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81.
Mai Miyamoto Masashi Kiyota Hiroto Murase Takeshi Nakamura Takeshi Hayashibara 《Marine Geodesy》2017,40(4):205-223
We investigated the effects of the spatial resolution of bathymetry data on the predicted local distribution of large gorgonian corals on the southern Emperor Seamounts in the high seas of North Pacific. Terrain attributes were calculated from bathymetric survey data at six different grid-cell sizes (25–800 m) to investigate how the values of bottom terrain attributes and the prediction of MaxEnt habitat suitability models would vary with grid-cell size. The values of each terrain attribute showed different patterns among different grid-cell sizes, and MaxEnt demonstrated better performance at grid-cell size of 100 m or less than at larger sizes. 相似文献
82.
J.?Miku?kaEmail author R.?Pa?teka J.?Mrlina I.?Maru?iak 《Studia Geophysica et Geodaetica》2008,52(3):381-396
We analyzed the gravitational effect of topography and bathymetry beyond the angular distance of approximately 1.5 degrees
(referred to as the distant relief effect or DRE), and its impact on measured gravity values in the region of the former Czechoslovakia.
Our work was strongly motivated by the contents of the pioneering contribution of outstanding Czech geophysicists Miloš Pick,
Jan Pícha and Vincenc Vyskočil, which appeared at the turn of the 1950’s and 1960’s. Our numerical calculations were based
upon the direct evaluation of the gravitational effects of compartments of a spherical layer, while the respective heights
and depths were obtained from the 2 × 2 minutes digital elevation model (DEM) ETOPO2, taking into consideration also the influence
of distant bathymetry. Our results are in close agreement with, but not identical to, those of the above cited authors. We
also analyzed the influence of the grid cell size of the involved DEM upon the calculation results. We introduced an approximation
of the analyzed effect, based on a simple linear relationship between the calculation point height, the DRE and its vertical
gradient (VGDRE). Since when calculated at zero elevation the involved quantities DRE and VGDRE are smooth functions of latitude
and longitude and can be easily interpolated, the approximation gives acceptable results in terms of desired accuracy of several
μGal (1 μGal = 10−8 m/s2). In general, we can state that within the territories of the Czech and Slovak Republics the studied distant relief effect
has negligible impact upon local gravity survey data. However, when applied to regional gravity studies, there could be a
question of its possible influence in the form of a quasilinear W-E trend ranging approximately from −106.6 to −102.5 mGal
within the territory of former Czechoslovakia. If we wanted to correct for this phenomenon, we should subtract this negative
quantity from the standard Bouguer anomalies as they have been defined in the recent geophysical literature, thereby considerably
increasing their values. But, instead of straightforward correcting the Bouguer anomalies for DRE only, we would rather recommend
to wait until after the crustal and even lithospheric effects have been studied more carefully based upon the present day
independent knowledge about the deep seated sources of those effects. 相似文献
83.
84.
85.
CUBE算法及其在多波束数据处理中的应用 总被引:5,自引:0,他引:5
阐述了一种基于表面生成的多波束数据处理方法——CUBE(Combined Uncertainty and Bathymetry Estimator)算法,用该方法可以对观测区域网格节点"真实"水深及相关误差进行估计。与从测量水深中选择出"最佳"数据的手工交互方式的多波束数据编辑手段不同,CUBE算法具有很强的抗差性和较高的效率,适合于实时多波束数据处理。对南海某测区多波束数据处理结果表明,在没有人工干预的情况下,利用CUBE算法去噪生成的海底DTM图与手工编辑生成的相当吻合。CUBE算法和手工编辑方法综合对比得出,CUBE算法能够很好地保留水深地形细节,在计算效率、误差评估、实时处理等方面比手工编辑方法具有较大的优势。 相似文献
86.
利用Bayes估计进行多波束测深异常数据探测 总被引:1,自引:1,他引:0
在海底地形变化连续、平缓的假设条件下,基于Bayes估计理论提出了多波束测深异常数据探测方法,并与选权迭代加权平均滤波法进行了分析和比较。结果证明,该方法可以解决测深异常值判断标准可靠性的问题,而且能合理、有效地探测出异常值。 相似文献
87.
浅水多波束测深潮汐改正技术研究 总被引:2,自引:0,他引:2
提出了一种顾及潮时差变化的多验潮站多边形潮汐分区改正数学模型,设计了海量多波束数据通用的虚拟单验潮站改正模式。应用结果表明,该模型准确地再现了时变水位场,实现了区域瞬时海面的无缝拼接,较好地解决了多波束条带采用传统潮汐分区改正模型引起的断层及锯齿状问题。 相似文献
88.
We evaluate the strengths and weaknesses of six publicly available global bathymetry grids: DBDB2 (Digital Bathymetric Data
Base; an ongoing project of the Naval Research Laboratory), ETOPO2 (Earth Topography; National Geophysical Data Center, 2001,
ETOPO2 Global 2’ Elevations [CD-ROM]. Boulder, Colorado, USA: U.S. Department of Commerce, National Oceanic and Atmospheric
Administration), GEBCO (General Bathymetric Charts of the Oceans; British Oceanographic Data Centre, 2003, Centenary Edition
of the GEBCO Digital Atlas [CD-ROM] Published on behalf of the Intergovernmental Oceanographic Commission and the International
Hydrographic Organization Liverpool, UK), GINA (Geographic Information Network of Alaska; Lindquist et al., 2004), Smith and
Sandwell (1997), and S2004 (Smith, unpublished). The Smith and Sandwell grid, derived from satellite altimetry and ship data
combined, provides high resolution mapping of the seafloor, even in remote regions. DBDB2, ETOPO2, GINA, and S2004 merge additional
datasets with the Smith and Sandwell grid; but moving from a pixel to grid registration attenuates short wavelengths (<20
km) in the ETOPO2 and DBDB2 solutions. Short wavelengths in the GINA grid are also attenuated, but the cause is not known.
ETOPO2 anomalies are offset to the northeast, due to a misregistration in both latitude and longitude. The GEBCO grid is interpolated
from 500 m contours that were digitized from paper charts at 1:10 million scale, so it is artificially smooth; yet new efforts
have captured additional information from shallow water contours on navigational charts. The S2004 grid merges the Smith and
Sandwell grid with GEBCO over shallow depths and polar regions, and so is intended to capture the best of both products. Our
evaluation makes the choice of which bathymetry grid to use a more informed one.
The U.S. government right to retain a non-exclusive royalty-free license in and to any copyright is acknowledged. 相似文献
89.
90.
2008年奥运帆船比赛将在青岛举行。预选赛场如何符合帆船比赛的要求?海底是否有影响运动员安全的障碍物7为此,建议对预选赛场海区进行多波束全覆盖水深地形测量。同时介绍了多波束测深系统的先进性以及在许多海洋工程中的应用。 相似文献