热带大西洋年际和年代际变率的时空结构模拟   总被引：10，自引：3，他引：10       下载免费PDF全文

赵珊珊  杨修群  朱益民 《海洋学报》2003,25(3):8-19

使用美国夏威夷大学发展的中等复杂程度海洋模式(IOM)在给定表面强迫条件下模拟了热带大西洋上层海洋年际和年代际变率的时空结构.利用NCEP的41a(1958～1998年)逐月平均表面资料作为强迫场,积分海洋模式41a作为控制试验,并利用模式分别做动量(风应力)通量和热量通量无异常变化的平行试验,与控制试验作比较.对3组试验模拟上层海洋变率状况的比较,并按年际和年代际时间尺度分别分析,揭示表面风应力和热通量异常对海表面温度和温跃层深度变化的影响,并比较了其影响的相对重要性.结果表明模式成功地模拟出了热带大西洋上层海洋的变率.模式模拟的海表面温度年际变化主要表现为弱ENSO型,年代际变化表现为南、北大西洋变化相反的偶极子型.在年际时间尺度上,热力强迫和动力强迫对海表温度变化都有贡献,其中赤道外海表面温度异常(SSTA)变化主要由热通量异常引起,而近赤道SSTA的变化主要由动量异常强迫引起.在年代际时间尺度上,热通量强迫的作用远比动量强迫重要.模式不仅能够模拟SST在年际和年代际时间尺度上的变率,还能够模拟温跃层深度在年际和年代际时间尺度上的变率.年际和年代际时间尺度上,温跃层深度的变率主要由动量异常决定,热通量异常强迫的贡献很小.  相似文献   

Spatial, temporal and diel variations of fish assemblages at two sandy beaches in the Sepetiba Bay, Rio de Janeiro, Brazil     

Andr Luiz Machado Pessanha  Francisco Gerson Araújo 《Estuarine, Coastal and Shelf Science》2003,57(5-6):817-828

Fish assemblages from two beaches, one in the inner and the other in the outer Sepetiba Bay (latitude: 22°54′–23°04′S; longitude: 43°34′–44°10′W), Southeast Brazil, were sampled by beach seine net, simultaneously, on both seasonal and diel scales, between August 1998 and June 1999. Sites were selected to encompass different environmental conditions which reflect the two bay zones, thus providing a comprehensive assessment of the factors influencing surf zone fish assemblages, and their spatial, seasonal and diel variations. A total of 55 fish species was recorded, mostly young-of-the-year. Anchoa tricolor, Micropogonias furnieri, Gerres aprion, Diapterus rhombeus, Harengula clupeola, Atherinella brasiliensis and Mugil liza were numerically dominant and contributed to 95.2% of the total fish catches. Strong differences in fish assemblages were observed between the two areas, with higher number of species in the outer bay. Increases in fish numbers occurred in winter, while the highest biomass occurred in winter and summer. Transparency, followed by salinity, was responsible for most of the spatial variability and played an important role in structuring fish assemblages. Overall, diel patterns did not reveal any significant trends; however, if we consider each season separately, an increase in fish numbers during the day with peak at sunset was observed in winter, and a higher biomass occurred at night in winter and summer. Species preferences for various combinations of environmental variables are responsible for shifts in the structure and overall abundance of assemblages and dictated some patterns. The sciaenid M. furnieri, the second most abundant species, occurred only in the inner zone, being more abundant in winter. The species of Engraulidae were more abundant in the outer zone in winter/spring during the day. The gerreids G. aprion and D. rhombeus occurred mainly in summer. Overall, temporal fluctuations act more at a specific level than at a structural one, and may be linked to some particular stages of the fish life cycle, but do not significantly influence the spatial organization.  相似文献   

基于EOF分析对南海西北海域水体光谱特性的研究   总被引：1，自引：0，他引：1  

付东洋  黄宇业  刘大召  廖珊  余果  张小龙 《海洋学报(英文版)》2020,39(7):107-114

This study presents an analysis of the spectral characteristics of remote sensing reflectance(R_(rs)) in northwestern South China Sea based on the in situ optical and water quality data for August 2018.R_(rs)was initially divided into four classes,classes A to D,using the max-classification algorithm,and the spectral properties of whole R_(rs) were characterized using the empirical orthogonal function(EOF) analysis.Subsequently,the dominant factors in each EOF mode were determined.The results indicated that more than 95% of the variances of R_(rs) are partly driven by the back-scattering characteristics of the suspended matter.The initial two EOF modes were well correlated with the total suspended matter and back-scattering coefficient.Furthermore,the first EOF modes of the four classes of R_(rs)(A-D R_(rs)-EOF_1) significantly contributed to the total variances of each R_(rs) class.In addition,the correlation coefficients between the amplitude factors of class A-D R_(rs)-EOF_1 and the variances of the relevant water quality and optical parameters were better than those of the unclassified ones.The spectral shape of class AR_(rs)-EOF_1 was governed by the absorption characteristic of chlorophyll a and colored dissolved organic matter(CDOM).The spectral shape of class B R_(rs)-EOF_1 was governed by the absorption characteristic of CDOM since it exhibited a high correlation with the absorption coefficient of CDOM(a_g(λ)),whereas the spectral shape of class C R_(rs)-EOF_1 was governed by the back-scattering characteristics but not affected by the suspended matter.The spectral shape of class D R_(rs)-EOF_1 exhibited a relatively good correlation with all the water quality parameters,which played a significant role in deciding its spectral shape.  相似文献   

Influence of Current Width Variation on the Annual Mean Transport of the East Sakhalin Current: A Simple Model     

Yoichi?ShimadaEmail author  Atsushi?Kubokawa  Kay?I.?Ohshima 《Journal of Oceanography》2005,61(5):913-920

Recent observations suggest that the annual mean southward transport of the East Sakhalin Current (ESC) is significantly larger than the annual mean Sverdrup transport. Motivated by this observational result, transport of a western boundary current has been investigated using a simple numerical model with a western slope. This transport is defined as the instantaneous barotropic transport integrated from the western boundary to the offshore point where the barotropic velocity vanishes. The model, forced by seasonally varying wind stress, exhibits an annual mean of the western boundary current transport that is larger than that of the Sverdrup transport, as observed. The southward transport from October to March in the model nearly equals the instantaneous Sverdrup transport, while the southward transport from April to September decreases slowly. Although the Sverdrup transport in July vanishes, the southward transport in summer nearly maintains the annual mean Sverdrup transport, because the barotropic Rossby wave cannot intrude on the western slope. This summer transport causes the larger annual mean. Although there are some uncertainties in the estimation of the Sverdrup transport in the Sea of Okhotsk, the seasonal variation of the southward transport in the model is qualitatively similar to the observations.  相似文献   

A permanent seismic station beneath the Ocean Bottom     

David Harris  Robert K. Cessaro  Fred K. Duennebier  David A. Byrne 《Marine Geophysical Researches》1987,9(1):67-94

The Hawaii Institute of Geophysics began development of the Ocean Subbottom Seisometer (OSS) system in 1978, and OSS systems were installed in four locations between 1979 and 1982. The OSS system is a permanent, deep ocean borehole seismic recording system composed of a borehole sensor package (tool), an electromechanical cable, recorder package, and recovery system. Installed near the bottom of a borehole (drilled by the D/V Glomar Challenger), the tool contains three orthogonal, 4.5-Hz geophones, two orthogonal tilt meters; and a temperature sensor. Signals from these sensors are multiplexed, digitized (with a floating point technique), and telemetered through approximately 10 km of electromechanical cable to a recorder package located near the ocean bottom. Electrical power for the tool is supplied from the recorder package. The digital seismic signals are demultiplexed, converted back to analog form, processed through an automatic gain control (AGC) circuit, and recorded along with a time code on magnetic tape cassettes in the recorder package. Data may be recorded continuously for up to two months in the self-contained recorder package. Data may also be recorded in real time (digital formal) during the installation and subsequent recorder package servicing. The recorder package is connected to a submerged recovery buoy by a length of bouyant polypropylene rope. The anchor on the recovery buoy is released by activating either of the acoustical command releases. The polypropylene rope may also be seized with a grappling hook to effect recovery. The recorder package may be repeatedly serviced as long as the tool remains functionalA wide range of data has been recovered from the OSS system. Recovered analog records include signals from natural seismic sources such as earthquakes (teleseismic and local), man-made seismic sources such as refraction seismic shooting (explosives and air cannons), and nuclear tests. Lengthy continuous recording has permitted analysis of wideband noise levels, and the slowly varying parameters, temperature and tilt.Hawaii Institute of Geophysics Contribution 1909.  相似文献   

安徽宣城地区中晚更新世风成堆积与环境变迁   总被引：25，自引：7，他引：25  

杨达源  房迎三 《海洋地质与第四纪地质》1991,11(2):97-104

通过对宣城向阳中晚更新世沉积剖面的综合研究,认为该剖面与中国北方同时代的黄土—古土壤剖面相比较,虽然长江下游以南地区中晚更新世多个冰期中风成堆积的单层厚度与累积厚度,亦即风成物质的沉积通量与沉积速率均比北方黄土区要小,但它们所反映的气候与环境的变化具有明显的可比性。  相似文献   

太阳反射光对海洋水色卫星遥感的影响研究   总被引：3，自引：0，他引：3  

李淑菁  毛天明  潘德炉 《热带海洋学报》1997,(4)

海洋水色卫星遥感的关键是水色图像资料的利用率。受到太阳反射光的影响使图像饱和是水色卫星图像的主要噪声之一。笔者首先论述了卫星海洋水色遥感中到达水色扫描仪的太阳反射光（即太阳耀光）的辐射量计算模式；然后介绍了产生太阳耀光模拟图像的全过程，并对我国FY－1B、美国的SeaSTAR和台湾省的ROCSAT－1号卫星作了全轨道下的太阳耀光模拟图像；最后，讨论了影响太阳耀光的主要因素，同时提出了减小太阳耀光提高海洋水色卫星遥感图像利用率的建议。  相似文献   

天津海岸带经济开发的地质环境和环境工程地质问题   总被引：3，自引：0，他引：3       下载免费PDF全文

杨锦贤 《海洋开发与管理》1994,11(3):36-40

本文揭示了天津海岸带影响经济开发的四个方面的地质环境特点；着重探讨三个方面的环境工程地质问题；并防止其形成和减轻地灾害的对策进行了研究。  相似文献   

胶州湾海域水质预测   总被引：3，自引：0，他引：3  

孙英兰  孙长青  王丽霞  徐鸿楷 《中国海洋大学学报(自然科学版)》1994,(Z1)

在已建潮流模型的基础上,用ADI法建立了胶州湾扩大域变动边界的平流—扩散输运模型,以COD为指示因子,预测了胶州湾海域1995年、2000年的水质、青岛环海公路海上段、沧口区北半部污水截流、北水南调、集中排放以及胶州湾西部经济开发对海域水质的影响等。为青岛市环保部门制定环保规划提供决策依据。  相似文献   

Study on short-range numerical forecasting of ocean current in the East China Sea——Ⅰ Basic problems of ocean current forecasting and structure of the models     

Zhao Jinping  Chen Zhongyong  Shi Maochong 《海洋学报(英文版)》1993,12(3):335-345

Ocean current forecasting is still in explorative stage of study. In the study, we face some problems that have not been met before. The solving of these problems has become fundamental premise for realizing the ocean current forecasting. In the present paper are discussed in depth the physical essence for such basic problems as the predictability of ocean current, the predictable currents, the dynamical basis for studying respectively the tidal current and circulation, the necessity of boundary model, the models on regions with different scales and their link. The foundations and plans to solve the problems are demonstrated. Finally a set of operational numerical forecasting system for ocean current is proposed.  相似文献