Temporal population dynamics of dinoflagellate Prorocentrum minimum in a semi-enclosed mariculture pond and its relationship to environmental factors and protozoan grazers

The ecological processes and interrelationships between protists,either autotrophic or heterotrophic,and environmental factors in mariculture ponds are largely unknown.This study investigated the temporal dynamics of potentially harmful dinoflagellate,Prorocentrum minimum (Pavillard) Schiller,and its relationship to physico-chemical factors and protozoan grazers over a complete cycle in a semi-enclosed shrimp-farming pond near Qingdao,Northern China.P.minimum occurred frequently in low numbers from June to ...     

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.     

Physiological differences in the growth and maturation of Eisenia bicyclis and Ecklonia cava gametophytes in Korea

The objective of this study was to examine the ef fects of temperature and light intensity on growth of female gametophytes of Eisenia bicyclis and Ecklonia cava and responses of these female gametophytes to Fe addition and daylength. Female gametophytes of each species were cultured at four temperatures(10, 15, 20, and 25°C) and under a combination of four light intensities(10, 20, 40, and80 μmol photons/(m 2 ·s)) with two temperatures(15 and 20°C for E i. bicyclis; 20 and 25°C for E c. cava) to clarify their optimal growth conditions. Growth and maturation of female gametophytes of these two species under a combination of five Fe-EDTA concentrations(0, 1, 2, 4, and 8 μmol/L) and three daylengths(10,12, and 14 h) were also examined. The growth of E i. bicyclis gametophyte was maximal at approximately15–20°C, 20 μmol photons/(m 2 ·s), Fe-EDTA concentration of 8 μmol/L and daylengths of 12–14 h. While E c. c ava gametophytes showed optimal growth at approximately 20–25°C, 20 μmol photons/(m 2 ·s), FeEDTA concentration of 8 μmol/L and daylength of 14 h. Maturation of gametophytes was enhanced at Fe-EDTA concentration of 4 μmol/L for E i. bicyclis and at 2 μmol/L for E c. c ava. In conclusion, optimal growth temperatures and Fe-EDTA concentrations for maturation of E i. bicyclis and E c. c ava gametophytes were dif ferent. Higher optimal growth temperature for E c. c ava gametophytes may contribute to its wider geographical distribution compared to E i. bicyclis which has restricted habitats in Korea. This suggests that addition of Fe ion could be used to recover beds of these two species in barren grounds of Korea.     

Thermal histories of Cretaceous basins in Korea: Implications for response of the East Asian continental margin to subduction of the Paleo‐Pacific Plate

Thermal histories of Cretaceous sedimentary basins in the Korean peninsula have been assessed to understand the response of the East Asian continental margin to subduction of the Paleo‐Pacific (Izanagi) Plate. The Izanagi Plate subducted obliquely beneath the East Asian continent during the Early Cretaceous and orthogonally in the Late Cretaceous. First, the Jinan Basin, a pull‐apart basin, was studied by illite crystallinity and apatite fission‐track analyses. Analytical results indicate that Jinan Basin sediment was heated to a maximum temperature of approximately 287°C by burial. The sediment experienced two cooling episodes during ca 95–80 Ma and after ca 30 Ma, with a quiescent period between them. A similar cooling pattern is recognized in the Gyeongsang Basin, the largest Cretaceous basin in Korea. The Jinan and Gyeongsang Basins were cooled mainly by exhumation between ca 95 and 80 Ma, but the former was exhumed slightly earlier than the latter by transpressional force due to the subduction direction change of the Izanagi Plate. Comparison of thermal history of Korean Cretaceous basins with those of granitoids in northeastern China and the accretionary complexes in southwestern Japan reveals that the Upper Cretaceous regional exhumation of the East Asian continental margin including the Korean peninsula during ca 95–80 Ma was facilitated by the subduction of the Izanagi–Pacific ridge, which migrated northeastwards with time, resulting in the end of regional exhumation at ca 80 Ma in this region.     

日本海西部大陆坡自生碳酸盐的特征与成因

对日本海西部大陆坡沉积物柱状样中的自生碳酸盐样品进行了X射线衍射、扫描电镜、地球化学和碳氧同位素组成的系统研究。X射线衍射和扫描电镜分析结果表明,碳酸盐主要组成矿物为颗粒状自生高镁方解石微晶,放射状自生文石微晶仅在一个层位出现。结合碳酸盐的地球化学组成,认为研究区碳酸盐来自于富Ca2+、Mg2+和HCO3-流体的沉淀。中度亏损的13C(-33.85‰～-39.53‰)表明碳来自于甲烷的厌氧氧化,同时,这也是研究区海底存在甲烷冷泉的重要证据。重氧同位素比值(5.28‰～5.31‰)则指示着富18O流体来源,而该流体应源于天然气水合物的分解。综上可知,研究区碳酸盐来自于研究区甲烷冷泉上升流的沉淀,指示着海底更深处天然气水合物的存在与分解。     

Numerical simulation of a short flexible pipe subject to forced motion and vortex-induced vibration

A series of numerical simulations about a small scale(aspect ratio:63.2) flexible pipe undergoing forced harmonious oscillation and vortex-induced vibration(VIV) have been taken into account.The wake hydrodynamics and pipe deformation were accomplished by ANSYS MFX solution strategy designed for fluid-structure interaction(FSI) problem with well-performed LES model.The configuration of structured mesh,multi-domain design,different mesh stiffness admeasured by User Fortran ensured that the numerical task was competent to deal with large deformation related to this case.The introduction of instantaneous amplitude definition and modeless component decomposition method(Chen and Kim,2008) was helpful to reveal much more information from modal analysis.Most results from numerical simulation are generally consistent with those from model test(Choi and Hong,2000) via the comparison between them.As supplementary to model test,visualization of the vortex wake was also provided.It has been proved that the forced oscillation doesn't only excite a complicated dumbbell-like wake pattern around the outer thimble,but also results in inner flow inside the PVC pipe.The velocity of the inner flow increases with the frequency of forced oscillation.     

Two climate factors in May that affect Korean rainfall in September

This study revealed a high positive correlation between rainfall in Korea during September and the trade wind (TW)/Arctic Oscillation (AO) index in May that combines two climate factors, low-level TWs and the AO. This correlation was identified on the basis of the difference in the 850 hPa streamline analysis between the positive and negative phases selected using the combined TW/AO index. In May, the spatial pattern of the anomalous pressure systems is similar to that in the positive AO phase. These anomalous pressure systems continue in June to August (JJA) and September, but the overall spatial distribution shifts a little to the south. Particularly in September, a huge anomalous anticyclone centered over the southeast seas of Japan strengthens in most of the western north Pacific region and supplies a large volume of warm and humid air to the region near Korea. This characteristic is confirmed by the facts that during the positive TW/AO phase, the subtropical western north Pacific high (SWNPH) is more developed to the north and that the continuous positioning of the upper troposphere jet over Korea from May to September strengthens the anomalous upward flow, bringing warm and humid air to all layers. These factors contribute to increasing September rainfall in Korea during the positive TW/AO phase. Because the SWNPH develops more to the north in the positive phase, tropical cyclones tend to make landfall in Korea frequently, which also plays a positive role in increasing September rainfall in Korea.The above features are also reflected by the differences in average rainfall between the six years that had the highest May Ni o 3.4 indices (El Ni o phase) and the six years that had the lowest May Ni o 3.4 indices (La Ni a phase).     

1998年南海夏季风爆发过程中副热带高压减弱的诊断分析

1998年南海夏季风爆发于5月21日。利用NCEP再分析资料,用Zwack-Okossi涡度方程诊断分析引起季风爆发前后南海-西太平洋副热带反气旋脊迅速减弱的物理因子,结果表明:在夏季风爆发前,华东-华南沿岸附近高空槽前的正涡度平流区随高空槽的东南移动向南海和菲律宾中部附近地区推进;正涡度平流是引起上述地区850 hPa气旋性涡度增大的最主要的物理因子,其次是暖平流。在夏季风爆发后,潜热加热项的作用迅速增大至与正涡度平流项大小相当,这两项是引起区域平均气旋性涡度增加的最主要的物理因子;它们和暖平流项一起抵偿了辐散项和绝热项的负贡献,令季风区的气旋性涡度得以发展/维持。因此,正涡度平流是直接导致南海-西太平洋副热带反气旋脊迅速减弱最重要的物理因子。     

Observational Diagnosis of Cloud Phase in the Winter Antarctic Atmosphere for Parameterizations in Climate Models

The cloud phase composition of cold clouds in the Antarctic atmosphere is explored using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instruments for the period 2000--2006. We used the averaged fraction of liquid-phase clouds out of the total cloud amount at the cloud tops since the value is comparable in the two measurements. MODIS data for the winter months (June, July, and August) reveal liquid cloud fraction out of the total cloud amount significantly decreases with decreasing cloud-top temperature below 0oC. In addition, the CALIOP vertical profiles show that below the ice clouds, low-lying liquid clouds are distributed over ～20% of the area. With increasing latitude, the liquid cloud fraction decreases as a function of the local temperature. The MODIS-observed relation between the cloud-top liquid fraction and cloud-top temperature is then applied to evaluate the cloud phase parameterization in climate models, in which condensed cloud water is repartitioned between liquid water and ice on the basis of the grid point temperature. It is found that models assuming overly high cut-offs (》-40oC) for the separation of ice clouds from mixed-phase clouds may significantly underestimate the liquid cloud fraction in the winter Antarctic atmosphere. Correction of the bias in the liquid cloud fraction would serve to reduce the large uncertainty in cloud radiative effects.