동해 울릉분지에서 봄과 여름동안 시계방향 와류가 영양염과 엽록소에 미치는 영향

김동선,김경희,심정희,유신재,Kim, Dong-Seon,Kim, Kyung-Hee,Shim, Jeong-Hee,Yoo, Sin-Jae 한국해양학회 2007 바다 Vol.12 No.4

동해 울릉분지에서 봄과 여름 동안 난수성 시계방향 와류가 영양염과 엽록소에 미치는 영향을 파악하기 위해서, 2005년 7월과 2006년 4월에 5개 정점에서 표층부터 수심 200 m까지 수온, 염분, 영양염, 엽록소 등을 관측하였다. 봄에는 와류 내부해역에서 표층 혼합층의 깊이가 150 m 이상으로 매우 깊은 반면, 외부해역에서는 $20{\sim}60$ m로 비교적 얕았다. 와류 내부해역에서 수직혼합이 활발히 일어나 표층해수에 영양염이 풍부한 반면, 외부해역에서는 표층에서 성층화가 생겨 심층에서 표층으로 영양염 공급이 충분하지 않아 농도가 낮았다. 봄에는 와류 내부해역에서 표층 혼합층 깊이가 유광층 깊이보다 훨씬 더 깊어서 엽록소 농도가 낮았으며, 와류 외부해역에서 측정한 총 엽록소(depth-integrated chlorophyll) 양은 내부해역에서 측정한 것보다 보다 두 배 이상 높았다. 여름에는 봄과 달리 모든 정점에서 표층 성층화가 강하게 발생하여, 영양염이 표층에서 완전히 고갈되었다. 여름에 관측한 엽록소는 모든 정점 수심 30 m 내외에서 최고 농도를 나타내어, 아표층 엽록소 최대(subsurface chlorophyll maximum)를 보였으며, 와류 내부해역에서 측정한 총 엽록소 양은 외부해역에서 측정한 것보다 두 배가량 높았다. 동해 울릉분지에서 거의 매해 나타나는 시계방향 와류는 식물플랑크톤 생물량에 매우 큰 영향을 미치는데, 그 영향이 봄과 여름에 다르게 나타났다; 봄에는 시계방향 와류가 식물플랑크톤 생물량을 제한하는 반면, 여름에는 반대로 식물플랑크톤 생물량을 증가시킨다. In order to find out the effects of the anticyclonic eddy on the distribution of nutrients and chlorophyll concentrations in the Ulleung Basin during spring and summer, we measured temperature, salinity, nutrients, and chlorophyll from the surface to 200 m water depth at five stations in July 2005 and April 2006. In spring, surface mixed layer was very deep inside the eddy, about 200 m, but it was relatively shallow outside the eddy, about $20{\sim}60$ m. Inside of the eddy, nutrients in the surface waters were sufficient by supply from the deep layer, whereas outside of the eddy, they were fairly depleted due to the stratification in the surface layer. In spring, chlorophyll concentrations were relatively low inside of the eddy due to the deeper surface mixed layer compared with the euphotic depth, and the depth-integrated chlorophyll concentrations outside of the eddy were twice as much as those inside of the eddy. In summer, nutrients in the surface waters were completely depleted at all stations due to the well stratification in the surface layer. The typical distribution pattern of subsurface chlorophyll maximum was observed at all stations, and the depth-integrated chlorophyll concentrations inside of the eddy were almost twice as much as those outside of the eddy. The anticyclonic eddy appearing in the Ulleung Basin every year significantly affects the phytoplankton biomass, with the opposing effects in spring and summer; in spring, the anticyclonic eddy suppresses phytoplankton growth, but in summer, it enhances the phytoplankton biomass.

1992년 5월 속초 근해 와동류의 구조

이재철 ( Jae Chul Lee ),민덕홍 ( Dug Hong Min ),유홍선 ( Hong Sun Yu ),이형선 ( Hyong Sun Lee ),양한섭 ( Han Seob Yang ) 한국수산학회 1995 한국수산과학회지 Vol.28 No.3

1992년 1월부터 6월까지의 인공위성 적외선 영상자료를 이용하여 속초 근해에 형성된 와동류의 시간적 변화에 대하여 연구하였고 동년 5월에 그 구조를 관측하였다. 와동류의 형성에는 두가지 종류의 과정이 있는 것으로 나타났는데, 첫번째로 1월의 영상자료에 의하면 난류의 대량 공급으로 인하여 약 200㎞ 크기의 와동류가 형성되었다. 그 이후에 약간의 변형과 냉각과정을 거쳐서 3월에는 난류의 좁은 필라멘트가 북쪽으로 침투하면서 어느정도 냉각된 기존의 와동류를 포위함으로써 4-5월에는 반지모양의 와동류로 발달하는 두번째의 형성과정이었다. 와동류의 내부에는 수온 10.0~10.4℃의 균질 중층수가 최대 170m의 두께로 존재하였다. 속초 근처 동한난류의 축에서의 유속 약 80㎝/sec를 제외하면 나머지 부분의 와동류 내부에는 대체로 30-50㎝/sec의 유속분포를 보였고 주수온약층 밑으로는 유속이 급격히 감소하였다. Temporal change of a warm eddy off Sogcho was studied using satellite infrared images from January to June 1992 and its structure was investigated by the observations in May. There were two kinds of event for eddy formation. IR images in January indicated that the eddy having a horizontal dimension of about 200㎞ was first formed by an injection of warm water. After some deformation and cooling processes the second restrengthening event took place in late March when a warm filament began to penetrate northward and circumvented the preexisting eddy. This eddy became a complete ring-shape with cooled water arrested inside from April to May. The maximum thickness of the isothermal subsurface layer with temperature of 10.0~10.4℃ was about 170m. Except that the current velocity was about 80㎝/sec near the axis of the East Korea Warm Current close to Sogcho, the interior of the eddy had an anticyclonic motion with overall swirl velocity of 30~50㎝/sec. Velocity rapidly decreased vertically below the main thermocline.

Enhanced Biological Activity by an Anticyclonic Warm Eddy during Early Spring in the East Sea (Japan Sea) Detected by the Geostationary Ocean Color Satellite

임재현,손승현,박정우,곽정현,강창근,손영백,권정노,이상헌 한국해양과학기술원 2012 Ocean science journal Vol.47 No.3

The high primary production enhanced by anticyclonic eddies and hourly variation pattern in the productivity during the spring season in the East Sea were first investigated using the first Korean Geostationary Ocean Color Imager (GOCI). Even though the stratification for a seasonal spring bloom is not well developed in the water column in early April in the East Sea, a physical upward water flux movement at the periphery of the anticyclonic eddies could remain the phytoplankton in euphotic zone to sustain high chlorophyll-a concentration conditions in the Ulleung Basin. At this time, nutrients were no major controlling factor for phytoplankton growth since concentrations of major nutrients (nitrate, silicate, and phosphate) were relatively high in the observed eddy sites based on the observation data from the Korean Oceanographic Data Center (KODC). The estimated mixed layer depth (MLD) significantly shallower at the periphery supports for this mechanism. The hourly primary productivity estimation based on a Carbon-based Productivity Model (CbPM) provides a bimodal pattern along the time especially in L1 with an approximately one order magnitude difference between the lowest and highest values of productivities on 5 April, 2011. Potential possibilities for this large discrepancy in the hourly productivity and some thoughts on a short time in situ incubation method were discussed.

Spatial and Temporal Aspects of Phytoplankton Blooms in Complex Ecosystems Off the Korean Coast from Satellite Ocean Color Observations

Ahn, Yu-Hwan,Shanmugam, Palanisamy,Chang, Kyung-Il,Moon, Jeong-Eon,Ryu, Joo-Hyung The Korean Society of Oceanography 2005 Ocean science journal Vol.40 No.2

Complex physical, chemical and biological interactions off the Korean coast created several striking patterns in the phytoplankton blooms, which became conspicuous during the measurements of ocean color from space. This study concentrated on analyzing the spatial and temporal aspects of phytoplankton chlorophyll variability in these areas using an integrated dataset from a Sea-viewing Wide Field-of-view Sensor (SeaWiFS), Advanced Very High Resolution (AVHRR) sensor, and Conductivity Temperature Depth (CTD) sensor. The results showed that chlorophyll concentrations were elevated in coastal and open ocean regions, with strong summer and fall blooms, which appeared to spread out in most of the enclosed bays and neighboring waters due to certain oceanographic processes. The chlorophyll concentration was observed to range between 3 and $54\;mg\;m^{-3}$ inside Jin-hae Bay and adjacent coastal bays and 0.5 and $8\;mg\;m^{-3}$ in the southeast sea offshore waters, this gradual decrease towards oceanic waters suggested physical transports of phytoplankton blooms from the shallow shelves to slope waters through the influence of the Tsushima Warm Current (TWC) along the Tsushima Strait. Horizontal distribution of potential temperature $(\theta)$ and salinity (S) of water off the southeastern coast exhibited cold and low saline surface water $(\theta<l9^{\circ}C;S<32.4)$ and warm and high saline subsurface water $({\theta}>12^{\circ}C; S>34.4)$ at 75dBar, corroborating TWC intrusion along the Tsushima Strait. An eastward branch of this current was called the East Korean Warm Current (EKWC), tracked with the help of CTD data and satellite-derived sea surface temperature, which often influenced the dynamics of mesoscale anticyclonic eddy fields off the Korean east coast during the summer season. The process of such mesoscale anticyclonic eddy features might have produced interior upwelling that could have shoaled and steepened the nutricline, enhancing phytoplankton population by advection or diffusion of nutrients in the vicinity of Ulleungdo in the East Sea.