Diurnal changes in the bio-optical properties of the phytoplankton in the Alborán Sea (Mediterranean Sea)

The changes in the phytoplankton absorption properties during a diurnal cycle were investigated at one station located in the north-western area of the Alborán Sea. The experiment was performed in spring when the water column was strongly stratified. This hydrological situation permitted the establishment of a deep chlorophyll a (chl a) fluorescence maximum (DFM) which was located on average close to the lower limit of the mixed layer and the nutricline. The relative abundance of pico-phytoplankton (estimated as its contribution to the total chl a) was higher in the surface, however, micro-phytoplankton dominated the community at the DFM level. Chl a specific absorption coefficient (a*(λ)) also varied with optical depth, with a* (the spectrally average specific absorption coefficient) decreasing by 30% at the DFM depth with respect to the surface. A significant negative correlation between the contribution of the micro-phytoplankton to the total chl a and a* was obtained indicating that a* reduction was due to changes in the packaging effect. Below the euphotic layer, a* increased three-fold with respect to the DFM, which agrees with the expected accumulation of accessory pigments relative to chl a as an acclimation response to the low available irradiance. The most conspicuous change during the diurnal cycle was produced in the euphotic layer where the chl a concentration decreased significantly in the afternoon (from a mean concentration of 1.1 μg L⁻¹ to 0.7 μg L⁻¹) and increased at dusk when it averaged 1.4 μg L⁻¹. In addition, a* and the blue-to-red absorption band ratio increased in the afternoon. These results suggest that a*(λ) diurnal variability was due to increase in photo-protective and accessory pigments relative to chl a. The variation ranges of a*(λ) at 675 and 440 nm (the absorption peaks in the red and blue spectral bands, respectively) in the euphotic layer were 0.01–0.04 and 0.02–0.10 m² mg⁻¹ chl a, respectively. Approximately 30% out of this variability can be attributed to the diurnal cycle. This factor should therefore be taken into account in refining primary production models based on phytoplankton light absorption.     

Modeling of coupled tide–wave–surge process in the Yellow Sea

A coupled wave–tide–surge model has been developed in this study in order to investigate the effect of the interactions among tides, storm surges, and wind waves. The coupled model is based on the synchronous dynamic coupling of a third-generation wave model, WAM cycle 4, and the two-dimensional tide–surge model. The surface stress, which is generated by interactions between wind and wave, is calculated by using the WAM model directly based on an analytical approximation of the results using the quasi-linear theory of wave generation. The changes in bottom friction are created by the interactions between waves and currents and calculated by using simplified bottom boundary layer model. In consequence, the combined wave–current-induced bottom velocity and effective bottom drag coefficient were increased in the shallow waters during the strong storm conditions.     

A synchronously coupled tide–wave–surge model of the Yellow Sea

A coupled wave–tide–surge model has been established in this study in order to investigate the effect of tides, storm surges, and wind waves interactions during a winter monsoon on November 1983 in the Yellow Sea. The coupled model is based on the synchronous dynamic coupling of a third-generation wave model, WAM-Cycle 4, and the two-dimensional tide–surge model. The surface stress generated by interactions between wind and waves is calculated using the WAM-Cycle 4 directly based on an analytical approximation of the results obtained from the quasi-linear theory of wave generation. The changes of bottom friction factor generated by waves and current interactions are calculated by using simplified bottom boundary layer model. The model simulations showed that bottom velocity and effective bottom drag coefficient induced by combination of wave and current were increased in shallow waters of up to 50 m in the Yellow Sea during the wintertime strong storm conditions.     

Sediment waves on the South China Sea Slope off southwestern Taiwan: Implications for the intrusion of the Northern Pacific Deep Water into the South China Sea

Using an integrated multi-beam bathymetry, high-resolution seismic profile, piston core, and AMS ¹⁴C dating data set, the current study identified two sediment wave fields, fields 1 and 2, on the South China Sea Slope off southwestern Taiwan. Field 1 is located in the lower slope, and sediment waves within it are overall oriented perpendicular to the direction of down-slope gravity flows and canyon axis. Geometries, morphology, and internal seismic reflection configurations suggest that the sediment waves in field 1 underwent significant up-slope migration. Field 2, in contrast, is located more basinward, on the continental rise. Instead of having asymmetrical morphology and discontinuous reflections as observed in field 1, the sediment waves in field 2 show more symmetrical morphology and continuous reflections that can be traced from one wave to another, suggesting that vertical aggradation is more active and predominant than up-slope migration.Three sediment wave evolution stages, stage 1 through stage 3, are identified in both field 1 and field 2. During stage 1, the sediment waves are built upon a regional unconformity that separates the underlying mass-transport complexes from the overlying sediment waves. In both of these two fields, there is progressive development of the sediment waves and increase in wave dimensions from the oldest stage 1 to the youngest stage 3, even though up-slope migration is dominant in field 1 whereas vertical aggradation is predominant in field 2 throughout these three stages.The integrated data and the depositional model show that the upper slope of the study area is strongly dissected and eroded by down-slope gravity flows. The net result of strong erosion is that significant amounts of sediment are transported further basinward into the lower slope by gravity flows and/or turbidity currents. The interactions of these currents with bottom (contour) currents induced by the intrusion of the Northern Pacific Deep Water into the South China Sea and preexisting wavy topography in the lower slope result in the up-slope migrating sediment waves in field 1 and the contourites as observed from cores TS01 and TS02. Further basinward on the continental rise, turbidity currents are waned and diluted, whereas along-slope bottom (contour) currents are vigorous and most likely dominate over the diluted turbidity currents, resulting in the vertically aggraded sediment waves in field 2.The results from this study also provide the further evidence for the intrusion of the Northern Pacific Deep Water into the South China Sea and suggest that this intrusion has probably existed and been capable of affecting sedimentation in South China Sea at least since Quaternary.     

Vertical structure of the M<Subscript>2</Subscript> tidal current in the Yellow Sea

The vertical structure of the M₂ tidal current in the Yellow Sea is analyzed from data acquired using an acoustic Doppler current profiler. The observed vertical profiles of the M₂ tidal current are decomposed into two rotating components of counter-clockwise and clockwise, and restructured using a simple one-point model with a constant vertical eddy viscosity. The analyzed results show that the internal fictional effect dominates the vertical structure of the tidal current in the bottom boundary layer. In the Yellow Sea, the effect of the bottom friction reduces the current speed by about 20–40% and induces the bottom phase advance by about 15–50 minutes. In the shallower coastal regions, the effects of bottom topography are more prominent on the vertical structure of tidal currents. The vertical profile of the tidal current in summer, when the water column is strongly stratified, is disturbed near the pycnocline layer. The stratification significantly influences the vertical shear and distinct seasonal variation of the tidal current.     

‘NO’ as a conservative tracer in the Weddell Sea

The salinity maximum of the Warm Deep Water advecting into the Weddell Sea lies about 200 m below the temperature maximum and an NO minimum. The NO minimum is horizontally as well as vertically resolved on two sections towards the eastern and southern coast of the Weddell Sea, one towards Cap Norvegia, the other towards the Filchner Ice Shelf, whereas the temperature and salinity maxima are horizontally resolved on the former section only. Thus NO is a valuable complementary tool in studying the boundary current along the coast of the Weddell Sea. The NO signal indicates a non-continuity within the boundary current, as the minimum in the downstream section (less than 480 μmol kg⁻¹ ) is deeper than the upstream one ( more than 490 μmol kg⁻¹). The temperature maximum as well as the NO minimum descend from a depth of about 400 m in the Cap Norvegia section to about 600 m in the Filchner Ice Shelf section, the salinity maximum being correspondingly lowered. A plot of NO vs. salinity shows a continuous mixing line between Warm Deep Water and the freshest part of the Winter Water interval, thus essentially displaying Winter Water as itself lying on a mixing line. This indicates that Warm Deep Water is being advected well into the winter surface layer.     

Variability of Sea Surface Circulation in the Japan Sea

Composite sea surface dynamic heights (CSSDH) are calculated from both sea surface dynamic heights that are derived from altimetric data of ERS-2 and mean sea surface that is calculated by a numerical model. The CSSDH are consistent with sea surface temperature obtained by satellite and observed water temperature. Assuming the geostrophic balance, sea surface current velocities are calculated. It is found that temporal and spatial variations of sea surface circulation are considerably strong. In order to examine the characteristics of temporal and spatial variation of current pattern, EOF analysis is carried out with use of the CSSDH for 3.5 years. The spatial and temporal variations of mode 1 indicate the strength or weakness of sea surface circulation over the entire Japan Sea associated with seasonal variation of volume transport through the Tsushima Strait. The spatial and temporal variations of mode 2 mostly indicate the temporal variation of the second branch of the Tsushima Warm Current and the East Korean Warm Current. It is suggested that this variation is possibly associated with the seasonal variation of volume transport through the west channel of the Tsushima Strait. Variations of mode 3 indicate the interannual variability in the Yamato Basin.     

Hydrocarbons in the Mediterranean Sea, 1974–1975

Hydrocarbons in the Mediterranean Sea were analyzed from 1 m depth during the winter of 1974–1975. Petroleum hydrocarbons averaged from 6.9 to 25.8 μg/l, with the Alboran Sea and the area off Libya having the highest concentrations. The freshest petroleum material was found off Libya and in the Tyrrhenian Sea.Considerable amounts of biologically produced hydrocarbon material were also present (0.8–22.8 μg/l). They could only be identified semi-qualitatively but appeared to be quite similar, with the exception of the material from the Tyrrhenian Sea.     

Oil and fishing — conflict in the North Sea

A programme of research is underway at Aberdeen University on the conflicts arising in the North Sea between the fishing and offshore oil and gas industries. This research note summarizes the work that has been undertaken to date and the main aspects on which future work will concentrate.     

北极海盆的深海热液

从海底地壳开裂处涌出一般带有大量生物的深海热泉的现象已众所周知。一开始在太平洋和大西洋中找到了它们 ,而在 2 0世纪和 2 1世纪交接期印度洋中也发现了热液 ,而后就输到高纬度的北极海区了。在极区盆地中应当有热液已有过报道。例如 ,1 993年 9月 ,俄 德联合北极考察队乘坐“极地”(Polarstern)号破冰船 ,在拉普帖夫海加克利 (Гакке х)海岭东端 (77°45′N、1 2 5° 55′E ,水深 1 990m) ,获得了对研究热液非常有意义的样品 ,证实了在这个海岭上存在着热液活动 ;但是 ,在 2 0 0 1年 ,美国和德国破冰船“健康”(Healy)号和“极…     

渤、黄海海冰的变化和预报结果分析

利用1951—2000年的渤、黄海的海冰资料，用小波分析和最优气候均态法对渤、黄海的海冰冰级进行分析和预测。小波分析结果较好地反映了渤、黄海海冰的变化规律，使对海冰的研究更符合实际情况。这必将有助于研究海冰变化的机理和不同尺度变化的相互作用。最优气候均态法较好地实现了对渤、黄海海冰的预测。此方法在海冰预报中不失为一种可用的方法。     

黄渤海区捕捞结构的研究

根据2010年对黄渤海沿海32个主要渔港、渔村和5家网具生产厂家的实地调查和现场测量资料,结合2009年度三省一市(河北、辽宁、山东、天津)的渔具渔法调查报告以及1983~2009年中国渔业年鉴中记载的捕捞产量分类统计资料,对黄渤海区捕捞结构进行了研究.研究结果表明,黄渤海区主要捕捞品种有30种之多,其中年渔获量超过万吨的有14种鱼类、5种甲壳类、4种头足类、2种海蜇和6种贝类.渔业资源品种的多样性决定了黄渤海区捕捞结构的多样化和多层次的特点,现有9大类19型23式130种网型或作业方式,同时受渔业资源变动的影响,捕捞网具也在变化,不断有旧的渔具消失和新的网具出现.其中,拖网是主要作业方式,贡献率为38.47%~51.79%,且近几年还有上升的趋势;其次为刺网,贡献率从1983年最低时的7.66%逐步上升到目前的30.14%;第三为张网,贡献率从1985年最高时的34.31%下降到目前的10.49%;围网和钓具的贡献率一直较低,均不足4%,其他渔具的贡献率为5.98%~13.30%.目前黄渤海区渔业结构的调整方向应当是减少拖网作业,控制刺网总量,限制张网、陷阱类渔具和地笼,鼓励发展钓渔业     

一次黄海海雾的集合预报试验

基于WRF(Weather Research and Forecasting)模式及其杂合三维变分(Hybird-3DVAR)同化模块,对2006年3月发生的一次大范围黄海海雾进行了集合预报尝试。详细分析了其预报效果,并与决定性预报结果作了比较。研究揭示:集合预报50%概率雾区预报的公正预兆得分(Equitable threat score,ETS)优于决定性预报大约29%;集合预报中加入海温扰动非常必要,对浓雾预报改善作用明显,ETS提高至少10%;在集合预报中混用YSU与MYNN边界层方案的做法,可以降低只使用其中之一可能导致的预报误差。研究表明,借助Hybrid-3DVAR开展黄海海雾的集合预报技术上可行,集合预报将成为黄海海雾数值预报的一种有希望的途径。     

Sea level induced variations in clay mineral composition in the southwestern South China Sea over the past 17,000 yr

Variations in clay mineral composition of sediment cores from the margin and continental slope of the Sunda Shelf (southern South China Sea, SE Asia) covering the past 17,000 yr reflect changing influences of sediment sources together with clay mineral partitioning processes in shallow waters. We identify the deglacial sea level rise as the principal factor driving these changes. During the late glacial, high values of kaolinite are interpreted to reflect a higher contribution of clays from soils that have formed on the exposed Sunda Shelf and in the southern archipelagos of Indonesia. At this time core sites were located in close proximity to the mouths of the Sunda Shelf palaeo-drainage systems on the emerged shelf (“Sundaland”). The progressive landward displacement of the coastline and breakdown of these vast drainage systems during deglaciation led to a decrease in influence of the kaolinite-rich southern sources. When the coastline had retreated closely to its present-day position in mid-Holocene times, the former dominance of southern sources was replaced by a stronger influence of illite-rich sources (e.g. Borneo). The overriding control of sea level changes on the clay mineral distribution patterns precludes a definite climatic interpretation of clay mineral data in terms of climatic/monsoonal changes in such highly dynamic sedimentary environment.     

Response of the Baltic Sea to climate change—theory and observations

The dynamics controlling the response of the Baltic Sea to changed atmospheric and hydrologic forcing are reviewed and demonstrated using simple models. The response time for salt is 30 times longer than for heat in the Baltic Sea. In the course of a year, the Baltic Sea renews most of its heat but only about 3% of its salt. On the seasonal scale, surface temperature and ice-coverage are controlled by the atmospheric conditions over the Baltic Sea as demonstrated by e.g. the strong inter-annual variations in winter temperature and ice-coverage due to variations in dominating wind directions causing alternating mild and cold winters. The response of surface temperature and ice-coverage in the Baltic Sea to modest climate change may therefore be predicted using existing statistics. Due to the long response time in combination with complicated dynamics, the response of the salinity of the Baltic Sea cannot be predicted using existing statistics but has to be computed from mechanistic models. Salinity changes primarily through changes in the two major forcing factors: the supply of freshwater and the low-frequency sea level fluctuations in the Kattegat. The sensitivity of Baltic Sea salinity to changed freshwater supply is investigated using a simple mechanistic steady-state model that includes baroclinic geostrophic outflow from the Kattegat, the major dynamical factor controlling the freshwater content in the Kattegat and thereby the salinity of water flowing into the Baltic Sea. The computed sensitivity of Baltic Sea surface salinity to changes of freshwater supply is similar to earlier published estimates from time-dependent dynamical models with higher resolution. According to the model, the Baltic Sea would become fresh at a mean freshwater supply of about 60 000 m³ s⁻¹, i.e. a 300% increase of the contemporary supply. If the freshwater supply in the different basins increased in proportion to the present-day supply, the Bothnian Bay would become fresh already at a freshwater supply of about 37 000 m³ s⁻¹ and the Bothnian Sea at a supply of about 45 000 m³ s⁻¹. The assumption of baroclinic geostrophic outflow from the Kattegat, crucial for the salinity response of the Baltic Sea to changed freshwater supply, is validated using daily salinity profiles for the period 1931–1977 from lightship Läsö Nord.     

东海大陆架区海胆分类研究

海胆是重要的大型海洋底栖生物类群之一，某些海胆既是人工养殖对象，又是捕捞对象。因此，对海胆进行分类研究，摸清其地理分布特点，对合理利用海胆资源以及生物多样性研究都可提供基本科学依据。 对我国海胆的分类学研究始于1948年，当时张凤瀛先生对青岛的6种海胆进行了描述(张凤瀛，1948)。1957年张凤瀛和吴宝铃先生对广东沿海的37种海胆进行了研究(张凤瀛等，1957)。张凤瀛先生等1964年在《中国动物图谱，棘皮动物门》中记录了30种我国常见海胆(张凤瀛等，1964)。廖玉麟先生在20世纪70年代对西沙群岛的棘皮动物进行了分类研究，其中包括26种海胆(廖玉麟，1978)。 中国科学院海洋研究所于1958-1982年在东海大陆架进行过多次的综合性海洋调查。调查范围:26°~33°45′N，122°~129°E。该海域的底栖生物种类繁多，多样性丰度高。本文对中国科学院海洋研究所历年采自东海大陆架的海胆进行了较系统的研究，共包括21种，隶属于7目、11科、17属。其中有11种在我国是首次记录。名录如下，有*者为新记录。     

Regularities of C<Subscript>org</Subscript> distribution in bottom sediments of the Russian part of the Sea of Azov

The principal regularities were ascertained for the spatiotemporal distribution of organic carbon in the water and bottom sediments of the Russian part of the Sea of Azov. The relationships between allo- and autochthonous organic matter in water and bottom sediments from different parts of the sea aquatic area were found. The behavior of organic carbon in the water-bottom sediments system was characterized as the effect of the variability of hydrochemical, biological, and hydrological factors ad processes.     

渤海海峡跨海通道建设对环渤海物流系统影响分析

跨渤海海峡运输通道的建设是我国21世纪初规划的一项世界级工程,其建成将为中国,尤其是环渤海区域带来巨大的影响,其中最直接的是对物流系统的影响.文章首先介绍环渤海区域物流系统格局现状和跨海通道的建设情况,通过对比建设前后的区域物流体系改变情况,分析跨渤海海峡通道建成后,环渤海物流系统的发展演变趋势,并提出相应的对策建议,以最大地发挥跨海通道的积极物流辐射效应.