首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
利用国家海洋信息中心国内海洋文档资料(1953-1988)和日本气象厅《东中国海表层月平均水温30年(1953-1982)报》等资料,将中国近海按153个统计区统计了水、气温频率分布的数字特征值,经主因子分析,求得累积贡献率达95.29%的3个主要因子,再用模糊聚类软划分方法将中国近海划分为3个气候带和10个气候区,本方法所取特征值能完整地反映数列的频率分布特征,避免了选取气候特征值时的主观随意性  相似文献   

2.
A number of significant hydrologicla and chemical parameters of the Black Sea shelf area have been identified and investigated: the inter-annual variability of the mean annual and seasonal (winter and summer) values of the air and seawater temperatures and salinity in the vicinity of Odessa; silicon and phosphate concentrations averaged over the north-western Black Sea shelf area (NWBS); discharges of the Danube and Dnieper rivers; mean surface and near-bottom oxygen concentrations in summer acquired through the analysis of the summarized data collected at three oceanographic stations occupied between Bolshoi Fontan and the Tendra isthmus from the early 1950s up to date. From these data, the variability of the areas subject to oxygen deficit in the near-bottom layer of the NWBS shelf during the summers of 1973–1994 has been assessed. Predominant oscillation periods and trends in the inter-annual variability of the studied parameters have been revealed and their relationship and climatic dependence has been demonstrated. Translated by Vladimir A. Puchkin.  相似文献   

3.
X.H. Wang   《Ocean Modelling》2005,10(3-4):253-271
The Princeton Ocean Model was implemented to investigate the response of northern Adriatic Sea during the Bora event in January 2001 when strong wind and surface cooling was reported. The model has been run with realistic wind stress, surface heat flux and river runoffs forcings continuously from 1 January 1999 to 31 January 2001. The wind stress and surface heat flux was computed by the bulk parameterization, using the European Centre for Medium Range Weather Forecast analysis fields and the Comprehensive Ocean Atmosphere Data Set cloud data. All the freshwater sources along the Adriatic coastlines were represented by point or line source functions. Open boundary conditions in the Ionian Sea along a latitudinal boundary were nested within a large scale model of the Mediterranean Sea. The numerical study found that, before the Bora event of 13–17 January 2001, the water column of the northern Adriatic Sea was stratified by salinity, and the temperature was already cooler at the surface and over the shallower shelf region. The pre-Bora circulation of the northern Adriatic Sea was relatively weak and baroclinic with maximum surface currents occurred near the Italian coast. During the Bora event, the water column was well mixed in the most of coastal region of the northern Adriatic Sea. The atmospheric cooling produced colder water over the northern and western Adriatic Coast. The circulation of the northern Adriatic Sea was barotropic and dominantly wind driven, with maximum current speed of about 1 m s−1. The numerical study also demonstrated that the Bora event decreased the heat content of the water column with an area averaged value of 205 W m−2 over the shallow northern shelf. It was concluded that the heat budget of the northern Adriatic Sea during the Bora event was a balance between the surface heat loss, horizontal net heat inflow and resulting heat content decrease. The horizontal advection played a particularly important role in controlling the water temperature change over the shallower northern shelf.  相似文献   

4.
Abstract. Polychaete community structure in Valle Magnavacca, the largest basin of the Valli di Comacchio (Northern Adriatic Sea) lagoonal ecosystem, was analyzed in a three‐year study. Three shallow‐water stations were sampled at about 3‐month intervals. Univariate and multivariate analyses were utilized to investigate community structure changes in relation to natural and man‐induced disturbance. The polychaete community at station 3, in the central area of the lagoon, was the most disturbed, while that of station 2 was the most well structured. We hypothesize that polychaete community structure results from regular seasonal disturbances which lead to almost predictable fluctuations in species abundance. Superimposed on these regular cycles are acute disturbance events that further reduce species abundance or exclude species from the habitat.  相似文献   

5.
The Adriatic Sea is a modern epicontinental basin where the late Quaternary transgressive systems tract shows substantial variations within two contrasting shelf domains, separated by a 250-m-deep remnant basin: a lowgradient shelf in the north, and a steeper margin in the south. Four differentiated sedimentary responses reflect contrasting physiographic domains and differences in the ratio between oceanographic regime and sediment input during relative sea-level rise. The progressive widening of the Adriatic epicontinental shelf, up to seven times its low-stand extent, also determines variations in the style of transgressive deposition by controlling major changes in oceanographic circulation.  相似文献   

6.
This paper introduces a new hydrographic climatology of the Okhotsk Sea; this climatology was constructed from the Far Eastern Regional Hydrometeorological Research Institute (FERHRI) database. The FERHRI database has a volume of data three to five times larger than the data used in previous studies because unpublished Russian observation data have been included in the FERHRI database. After removing erroneous data from the database by pertinent quality control methods, the climatology for 1/4°?×?1/4° grids is produced by applying objective analysis procedures. Features similar to those in previous studies are seen in the intermediate layers in the Okhotsk Sea, whereas our climatology provides values that fill in gaps in previous climatologies. It is obvious from the monthly climatologies that temperature and salinity distributions evolve in accordance with seasonal variations in the Eastern Sakhalin Current and inflow from the North Pacific. We also reconstructed climatologies for the winter mixed layer and dense shelf water from data obtained from the temperature minimum waters identified as the remnants of these two layers. Free access to the 1°?×?1° versions of all climatologies constructed in this study is available through the website.  相似文献   

7.
Abstract. This paper describes a new Ocean Acoustic Tomography (OAT) methodology - a passive tomography - presently in an advanced development phase. This technique has been developed for long-term, extensive, remote monitoring of the seawater temperature spatial distribution, which is estimated from the received noise emitted from ships of opportunity. To test the passive tomographic processor under controlled conditions, the components of the naval noise from different kinds of vessels was analysed and realistic naval noise was simulated. The feasibility of the proposed methodology was confirmed by test-runs on semi-synthetic data; its capability to resolve temperature profiles will be better assessed with the use of real acoustic and environmental data collected during the INTIMATE00 experiment performed in October 2000 in the Atlantic Ocean off the Portuguese coast. An analysis of the space and time variability of the Empirical Orthogonal Function (EOF) decomposition of the sound speed (SSP) in the Mediterranean Sea has been carried out to identify areas where acoustic tomography can be successfully applied. Results from simulations in the South Adriatic Sea, which was identified as a region with a high sound speed variability associated with the seasonal cycle and with the main oceanographic processes, are reported.  相似文献   

8.
Four seasonal oceanographic cruises were carried out in the Eastern Mediterranean Sea, within the framework of the CEC/MAST-MTP Project PELAGOS, during 1994–1995. The surveys covered the South Aegean Sea and the adjacent open sea regions (southeastern Ionian, northwestern Levantine). Analysis of CTD data revealed that a multiscaled circulation pattern prevails in the area. It differs from the circulations detected during the 1986–87, thus indicating interannual variability. Cyclonic and anticyclonic gyres and eddies are interconnected by currents and jets variable in space and time. Most of the features are persistent, others seem transitional or recurrent. The hydrological structure is also complex and apart from the upper layer does not present basinwide any significant seasonality. Dynamical and hydrological regimes are variable in the upper and intermediate layers at the Straits of the Cretan Arc, while the deep regime seems rather constant. Topographic control is evident on the flows through the straits. The new very dense deep water mass, namely the Cretan Deep Water (CDW) and a well-defined intermediate layer of minimum temperature and salinity, the so-called Transition Mediterranean Water (TMW), consists the new important structural elements of the South Aegean Sea. The CDW outflows towards the deep and bottom layers of the Eastern Mediterranean, thus considerably contributing to the formation of the new, denser Deep and Bottom Water of the Eastern Mediterranean, which sinks and displaces the Eastern Mediterranean Deep Water of Adriatic origin in the adjacent sea regions outside the Aegean Sea.  相似文献   

9.
The life cycle of the stoloniferan Cornularia cornucopiae (Pallas, 1766) (Anthozoa: Octocorallia) was studied from March 2009 to October 2010 on the rocky cliff of the Conero Promontory (North Adriatic Sea, 43°34.865′ N, 13°34.320′ E). In this area the species showed unusual high densities never recorded in other sites of the Mediterranean Sea. The density trend of the species showed a marked seasonal cycle, with a winter minimum of about 1000 polyps m?2 and a summer maximum of about 30,000 polyps m?2. In accordance with other Mediterranean literature data, polyps were fertile during spring–summer, from March to August, but the number of eggs per polyp continuously decreased during this span of time. Variations of polyp density were strongly correlated to water temperature, which can be considered the main environmental factor triggering this seasonal behaviour. The possibility, for C. cornucopiae, to face adverse winter conditions is probably related to the presence of a characteristic perisarcal envelope covering the stolon and the calyx of each polyp, which isolates the living tissues from the exterior. During winter, polyps degenerate but the stolons remain dormant inside their envelopes. The perisarc covering represents a morphological convergence of C. cornucopiae with benthic hydrozoans. As the latter, the studied stoloniferans are able to live in habitats characterized by periodic favourable conditions thanks to a seasonal life strategy. A similar trend is shared also by other important components (cnidarians and some sponges) of the filter‐feeding community of the North Adriatic Sea. Differently to the Western Mediterranean basin, this area is characterized by high food availability all year around, so benthic organisms are strongly constrained by the very low winter temperatures.  相似文献   

10.
This study analyzes the heat budget of the Arabian Sea using satellite-derived sea-surface temperature (SST) from 1985 to 1995 along with other data sets. For a better understanding of air–sea interaction, canonical average monthly fields representing the spatial and temporal structure of the various components of the heat balance of the Arabian Sea are constructed from up to 30 years of monthly atmospheric and oceanic data. The SST over the Arabian Sea is not uniform and continually evolves with time. Cooling occurs over most of the basin during November through January and May through July, with the greatest cooling in June and July. Warming occurs over most of the basin during the remainder of the year, with the greatest warming occurring in March and September. Results indicate that the sign of the net heat flux is strongly dependent on the location and month. The effects of net heat flux and penetrative solar radiation strongly influence the change in SST during February and are less important during August and September. Horizontal advection acts to cool the sea surface during the northeast monsoon months. During the southwest monsoon horizontal advection of surface waters warms the SST over approximately the southern half of the basin, while the advection of upwelled water from the Somalia and Oman coasts substantially cools the northern basin. The central Arabian Sea during the southwest monsoon is the only area where the change in SST is balanced by the entrainment and turbulent diffusion at the base of the mixed layer. Agreement between the temporal change in the satellite-derived SST and the change calculated from the conservation of heat equation is surprisingly good given the errors in the measured variables and the bulk formula parameters. Throughout the year, monthly results over half of the basin agree within 3°. Considering that the SST changes between 8° and 12° over the year, this means that our results explain from 62% to 75% of the change in SST over 56% of the Arabian Sea. Two major processes contribute to the discrepancy in the change in SST calculated according to the heat budget equation and the change in SST derived from satellite observations. The first is the effect of the horizontal advection term. The position of the major eddies and currents during the southwest monsoon greatly affects the change in SST due to the large gradient in temperature between the cold upwelled waters along the Somali coast to the warm waters in the interior of the basin. The second major process is the thermocline effect. In areas of shallow mixed-layer depth, high insolation and wind speeds of either less than 3 m/s or greater than 15 m/s, the bulk formulae parameterization of the surface heat fluxes is inappropriate.  相似文献   

11.
GEOSAT卫星遥感资料研究南海海面动力高度场和地转流场   总被引:10,自引:1,他引:9  
利用GEOSAT卫星在1987年和1988年执行ERM任务的雷达高度计资料来分析获取南海海面动力高度偏差的季节分布.根据卫星轨道误差和海域的特点,提出了适用于内海及边缘海域的二维共线轨道校正法,由此方法而得出的南海海面动力高度偏差的季节分布表明,南海表层流场在夏季总的环流形势是反气旋式环流,而冬季是气旋式环流.分析的结果同海上常规调查资料的分析结果相比较表明,在海流季节变化信号较强的海区(如南海中部和北部海区),利用高度计资料能很好地反映该海区的海流季节变化特征.  相似文献   

12.
Produced formation waters (PFWs), a by-product of both oil and gas extraction, are separated from hydrocarbons onboard oil platforms and then discharged into the sea through submarine outfalls. The dispersion of PFWs into the environment may have a potential impact on marine ecosystems. We reproduce the initial PFW-seawater mixing process by means of the UM3 model applied to offshore natural gas platforms currently active in the Northern Adriatic Sea (Mediterranean Sea). Chemical analyses lead to the identification of a chemical tracer (diethylene glycol) which enables us to follow the fate of PFWs into receiving waters. The numerical simulations are realized in different seasonal conditions using both measured oceanographic data and tracer concentrations. The numerical results show the spatial and temporal plume development in different stratification and ambient current conditions. The analytical approach measures concentrations of the diethylene glycol at a maximum sampling distance of 25 m. The results show a good agreement between field observations and model predictions in the near-field area. The integration of numerical results with chemical analyses also provides new insight to plan and optimize PFW monitoring and discharge.  相似文献   

13.
Bottlenose dolphins are the only cetaceans regularly observed in the northern Adriatic Sea, but they survive at low densities and are exposed to significant threats. This study investigates some of the factors that influence habitat use by the animals in a largely homogeneous environment by combining dolphin data with hydrological and physiographical variables sampled from oceanographic ships. Surveys were conducted year-round between 2003 and 2006, totalling 3,397 km of effort. Habitat modelling based on a binary stepwise logistic regression analysis predicted between 81% and 93% of the cells where animals were present. Seven environmental covariates were important predictors: oxygen saturation, water temperature, density anomaly, gradient of density anomaly, turbidity, distance from the nearest coast and bottom depth. The model selected consistent predictors in spring and summer. However, the relationship (inverse or direct) between each predictor and dolphin presence varied among seasons, and different predictors were selected in fall. This suggests that dolphin distribution changed depending on seasonal forcing. As the study area is relatively uniform in terms of bottom topography, habitat use by the animals seems to depend on complex interactions among hydrological variables, caused primarily by seasonal change and likely to determine shifts in prey distribution.  相似文献   

14.
在海洋学和气象学的研究中,海洋表层水温是最重要而又易于观测的基本参数之一,对其观数据进行收集、整理和分析研究,向为海洋和气象业务部门所重视。就东海来说,日本气象厅长崎海洋气象台自1953年以来即已系统收集该海区的表层水温观测资料,逐旬发布《东海表层水温旬报》。并先后出版了三卷详尽的资料汇编:《东海逐旬表层水温五年报(1953-1957)》,《东海及黄海逐旬表面水温十年报(1953-1962)》,《东海表层水温二十年报(1953-1972)》。 现有关于东海表层水系配置以及与之有关的海流系统和海况变动等方面的知识,大多是通过这些资料的分析研究而得到的。其中,特别应该提到的是日本学者菊池繁雄(1959)、小泉政美(1964)和佐原勉(1974,1975)的工作。他们分别依据上列三项资料,对东海表层水温旬报中的一百多个测站的水温季节変化作了常规统计分析,并在些分析基础上定性地勾划出东海表层水系配置和海流系统的大致轮廓。这些研究成果迄今仍是讨论东海水文特征的重要依据。 然而,上述三位作者提出的东海表层水系划分方案,尽管大体相同,但在测站类别的划分或合并以及代表站的选择等具体问题上却有颇大的出入,如表1及图1所示。在我们看来,这三种基于表层水温季节变化统计特征而提出的水系划分方案之所以有如此显著的差别,其原因主要不在于资料的年限不一,而是在于缺乏客观的分类判据。迄今为止,在海洋水文特征的分析研究中,水系(或水团)划分判据的选择是一件相当主观的事情。一般都是根据分析者的经验和直观判断来作出选择。表1列举的三位作者所依据的统计特征,除菊池繁雄(1959)采用的水温年变化调和常数以外,大多并不提供独立的信息,因而未能充分揭示各测站表层水温季节变化之间错综复杂的关系。况且,这三位作者在具体分析各测站的各种统计特征的相似性或差异性时,并未给出客观的判据,而只是先验地从不同的角度对这些特征加以删简或强调,这就给测站的聚类和相应代表站的选择带来了不同程度的片面性,以致得到不同的聚类结果。 为了避免上述关于东海表层水系划分方案所蕴含的不确定性,我们试图采用数据矩阵的奇异值分解技术,对东海82个1°×1°(经、纬度)网格点的多年(1953-1972)旬平均表层水温季节距平数据矩阵进行正交分解,从而确定表征该海区表层水温时-空变异的前几对最具特征意义的奇异矢量,以之作为东海表层水系划分的一项客观依据。  相似文献   

15.
Seventeen models participating in the Coupled Model Intercomparison Project phase 5(CMIP5) activity are compared on their historical simulation of the South China Sea(SCS) ocean heat content(OHC) in the upper 300 m. Ishii's temperature data, based on the World Ocean Database 2005(WOD05) and World Ocean Atlas 2005(WOA05), is used to assess the model performance by comparing the spatial patterns of seasonal OHC anomaly(OHCa) climatology, OHC climatology, monthly OHCa climatology, and interannual variability of OHCa. The spatial patterns in Ishii's data set show that the seasonal SCS OHCa climatology, both in winter and summer, is strongly affected by the wind stress and the current circulations in the SCS and its neighboring areas. However, the CMIP5 models present rather different spatial patterns and only a few models properly capture the dominant features in Ishii's pattern. Among them, GFDL-ESM2 G is of the best performance. The SCS OHC climatology in the upper 300 m varies greatly in different models. Most of them are much greater than those calculated from Ishii's data. However, the monthly OHCa climatology in each of the 17 CMIP5 models yields similar variation and magnitude as that in Ishii's. As for the interannual variability, the standard deviations of the OHCa time series in most of the models are somewhat larger than those in Ishii's. The correlation between the interannual time series of Ishii's OHCa and that from each of the 17 models is not satisfactory. Among them, BCC-CSM1.1 has the highest correlation to Ishii's, with a coefficient of about 0.6.  相似文献   

16.
Meteorological and oceanographic conditions in the Northern Adriatic Sea in a year notable for massive mucilage formation (2004) were compared with those in years where this phenomenon did not occur (2003, 2005 and 2006) to suggest possible links. The months preceding the mucilage event in 2004 were considered the ‘incubation period’ and were characterized by a strong freshet in May which increased the water column stability. Winter cooling and scarcity of freshwater inputs from the Po River triggered the dense water formation and intrusion in the northern basin. Weak southeasterly winds and an increase in surface seawater temperatures contributed to maintain and reinforce the water column stability, and at the same time an intense diatom spring bloom created the conditions for accumulation of organic matter. The interplay of climatological forcings and biological processes caused temporal variations of dissolved organic carbon (DOC) and particulate organic carbon (POC) in the basin, with POC playing an important role in the aggregation process, as suggested by its increase relative to DOC before massive mucilage formation. We therefore suggest that high POC/total particulate nitrogen ratios in the suspended particulate organic fraction, a steep increase of POC/Chlorphyll a, and the decreased DOC/POC ratios represent ‘early warning’ signals of the main processes that lead to mucilage events in the Northern Adriatic Sea.  相似文献   

17.
《Marine Geology》1999,153(1-4):253-274
The planktic foraminiferal distribution identified in 60 cores collected in different basins of the Mediterranean Sea allowed to establish an ecostratigraphical scheme which provides a very important tool for the biochronological subdivision of the uppermost Quaternary. We identified a succession of ten ecozones during the last 23 ka in the Tyrrhenian basin and eight ecozones in the Adriatic Sea during the last 15 ka. The ecozones boundaries have been calibrated by 14C AMS radiometric data and by the stable oxygen isotope record. The chronological framework defined by the successive bioevents shows a very high resolution (millenary scale) and evidences that the changes in the planktic microfauna occurred more or less synchronously throughout the central Mediterranean Sea. Differences due to different oceanographic settings of the basins do not affect the general distributional pattern of planktic foraminifera.  相似文献   

18.
吕宋海峡西部深海盆内孤立波潜标观测研究   总被引:2,自引:0,他引:2  
Using a net surface heat flux (Qnet) product obtained from the objectively analyzed air-sea fluxes (OAFlux) project and the international satellite cloud climatology project (ISCCP), and temperature from the simple ocean data assimilation (SODA), the seasonal variations of the air-sea heat fluxes in the northwestern Pa cific marginal seas (NPMS) and their roles in sea surface temperature (SST) seasonality are studied. The seasonal variations of Qnet, which is generally determined by the seasonal cycle of latent heat flux (LH), are in response to the advection-induced changes of SST over the Kuroshio and its extension. Two dynamic regimes are identified in the NPMS: one is the area along the Kuroshio and its extension, and the other is the area outside the Kuroshio. The oceanic thermal advection dominates the variations of SST and hence the sea-air humidity plays a primary role and explains the maximum heat losing along the Kuroshio. The heat transported by the Kuroshio leads to a longer period of heat losing over the Kuroshio and its Extension. Positive anomaly of heat content corresponds with the maximum heat loss along the Kuroshio. The oceanic advection controls the variations of heat content and hence the surface heat flux. This study will help us understand the mechanism controlling variations of the coupled ocean-atmosphere system in the NPMS. In the Kuroshio region, the ocean current controls the ocean temperature along the main stream of the Ku roshio, and at the same time, forces the air-sea fluxes.  相似文献   

19.
Recurrent climate‐induced mass mortality episodes have been recorded in the Mediterranean Sea over the past 15 years, affecting rocky benthic communities. In this study, we provide for the first time a report on the annual mortality events of benthic sessile invertebrates occurring in the eastern part of the Adriatic Sea. Over the course of 14 consecutive years, we studied the sea temperature gradient to a depth of 40 m and found an abnormal summer warming trend and an increased frequency of above‐average temperatures. Mortality events were recorded in the summers of 10 observed years, in particular in 2009, when the highest mortality rates were recorded. Late in summer 2009, extensive mass mortality of sessile invertebrates was observed in the entire Eastern Adriatic Sea. We performed an analysis of selected target benthic species associated with mass mortality events with inter‐regional differences in hydrological and temperature conditions. We were able to characterize the mortality event by studying five areas covering the northern, central and southern regions of the Eastern Adriatic Sea. The degree of impact on each study area was quantified at 28 sites by estimating the proportion of affected target species. According to the obtained data, the northern sites (Cres area) were the least affected, whereas sites in the Central and Southern Adriatic [Tela??ica and Lastovo Nature Parks, Mljet National Park (NP)] displayed the highest impact. In summer 2009, sea surface temperatures reached values of 28 °C in the Cres area and 30 °C in Mljet NP. These thermal conditions were concomitant with moderate to severe mass mortalities of benthic populations. Mass mortality events reached depths of 45 m in most parts of the affected areas. Amongst studied species, the scleractinian coral and gorgonian populations suffered the most extensive damage during the mass mortality events.  相似文献   

20.
A biomass-based ecological model is presented here for the Adriatic Sea. The hydrodynamical part is composed of the Princeton Ocean Model, while the European Regional Seas Ecosystem Model describes the biogeochemical processes. An idealized Adriatic basin geometry has been used, with perpetual year seasonal cycle forcing the hydrodynamics and river-borne nutrient input forcing externally the biogeochemical processes. The simulation results highlight the role of the physical processes in determining and maintaining some of the nutrient and phytoplankton biomass distribution and characteristics in the basin. The characteristics of the phytoplankton seasonal cycle have been found to depend, in order of priority, on the river-borne nutrient input and physical horizontal and vertical processes.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号