共查询到17条相似文献,搜索用时 46 毫秒
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The sediment backscatter strength measured by multibeam echosounders is a key feature for seafloor mapping either qualitative (image mosaics) or quantitative (extraction of classifying features). An important phenomenon, often underestimated, is the dependence of the backscatter level on the azimuth angle imposed by the survey line directions: strong level differences at varying azimuth can be observed in case of organized roughness of the seabed, usually caused by tide currents over sandy sediments. This paper presents a number of experimental results obtained from shallow-water cruises using a 300-kHz multibeam echosounder and specially dedicated to the study of this azimuthal effect, with a specific configuration of the survey strategy involving a systematic coverage of reference areas following “compass rose” patterns. The results show for some areas a very strong dependence of the backscatter level, up to about 10-dB differences at intermediate oblique angles, although the presence of these ripples cannot be observed directly—neither from the bathymetry data nor from the sonar image, due to the insufficient resolution capability of the sonar. An elementary modeling of backscattering from rippled interfaces explains and comforts these observations. The consequences of this backscatter dependence upon survey azimuth on the current strategies of backscatter data acquisition and exploitation are discussed. 相似文献
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为了研究西太平洋声散射层的垂向分布特征和日变化规律,分析了多波束测深系统的水体影像数据。观测结果表明,西太平洋存在着两个声散射层,一个声散射层位于0~200 m,另一个声散射层位于500~700 m,两个声散射层散射强度具有明显的日变化特征,上层散射层的散射强度呈现白天弱,夜晚强的特征,而下层散射层的散射强度日变化规律与上层相反,并且发现深散射层的厚度也存在日变化特征;分析了此种方法的优缺点,对以后声散射层的观测分析提供了新的思路。此外,利用同时下放的声速仪(SVP)的温度和深度数据对下放式声学多普勒流速剖面仪(LADCP)的观测结果进行了修正,得到了更为精确的声散射层垂向位置分布。 相似文献
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以一个常见桩腿结构为例,介绍使用AutoCAD建立海洋平台结构三维数字模型。提取结构零件属性、生成零件明细表、合并所有零件、构造整个桩腿结构三维实体模型。查询桩腿结构质量和质心,自动生成桩腿结构视图的方法和操作过程。说明基于通用软件进行海洋平台结构三维数字模型的开发与应用切实可行。 相似文献
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原位测量技术在黄海沉积声学调查中的应用 总被引:8,自引:3,他引:8
介绍了最新研制的基于液压驱动贯入的自容式海底沉积声学原位测量系统及其在南黄海中部海底沉积声学调查中的应用。该系统可以实现对海底沉积物声速和声衰减系数进行原位测量,通过液压驱动装置将四根声学探杆匀速贯入到海底沉积物中,减少了对沉积物的扰动,可按照预设的工作参数在海底全自动工作,无需甲板上人员实时控制,采集的声波信号自容式存储于存储单元。系统工作水深为500 m,测量深度为1 m,测量频率为30 kHz,采样频率为10 MHz。使用该系统在南黄海中部获得了40个站位不同类型沉积物的声学特性原位测量数据,并使用CTD剖面仪对该系统声速测量进行了标定,相对误差均小于0.5%,表明该系统测量数据准确、可靠。 相似文献
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Development of means and methods of drifter technology applied to the problem of the Black Sea research 总被引:1,自引:0,他引:1
During the last ten years, autonomous drifting platforms for data collection (drifters) equipped with Argos satellite communication devices have become one of the main components for the observation system in the upper layer of the ocean and surface atmosphere. This article presents the results of the Black Sea drifter monitoring in 2002–2006 within a number of international programs and projects. During this period, about 70 drifters manufactured by NPF Marlin-Yug Ltd. (Sevastopol, Ukraine) were deployed in the western part of the Black Sea. The drifters were mainly standard barometric Lagrangian tracers and a part of them were principally new temperature profiling buoys. Unique long-term data were obtained about the circulation of the surface currents and the dynamics of the temperature stratification within the seasonal thermocline and the cold intermediate layer. 相似文献
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水下考古涉及不同的调查阶段,其调查范围、水下环境、调查目标存在很大差异,对应使用的调查技术和策略也不同。系统分析了常规的和最前沿的水下考古地球物理及潜水器技术的现状和优缺点,包括声学(多波束、侧扫声呐、浅地层剖面、单道/小多道地震)、磁力、电磁法、激光雷达、潜水器(HOV、ROV、AUV)等。目前水下考古在海床遗存图像识别、埋藏的小尺寸人工遗物探测、洞穴遗存的探测发掘、潮间带遗存探测和深海考古发掘等方面仍存在大量挑战。建议通过加强海洋行业合作,升级改进现有调查技术,建立技术装备共享机制,从而提升考古遗址发现数量和几率,避免遗址受破坏流失,降低考古经济成本。 相似文献
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中国科学院海洋研究所在开展西太平洋马里亚纳海山区多学科综合科学考察的过程中,利用"科学"轮船载的全水深多波束测深系统Seabeam3012对多个海山进行了地形测量工作。针对作业过程中遇到的恶劣海况导致采集数据质量差、多波束系统易检测错误海底信息、测线布设难度大等问题,提出了基于船体姿态对数据质量影响分析的多波束测线方向优化、基于地形变化并参考浅地层剖面资料的作业参数优化和基于实时采集情况的多波束采集测线布设优化等一系列措施,有效地提高了海山区多波束数据采集质量,并提高了作业效率。获得的高品质地形数据,为多学科协同研究奠定了基础,为ROV等设备的现场作业提供了安全保障。 相似文献
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J. Acosta A. Muñoz P. Herranz C. Palomo M. Ballesteros M. Vaquero E. Uchupi 《Geo-Marine Letters》2001,21(3):123-130
Pockmarks ranging in width from <10 to 700 m, and with reliefs of 2 to 55 m were discovered in the Ibiza Channel and on the Balearic Promontory, Western Mediterranean, during a multibeam survey. In the Ibiza Channel the larger structures are found within a field of small craters less than 10 m wide and 5 m deep which give the seafloor an "orange peel" texture. The abundant 30 Ma-Present volcanic structures in the region suggests that most of the craters may have been formed by the escape of gases and associated waters via faults from a hydrothermal field beneath the surficial sediments. Others may be the result of neotectonism. 相似文献