• 한국지구과학회지
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• 제42권6호
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• pp.605-622
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• 2021

Seasonal forecasting has numerous socioeconomic benefits because it can be used for disaster mitigation. Therefore, it is necessary to diagnose and improve the seasonal forecast model. Moreover, the model performance is partly related to the ocean model. This study evaluated the hindcast performance in the upper ocean of the Global Seasonal Forecasting System version 5-Global Couple Configuration 2 (GloSea5-GC2) using a multivariable integrated evaluation method. The normalized potential temperature, salinity, zonal and meridional currents, and sea surface height anomalies were evaluated. Model performance was affected by the target month and was found to be better in the Pacific than in the Atlantic. An increase in lead time led to a decrease in overall model performance, along with decreases in interannual variability, pattern similarity, and root mean square vector deviation. Improving the performance for ocean currents is a more critical than enhancing the performance for other evaluated variables. The tropical Pacific showed the best accuracy in the surface layer, but a spring predictability barrier was present. At the depth of 301 m, the north Pacific and tropical Atlantic exhibited the best and worst accuracies, respectively. These findings provide fundamental evidence for the ocean forecasting performance of GloSea5.

• Journal of Korean Society for Atmospheric Environment
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• 제20권E1호
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• pp.1-14
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• 2004

Meteorological mechanisms in association with long-range transport of Asian dust in April 2001 have been investigated using weather maps, satellite images, TOMS and surface $PM_{10}$ data, backward trajectories, plus modeling output results (geopotential heights, horizontal wind vectors, potential temperatures, and streamlines). The results indicated that long -range transport of Asian dust to the west coast of North America was associated with strong westerlies between the Aleutian low and the Pacific high acting as a conveyor belt. Accelerating westerly flows due to cyclogenesis at the source regions over East Asia transported pollution from the continent to the central Pacific. When the system reached the Aleutian Islands, the intensity of troughs and the westerlies were amplified in the North Pacific. Thereafter the winds between the Aleutian Islands and the Pacific Ocean were more intensified from the air flow transport of the conveyor belt. Consequently, the strong wind in the conveyor belt enhanced the dust transport from the Pacific Ocean to the west coast of North America. This was evidenced by $PM_{10}$ concentration (maximum of about $100{\mu}g\;m^{-3}$) observed In California. Further evidence of the dust transport was found through the observation of satellite images, the distribution of TOMS aerosol index, and the analyses of streamlines and backward trajectories.

• 수산해양기술연구
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• 제54권2호
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• pp.116-123
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• 2018

Pacific bluefin tuna (Thunnus orientalis) has been mostly caught by the Korean offshore large purse seine fishery in Korean waters. The annual catch of Pacific bluefin tuna caught by the offshore large purse seine fishery in Korean waters showed less than 1,000 mt until the 1990s except for 1997. The catch sharply increased to 2,401 mt in 2000 and recorded the highest of 2,601 mt in 2003, but the catch has generally decreased with a fluctuation thereafter. The main fishing ground of Pacific bluefin tuna of this fishery is formed around Jeju Island. However, it expanded to the Yellow Sea, the coastal of Busan, and the East Sea, which depends on the migration patterns of Pacific bluefin tuna by season. The CPUE standardization of Pacific bluefin tuna was conducted using Generalized Linear Model (GLM) to assess the proxy of the abundance index. The data used for the GLM were catch (weight), effort (number of hauls), catch ratio of Pacific bluefin tuna, moon phase by year, quarter and area. The standardized CPUE from 2004 to 2011, except for 2003 and 2010, showed a steady trend, and then increased until 2014. The CPUE in 2015 decreased, and in 2016 was higher than that in 2015. The result of GLM suggests that the effect of the catch ratio of Pacific bluefin tuna is the largest factor affecting the nominal CPUE.

• Ocean and Polar Research
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• 제28권4호
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• pp.395-405
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• 2006

We measured the fugacity of $CO_2$ $(fCO_2)$, temperature, salinity, nutrients and chlorophyll a in the surface water of the western North Pacific $(4^{\circ}30'{\sim}33^{\circ}10'N,\;144^{\circ}20'{\sim}127^{\circ}35'E)$ in September 2002. There were zonally several major currents which have characteristics of specific temperature and salinity (NECC, North Equatorial Counter Current; NEC, North Equatorial Current; Kuroshio etc.). Surface $fCO_2$ distribution was clearly distinguished into two groups, tropical and subtropical areas of which boundary was $20^{\circ}N$. In the tropical Int surface $fCO_2$ was mainly controlled by temperature, while in the subtropical area, surface $fCO_2$ was dependent on total inorganic carbon contents. Air-sea $CO_2$ flux showed a large spatial variation, with a range of $-0.69{\sim}0.79 mmole\;m^{-2}day^{-1}$. In the area of AE (Anticyclonic Eddy), SM(Southern Mixed region) and NM (Northern Mixed region), the ocean acted as a weak source of $CO_2$ $(0.6{\sim}0.79 mmole\; m^{-2}day^{-1})$. In NECC, NEC, Kuroshio and ECS (East China Sea), however, the fluxes were estimated to be $-0.3mmole\; m^{-2}day^{-1})$ for the first three regions and $-1.2mmole\; m^{-2}day^{-1})$ for ECS respectively, indicating that these areas acted as sinks of $CO_2$. The average air-sea flux in the entire study area was $0.15mmole\;m^{-2}day^{-1})$, implying that the western North Pacific was a weak source of $CO_2$ during the study period.

• 대기
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• 제26권4호
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• pp.687-696
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• 2016

The western North Pacific subtropical high (WNPSH) in boreal summer has interannual and interdecadal variability, which affects East Asian summer monsoon variability. In particular, it is well known that the intensity of WNPSH is reversely related to that of summer monsoon in North East Asia in association with Pacific Japan (PJ)-like pattern. Many coupled climate models weakly simulate this large-scale teleconnection pattern and also exhibit the diverse variability of WNPSH. This study discusses the inter-model differences of WNPSH simulated by different climate models, which participate in the Coupled Model Intercomparison Project phase 5 (CMIP5). In comparing with reanalysis observation, the 29 CMIP5 models could be assorted into two difference groups in terms of interannual variability of WNPSH. This study also discusses the dynamical or thermodynamics factors for the differences of two groups of the CMIP5 climate models. As results, the regressed precipitation in well-simulating group onto the Nino3.4 index ($5^{\circ}N-5^{\circ}S$, $170^{\circ}W-120^{\circ}W$) is stronger than that in poorly-simulating group. We suggest that this difference of two groups of the CMIP5 climate models would have an effect on simulating the interannual variability of WNPSH.

• Ocean and Polar Research
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• 제36권2호
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• pp.145-156
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• 2014

Macrobenthic biodiversity in the rocky intertidal areas of the Tae-an region, Republic of Korea, has decreased since the Hebei Spirit oil spill in December 2007. We aimed to investigate ecological roles of Pacific oyster (Crassostrea gigas) because recruitment and growth of oysters are critical to the recovery of damaged rocky shore ecosystem. We surveyed two sites monthly: natural rocky substrate and farming substrate, from July 2012 to January 2013 to identify and compare the changes in macrobenthic fauna. The abundance of young oysters was higher at the natural site. On the other hand, the mean height of oyster on the farming substrate was more than twice as great. The abundance of oyster at the natural site increased until October and then continuously decreased until end of study period. However, the abundance of oyster at the farming site constantly decreased from the beginning of study period. These different growth patterns might be attributable to spatial competition between oyster and a barnacle species (Balanus albicostatus) and environmental factors. At the natural site, physical stress factors including dramatic temperature changes and desiccation a few of the major factors limiting growth during aerial exposure. In addition, motile macrobenthos could be detrimental to oysters because they interrupt filter-feeding activities and hence hamper the growth of oysters. We show the higher recruitment of oysters at the natural site and healthy growth in the farming substrate are due to complicated differences in physical and biological stress factors.

• 한국수산과학회지
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• 제43권6호
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• pp.740-746
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• 2010

This study standardized the catch per unit effort (CPUE) of bigeye tuna (Thunnus obesus) caught by the Korean longline fishery in the Pacific Ocean. The study used a general linear model (GLM) to standardize the CPUE using catch and effort data aggregated by year, month, and $5{\times}5$ degrees of latitude and longitude in the tropical Pacific Ocean from 1982 to 2008 (except for 1988 and 1989). Explanatory variables in the GLM analysis included year, month, subtropical area, and number of hooks between floats (HBF). The study area and HBF were subdivided into three subtropical areas and six classes, respectively. During the study period, the standardized CPUE was significantly related to the nominal CPUE. The standardized CPUE declined sharply, as compared to the nominal CPUE, after the mid 1990s. In particular, the decline in the standardized CPUE in all subtropical areas in the 2000s was clearer than that of the nominal CPUE.

• 한국수산과학회지
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• 제44권1호
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• pp.58-63
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• 2011

This study investigated the effects of stocking density and feeding frequency (three and five times per week) on the growth of Pacific cod, Gadus macrocephalus. In the first experiment, experimental groups of fish (mean weight $167.8{\pm}41.4\;g$) were reared at three stocking densities (4, 8 and 12 kg/$m^3$) for 16 weeks. The total weight gain was 17.8, 17.1 and 35.4% at 4, 8 and 12 kg/$m^3$, respectively. The specific growth rates, survival rates and feeding efficiency increased with the density, but there were no significant differences (P>0.05). The daily feed intake decreased as the stocking density increased, whereas the condition factors increased with the stocking density (P<0.05). In the second experiment, groups of fish ($194.1{\pm}68.3\;g$) were fed either three or five times a week. The total wight gain was 14.4 and 18.5% for the fish fed three and five times per week, respectively. The specific growth rates of Pacific cod fed to satiation increased with the feeding frequency, although the difference was not significant (P>0.05). The survival rates, daily feed intake, feed efficiency, and condition factors of the Pacific cod were not significantly different (P>0.05). Based on these results, the optimum stocking density for juvenile cod is above 12 kg/$m^3$, and the best feeding frequency is three times a week, under the conditions used in this experiment.

• 한국해양학회지:바다
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• 제13권3호
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• pp.190-199
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• 2008

북동태평양 열대 해양의 해수특성과 해양구조를 파악하기 위하여 2005년 7-8월에 $131.5^{\circ}W$ 관측선에서 관측한 CTD 자료를 분석하였다. 또한 적도 부근 태평양의 해수특성을 전반적으로 이해하기 위하여 서태평양 $137^{\circ}-142^{\circ}E$에서의 CTD 자료도 분석하여 동태평양의 분석 결과와 비교하였다. 여름철 동태평양의 표층수온은 적도반류 해역에서 가장 높았다. 이것은 $28^{\circ}C$ 이상의 고온수가 봄과 여름철에 적도반류를 타고 서태평양으로부터 동태평양으로 이동하여 약 $4^{\circ}-15^{\circ}N$ 사이에서 동서로 연결되기 때문이다. 북적도해류의 표층에 나타나는 저염분 고용존산소의 해수는 동태평양의 파나마만으로부터 서태평양의 필리핀 부근까지 이동하는 저염분수 때문이다. 반면 남적도해류의 표층에 고염분과 저용존산소의 해수가 분포하는 것은 남태평양 아열대 기원의 고염분수가 적도를 넘어 남적도해류 표층의 열대해수(Tropical Water)와 심층의 고염분수를 형성하고 있기 때문이다. 수심 약 500-1500 m 사이의 중층에서는 염분최소층이 분포하는데, $5^{\circ}N$ 이남은 남극중층수(AAIW) 기원의 해수가, $5^{\circ}N$ 이북은 북태평양중층수(NPIW) 기원의 해수가 분포한다. $4^{\circ}-6^{\circ}N$ 해역에서는 직경 약 200 km이며 반시계 방향으로 회전하는 냉수성 소용돌이(cold eddy)가 관측되었다. 서태평양에 비해 동태평양에서 표층수온은 $1^{\circ}C$ 이상 낮았으며 표층염분은 높았다. 적도 부근의 표층 아래에 분포하는 고염분수는 동태평양에서 상대적으로 저염분(약 0.5 psu) 이었고, $14^{\circ}N$ 이남에서 염분최소층의 염분과 밀도는 동태평양에서 높았다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.52-53
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• 2005

Time series of gridded surface wind and wind-stress vectors over the world ocean have been constructed by satellite scatterometer data. The products are derived from the ERS-l,2 covering 9 years during 1992-2000 and the Sea Winds on board QuikSCAT (Qscat) which has been operating up to the present since June 1999, so they allows us to analyze variabilities with various time scales. In this study, we focus on interannual variability of the wind stress in the mid- and high-latitude region of North Pacific. These are compared with those by numerical weather prediction(NWP) ones (NCEP Reanalysis). We also examine variability in the wind-stress curl field that is an important factor for ocean dynamics and focus its time and spatial characters in the northwestern Pacific around Japan. It is found that the vorticity field in the lower atmosphere tends to increase gradually with time, suggesting the enhancement of the North Pacific subtropical gyre.