Inversion method of deflection of the vertical based on SWOT wide-swath altimeter data

The deflection of the vertical(DOV)is the key information in the study of ocean gravity field.However,in most areas,the precision of the prime component of DoV is significantly lower than that of the meridian component.To obtain higher accuracy and resolution of ocean gravity information,researchers have proposed a novel altimeter called the wide-swath altimeter.This altimeter allows for the simultaneous acquisition of high-precision and high-resolution two-dimensional measurements of sea surface height(SSH).In this paper,the Surface Water and Ocean Topography(SWOT)mission with a wide-swath altimeter on board is selected for research.One cycle of swoT sea surface height data is simulated to inverse the DOV in the Arabian Sea(45°E—80°E,0°-30°N),and the inversion results are compared with those of conventional altimeter data.The results demonstrate that the difference between the meridian and prime components derived from the inversion of swoT wide-swath data is minimal,significantly outperforming the inversion results of conventional nadir altimeter data.The advantage of swoT wide-swath altimeter lies in its ability to use the multi-directional geoid slope at any sea surface measurement point to invert the components in the meridian and prime directions.To investigate the impact of this advantage on inversion precision,this paper employs a method to calculate the gradient of the geoid in multiple directions to invert DoV components.The improvement effect of calculating the gradient of the geoid in multiple directions on the precision of DoV component is analyzed.It is found that the accuracy of DoV inversion has significantly improved with the increase of geodetic gradient calculation direction.In addition,the effects of various errors and grid spacing in SwoT wide sea surface height data on the precision of Dov inversion are also analyzed.

Predicting bathymetry based on vertical gravity gradient anomaly and analyses for various influential factors

The prediction of bathymetry has advanced significantly with the development of satellite altimetry.However,the majority of its data originate from marine gravity anomaly.In this study,based on the expression of vertical gravity gradient(VGG)of a rectangular prism,the governing equations for determining sea depths to invert bathymetry.The governing equation is solved by linearization through an iterative process,and numerical simulations verify its algorithm and its stability.We also study the processing methods of different interference errors.The regularization method improves the stability of the inversion process for errors.A piecewise bilinear interpolation function roughly replaces the low-frequency error,and numerical simulations show that the accuracy can be improved by 41.2%after this treatment.For variable ocean crust density,simulation simulations verify that the root-mean-square(RMS)error of prediction is approximately 5 m for the sea depth of 6 km if density is chosen as the average one.Finally,two test regions in the South China Sea are predicted and compared with ship soundings data,RMS errors of predictions are 71.1 m and 91.4 m,respectively.

基于三角形面积的海空重力交叉点搜索法

目前海空重力测量中测线网交叉点搜索的计算方法存在精度不高和操作复杂等缺点,可以通过改善交叉点搜索方法使得海空重力测量数据处理过程进一步优化。新提出一种基于三角形面积原理实现交叉点搜索的方法,并通过仿真数据和实测数据验证此方法的简洁性和有效性。计算结果表明,利用新提出的交叉点搜索法求解的测线网内符合精度要比主副测线斜率法提升0.02 mGal左右,计算速度要比行列式法快。本文的研究对于进一步优化海空重力测量中交叉点搜索方法具有一定的借鉴意义。

基于改进变分模态分解算法的海洋绝对重力数据滤波处理

原子重力仪具有采样率高、精度高及长期稳定性好等优点,适用于远洋深海高精度绝对重力测量工作。受恶劣海况影响,原子重力仪测量的绝对重力数据中存在大量非平稳、非线性的噪声信号,影响重力测量的精度,进而影响地质构造解释的准确性。为了消除重力测量数据中的噪声,本文分析了创新性地引入改进变分模态分解(improved variatio nal modal decomposition,IVMD)算法进行滤波处理。

Gravity anomalies determined from mean sea surface model data over the Gulf of Mexico

With the improvements in the density and quality of satellite altimetry data,a high-precision and high-resolution mean sea surface model containing abundant information regarding a marine gravity field can be calculated from long-time series multi-satellite altimeter data.Therefore,in this study,a method was proposed for determining marine gravity anomalies from a mean sea surface model.Taking the Gulf of Mexico(15°–32°N,80°–100°W)as the study area and using a removal-recovery method,the residual gridded deflections of the vertical(DOVs)are calculated by combining the mean sea surface,mean dynamic topography,and XGM2019e_2159 geoid,and then using the inverse Vening-Meinesz method to determine the residual marine gravity anomalies from the residual gridded DOVs.Finally,residual gravity anomalies are added to the XGM2019e_2159 gravity anomalies to derive marine gravity anomaly models.In this study,the marine gravity anomalies were estimated with mean sea surface models CNES_CLS15MSS,DTU21MSS,and SDUST2020MSS and the mean dynamic topography models CNES_CLS18MDT and DTU22MDT.The accuracy of the marine gravity anomalies derived by the mean sea surface model was assessed based on ship-borne gravity data.The results show that the difference between the gravity anomalies derived by DTU21MSS and CNES_CLS18MDT and those of the ship-borne gravity data is optimal.With an increase in the distance from the coast,the difference between the gravity anomalies derived by mean sea surface models and ship-borne gravity data gradually decreases.The accuracy of the difference between the gravity anomalies derived by mean sea surface models and those from ship-borne gravity data are optimal at a depth of 3–4 km.The accuracy of the gravity anomalies derived by the mean sea surface model is high.

南海区域测高海洋重力场模型精度和空间分辨率估算

随着新型测高卫星的发射以及测高数据的持续更新,测高海洋重力场模型的精度和分辨率也越来越高。为评估测高海洋重力场模型的精度和真实的空间分辨率,本文对南海区域三个测高重力场模型(DTU17、SS V32.1和SDUST)和两组不同来源的船测数据进行了多元分析和评估。首先,对船测数据进行了预处理和各项改正,利用交叉点评估了船测数据的精度;然后,将三个测高海洋重力场模型与处理好的船测数据进行比较,估算了三个模型在南海区域的精度;最后,基于滤波以及频率相干性这两种方法,利用高精度的船测数据计算了南海区域上述三种测高海洋重力场模型的精度与真实空间分辨率。最终的结果表明,在南海区域三个模型与船测数据之差的均方根分别为:3.48~7.01 mGal、3.38~6.80 mGal和2.64~6.83 mGal,三个模型的真实空间分辨率分别为:9.1~11.5 km、6.7~11.2 km和8.9~11.3 km。

Research Progress in Surface and Marine Gravimetry

Gravity field is the most basic physical field generated by the material properties of the Earth system.It reflects the spatial distribution,movement and change of materials determined by the interaction and dynamic process inside the Earth.Over the years,a variety of technical means have been used to detect the Earth’s gravity field and supported numerous studies on the global change,resource detection,geological structure movement,water resources change and other related fields of research.Here is part of the progress in surface and marine gravimetry obtained by Chinese geodesy scientists from 2019 to 2023 from the following aspects,including:①Continuous gravity network in Chinese mainland;②Application of superconducting gravity measurement;③Network adjustment for continental-scale gravity survey campaign and data quality control;④Regional time-variable gravity field and its application;⑤Research progress on novel technologies for gravity inversion;⑥Research progress on marine gravity field determination;⑦Application research on marine gravity field.

联合TOPEX/Poseidon,ERS2和Geosat卫星测高资料确定中国近海重力异常

处理了 TOPEX/Poseidon(第 9周期至第 2 4 9周期 ) ,ERS2 (第 0周期至第 44周期 )和Geosat/GM(第 1周期至第 2 5周期 )以及 Geosat ERM(第 1周期至第 66周期 )卫星测高资料 ,求解了各自卫星任务的交叉点和垂线偏差 ,利用逆 Vening- Meinesz公式确定了 2 .5′×2 .5′中国近海海洋重力异常 ,并与我国南海船测重力异常作了比较 ,其精度为± 9.3m Gal( 1 Gal=1 cm/s2 )。本文同时导出了严密的 2维平面卷积公式 ,它与 1维严密卷积公式计算结果差值的标准差为± 0 .1 m Gal,而 2维球面公式为± 0 .5 m

海空重力测量及应用技术研究进展与展望(一):目的意义与技术体系

作为海空重力测量及应用技术研究进展的开篇,首先简要介绍了该项技术的研究背景,然后详细论述了海空重力测量信息的应用价值及开展该项技术研究的目的意义和应用需求,分析了海空重力测量的技术特点,提出了海空重力测量及应用技术体系的基本架构,明确了该项技术的研究内容、作业流程及各个技术环节的相互关系。

海空重力测量及应用技术研究进展与展望(三):数据处理与精度评估技术

系统分析总结了海空重力测量数据预处理即各项环境效应改正技术的研究现状及发展方向,简要论述了海空重力测量数据精细处理即数据滤波与误差补偿技术的研究动态及发展前景,分析讨论了海空重力测量精度评估技术的研究进展及发展思路,为海空重力测量数据处理及精度评估技术的未来发展提供参考。

海洋重力测量动态环境效应分析与补偿

针对使用小型测量船搭载摆杆型海洋重力仪获取数据质量不高的问题,在深入分析海洋环境动态效应误差特性基础上,提出了一种基于互相关分析的交叉耦合效应修正法,对高动态海洋重力测量数据实施综合误差补偿和精细处理。使用典型恶劣海况条件下的观测数据对该方法的有效性进行了验证,结果显示,重力测线成果内符合精度从原先的±9.35×10-5m/s2大幅提升到±1.43×10-5m/s2,同时使用卫星测高反演重力对精细处理结果的可靠性进行了外部检核,外符合精度也从原先的±7.73×10-5m/s2提高到±5.63×10-5m/s2。

融合多源重力数据的Tikhonov正则化配置法

针对最小二乘配置法在融合处理多源重力数据过程中可能出现的病态性问题,特别引入Tikhonov正则化方法,对配置法计算模型进行正则化改造,建立了相应的正则化配置模型。使用EGM2008位模型模拟产生航空重力和海面船测重力数据进行了融合处理仿真实验,实际验证了正则化处理方法的有效性。

小波多尺度分析在重力仪数据处理中的应用研究

为了有效地消除重力异常畸变对重力仪测量数据的影响,得到更高精度的重力异常测量值,在分析小波多尺度分析原理的基础上,首次将其应用到重力仪数据处理中,并与自适应卡尔曼滤波进行了对比分析,以实际数据与处理后数据偏差平方和的平均数作为衡量两种数据处理方法性能的指标。理论分析和仿真实验表明:小波多尺度分析和自适应卡尔曼滤波都能在一定程度上抑制重力异常畸变对重力仪测量数据的影响,但小波多尺度分析的性能优于自适应卡尔曼滤波。

基于参考场的多航次船载重力测量系统偏差调整

由于不同部门的船载重力测量规范不统一,导致不同部门不同航次之间获取的船载重力测量数据可能存在比较明显的系统性偏差。提出了基于参考场进行多航次船载重力测量系统偏差调整方法,即以某参考场(如DTU10GRA数值模型)为背景,基于平差思想,将航次实测数据与参考场数据之间差异的统计平均值作为观测量,进行系统偏差计算、分析、检验及调整。实验结果表明,依据本文方法能够有效消除多航次船载重力测量数据基准的不协调性。

Surfer8.0在重力异常数据格网化中的应用

介绍了利用Surfer8.0软件进行重力异常数据格网化的方法,并结合重力场数据的特点,编制了相应的数据格式转换程序,直接利用Surfer8.0软件中几种数据插值方法,对陆地、山区、海洋等不同地形数据进行格网化处理,并对结果进行交叉验证和对比分析,结果表明利用Surfer8.0软件进行重力异常数据格网化的方法是切实可行的。

自适应卡尔曼滤波在大跨径桥梁安全监控中的应用

对由卡尔曼滤波理论建立的数据模型进行了研究 ,建立了自适应动态滤波模型 ,并用该模型对南京长江某大跨径桥梁的实际监测资料进行了分析 ,结果表明该模型能正确反映桥梁变化。

海洋重力测量实时处理系统

介绍了我国第一套海洋重力测量实时处理系统的软、硬件结构、技术性能、与其相关的理论研究成果以及试验、应用情况。

基于窗口移动中误差模型探测船载重力数据粗差

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。

Etvs效应改正中航向航速计算间隔分析

Etvs效应改正误差一直被认是影响海洋重力测量精度的主要误差,为了减小由定位误差引起的Etvs效应改正误差,本文提出采用合理的测量点间隔计算航向、航速以提高Etvs效应改正精度的方法。通过必要理论分析与实际计算,证实了采用合适航向、航速计算间隔将提高Etvs效应改正精度,从而提高海洋重力测量精度。

基于小波多尺度积的图像配准方法

由于基于特征的图像配准方法,对提取图像特征的鲁棒性和精确性都有很高的要求.本文提出了一种基于小波多尺度积的图像配准方法。该方法利用小波多尺度积提取边缘图像和特征点,同时保存特征点的方向信息,具有抗噪性强和边缘定位精确等优点;然后利用特征点的方向信息,定义角度直方图来得到图像之间的精确旋转角度;最后可以选择多种匹配准则来确定匹配点对。实验结果表明,本文提出的方法具有精确性、抗噪性、有效性和鲁棒性等优点。