航空重力梯度的模拟退火参数反演

针对目前地球物理问题反演时,通常利用线性或拟线性反演方法,从而导致反演过程不稳定或反演结果陷于局部最优的问题,该文采用了模拟退火算法的非线性全局反演技术,从航空重力梯度全张量数据中反演了地下密度异常体的几何参数信息。同时,利用无噪声和有噪声的两组航空重力梯度数据进行对比实验。结果表明,在重力梯度数据信噪比小于21.584 3的情况下,通过引入噪声加权的价值函数,可以提高地下密度异常体几何参数反演的准确性。     

重力梯度特征向量和多尺度分析法在密度异常深度探测中的应用

相较于传统的重力测量手段,重力梯度测量能够以更高的灵敏度和分辨率反映出地下密度异常体的结构特征。随着科学技术的不断发展,航空及卫星重力梯度测量系统已经投入使用,并实现了大范围高精度的重力梯度测量。因此,现阶段的主要挑战在于对越来越多的重力梯度数据进行分析、处理和解释。本文根据重力梯度全张量主特征值对应的特征向量,对密度异常体的深度探测进行了研究。由于不同埋深的密度异常体具有不同的波长反映,利用多尺度分析法可以分解出不同频段重力梯度张量,从而增强对更大埋深密度异常体的探测分析能力。通过对模型和实测重力梯度数据的分析解算,结果表明,重力梯度的特征向量和多尺度分析法能够有效地确定密度异常体的深度信息,并且对干扰场源和随机噪声也具有一定的抗干扰能力。     

利用重力异常数据构建重力梯度场的方法比较

为实现大范围、高精度基准重力梯度数据库的构建,考虑到重力梯度场对地形质量的敏感效应,一般利用恒密度数字高程模型来求取重力梯度值,从而忽略了地形密度变化以及水准面以下密度异常对重力梯度的影响。根据重力位理论中求解边值问题的数值应用方法,直接利用重力异常数据求取重力梯度场,弥补了密度变化和密度异常在重力梯度上的反映。根据模型算例和实测重力异常数据求取了剖面重力梯度值,结果表明,限于重力数据空间分辨率的影响,利用重力异常数据可恢复中长波段重力梯度场。该方法与地形数据求取重力梯度和卫星重力梯度测量等方法技术相结合,对重力梯度数据库的建设具有实际应用价值。     

结合非线性贝叶斯反演算法的油田储层参数反演

基于地球物理反演算法,利用地表沉降信息快速获取油田储层状态信息,对于油田储层安全的实时监控具有重要意义。目前国内外对油田储层参数反演的研究相对较少,因此本文以典型的因石油开采引起地表沉降的辽河盘锦地区作为研究区域,以InSAR沉降监测结果作为观测数据,以Okada模型作为反演模型,首次将非线性贝叶斯反演算法引入到油田储层参数反演中。在试验过程中,发现油田地下存在不止一个油层,首次将双Okada模型引入到油田储层参数反演中。试验表明：①非线性贝叶斯反演算法不仅能够获取模型参数的最优值,同时可以对反演结果的不确定性做出解释。②与单源Okada模型相比,双Okada模型更符合该地区油田储层参数变化与地表沉降之间的映射关系,基于双Okada模型反演得到的油田储层参数更可靠。     

基于TM数据的地下煤火区地表温度反演与验证

以新疆维吾尔自治区水西沟火区为例,利用与Landsat 5卫星2011年7月31日过境同时段的红外辐射计地表温度观测数据,通过多种方法获取了像元尺度的地表温度实测值,并对基于TM数据反演地表温度的单窗算法、普适性单通道算法和Weng算法得到的地下煤火区地表温度进行对比分析与验证.结果表明,3种遥感反演算法得到的水西沟地下煤火区地表温度的空间分布趋势一致,其中,单窗算法与普适性单通道算法较为接近,研究区整体的平均地表温度差值为1.60℃.与地面实测数据相比,3种反演算法结果均低于地表温度实测值.其中,普适性单通道算法与地面实测值一致性最好,决定系数R2为0.886,均方差为1.48℃,其反演结果符合地下煤火区温度的空间分布规律,高温异常区范围明显;反演结果符合要求,在地下煤火区地表温度获取中具有一定的适用性,为提升新疆地下煤火区的动态监测与评价能力选择了有效方法.     

由垂直重力梯度异常反演全球海底地形模型

本文给出了海底地形起伏与垂直重力梯度异常之间的响应函数关系。据此,联合船测海深和垂直重力梯度异常数据,构建了全球75°S~70°N范围内1′×1′海底地形模型。以船测海深为检核参考,考察了本文模型在印度洋南部和西北太平洋地区的精度。结果表明,在考察区域内,本文模型精度优于ETOPO1、GEBCO和DTU10模型,且在印度洋南部与SIO的最新海底地形模型V15.1精度相当,在西北太平洋地区略优于V15.1。探讨了高次项和地壳均衡现象的影响量级,发现两者对反演结果的影响很小,可以忽略。通过与重力异常反演结果的比较,发现垂直梯度异常反演在中短波长部分（100~200km）表现较优。在西北太平洋地区,联合重力异常和垂直梯度数据进行海底地形反演计算,反演结果的精度较V15.1模型提高了约29.5％,说明联合这两种数据可以计算精度更高的海底地形模型。     

近岸及内陆二类水体漫衰减系数的遥感反演研究进展

漫衰减系数作为水体表观光学的一个重要参数,是水下光场结构和光强的直观反映,其反演算法被应用于大面积水域的水下光场和组分变化的研究。本文首先介绍漫衰减系数反演算法基本原理,传统测量方法和现代反演算法,分析近十年国内外研究成果和存在的问题,提出今后漫衰减系数遥感反演算法的发展方向。研究结果表明:传统测量方法在适用范围和精度上都不能满足当今需求,而现代反演算法不仅弥补了传统测量方法的不足,且具有较好的普适性和更广泛的应用领域。其反演算法主要有两种:经验法和半解析法。优点是经验法偏重于特定区域,反演精度高;半解析法具有一定的普适性,引入模型参数多。缺点是经验法受实测数据影响较大,半解析法受物理模型限制。今后应加强对大气纠正和物理模型的研究,拓展其适用性。研究成果有助于研究者更为全面的了解漫衰减系数反演算法,为水色遥感研究提供理论和实践参考。     

一种改进的PolInSAR PCT方法反演植被垂直结构

针对传统PCT方法中“相干相位-幅度联合反演算法”的缺点,采用RVOG模型,利用改进的非线性迭代算法反演植被高、地表相位.改进的非线性迭代算法不仅充分利用不同极化方式对应的复相干系数,同时兼顾复相干系数的先验统计误差,提高参数解算的可靠性,进而提高PCT结果的反演精度.最后,采用两景德国E-SAR数据进行实验,实验结果表明：文中提出的方法能较好地反映植被的垂直结构信息;植被冠层对应的平均相对反射率函数近似服从高斯分布;反演的相对反射率值与植被的种类、密度存在一定关联.     

Moho面扰动重力梯度信息的提取

在运用重力和重力梯度资料反演Moho面时,关键步骤之一即是从原始测量信号精确提取只包含该层面单一密度信息的扰动(异常)值。本文主要工作有:1为减小GEMMA Moho团队的点质量模型计算误差而采用正演精度更高的空间域Tesseroid单元体和频谱域球谐分析与综合方法,并对这两种方法进行了结果对比;2如何合理利用地壳先验模型资料。本文中最后提供了基于GOCO03S模型可以用于后续Moho面反演的重力梯度主对角线分量的全球扰动值,并对所有试验数据进行了讨论和分析。     

航天飞机极化干涉雷达数据反演地表植被参数

利用基于极化干涉测量的基本原理和相干散射模型。提出了基于模拟加温-退火算法的极化干涉雷达数据地表植被参数的反演算法，首先，对极化干涉测量的基本原理和一个考虑了地表和植被散射的二层相干散射模型进行了阐述。接着，对模拟退火算法的基本理论和基于模拟加温-退火算法的地表植被参数反演模型进行了论述，最后，利用和田地区1994年10月9日和10日的航天飞机SIR-CL波段单视散射短阵复数据进行了地表植被参数反演的计算，将反演结果与实测数据比较，表明该反演算法能以较好的精度获取地表植被的高度。     

GOCE卫星重力梯度数据反演重力场的滤波器设计与比较分析

地球重力场和海洋环流探测（gravity field and steady-state ocean circulation explorer,GOCE）卫星重力梯度数据有色噪声和低频系统误差的滤波处理是反演高精度地球重力场的一个关键问题。针对GOCE卫星重力梯度数据的滤波处理,基于移动平均（moving average,MA）方法和CPR(circle per revolution)经验参数方法设计了两类低频系统误差滤波器,并分别将这两类滤波器与基于自回归移动平均（auto-regressive and moving average,ARMA）模型设计的有色噪声滤波器组合起来形成级联滤波器。为了分析滤波器处理的实际效果,基于空域最小二乘法采用70 d的GOCE观测数据,并联合重力恢复与气候实验（gravity recovery and climate experiment,GRACE）数据分别反演了224阶次的重力场模型GOGR-MA(MA+ARMA级联滤波)和GOGR-CPR(CPR+ARMA级联滤波)。将反演模型与采用同期数据求解的第一代GOCE系列模型及GOCE和GRACE联合模...     

Truncated geoid and gravity inversion for one point-mass anomaly

The truncated geoid, defined by the truncated Stokes' integral transform, an integral convolution of gravity anomalies with the Stokes' function on a spherical cap, is often used as a mathematical tool in geoid computations via Stokes' integral to overcome computational difficulties, particularly the need to integrate over the entire boundary spheroid. The objective of this paper is to demonstrate that the truncated geoid does, besides having mathematical applications, have physical interpretation, and thus may be used in gravity inversion. A very simple model of one point-mass anomaly is chosen and a method for inverting its synthetic gravity field with the use of the truncated geoid is presented. The method of inverting the synthetic field generated by one point-mass anomaly has become fundamental for the authors' inversion studies for sets of point-mass anomalies, which are published in a separate paper. More general applications are currently under investigation. Since an inversion technique for physically meaningful mass distributions based on the truncated geoid has not yet been developed, this work is not related to any of the existing gravity inversion techniques. The inversion for one point mass is based on the onset of the so-called dimple event, which occurs in the sequence of surfaces (or profiles) of the first derivative of the truncated geoid with respect to the truncation parameter (radius of the integration cap), its only free parameter. Computing the truncated geoid at various values of the truncation parameter may be understood as spatial filtering of surface gravity data, a type of weighted spherical windowing method. Studying the change of the truncated geoid represented by its first derivative may be understood as a data enhancement method. The instant of the dimple onset is practically independent of the mass of the point anomaly and linearly dependent on its depth. Received: 26 September 1996 /Accepted: 28 September 1998     

多尺度源网重力与重力梯度联合聚焦反演

在重力聚焦反演基础上提出多尺度源网聚焦反演算法.首先,对源网进行粗网格剖分,用共轭梯度法求解粗网格源网模型的聚焦解,直到拟合差下降至设定的数值;然后,将粗网格得到的密度映射到细网格;最后,以细网格模型为初始模型,进一步迭代直到拟合差下降至符合反演要求.模型试验结果显示,相比于固定源网反演,多尺度源网聚焦反演迭代的总耗时...     

由地面重力数据确定扰动位径向二阶梯度

提出利用地面重力异常数据计算地面扰动位径向二阶梯度，将该梯度的积分表达式转换为卷积形式的谱表达式，便于应用ＦＦＴ／ＦＨＴ技术进行快速计算。这一将地面重力异常化为重力梯度的实用算法为将卫星重力梯度和航空重力梯度观测数据与地面重力数据的联合处理提供了一种有效途径。最后，以本文导出的数学模型为基础，给出了模型（ＷＤＭ９４）数据的试算结果并作了分析     

重力数据的多尺度边缘分析及其应用(英文)

In order to improve the processing and interpretation of gravity data, multiscale edge theory in image processing is introduced into the study of gravity field. Multiscale edges of gravity anomaly are analyzed based on a special wavelet. It shows that the multiscale edges are the extrema points of the horizontal gravity gradient at different heights, which are related to the sharp discontinuities of underground sources. The applications of multiscale edge in downward continuation and gravity inversion are discussed. The simulated examples show that the multiscale edges can be applied to stabilize the downward continuation operator when the continuation height is low. The multiscale edges also have a convenient application to infer the geometry of the underground source. Moreover, the gravity inversion algorithm based on the multiscale edges has a good antinoise property. Supported by the National Natural Science Foundation of China(No.40704003), the National 973 Program of China(No.2007CB714405), the Open Research Fund from Key Laboratory of Geospace Environment and Geodesy(No.04-01-08).     

联合多源重力数据反演菲律宾海域海底地形

对比分析重力-海深的“理论导纳”和实际数据的“观测导纳”,获得研究海域有效弹性厚度理论值为10 km。联合重力异常和重力异常垂直梯度数据,应用自适应赋权技术,采用导纳函数方法构建菲律宾海域1'×1'海底地形模型。试验发现,当重力异常垂直梯度反演海深结果与重力异常反演海深结果的权比为2∶3时,所构建的海深模型检核精度最高。同时,联合多源重力数据反演海深能够综合重力异常和重力异常垂直梯度在对待不同海底地形上的反演优势,生成精度优于单独使用重力异常数据和重力异常垂直梯度数据反演的海底地形模型。以船测数据作为外部检核条件,反演模型检核精度略低于V18.1海深模型,而相较于ETOPO1海深模型和DTU10海深模型检核精度分别提高了27.17%和39.02%左右;反演模型相对误差的绝对值在5%范围内的检核点大约占检核点总数的94.25%。     

Density interface topography recovered by inversion of satellite gravity gradiometry observations

A radial integration of spherical mass elements (i.e. tesseroids) is presented for evaluating the six components of the second-order gravity gradient (i.e. second derivatives of the Newtonian mass integral for the gravitational potential) created by an uneven spherical topography consisting of juxtaposed vertical prisms. The method uses Legendre polynomial series and takes elastic compensation of the topography by the Earth’s surface into account. The speed of computation of the polynomial series increases logically with the observing altitude from the source of anomaly. Such a forward modelling can be easily applied for reduction of observed gravity gradient anomalies by the effects of any spherical interface of density. An iterative least-squares inversion of measured gravity gradient coefficients is also proposed to estimate a regional set of juxtaposed topographic heights. Several tests of recovery have been made by considering simulated gradients created by idealistic conical and irregular Great Meteor seamount topographies, and for varying satellite altitudes and testing different levels of uncertainty. In the case of gravity gradients measured at a GOCE-type altitude of \(\sim \)300 km, the search converges down to a stable but smooth topography after 10–15 iterations, while the final root-mean-square error is \(\sim \)100 m that represents only 2 % of the seamount amplitude. This recovery error decreases with the altitude of the gravity gradient observations by revealing more topographic details in the region of survey.     

Geoid and high resolution sea surface topography modelling in the mediterranean from gravimetry,altimetry and GOCE data: evaluation by simulation

The determination of local geoid models has traditionally been carried out on land and at sea using gravity anomaly and satellite altimetry data, while it will be aided by the data expected from satellite missions such as those from the Gravity field and steady-state ocean circulation explorer (GOCE). To assess the performance of heterogeneous data combination to local geoid determination, simulated data for the central Mediterranean Sea are analyzed. These data include marine and land gravity anomalies, altimetric sea surface heights, and GOCE observations processed with the space-wise approach. A spectral analysis of the aforementioned data shows their complementary character. GOCE data cover long wavelengths and account for the lack of such information from gravity anomalies. This is exploited for the estimation of local covariance function models, where it is seen that models computed with GOCE data and gravity anomaly empirical covariance functions perform better than models computed without GOCE data. The geoid is estimated by different data combinations and the results show that GOCE data improve the solutions for areas covered poorly with other data types, while also accounting for any long wavelength errors of the adopted reference model that exist even when the ground gravity data are dense. At sea, the altimetric data provide the dominant geoid information. However, the geoid accuracy is sensitive to orbit calibration errors and unmodeled sea surface topography (SST) effects. If such effects are present, the combination of GOCE and gravity anomaly data can improve the geoid accuracy. The present work also presents results from simulations for the recovery of the stationary SST, which show that the combination of geoid heights obtained from a spherical harmonic geopotential model derived from GOCE with satellite altimetry data can provide SST models with some centimeters of error. However, combining data from GOCE with gravity anomalies in a collocation approach can result in the estimation of a higher resolution geoid, more suitable for high resolution mean dynamic SST modeling. Such simulations can be performed toward the development and evaluation of SST recovery methods.     

利用多元回归分析反演西南印度洋区域海底地形

针对海底地形与重力异常和重力异常垂直梯度在相应频段呈现强线性相关的特点,引入多元回归分析技术,提出并详细推导了联合多元重力数据的海底地形建模方法。然后,在西南印度洋SWIR(Southwest India Ridge)所在部分海域开展了海底地形反演试验及地形地貌分析研究。试验结果表明:6种海深模型中,基于多元回归分析技术构建的海深模型(BDVG模型)检核精度最高,相较于S&S V18.1模型和ETOPO1模型精度分别提高了11.51%和57.81%左右;2000 m以上水深海域,各个海深模型的检核精度较高,相对误差波动较小,反映了深海海域具有良好的反演效果;地形起伏剧烈海域或者浅海海域,BDVG海深模型,相较于以重力异常和重力异常垂直梯度作为单一输入源建立的BDG模型和BVGG模型相对误差及相对误差波动变化较小,反映了BDVG模型拥有更好的稳定性,从而体现了联合反演的必要性和优势。Indomed FZ—Gallieni FZ上唯一轴部缺失裂谷洋脊段(27洋脊段)目前属于岩浆供应充足阶段,构造作用的海底扩张对其影响较小;同时由于对称裂离方式影响,27洋脊段沿轴南北对称分布有地形隆起。