The Effect of the Irrigated Gudeuljang Paddy System on Biodiversity on Cheongsan-do (“island”)

This study has been conducted to identify the characteristics of the biodiversity promoted and maintained by gudeuljang paddy field. For this purpose, a literature review was used to identify the distribution of gudeuljang paddy field on Cheongsan-do. Based on the results of the review, a target area was selected to conduct an investigation of the flora of the vascular plants and a phytosociological examination, which included general farmlands and neighboring areas, was made for comparison. As a result of the study, we were able to identify the differences between the type of gudeuljang paddy field that uses continuous irrigation and other types of land use. We found that the unique physical structure for water passage found in gudeuljang paddy fields with continuous irrigation is more effective in promoting biodiversity than the other types of land use in this area. In conclusion, the presence of gudeuljang paddy fields on Cheongsan-do contributes more to the creation of an appropriate biohabitat than it detracts from such a creation. Also, the presence of gudeuljang paddy fields is significant in that it exercises positive influence on the promotion of biodiversity, such as propagation of species, and the connection of habitats in adjacent forest, village, and farm lands. Our result shows that the maintenance and preservation of gudeuljang paddy fields on Cheongsan-do plays a crucial part in the preservation and maintenance of the biodiversity for vegetation that grows among rocks and in adjacent forest areas.     

集合同化方法在黄海海域海表面温度同化中的应用

The effects of sea surface temperature(SST) data assimilation in two regional ocean modeling systems were examined for the Yellow Sea(YS). The SST data from the Operational Sea Surface Temperature and Sea Ice Analysis(OSTIA) were assimilated. The National Marine Environmental Forecasting Center(NMEFC) modeling system uses the ensemble optimal interpolation method for ocean data assimilation and the Kunsan National University(KNU) modeling system uses the ensemble Kalman filter. Without data assimilation, the NMEFC modeling system was better in simulating the subsurface temperature while the KNU modeling system was better in simulating SST. The disparity between both modeling systems might be related to differences in calculating the surface heat flux, horizontal grid spacing, and atmospheric forcing data. The data assimilation reduced the root mean square error(RMSE) of the SST from 1.78°C(1.46°C) to 1.30°C(1.21°C) for the NMEFC(KNU) modeling system when the simulated temperature was compared to Optimum Interpolation Sea Surface Temperature(OISST) SST dataset. A comparison with the buoy SST data indicated a 41%(31%) decrease in the SST error for the NMEFC(KNU) modeling system by the data assimilation. In both data assimilative systems, the RMSE of the temperature was less than 1.5°C in the upper 20 m and approximately 3.1°C in the lower layer in October. In contrast, it was less than 1.0°C throughout the water column in February. This study suggests that assimilations of the observed temperature profiles are necessary in order to correct the lower layer temperature during the stratified season and an ocean modeling system with small grid spacing and optimal data assimilation method is preferable to ensure accurate predictions of the coastal ocean in the YS.     

Intermediate Waters in the East/Japan Sea

Properties of the intermediate layer in the East/Japan Sea are examined by using CREAMS data taken mainly in summer of 1995. Vertical profiles of potential temperature, salinity and dissolved oxygen and relationships between these physical and chemical properties show that the dissolved oxygen concentration of 250 μmol/l, roughly corresponding to 0.6°C at the depth of about 400 db, makes a boundary between intermediate and deep waters. Water colder than 0.6°C has a very stable relationship between potential temperature and salinity while salinity of the water warmer than 0.6°C is lower in the western Japan Basin than that in the eastern Japan Basin. The low salinity water with high oxygen corresponds to the East Sea Intermediate Water (ESIW; <34.06 psu, >250 μmol/l and >1.0°C) which was previously identified by Kim and Chung (1984) and the high salinity water with high oxygen found in eastern Japan Basin is named as the High Salinity Intermediate Water (HSIW; >34.07 psu, >250 μmol/l and >0.6°C). Spatial distribution of salinity and acceleration potential on the surface of σ_ϑ = 27.2 kg/m³ shows that the ESIW prevailing in the western Japan Basin is transported eastward by a zonal flow along the polar front near 40°N and a cyclonic gyre in the eastern Japan Basin is closely related to the HSIW. This revised version was published online in August 2006 with corrections to the Cover Date.     

Geochemistry and Petrogenesis of Neoarchean Metamorphic Mafic Rocks in the Wutai Complex

Neoarchean metamorphic mafic rocks in the lower and the middle Wutai Complex mainly comprise metamorphic gabbros, amphibolites and chlorite schists. They can be subdivided into three groups according to chondrite normalized REE patterns. Rocks in Group #1 are characterized by nearly flat REE patterns （Lan/Ybn=0.86-1.3）, the lowest total REEs （29-52 ppm）, and weak negative to positive Eu anomalies （Eun/Eun=0.84-1.02）, nearly flat primitive mantle normalized patterns and strong negative Zr（Hf） anomalies. Their geochemical characteristics in REEs and trace elements are similar to those of ocean plateau tholeiite, which imply that this group of rocks can represent remnants of Archean oceanic crust derived from a mantle plume. Rocks in Group #2 are characterized by moderate total REEs （34-116 ppm）, LREE-enriched （Lan/Ybn=1.76-4.34） chondrite normalized REE patterns with weak Eu anomalies （Eun/Eun=0.76-1.16）, and negative Nb, Ta, Zr（Hf）, Ti anomalies in the primitive mantle normalized spider diagram. The REE and trace element characteristics indicate that they represent arc magmas originating from a sub-arc mantle wedge metasomatized by slab-derived fluids. Rocks in Group #3 are characterized by the highest total REEs （61-192 ppm）, the strongest LREEs enrichment （Lan/Ybn=7.12-16） with slightly negative Eu anomalies （Eun/Eun=0.81-0.95） in the chondrite normalized diagram. In the primitive mantle normalized diagram, these rocks are characterized by large negative anomalies in Nb, Ta, Ti, negative to no Zr anomalies. They represent arc magmas originating from a sub-arc mantle wedge enriched in slab-derived melts. The three groups of rocks imply that the formation of the Neoarchean Wutai Complex is related to mantle plumes and island-arc interaction.     

Lagrangian Approach for a New Separation Index of the East Korea Warm Current

Ocean Science Journal - In this study, a separation index for the East Korea Warm Current (EKWC) is defined by Lagrangian particle tracking using surface geostrophic currents based on...     

Integration of the nuclease protection assay with sandwich hybridization (NPA-SH) for sensitive detection of Heterocapsa triquetra

Microalgae are photosynthetic microorganisms that function as primary producers in aquatic ecosystems. Some species of microalgae undergo rapid growth and cause harmful blooms in marine ecosystems. Heterocapsa triquetra is one of the most common bloom-forming species in estuarine and coastal waters worldwide. Although this species does not produce toxins, unlike some other Heterocapsa species, the high density of its blooms can cause significant ecological damage. We developed a H. triquetra species-specific nuclease protection assay sandwich hybridization (NPA-SH) probe that targets the large subunit of ribosomal RNA (LSU rRNA). We tested probe specificity and sensitivity with five other dinoflagellates that also cause red tides. Our assay detected H. triquetra at a concentration of 1.5×10⁴ cells/mL, more sensitive than required for a red-tide guidance warning by the Korea Ministry of Oceans and Fisheries in 2015 (3.0×10⁴ cells/mL). We also used the NPA-SH assay to monitor H. triquetra in the Tongyeong region of the southern sea area of Korea during 2014. This method could detect H. triquetra cells within 3 h. Our assay is useful for monitoring H. triquetra under field conditions.     

Seasonal Variation of Submesoscale Flow Features in a Mesoscale Eddy-dominant Region in the East Sea

Seasonal changes in the distribution of submesoscale (SM) flow features were examined using a fine-resolution numerical simulation. The SM flows are expected to be strong where mesoscale (MS) eddies actively develop and also when the mixed layer depth (MLD) is deep due to enhanced baroclinic instability. In the East Sea (ES), MS eddies more actively develop in summer while the MLD is deeper in winter, which provided the motivation to conduct this study to test the effects of MLD and MS eddies on the SM activity in this region. Finite-scale Liapunov exponents and the vertical velocity components were employed to analyze the SM activities. It was found that the SM intensity was marked by seasonality: it is stronger in winter when the mixed layer is deep but weaker in summer - despite the greater eddy kinetic energy. This is because in summer the mixed layer is so thin that there is not enough available potential energy. When the SM activity was quantified based on parameterization, (MLD × density gradient), it was determined that the seasonal variation of MLD plays a more important role than the lateral density gradient variation on SM flow motion in the ES.     

Local advective mechanism for interdecadal variability in circulations driven by constant surface heat fluxes in idealized basins

Idealized numerical experiments with a depth level coordinate ocean circulation model (GFDL MOM3) have been conducted to investigate the structure of interdecadal variability from thermally driven circulations. The model oceans are driven by steady surface heat fluxes in the absence of surface wind stresses. Interdecadal variability is observed, with characteristics similar to those reported in many previous studies. To explain the nature of the variability we propose a new mechanism based on two local horizontal advective processes. This overcomes the limitations in previous theories based on the interplay between global properties such as zonal and meridional temperature gradients and overturning. One of the two advective processes is a zonal flow anomaly induced by a temperature anomaly along the northern wall through geostrophy southward of the temperature anomaly. A cold (warm) anomaly along the northern wall produces a positive (negative) zonal flow anomaly that induces a warm (cold) temperature anomaly by enhancing (weakening) warm advection from the western boundary along the path of the zonal flow anomaly. The temperature and flow anomalies are transported toward the eastern boundary by the mean eastward zonal flow. When the positive (negative) zonal flow anomaly that accompanies the warm (cold) temperature anomaly encounters the eastern wall, a downwelling (upwelling) anomaly is produced. To dissipate the vorticity due to this downwelling (upwelling) anomaly, a northward (southward) flow anomaly, which is another advective process governing the variability, is generated within a frictional boundary layer next to the eastern wall. The northward (southward) flow anomaly circulates cyclonically along the perimeter of the basin while enhancing (reducing) warm advection. So does the warm (cold) temperature anomaly carried to the eastern wall by the mean zonal flow while pushing the cold (warm) anomaly that produced the positive (negative) zonal flow anomaly westward and initiating the other half cycle of the variability. During the anomalous downwelling or upwelling, the available potential energy stored in the anomalous density field is released to maintain the variability. Thus, neither barotropic nor baroclinic instability supplies energy for the variability. The anomalous vertical velocity is stronger along the northern boundary and the northern part of the eastern boundary. A shallow continental slope added along those boundaries prohibits the anomalous vertical motion and weakens variability very effectively, while one along the western boundary does not.     

Comparisons of Net Heat Flux Data Sets Over the Western North Pacific

Ocean Science Journal - This study focuses on the intercomparisons of 22 net heat flux (NHF) data sets in terms of mean, linear trend, and interannual variability during 1993–2007 over the...