Seasonal variation of sedimentary processes in a semi-enclosed bay: Hampyong bay,Korea

Multi-annual sedimentological observations on tidal-flat sediments were carried out in Hampyong Bay, southeastern Yellow Sea, to infer the budget of modern muddy sediments in the bay. Sedimentation rates over a four-year period show contrasting types of seasonal sedimentary cycles occurring in the tidal flats within the elongated bay. Both sides of the bay are largely sheltered from winter waves, resulting in surface mud deposition during winter and erosion during summer. In contrast, tidal flats along the head of the bay are influenced by winter waves, resulting in a reversed trend where erosion occurs during winter and deposition during summer. Tidal flats near the bay-mouth, however, show a sedimentary cycle disrupted by the construction of sea walls undergoing consistent erosion throughout the observational period. The shoreline artificially straightened seems to cause tidal currents to bypass the tidal flat and hence to be much stronger. These differences in sedimentary cycles suggest the critical importance of the orientation of tidal flats relative to the propagating direction (from N–NW) of the monsoon winter-storm waves on the tidal-flat sedimentation in the eastern coastal area of the Yellow Sea. The preliminary budget estimation for the tidal-flat mud suggests that the tidal flats in Hampyong Bay are subject to the slight but consistent erosion as a whole.     

Les flotilles de pêche de l'Union Européenne dans le golfe de Gascogne vues du ciel

Regular flights over the Bay of Biscay by the French Customs Air Service, have enabled us to record more precisely, from 1989 to 1995, the geographical locations of French and other European Community (EU) fishing boats. Data showed three main ‘métiers’ within the Bay of Biscay fishing fleet: French and Spanish bottom trawlers (61 %), French gill-netters and Spanish longliners. More than 80 % of gill-netters worked inside the territorial sea (12 nautical miles) and 60 % of them worked south of Noirmoutier (47°N). Longliners moved according to the seasons, from the edge of the continental shelf to the 50–100 m sounding lines. Since they work at night, only few pelagic trawlers have been recorded (records being made in daylight). The potters, liners and other small ‘métier’ boats of the bay were only located along the coast. The position of the French boats' positions according to their registration district showed that most boats worked close to their landing ports and that the overlap is small between the areas of two neighbouring fleets. Further analysis of the spatial distribution of boats in the French EEZ showed that Spanish boats were mainly recorded in the southern part of the Bay of Biscay, and that most were Basque. Belgian and Dutch beam trawlers fished their quota of sole off the ‘Pertuis Charentais’, the Gironde estuary and the ‘bassin d'Arcachon’. The 100 m sounding line appeared to constitute a demarcation line between the major fraction of the French fleet and other EU fishing boats. Although some fishing areas were only visited by boats practising a particular ‘métier’, others were coveted by everybody and, consequently, were areas with the most serious risk of conflicts.     

胶州湾浮游植物粒级结构及其时空变化

基于2003—2010年间对胶州湾分粒级叶绿素a浓度的连续观测,系统研究了胶州湾浮游植物粒级结构的季节变化、年际变化及长期变化特征。结果表明,胶州湾表层浮游植物粒级组成以小型和微型浮游植物为主,其浓度由东北部和北部向湾中间及湾外逐渐递减。不同区域分粒级叶绿素a浓度的季节与年际变化规律相似。小型和微型浮游植物表现出明显的双峰型季节变化,小型浮游植物的高峰值通常出现在冬季,而微型浮游植物则出现在夏季。长期变化结果表明,冬季小型浮游植物所占比例自90年代起表现为增加的趋势,而夏季的变化规律与冬季相反,自1998年开始,小型浮游植物所占比例下降,微型浮游植物比例有所上升。春季和秋季小型和微型浮游植物的贡献率没有表现出明显的升高或降低趋势,但微微型浮游植物的贡献率在2000年之后显著低于2000年之前。统计分析结果表明,温度、营养盐浓度与结构是影响胶州湾浮游植物粒级结构变动的重要因素。     

孟加拉湾及其邻近海域海表日增温的季节变化特征及其机制研究

利用1998―2007年Seaflux资料结合太阳短波辐射及海面风场数据,分析了孟加拉湾海表日增温（Diurnal Warming of Sea Surface Temperature, dSST）的季节变化特征及其形成机制。结果显示,在赤道海域（5.0°N以南）,dSST以年周期变化为主并呈现12月至次年5月高、6—11月低的单峰结构,在湾内（5.0°N以北）,dSST则表现出显著的半年周期变化而呈现独特的春、秋季高,夏、冬季低的双峰结构。dSST空间分布形态春季呈湾中部高、四周低的态势;秋季湾口较低、湾内及赤道海域较高;夏、冬季形态基本一致均呈赤道高、湾内低的格局,但夏、冬季湾内高值中心略有不同,分别位于斯里兰卡岛东北部近海及湾西边界区。进一步分析表明,海面风速对整个研究海域的影响均较为重要,因此决定了dSST空间分布形态的季节变化。太阳短波辐射对湾内dSST季节变化的影响也较为重要,但在湾口以南至赤道大部分海域的影响较弱。     

Seasonal response of surface wind to SST perturbation in the Northern Hemisphere

The seasonal response of surface wind speed to sea surface temperature (SST) change in the Northern Hemisphere was investigated using 10 years (2002-2011) high-resolution satellite observations and reanalysis data. The results showed that correlation between surface wind speed perturbations and SST perturbations exhibits remarkable seasonal variation, with more positive correlation is stronger in the cold seasons than in the warm seasons. This seasonality in a positive correlation between SST and surface wind speed is attributable primarily to seasonal changes of oceanic and atmospheric background conditions in frontal regions. The mean SST gradient and the prevailing surface winds are strong in winter and weak in summer. Additionally, the eddy-induced response of surface wind speed is stronger in winter than in summer, although the locations and numbers of mesoscale eddies do not show obvious seasonal features. The response of surface wind speed is apparently due to stability and mixing within the marine atmospheric boundary layer (MABL), modulated by SST perturbations. In the cold seasons, the stronger positive (negative) SST perturbations are easier to increase (decrease) the MABL height and trigger (suppress) momentum vertical mixing, contributing to the positive correlation between SST and surface wind speed. In comparison, SST perturbations are relatively weak in the warm seasons, resulting in a weak response of surface wind speed to SST changes. This result holds for each individual region with energetic eddy activity in the Northern Hemisphere.     

Spatial distributions and seasonal variations of particulate phosphorus in the Jiaozhou Bay in North China

Based on the measurements of particulate phosphorus(PP) in the Jiaozhou Bay from May 2003 to April 2004,the spatial distribution,seasonal variation and biogeochemical characteristics of PP were investigated to understand the fates and roles of phosphorus in the Jiaozhou Bay ecosystem.The concentration of the total PP ranged from 0.07 to 2.09 μmol/dm3.The concentration of POP was from 0.01 to 1.83 μmol/dm3,with an average of 0.32 μmol/dm3,which accounted for 49.6% in total PP.The concentration of PIP was fro...     

A new bathyphotometer for bioluminescence measurements on the Armorican continental shelf (northeastern Atlantic)

A new bathyphotometer has been developed by the Oceanographic Laboratory of the French Naval Academy which has performed a series of in situ bioluminescence measurements since 1994. It is used as an additional probe to a Seabird ® CTD. It measures planktonic bioluminescence. It is associated with a SeaTech ® fluorometer. The Armorican shelf has particularly been investigated since July 1994. Results obtained in January and April 1995 off Brittany (France), at the entrance to the Bay of Douarnenez and in the northern Bay of Biscay are presented as examples. A method to separate the bioluminescence background from sharp peaks is presented. The strength of bioluminescence signals was related to seasonal planktonic biomass fluctuations, low in winter, higher in spring.     

2009年湛江湾叶绿素a分布及其与主要环境因子的关系

2009-02—2009-11分4个季度调查了湛江湾叶绿素a的时空分布,并分析了其与主要环境因子的关系。结果表明,湛江湾海域叶绿素a变化范围为0.35～21.52mg/m3,年平均值4.47mg/m3;全海域叶绿素a呈现夏季(6.50mg/m3)>冬季(4.75mg/m3)>春季(3.58mg/m3)>秋季(3.01mg/m3)的季节变化模式;水平分布上,冬季的叶绿素a呈现由南三岛附近海域(即断面2和3)向外海和沿岸递减,春季、夏季和秋季呈现由外海向沿岸递减,年均值呈现由外海向沿岸递减的分布特征。主成分分析显示,湛江湾海域叶绿素a与pH、盐度呈极显著的正相关,与氨氮、硝氮、硅酸盐、磷酸盐和无机氮呈极显著负相关。以表征的叶绿素a为标准的水体营养状况评价结果显示湛江湾海域多为中营养或贫营养状态,与以营养盐和化学耗氧量为标准的评价结果不一,故湛江湾的水体营养状况评价需要综合多个因子考虑。     

福建东山湾浮游动物的种类组成和分布特点

1981年7月至1982年6月(每月1次)的周年调查结果表明:福建东山湾浮游动物的种类组成较丰富,已鉴定有176种,其中,暖水种占大多数;以暖水种和暖温带种为优势,分别在夏季和冬季形成总生物量高峰;阶段性浮游幼虫,特别是短尾类溞状幼虫等在夏季总生物量高峰中占有重要地位,以及多样性指数和均匀度的季节变化较显著等,显示了亚热带河口-港湾区浮游动物生态的基本特点。此外,东山湾浮游动物总生物量、种类数及多样性指数等的平面分布规律都较明显。     

Multitime scale variations of sea surface temperature in the China seas based on the HadISST dataset

The variability of the sea surface temperature(SST) in the China seas has been studied in seasonal,interannual and interdecadal scales based on the monthly data of HadISST spanning from 1870 to 2007. The main results obtained are SST in the China offshore changes most actively at the seasonal scale with the intensity diminishing from north to south,as the temperature differences between summer and winter reaching 17 and 4 C in the northern and southern areas,respectively. Moreover,seasonal variation near the coastal regions seems relatively stronger than that far from the coastline;significant interannual variations are detected,with the largest positive anomaly occurring in 1998 in the overall area. But as far as different domains are concerned,there exists great diversity,and the difference is also found between winter and summer. Differed from the seasonal variations,where the strongest interannual variability takes place,resides to the south of that of the seasonal ones in the northern section,nevertheless in the South China Sea,the most significant interannual variability is found in the deep basin;interdecadal changes of summer,winter and annual mean SST in different domains likewise present various features. In addition,a common dominant warming in recent 20 a are found in the overall China offshore with the strongest center located in the vicinity of the Changjiang Estuary in the East China Sea,which intensifies as high as 1.3 C during the past 130 a.     

“21世纪海上丝绸之路”风能资源时空变化评估

利用1979—2021 年的 ERA5 再分析资料,采用经验正交函数分解法、Mann-Kendall 趋势检验法等统计方法,对“21 世纪海上丝绸之路”相关海区的海表风场与风能密度的空间分布特征、季节变化特征以及长期变化趋势进行分析。结果表明：(1)研究海域风能密度在不同季节表现出很大的空间差异,夏季的阿拉伯海和孟加拉湾,冬季的中国南海,以及全年的热带南印度洋风能资源都极为丰富。(2)研究时段内,中国南海北部及附近海域、阿拉伯海西部、孟加拉湾西部以及热带西北印度洋风能密度等级整体较高。(3)研究海域的风能密度以年变化特征为主,其中中国南海风能密度的季节变幅最大且在春、秋两季表现出明显的转换特征。(4)在研究海区中,结合水深条件与风能密度时空变化特征的评估结果,可以重点关注台湾海峡、吕宋海峡、中南半岛东南沿海、阿拉伯海西部近岸海域及热带西北印度洋近岸大陆架海域风能资源的开发利用,加强其他海域风能资源的储备。此研究可为“21 世纪海上丝绸之路”风能资源的中长期开发规划提供依据。     

The long-term variability of sea surface temperature in the seas east of China in the past 40 a

The global surface temperature change since the mid-19th century has caused general concern and intensive study. However, long-term changes in the marginal seas, including the seas east of China, are not well understood because long-term observations are sparse and, even when they exist, they are over limited areas. Preliminary results on the long-term variability of sea surface temperature (SST) in summer and winter in the seas east of China during the period of 1957-2001 are reported using the Ocean Science Database of Institute of Oceanology, Chinese Academy of Sciences, the coastal hydrological station in situ and satellite data. The results show well-defined warming trends in the study area. However warming and cooling trends vary from decade to decade, with steady and rapid warming trends after the 1980s and complicated spatial patterns. The distribution of SST variation is intricate and more blurred in the areas far away from the Kuroshio system. Both historical and satellite data sets show significant warming trends after 1985. The warming trends are larger and spread to wider areas in winter than in summer, which means decrease in the seasonal cycle of SST probably linked with recently observed increase of the tropical zooplankton species in the region. Spatial structures of the SST trends are roughly consistent with the circulation pattern especially in winter when the meridional SST gradients are larger, suggesting that a horizontal advection may play an important role in the long-term SST variability in winter.     

Changes in zooplankton community structure in Sanmen Bay, China

Seasonal variations in zooplankton abundance,biomass,species diversity and community structure were investigated in the Sanmen Bay,China.Samples were collected from 15 stations,on the seasonal basis,in April(spring),July(summer) and October 2005(autumn) and January 2006(winter),respectively.The results show that zooplankton species number,abundance and biomass varied widely and had distinct spatial heterogeneity in the Sanmen Bay.A total of 72 species of zooplankton belonging to 56 genera and 17 groups of pelagic larvae were identified.The zooplankton species richness was strongly related to salinity.Based on hierarchical cluster analysis,zooplankton in this study area were classified into three groups:coastal,neritic and pelagic groups,which corresponded to the upper,middle and lower portion of the Sanmen Bay,respectively.The coastal low-saline species were dominant in the study area.The zooplankton abundance and biomass reached a peak in summer,moderate in spring and autumn,and the lowest in winter.Zooplankton abundance decreased from the upper to lower portion of the bay in April,when the highest biomass occurred in the middle portion of the bay.There were the same spatial distribution patterns for the biomass and abundance in July,with the maximum in the middle of the bay.However,zooplankton abundance was the highest in the middle of the bay in October,when maximum biomass occurred near the lower of the bay.Zooplankton abundance and biomass were evenly distributed in the Sanmen Bay in January.Spatial and temporal variations in zooplankton and their relationship with environmental factors were also analyzed.The BIOENV results indicate that the combination of chlorophyll a(Chl-a),salinity,dissolved inorganic nitrogen(DIN),dissolved oxygen(DO) and silicate(SiO3) was responsible for the variations in zooplankton community structure in the Sanmen Bay.The environmental changes played an important role in changes in the zooplankton community structure in the Sanmen Bay.     

Seasonal variation of atmospheric coupling with oceanic mesoscale eddies in the North Pacific Subtropical Countercurrent

This study investigated the seasonal variation in the atmospheric response to oceanic mesoscale eddies in the North Pacific Subtropical Countercurrent (STCC) and its mechanism, based on satellite altimetric and reanalysis datasets. Although mesoscale eddy in the study area is more active in summer, the sea surface temperature (SST) anomaly associated with mesoscale eddies is more intense and dipolar in winter, which is largely due to the larger background SST gradient. Similarly, the impact of the oceanic eddy on sea surface wind speed and heat flux is strongest in winter, whereas its effect on precipitation rate is more significant in summer. The study revealed that the SST gradient in STCC could impact the atmosphere layer by up to 800 hPa (900 hPa) in boreal winter (summer) through the dominant vertical mixing mechanism. Moreover, the intensity of the SST gradient causes such seasonal variation in mesoscale air-sea coupling in the study region. In brief, a stronger (weaker) background SST gradient field in wintertime (summertime) leads to a larger (smaller) eddy-induced SST anomaly, thus differently impacting atmosphere instability and transitional kinetic energy flux over oceanic eddies, leading to seasonal variation in mesoscale air-sea coupling intensity.     

Meteorological forcing of long-term temperature variations of the Dutch coastal waters

Time series of observations of the sea surface temperature (SST) at 12 stations in the Dutch coastal zone are analyzed to establish whether an earlier published nearly 150 year long SST time series from the Marsdiep tidal inlet is representative for the whole Dutch coastal zone. The annual cycles (SST range and phase) as well as the long-term SST trends at decadal scales from other estuaries agree with the Marsdiep time series. An increasing SST trend since 1982 is a phenomenon of the whole Dutch coastal zone. In order to increase the understanding of the causes of the observed SST variability, a multiple linear regression model is constructed, which links locally determined seasonal meteorological and oceanographic forcing factors to the seasonal mean SST. The oceanographic forcing factor is the SST value from the preceding season, representing persistence due to thermal inertia of the sea. Season to season changes of the atmospheric circulation, connected with SST variability, are represented by seasonal mean wind components as forcing factors, e.g. the western winds in winter which bring relatively warm air masses to Western Europe. For the seasons where shortwave solar radiation is the dominant term in the local heat budget (spring and summer), the number of bright sun hours is used as forcing factor, roughly representing the effects of changing cloudiness. The annual mean SST, derived from the regression models for the four seasons, applied to 4 locations along the Dutch coast, correlates quite well, not only for the year to year variability (R = 0.88) but also for the longer-term SST trends (R = 0.95). An explicit local greenhouse effect is not required as separate forcing factor to explain the recent warming trend of Dutch coastal waters starting in the early 1980s; coincident variations in wind statistics and cloudiness are a sufficient explanation.     

Seasonal variations of water temperature and salinity in Osaka Bay

The characteristics of seasonal variations of water temperature, salinity and density in the upper, middle and lower layers in Osaka Bay are described. Osaka Bay is considered to be an estuary, because the weak mixed state appears in spring and summer and the moderate mixed state in autumn and winter. Osaka Bay is divided into three areas, the eastern shallow area that has a large amplitude of seasonal variation of water temperature and low average salinity, the southwestern deep area which has small amplitude of seasonal variation of water temperature and high average salinity, and the northwestern deep area, which has small amplitude of seasonal variation of water temperature and low average salinity.     

Spatiotemporal variation and mechanisms of temperature inversion in the Bay of Bengal and the eastern equatorial Indian Ocean

In the northern Bay of Bengal, the existence of intense temperature inversion during winter is a widely accepted phenomenon. However, occurrences of temperature inversion during other seasons and the spatial distribution within and adjacent to the Bay of Bengal are not well understood. In this study, a higher resolution spatiotemporal variation of temperature inversion and its mechanisms are examined with mixed layer heat and salt budget analysis utilizing long-term Argo（2004 to 2020） and RAMA（2...     

琼东北海湾海滩地形年度变化特征对比分析

利用2016—2017年琼东北海湾海滩断面高程数据,对比分析了琼东北海湾-海口湾、铺前湾和木兰湾年度地形变化特征.结果表明,海口湾、铺前湾和木兰湾海滩断面地形均具有季节性变化特征,整体上夏缓冬陡,表现为前滨遭受侵蚀作用,而后滨则发生堆积作用.冬季,琼州海峡的海平面较高且风浪作用更强,这是导致冬季的海滩地形变化幅度较夏季...     

Seasonal variations of shelf circulation in Hidaka Bay,Hokkaido, Japan,with an interpretation of the migration route of juvenile walleye pollock

The outer shelf of Funka Bay, located at the bay head of Hidaka Bay, is a recognised main winter spawning ground for walleye pollock (Theragra chalcogramma), whose newly hatched juveniles migrate eastward along the Hidaka shelf to the nursery ground located in the Doto area. To examine the seasonal change of the coastal current along this migration route, four current moorings were deployed along the shelf in Hidaka Bay from April, 2004 to June, 2006. Since these mooring sites were close to the coast, the circulation was estimated after removal of the wind-driven component. It was found that the winter coastal flow, forced by a north-westerly monsoon wind, is clockwise along the Hidaka shelf. However, this flow is weak due to the superimposition of the opposite Coastal Oyashio flow trapped on the shelf. In summer, a bifurcation of the coastal current occurs along the north-eastern Hidaka shelf with a south-eastward flow, associated with the Tsugaru Gyre, and a north-westward flow, consisting of a branch from this gyre. Our results provide a new understanding of the migration of juvenile walleye pollock: (1) very slow transport of juveniles along the Hidaka shelf from winter to spring, and (2) selection of earlier spawning survivors due to the bifurcated flow in early summer.     

杭州湾营养盐时空分布特征及其影响研究

文章基于2015年1—12月杭州湾海域12个航次的调查资料,对杭州湾海域营养盐溶解无机氮(DIN)和活性磷酸盐(PO_4~(3-))的月度时空分布特征及其影响进行了探讨。结果表明,杭州湾表层海水DIN和PO_4~(3-)含量空间分布月际间变化明显,其变化受湾内、沿岸径流输入和长江冲淡水影响显著。杭州湾海域12个月DIN含量均超第四类海水水质标准,硝酸盐氮(NO_3~-)占DIN的94%及以上。N/P值处于较高水平,内湾(IB)和外湾(OB)的N/P值季节性变化幅度比中湾(CB)大,海湾生态系统对磷的变化敏感。营养盐-盐度对研究区域的水体混合状况有明显的指示作用,杭州湾营养盐的分布主要受物理混合作用所控制,浮游生物活动对营养盐分布的影响相对较小。