海洋调查数据的可视化建模及实现方法

科学计算可视化作为新一代的分析工具 ,正在进入物理海洋学领域。文中介绍对海洋调查数据进行可视化的关键问题——数据建模 ,并从分析海洋调查数据的特点出发提出针对海洋研究中可视化建模的原则和有效途径 ,给出相关的实现方法。其中 ,重点讨论局部体样条建模中必须面对的区域分割优化问题 ,引入遗传算法并给出较好的解决方案。     

Sources and hydrothermal alteration of organic matter in Quaternary sediments: A synthesis of studies from the Central Gulf of California

Deep sea drilling in the Central Gulf of California, a young and active spreading centre, shows that the high heat flow typical of these regions causes extensive alteration of sediment organic matter, especially near sills and above magma chambers where hydrothermal activity is concentrated. Even on the nearby passive margin, where there are no sills, heat flow is moderately high and hydrocarbon generation has begun in immature sequences. Migrating light hydrocarbons are detected especially where hydrothermal activity is concentrated. Thermogenic methane is more widespread, though not in the passive margin bordering the spreading centre. Despite the incidence of hydrocarbon generation and migration, the amounts of hydrocarbons involved are relatively small and apparently do not lead to commercially significant accumulations of petroleum.The organic matter in these sediments is mostly marine because the Gulf of California generally has low runoff from land and highly productive surface waters. Turbidites rich in terrigenous organic material are locally abundant in the mainly pelagic section in the Guaymas Basin. The highest concentrations of organic matter are found in laminated diatomites deposited on the Guaymas passive margin within the oxygen minimum zone.     

4D seismic time-lapse monitoring of an active cold vent,northern Cascadia margin

Two single-channel seismic (SCS) data sets collected in 2000 and 2005 were used for a four-dimensional (4D) time-lapse analysis of an active cold vent (Bullseye Vent). The data set acquired in 2000 serves as a reference in the applied processing sequence. The 4D processing sequence utilizes time- and phase-matching, gain adjustments and shaping filters to transform the 2005 data set so that it is most comparable to the conditions under which the 2000 data were acquired. The cold vent is characterized by seismic blanking, which is a result of the presence of gas hydrate in the subsurface either within coarser-grained turbidite sands or in fractures, as well as free gas trapped in these fracture systems. The area of blanking was defined using the seismic attributes instantaneous amplitude and similarity. Several areas were identified where blanking was reduced in 2005 relative to 2000. But most of the centre of Bullseye Vent and the area around it were seen to be characterized by intensified blanking in 2005. Tracing these areas of intensified blanking through the three-dimensional (3D) seismic volume defined several apparent new flow pathways that were not seen in the 2000 data, which are interpreted as newly generated fractures/faults for upward fluid migration. Intensified blanking is interpreted as a result of new formation of gas hydrate in the subsurface along new fracture pathways. Areas with reduced blanking may be zones where formerly plugged fractures that had trapped some free gas may have been opened and free gas was liberated.     

Fast static correction methods for high-frequency multichannel marine seismic reflection data: A high-resolution seismic study of channel-levee systems on the Bengal Fan

Very high-frequency marine multichannel seismic reflection data generated by small-volume air- or waterguns allow detailed, high-resolution studies of sedimentary structures of the order of one to few metres wavelength. The high-frequency content, however, requires (1) a very exact knowledge of the source and receiver positions, and (2) the development of data processing methods which take this exact geometry into account. Static corrections are crucial for the quality of very high-frequency stacked data because static shifts caused by variations of the source and streamer depths are of the order of half to one dominant wavelength, so that they can lead to destructive interference during stacking of CDP sorted traces. As common surface-consistent residual static correction methods developed for land seismic data require fixed shot and receiver locations two simple and fast techniques have been developed for marine seismic data with moving sources and receivers to correct such static shifts. The first method – called CDP static correction method – is based on a simultaneous recording of Parasound sediment echosounder and multichannel seismic reflection data. It compares the depth information derived from the first arrivals of both data sets to calculate static correction time shifts for each seismic channel relative to the Parasound water depths. The second method – called average static correction method – utilises the fact that the streamer depth is mainly controlled by bird units, which keep the streamer in a predefined depth at certain increments but do not prevent the streamer from being slightly buoyant in-between. In case of calm weather conditions these streamer bendings mainly contribute to the overall static time shifts, whereas depth variations of the source are negligible. Hence, mean static correction time shifts are calculated for each channel by averaging the depth values determined at each geophone group position for several subsequent shots. Application of both methods to data of a high-resolution seismic survey of channel-levee systems on the Bengal Fan shows that the quality of the stacked section can be improved significantly compared to stacking results achieved without preceding static corrections. The optimised records show sedimentary features in great detail, that are not visible without static corrections. Limitations only result from the sea floor topography. The CDP static correction method generally provides more coherent reflections than the average static correction method but can only be applied in areas with rather flat sea floor, where no diffraction hyperbolae occur. In contrast, the average static correction method can also be used in regions with rough morphology, but the coherency of reflections is slightly reduced compared to the results of the CDP static correction method.     

悬浮沙激光散斑图像处理的研究

本文以统计模式识别为基础，阐述了图像处理在悬浮沙粒粒径流量中的实际应用，提出了用图像层析来确定放大系数的方法，提出了测量的准确度。     

A Sensitivity Analysis of the Waterline Method of Constructing a Digital Elevation Model for Intertidal Areas in ERS SAR scene of Eastern England

A sensitivity analysis of the waterline method of constructing a Digital Elevation Model (DEM) of an intertidal zone using remote sensing and hydrodynamic modelling is described. Variation in vertical height accuracy as a function of beach slope is investigated using a set of nine ERS Synthetic Aperture Radar (SAR) images of the Humber/Wash area on the English east coast acquired between 1992 and 1994. Waterlines from these images are heighted using a hydrodynamic tide-surge model and interpolated using block kriging. On 1:500 slope beaches, an average block height estimation standard deviation of 18–22 cm is achieved. This rises to 27 cm on 1:100 slope beaches, and 32 cm on 1:30 slope beaches. The average heighting error at different slopes is decomposed into components due to waterline heighting error, inadequate sensor resolution and interpolation inaccuracy. It is shown that, at 1:500 slope, waterline heighting error and interpolation inaccuracy are the main error sources, whilst at 1:30 slope, errors due to inadequate sensor resolution become dominant. The ability of the technique to generate intertidal DEMs for almost the entire coastal zone in a complete ERS SAR scene covering 100×100 km is demonstrated.     

中国海区区域地质编图中重磁图的编制方法

本文简要介绍了局控项目《中国海区１∶５０万区域地质编图（大连幅）》重力异常图、磁力异常图的编制过程，给出了一种以计算机为手段、实现编图自动化的新方法，并分析了该方法与以往编图方法的不同和优点，以国际分幅在中国海区开展区域地质编图尚属首次，在既无海区地质调查规范，又无海区地质调查编图规范的情况下，这一工作无异具有开创性。从理论上系统总结出一套切实可行的编图方法，对于编制中国海区区域地质调查编图规范以     

走航测深数据的自动采集

本文介绍应用IBM微机实现走航实时水深及定位数据的自动采集系统。给出了联机系统方框图及采集、传送数据的程序流程图。并对IBM-PC/XT微机与测深仪之间的接口、数码转换和数据处理作了简要的叙述。     

北太平洋宽吻海豚正常生理指标数值的算法

连续5年对青岛海豚表演馆中北太平洋宽吻海豚(Tursiops gille Dall)进行现场实验和行为学研究，获取了大量的生理指标数据，运用不同的分析和计算方法对所得数据进行了筛选、剔除及处理，确立了海豚各生理指标的正常闽值和范围确定的方法，从而为准确了解海豚机体的生理状况、疾病诊断及治疗奠定了基础。