共查询到19条相似文献，搜索用时 418 毫秒
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粗差探测是评价船载重力测量数据成果质量的重要内容。卫星测高反演重力场技术提供了海域全覆盖的重力场数值模型,其精度水平已满足探测船载重力测量数据粗差的精度要求。以卫星测高反演重力场模型为基础,提出了基于窗口移动中误差模型探测船载重力测量粗差的数据处理方法,其基本思路是:以卫星测高反演重力场数值模型作为背景场,计算船载重力测点处的测高重力值的差值,以差值作为输入量,等权构建中误差背景场,以开窗中误差背景场作为参考,按照平差思想探测船载重力测量数据的粗差。实验结果表明,依据本文方法能有效探测船载重力测量数据的粗差。 相似文献
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重力垂直梯度异常反应了重力异常的空间变化率,在地球物理勘探等多学科中得到越来越多的应用。利用南海局部区域实测重力异常数据和Sandwell测高重力异常数据,将搜索范围、距离和精度多种因素融合考虑并对Shepard算法进行改进,给出了南海局部区域(19°N~20.5°N,114°E~115.5°E)分辨率1'×1'的重力异常并反演了对应分辨率的重力垂直梯度异常。结果表明,基于Shepard改进算法的高精度船测重力和测高重力的有机融合,增强了单一测高重力数据反演重力垂直梯度异常的细节纹理,提高了反演重力垂直梯度异常的分辨率和精度。 相似文献
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在海上复杂的环境下进行重力测量,重力仪及技术人员的操作难免会出现各种各样的问题,导致测量的成果精度降低,甚至不符合规范要求。目前检查海洋重力测量成果质量的主要方法是内符合法,主要采用主测线、检测线交叉点的差值,或重复测线相邻点的差值来评估测量成果的质量。介绍了内符合法存在的弊端,比较了DTU重力数据与重力仪实测数据的精度,叙述了基于DTU重力数据检查海洋重力测量成果较大系统差的可行性,以模型数据为外符合数据源来检查实测成果的质量,作为内符合法的补充,是十分必要的。 相似文献
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通过对南黄海及周边船载测量重力数据、现代卫星测高重力数据、陆地测量重力数据以及地球重力模型等多来源重力数据进行整理和融合,对南黄海地区布格重力异常特征进行了分析。利用基于切割法和插值迭代法的大深度位场向下延拓技术的视密度反演法对南黄海布格重力进行处理和解释,结合山东和朝鲜半岛的地质信息,推断了扬子块体和中朝块体在南黄海海域的界限。中朝和扬子块体在海上的分界位置为千里岩北缘断裂,向NE延伸到125°E后,折向NNW向并在36°N附近再次转为NE向进入朝鲜半岛并经过洪城南侧继续以NE向延伸。扬子的北缘为苏鲁造山带,穿过黄海与京畿造山带相接,苏鲁超高压变质带对应洪城杂岩。 相似文献
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利用中国-尼日利亚国际合作航次获得的船载重力数据,分析了尼日利亚南部大陆边缘的自由空间重力异常和布格重力异常特征,并通过两条从陆架—陆坡—陆隆一直延伸到深海盆地的重力剖面拟合出地壳密度结构。研究结果表明,地壳厚度总体上从陆架、陆坡至深海平原呈现阶梯状减薄的趋势,东侧的减薄幅度大于西侧,东侧从24 km减小到10 km,西侧从21 km减小到14 km。 相似文献
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Christian Hirt 《Marine Geodesy》2013,36(2):183-202
We apply the residual terrain modeling (RTM) technique for gravity forward-modeling to successfully improve high-resolution global gravity fields at short spatial scales in coastal zones. The RTM scheme is combined with the concept of rock-equivalent topography, allowing to use a single uniform constant mass-density in the RTM forward-modeling, both at land and sea. SRTM30_PLUS bathymetry is merged with higher-resolution SRTM V4.1 land topography, and expanded into spherical harmonics to degree 2160, yielding a new and consistent high-degree RTM reference surface. The forward-modeling performance is demonstrated in coastal zones of Greece and Canada using ground-truth vertical deflections, gravity from land and shipborne gravimetry, and geoid heights from GPS/leveling, with improvements originating from bathymetry clearly identified. We demonstrate that the SRTM30_PLUS bathymetry carries information on gravity field structures at spatial scales less than 5 arc minutes, which can be used to augment EGM2008 in (rugged) coastal zones, both over land and marine areas. This may be of value (i) to partially reduce the signal omission error in EGM2008/GOCE-based height transfer in areas devoid of dense gravity data, (ii) to fill the gap between land gravity and shipborne gravity along rugged coastlines, and (iii) for the development of next-generation altimetric gravity fields. 相似文献
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Chan Hong Park Jeong Woo Kim Nobuhiro Isezaki Daniel R. Roman Ralph R. B. von Frese 《Marine Geophysical Researches》2006,27(4):253-266
To facilitate geological analyses of the Ulleung Basin in the East Sea (Japan Sea) between Korea and Japan, shipborne and satellite altimetry-derived gravity data are combined to derive a regionally coherent anomaly field. The 2-min gridded satellite altimetry-based gravity predicted by Sandwell and Smith [Sandwell DT, Smith WHF (1997) J Geophys Res 102(B5):10,039–10,054] are used for making cross-over adjustments that reduce the errors between track segments and at the cross-over points of shipborne gravity profiles. Relative to the regionally more homogeneous satellite gravity anomalies, the longer wavelength components of the shipborne anomalies are significantly improved with minimal distortion of their shorter wavelength components. The resulting free-air gravity anomaly map yields a more coherent integration of short and long wavelength anomalies compared to that obtained from either the shipborne or satellite data sets separately. The derived free-air anomalies range over about 140 mGals or more in amplitude and regionally correspond with bathymetric undulations in the Ulleung Basin. The gravity lows and highs along the basin’s margin indicate the transition from continental to oceanic crust. However, in the northeastern and central Ulleung Basin, the negative regional correlation between the central gravity high and bathymetric low suggests the presence of shallow denser mantle beneath thinned oceanic crust. A series of gravity highs mark seamounts or volcanic terranes from the Korean Plateau to Oki Island. Gravity modeling suggests underplating by mafic igneous rocks of the northwestern margin of the Ulleung Basin and the transition between continental and oceanic crust. The crust of the central Ulleung Basin is about a 14–15 km thick with a 4–5 km thick sediment cover. It may also include a relatively weakly developed buried fossil spreading ridge with approximately 2 km of relief. 相似文献
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ABSTRACTDifferent types of gravity observations are available over coastal areas. The main challenge for coastal geoid determination is the proper fusion of heterogeneous gravity data including land, shipborne, airborne, and altimetry-derived gravity data. This paper describes the gravity data fusion and the computation of the gravimetric quasigeoid in the coastal area of mainland China. An iterative procedure of the weighted least-squares prediction based on rectangular harmonic functions is used for merging the land, altimetric, shipborne, and airborne gravity data. Applying the analytical continuation method in Molodensky's theoretic frame, the merged gravity data are then used to determine the gravimetric quasigeoid model by using the generalized Stokes' integral in a remove-compute-restore fashion. The gravimetric quasigeoid model is compared with the height anomalies determined at 662 GPS leveling points over the coastal region of mainland China, where both the geodetic height and the normal height are known. The standard deviations of the differences in the coastal provinces range from 1.8 to 4.4 cm. For the entire computation area, the mean and standard deviation of the differences are 27.9 and 3.9 cm, respectively. 相似文献
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Significant Wave Height (SWH) measurement data from the AltiKa Radar Altimeter (RA) for the first 13 cycles of satellite coverage are compared with the SWH from Wave Rider Buoys (WRB) located at nine stations along the Indian coast to assess the performance of the altimeter over the coastal region. AltiKa SWH observations within a 30-minute interval and 50 km distance from WRBs are found to be over estimated by 6%, the Root Mean Square Error (RMSE) is 0.36 m, the Scatter Index (SI) is 26%, and the correlation coefficient (r) is 0.91. Relaxing the distance criteria by 50 km leads to increase in RMSE and deterioration of r to 0.89. There is a marked difference in the statistics on the comparison pairs pooled separately for the buoys near west and east coasts, with the latter showing RMSE error 26% more than the former. The method of Cressman weights adopted to correct for the errors arising out of the temporal and spatial differences in altimeter and buoy data comparison pairs resulted in reduction of RMSE by 5% and 25%, respectively, for the 30-minute and 50 km criteria and 4% and 56% for the 30-minute and 100 km criteria. 相似文献
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Rene Forsbergbi Arne Vestergaard Olesen Adel Alshamsi Arne Gidskehaug Sahrum Ses Majid Kadir 《Marine Geodesy》2013,36(3):221-232
The Military Survey Department (MSD) of the United Arab Emirates (UAE) undertook an airborne gravity survey project for the marine area of the country in 2009, especially to strengthen the marine and coastal geoid in the near-shore regions. For the airborne gravity survey, 5 km spacing coast-parallel flight lines were planned and surveyed. These lines were supplemented by cross-lines in order to assess the quality of the airborne gravity surveys. The flight lines were extended 10 km, spacing lines further offshore. A Beech King Air 350 aircraft was used for the surveys, collecting data at a typical flight speed of 170 knots and a typical flight elevation of 900–1500 m, depending on weather conditions and topography. Gravity was measured with a ZLS-modified LaCoste and Romberg gravimeter (S-99), augmented with a Honeywell strap-down inertial navigation system unit. The estimated accuracy for the airborne gravity data is better than 2.0 mGal r.m.s., as judged from the airborne track crossovers. The new airborne gravimetry data changed the UAE coastal geoid by up to 30 cm in some regions, highlighting the importance of airborne gravity coastal surveys. 相似文献
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D. V. Ivonin V. A. Telegin P. V. Chernyshov S. A. Myslenkov S. B. Kuklev 《Oceanology》2016,56(4):591-600
We present the results of development and testing of a coastal X-band radar system for monitoring wind waves and currents at the Black Sea (near Gelendzhik) created on the basis of nautical radars. Radar measurements of wave heights were validated by data from a wave buoy and a moored acoustic Doppler current profiler (ADCP). The conditions for successful radar measurements of waves in the coastal environment have been determined. It was shown that a radar with an aperture 1° could successfully measure wave heights at a distance of 1.2 km from the radar, when waves arrive at an angle of ±31° to the main sensing direction. In this case, for wave height measurements, the correlation coefficient between the radar and independent data is 0.82 and the standard deviation is 0.26 m. 相似文献
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Ahmed Zaki Ahmed Hamdi Mansi Mohamed Selim Mostafa Rabah Gamal El-Fiky 《Marine Geodesy》2018,41(3):258-269
The determination of high-resolution geoid for marine regions requires the integration of gravity data provided by different sources, e.g. global geopotential models, satellite altimetry, and shipborne gravimetric observations. Shipborne gravity data, acquired over a long time, comprises the short-wavelengths gravitation signal. This paper aims to produce a consistent gravity field over the Red Sea region to be used for geoid modelling. Both, the leave-one-out cross-validation and Kriging prediction techniques were chosen to ensure that the observed shipborne gravity data are consistent as well as free of gross-errors. A confidence level equivalent to 95.4% was decided to filter the observed shipborne data, while the cross-validation algorithm was repeatedly applied until the standard deviation of the residuals between the observed and estimated values are less than 1.5 mGal, which led to the elimination of about 17.7% of the shipborne gravity dataset. A comparison between the shipborne gravity data with DTU13 and SSv23.1 satellite altimetry-derived gravity models is done and reported. The corresponding results revealed that altimetry models almost have identical data content when compared one another, where the DTU13 gave better results with a mean and standard deviation of ?2.40 and 8.71 mGal, respectively. A statistical comparison has been made between different global geopotential models (GGMs) and shipborne gravity data. The Spectral Enhancement Method was applied to overcome the existing spectral gap between the GGMs and shipborne gravity data. EGM2008 manifested the best results with differences characterised with a mean of 1.35 mGal and a standard deviation of 11.11 mGal. Finally, the least-squares collocation (LSC) was implemented to combine the shipborne gravity data with DTU13 in order to create a unique and consistent gravity field over the Red Sea with no data voids. The combined data were independently tested using a total number of 95 randomly chosen shipborne gravity stations. The comparison between the extracted shipborne gravity data and DTU13 altimetry anomalies before and after applying the LSC revealed that a significant improvement is procurable from the combined dataset, in which the mean and standard deviation of the differences dropped from ?3.60 and 9.31 mGal to ?0.39 and 2.04 mGal, respectively. 相似文献
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漫衰减系数是一个重要的海洋光学参数,能够为水体环境变化、水质分析以及水产养殖等方面提供基础性数据。针对目前船载实地测量效率与分辨率低、卫星遥感反演精度与分辨率较低的局限性,本文提出一种基于机载LiDAR测深水体波形的漫衰减系数提取方法。该方法首先通过分层异构模型的机载LiDAR波形分解算法得到水体散射回波,利用激光在水体中的衰减特性,构建漫衰减系数提取模型,最终获取大面积水域漫衰减系数的空间分布。采用西沙甘泉岛与江苏连云港两个航次的实测数据对所提算法进行了验证,本算法无需每个测深点的水底底部回波强度和深度即可反演得到漫衰减系数,并且在浑浊水域也可取得较好的效果,表明在中国近海利用机载LiDAR测深系统能够有效获取高精度的漫衰减系数。 相似文献