• Atmosphere
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• v.22 no.1
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• pp.117-128
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• 2012

Does snow depth initialization have a quantitative impact on sub-seasonal to seasonal prediction skill? To answer this question, a snow depth initialization technique for seasonal forecast system has been implemented and the impact of the initialization on the seasonal forecast of surface air temperature during the wintertime is examined. Since the snow depth observation can not be directly used in the model simulation due to the large systematic bias and much smaller model variability, an anomaly rescaling method to the snow depth initialization is applied. Snow depth in the model is initialized by adding a rescaled snow depth observation anomaly to the model snow depth climatology. A suite of seasonal forecast is performed for each year in recent 12 years (1999-2010) with and without the snow depth initialization to evaluate the performance of the developed technique. The results show that the seasonal forecast of surface air temperature over East Asian region sensitively depends on the initial snow depth anomaly over the region. However, the sensitivity shows large differences for different timing of the initialization and forecast lead time. Especially, the snow depth anomaly initialized in the late winter (Mar. 1) is the most effective in modulating the surface air temperature anomaly after one month. The real predictability gained by the snow depth initialization is also examined from the comparison with observation. The gain of the real predictability is generally small except for the forecasting experiment in the early winter (Nov. 1), which shows some skillful forecasts. Implications of these results and future directions for further development are discussed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.6
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• pp.493-504
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• 2008

In the seas around the Korean Peninsula, the seasonal cycle of zooplankton related to North Pacific regime shifts was investigated to understand the reaction of the ecosystem to climate change using long-term data on zooplankton biomass (1965-2000) and the abundance of four major zooplankton groups: copepods, amphipods, chaetognaths, and euphausiids (1978-2000). In general, the zooplankton biomass showed a large peak in spring and a small peak in autumnin Korean waters, but there was a slight difference in the peak time depending on the location and the period before and after the North Pacific regime shift. The zooplankton biomass showed conspicuous seasonal peaks in R-III (1990-2000) compared to R-I (1965-1976) and R-II (1977-1988), and the seasonal peak shifted from the autumn in R-II to the spring in R-III. The peak of copepods and euphausiids in abundance was from April to June, while chaetognaths peaked from August to October. We postulate that the time lag between the peaks for copepods and chaetognaths results from the predator-prey relationship. The regime shift in 1989 did not alter the seasonal cycle of the four major zooplankton groups, although it enhanced their production. The seasonal peaks of the four major zooplankton groups did not shift, while the seasonal peaks of the zooplankton biomass did shift. This was not only becausethe zooplankton biomass included other mesozooplankton groups but also because the abundance of the four major zooplankton groups increased significantly in spring.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.2
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• pp.120-128
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• 2003

Fishes were caught by a set net in the coastal waters off Yosu, Korea from April to October, 2001, and seasonal variation of abundance and species composition were studied. Fifty two species were identified as fish $(89\%)\;cephalopods\;(10\%)\;and\;crustaeans\;(1\%).$ Of the fishes Engraulis japonicus, Trachurus japonicus and Trichiurus lepturus were dominant species representing $64.1\%$ in total number of individuals. The number of species was high in spring and low in summer; number of individuals was high in spring and low in autumn. The diversity index (H') was 0.4-0.7 The abundance and species composition fluctuated seasonally. Occurrence of the various stages of fishes indicated that Scombia japonicus, T. japonicus and E japonicus utilized in the area as spawning ground, Conger myriaster larvae, Ammodytes personatus and Seriola quinqueradiata as nursery ground, and T. lepturus and Ilisha elongata as spawning and nursery grounds.

• Journal of Environmental Science International
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• v.20 no.9
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• pp.1141-1149
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• 2011

The three-dimensional hydrodynamic model was simulated to understand coastal sea front of formation and seasonal variation in the Southern Sea of Korea. In this study, we used to concept of stratification factor, to realize seasonal distribution of stratification coefficient which of seasonal residual flow, considered with, tide, wind and density effect. Tidal current tends to flow westward during the flood and eastward during ebb. The current by the wind stress showed to be much stronger the coastal than the offshore area in the surface layer. And the current by the horizontal gradient of water density showed to be relatively weak in the coastal area, with little seasonal differences. On the other hand, the flow in the offshore area showed results similar to that of the Tsushima Warm Current. The stratification factor (SHv) was calculated by taking into account the total flow of tide, wind and density effect. In summer, the calculated SHv distribution ranged from 2.0 to 2.5, similar to that of the coastal sea front. The horizontal temperature gradient showed to be strong during the winter, when the vertical stratification is weak. On the other hand, the horizontal gradient became weak in summer, during which vertical stratification is strong. Therefore, it is presume that the strength of vertical stratification and the horizontal temperature gradient affect the position of the coastal sea front.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.693-704
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• 2010

Seasonal variation in species composition around Dokdo, East Sea of Korea, was investigated using trammel-net catches, from 2006 to 2009. A total of 53 fish species belonging to 23 families in 12 orders were captured; the orders Perciformes (12 families, 22 species) and Scorpaeniformes (four families, 22 species) were dominant. Between 2008 and 2009, 43 species were collected by trammel net. The number of species was highest in August 2009 (25 species) and lowest in February 2009 (11 species). The number of individuals and total biomass peaked in November 2009. Diversity indices for fish catches were highest in August 2008 (2.4368) and lowest in November 2009 (0.4253). The dominant species were Thamnaconus modestus and Sebastes schlegeli. Hierarchical clustering analysis showed five fish groups, with frequency and number of individuals similar to results of correspondence analysis (CA), which showed a closer relationship to the year term than the season term. CA showed that temperature was an important factor influencing fish species richness and abundance. Three main fish assemblage types coexisted around Dokdo: an East Sea coastal fish assemblage, a subtropical fish assemblage, and a cold water fish assemblage.

• Journal of the korean society of oceanography
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• v.38 no.2
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• pp.68-79
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• 2003

Although seagrasses are relatively abundant, few studies have been conducted on seagrass physiology and ecology in Korea. Zostera marina is the most abundant seagrass species, widely distributed throughout all coastal areas of the Korean peninsula. To examine seasonal dynamics and spatial variations of eelgrass, Zostera marina distributed on the coast of Korea, morphological characteristics, biomass, tissue nutrient constituents, leaf productivity and environmental factors were monitored monthly from the eelgrass beds in Kabae Bay and Kosung Bay on the south coast of the Korean peninsula from June 2001 to June 2002. Eelgrass density, biomass, morphological characteristics, leaf productivities, and tissue nutrient constituents exhibited clear seasonal variations, and these seasonal trends reflected seasonal changes in water temperature. Eelgrass shoot density and biomass at Kabae Bay site showed more obvious seasonal trends than Kosung Bay. No strong seasonality in Kosung Bay site appeared to be caused by high water temperature ($>30{\circ}C$) during summer months at this site. Despite differences in nutrient availabilities between two study sites, eelgrass biomass and leaf productivities were not significantly different between study sites, and this lack of spatial variations implies that the ambient nutrient availabilities at the present study sites are in excess of seagrass nutrient demand. Eelgrass tissue N content and sediment pore water DIN concentrations exhibited reverse relationship at the present study. This reverse relationship suggests in situ nutrient concentrations are not good indicator of nutrient availabilities, and regeneration and turnover rates of sediment nutrients are also important factors to determine nutrient availabilities at the site.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.2
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• pp.176-185
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• 2013

Seasonal species composition and biomass of microphytobenthos were examined at the intertidal flats of Jinsanri, Taean, Korea, from April to December 2011. In total, 121 species were identified, including 109 diatoms, 5 blue-green algae, and 5 dinoflagellates. Seasonal variation in species number ranged from 49 to 56 species (minimum in October and maximal in April), while vertical variation across three different shore levels ranged from 64 to 77 species with maximum at high and minimum at low shore. Species diversity ranged from 3.22 to 3.42 seasonally and from 3.50 to 3.17 across vertical shore levels. Seasonal average values of the normalized difference vegetation index and the vegetation index were 0.06 and 1.14, respectively. Chlorophyll a concentrations were $66.00-120.73mg/m^2$, with a seasonal minimum and maximum in July and October, respectively, and a vertical shore maximum of $137.35mg/m^2$ at mid shore. Phaeopigment concentrations peaked in October ($50.78mg/m^2$) and at high shore ($61.58mg/m^2$) and were lowest in December ($22.53mg/m^2$) and at low shore ($15.28mg/m^2$). The number of microphytobenthos ranged from 78,556 to 287,898 cells/$cm^2$, reaching a maximum in April and a minimum in July. The diatoms Paralia sulcata, Navicula sp., and Delphines surirella were dominant at all tidal levels over the study period. Dinoflagellates were dominant in July at low shore, and blue-green algae were abundant between July and October at mid shore. In conclusion, species composition and primary production of microphytobenthos exhibited clear seasonal and vertical patterns.

• Journal of Environmental Science International
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• v.21 no.10
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• pp.1275-1286
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• 2012

Coastal marine ecosystem plays important role of spawning and nursery grounds for fisheries resources. Yongil Bay is one of major coastal marine ecosystems, which is located in the southwestern East Sea of Korea. Species composition and abundance of marine organism in the Yongil Bay were investigated by season from March to November 2009. Gill net and pot fisheries were used for survey of pelagic and demersal species composition, and collected 106 species, 67 families, and 7 taxa of fisheries resources from the coastal ecosystem. Species were included 2 species in Ascidiacea, 2 species in Bivalvia, 6 in Cephalopoda, 22 in Crustacea, 5 in Echinodermata, 12 in Gastropoda, and 57 in Pisces. Diversity indices (Shannon index, H') showed seasonal variation with low value of 2.11 in winter, and high value of 2.63 in autumn. Main dominant species were Asterias amurensis, Pleuronectes yokohamae, Siphonalia spadicea fuscolineata, Trachurus japonicas, Sillago japonica, Conger myriaster, Volutharpa ampullaceal, Engraulis japonicus, Asterina pectinifera, and Portunus (Portunus) sanguinolentus that were occupied over 71.5% of total individuals, and 52.9% of wet weight. Seasonal variations of fisheries resources composition were discussed on correlationships with those of environmental factors in the coastal ecosystem of the Yongil Bay in Korea. Those results from this study will provide scientific data and information to develop the ecosystem-based coastal fisheries assessment and management system in Korea.

• The Korean Journal of Malacology
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• v.18 no.1
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• pp.1-8
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• 2002

Seasonal changes in biochemical composition of Crassostrea giggas and Scapharca broughtonii in the Kosong bay and Kangjin bay, southern Korea were studied over 12 months in relation to their habitat. In Crassostrea giggas, protein was high during summer in all experimental station, but lipid and carbohydrate were high during winter, and no clear difference was between experimental station. Glycogen content was sharply decreased during summer, and energy content was low but carbohydrate was high during summer. In Scapharca broughtonii, protein was low, but carbohydrate was high during summer. Lipid was high from February to March, glycogen content was low from June to September. Energy content was low during winter and no clear difference biochemical composition was between experimental station of Scapharca broughtonii.

• Korean Journal of Agricultural Science
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• v.40 no.4
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• pp.289-296
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• 2013

To evaluate seasonal variation in fatty acid composition in broccoli, 12 commercial cultivars of broccoli were grown in spring and fall season at the field of NIHHS, and their floret, leaf and stem parts were used for the fatty acid composition analyses. Among 14 fatty acids detected in broccoli, linolenic, palmitic and linoleic acids were major fatty acids comprising more than 80% of total fatty acids in both the seasons and all the parts. Likewise, stearic and oleic acids were also present in considerable amount while remaining fatty acids; caproic, lauric, myristic, pentadecanoic, palmitoleic, heptadecanoic, arachidic, behenic and lignoceric acids showed their minor compositional ratio. Among the three parts, stem exhibited highest SFAs (49.681% in spring and 50.717% in fall season) compared to MUFA and PUFA, while highest compositional ratio of PUFAs were observed in leaves (62.588% in spring and 68.931% in fall season), which indicates leaves as a good source of health beneficial fatty acids. In contrast, floret part exhibited highest SFA (48.786%) and PUFA (57.518%) in spring and fall seasons, respectively. Major fatty acids; palmitic, linoleic and linolenic acid showed lowest cultivar dependent variation (below 10%) and leaf showed least variation in both the seasons compared to floret and stem. Our results suggest that all the fatty acids are significantly influenced by genotype of cultivars (C), plant parts (P) and growing seasons (S). Among the 14 fatty acids, myristic and palmitic acid showed highest positive or negative correlationship with oleic (r=$0.912^{**}$) and linolenic acid (r=-$0.933^{**}$), respectively. The most abundant fatty acid, linolenic acid, showed either negative or no correlation ship with other fatty acids while palmitic acid, a second major fatty acid, exhibited either positive or negative correlation ship.