic data processing techniques to the acquired seismic data to derive the final water-layer section and compared with the data obtained from the oceanographic instruments.
- Identified that the boundary of the mixed layer-thermocline in the seismic section was formed at about 100 m depth at 36° 4'N, 158° 22'E, but the depth of the boundary became shallower and formed between 60 and 70 m at 34° 52'N, 158° 8'E.
○ Variation of Kuroshio Extension in response to glacial-interglacial climatic cycles
- By obtaining three piston cores at the summits of Shatsky Rise, a meridional transect of sedimentary archives across the main pathway of Kuroshio Extension has been made.
- Each core has its unique sedimentary features including color, facies association, sedimentation rate, etc; allowing the identification of the KE main pathway from its meandering range.
- During the glacial and stadial periods, the more southerly positioning of meandering KE than the present was recognized in the oxygen isotope compositions and faunal assemblages of planktic foraminifera.
- Provenance of the terrigenous component in the Shatsky Rise sediment has also been varied in response to the glacial-interglacial cycles, possibly resulted from the changes in transport pathway by westerly jet.
- The changes in terrigenous provenance and paleoceanograpic indicators indicate the southward migration of westerly winds and Kuroshio Extension during the glacial periods.

(출처 : SUMMARY 13p)

목차 Contents

• 표지 ... 1제 출 문 ... 3보고서 초록 ... 5요 약 문 ... 7S U M M A R Y ... 12목차 ... 17CONTENTS ... 18표목차 ... 19그림목차 ... 21제1장 서 론 ... 35 제1절 연구개발의 필요성 ... 37 제2절 연구개발의 목표와 내용 ... 40제2장 국내외 기술 개발 현황 ... 43 제1절 국내 현황 ... 45 제2절 국외 현황 ... 47제3장 연구개발수행 내용 및 결과 ... 49 제1절 연구해역 탐사 ... 51 제2절 쿠로시오 확장역 물리 특성 관측과 분석 ... 64 제3절 하위 생태계 구조 및 C-export 조사와 정량화 ... 94 제4절 수층구조와 해양 혼합 특성 ... 126 제5절 과거 장주기 기후변화에 따른 쿠로시오확장역 변동성 ... 141제4장 연구개발목표 달성도 및 대외기여도 ... 151 제1절 목표 달성도 ... 153 제2절 대외 기여도 ... 157제5장 연구개발 결과의 활용계획 ... 159제6장 참고문헌 ... 163끝페이지 ... 171