Improved target illumination at Ludvika mines of Sweden through seismic-interferometric surface-wave suppression     

Florencia Balestrini  Deyan Draganov  Alireza Malehmir  Paul Marsden  Ranajit Ghose 《Geophysical Prospecting》2020,68(1):200-213

In mineral exploration, new methods to improve the delineation of ore deposits at depth are in demand. For this purpose, increasing the signal-to-noise ratio through suitable data processing is an important requirement. Seismic reflection methods have proven to be useful to image mineral deposits. However, in most hard rock environments, surface waves constitute the most undesirable source-generated or ambient noise in the data that, especially given their typical broadband nature, often mask the events of interest like body-wave reflections and diffractions. In this study, we show the efficacy of a two-step procedure to suppress surface waves in an active-source reflection seismic dataset acquired in the Ludvika mining area of Sweden. First, we use seismic interferometry to estimate the surface-wave energy between receivers, given that they are the most energetic arrivals in the dataset. Second, we adaptively subtract the retrieved surface waves from the original shot gathers, checking the quality of the unveiled reflections. We see that several reflections, judged to be from the mineralization zone, are enhanced and better visualized after this two-step procedure. Our comparison with results from frequency-wavenumber filtering verifies the effectiveness of our scheme, since the presence of linear artefacts is reduced. The results are encouraging, as they open up new possibilities for denoising hard rock seismic data and, in particular, for imaging of deep mineral deposits using seismic reflections. This approach is purely data driven and does not require significant judgment on the dip and frequency content of present surface waves, which often vary from place to place.  相似文献   

基于CEI测量的GEO目标快速轨道恢复          下载免费PDF全文

黄俊迦  杜兰  刘泽军  张中凯  周佩元  刘隆迪 《天文学报》2024,65(1):7

连线干涉测量(Connected Element Interferometry, CEI)是一种全天时全天候的被动测角技术, 已用于空间目标的跟踪监视. 地球静止轨道(Geostationary Earth Orbit, GEO)卫星需要频繁机动以保持轨位或完成其他任务, 其机动后的快速轨道恢复能力对于监视预警极为重要. 针对基于CEI的GEO短弧定轨和预报, 分析了定轨算法的形亏和数亏, 在附加先验轨道约束的短弧定轨基础上, 提出了轨道半长轴初值的自适应优化方法. 利用亚太七号卫星的CEI仿真和实测数据进行了短弧定轨和预报, 实验结果表明, 采用优化后的半长轴初值, 30min短弧定轨和10min预报的卫星位置分量精度均优于4km, 能够满足非合作GEO目标机动后快速轨道恢复的需求.  相似文献   

基于升降轨SBAS-InSAR技术的城市地区地表沉降监测     

符彦  王剑辉  杨斌 《地理信息世界》2019,26(2):110-115

研究采用SBAS-InSAR技术,结合Sentinel-1A升降轨道数据对青海省西宁市市区进行了地表沉降监测。实验结果发现西宁市市区中沉降速率大、下沉现象明显的4个沉降区域,这些沉降区域漏斗主要发生于新建城市居民楼小区、道路、高速公路和山区区域附近。其中,Ⅲ号区域在监测时间内地面点下沉速率最高值可超过-27 mm/a,累积沉降量甚至超过了50mm。经过研究分析,区域的大范围性沉降效应主要是由于近几年大规模的城市化建设和交通轨道建设损坏了地表的土层地质平衡状态,从而引起了地表土层不可逆转的下沉现象。同时,通过对两组数据的沉降速率值作地理同名点的线性函数分析可以得到相关系数高达0.9854,这很好地验证了数据成果的可靠性和精准性。  相似文献   

Evaluation of polarimetric capabilities of dual polarized Sentinel-1 and TerraSAR-X data to improve the PSInSAR algorithm using amplitude dispersion index optimization     

《International Journal of Applied Earth Observation and Geoinformation》2020

Polarimetric data is an additional source of information in PSI technique to improve its performance in land subsidence estimation. The combination of polarimetric data and radar interferometry can lead to an increase in coherence and the number of PS pixels. In this paper, we evaluated and compared the dual polarized Sentinel-1A (S1A) and TerraSAR-X (TSX) data to improve the PSInSAR algorithm. The improvement of this research is based on minimizing Amplitude Dispersion Index (ADI) by finding the optimum scattering mechanism to increase the number of PSC and PS pixels. The proposed method was tested using a dataset of 40 dual-pol SAR data (VV/VH) acquired by S1A and 20 dual-pol SAR data (HH/VV) acquired by TSX. The results revealed that using the TSX data, the number of PS pixels increased about 3 times in ESPO method than using the conventional channels, e.g., HH, and VV. This increase in S1A data was about 1.7 times in ESPO method. In addition, we investigated the efficiency of the three polarimetric optimization methods i.e. ESPO, BGSM, and Best for the dual polarized S1A and TSX data. Results showed that the PS density increased about 1.9 times in BGSM and about 1.5 times in Best method in TSX data. However, in S1A data, PS density increased about 1.1 times in BGSM. The Best method was not successful in increasing the PS density using the S1A data. Also, the effectiveness of the method was evaluated in urban and non-urban regions. The experimental results showed that the method was successful in significantly increasing the number of final PS pixels in both regions.  相似文献   

Using Sentinel-1A DInSAR interferometry and Landsat 8 data for monitoring water level changes in two lakes in Crete,Greece     

D. D. Alexakis  E. G. Stavroulaki  I. K. Tsanis 《国际地球制图》2019,34(7):703-721

Differential Interferometric Synthetic Aperture Radar (DInSAR) methodology has been successfully employed to detect water level changes and produce corresponding water level variation maps. In this study, Agia and Kournas lakes, located in Western Crete, Greece, were used as pilot areas to monitor water level change with means of SAR interferometry and auxiliary Earth Observation (EO) data. The water level variation was monitored for the period 2015–2016, using Sentinel-1A imageries and corresponding stage water level data. Landsat 8 data were additionally used to study vegetation regime and surface water extent and how these parameters affect interferograms performance. The results highlighted the fact that the combination of SAR backscattering intensity and unwrapped phase can provide additional insight into hydrological studies. The overall analysis of both interferometric characteristics and backscattering mechanism denoted their potential in enhancing the reliability of the water-level retrieval scheme and optimizing the capture of hydrological patterns spatial distribution.  相似文献   

Planetary atmospheres with ALMA     

Emmanuel Lellouch 《Astrophysics and Space Science》2008,313(1-3):175-181

Thanks to its sensitivity, spatial resolution and instantaneous uv-coverage, ALMA will permit many new studies related to the general topic of the couplings between chemistry and dynamics in planetary atmospheres. It will include: (1) three-dimensional mapping of composition, temperatures and winds in the atmospheres of Mars, Venus and Titan; (2) several aspects of Giant Planet composition and dynamics, such as the origin of oxygen, the evolution of Shoemaker–Levy 9 products in Jupiter’s atmosphere, and the deep atmosphere structure and meteorology; (3) the study of tenuous and distant atmospheres (Io, Enceladus, Pluto, Triton and other Kuiper Belt objects).  相似文献   

Subsidence mapping at regional scale using persistent scatters interferometry (PSI): The case of Tuscany region (Italy)     

《International Journal of Applied Earth Observation and Geoinformation》2016

In this paper the mapping of subsidences in Tuscany (Italy) is presented. To achieve our goal satellite SAR data processed with persistent scatters interferometry (PSI) technique have been used. Several subsiding areas have been identified and three of them have been analyzed in detail and subsequently compared with literature work both to validate the results and to analyze the evolution of the identified subsidences. In general, this comparison confirmed the quality of the analyses and, furthermore, lead to the identification of an important ground uplift close to Prato city, an area that was historically affected by subsidence.  相似文献   

PSInSAR永久散射体的自动探测   总被引：1，自引：0，他引：1  

胡波  汪汉胜  贾路路 《测绘科学》2011,36(2):50-52

为了有效探测合成孔径雷达差分干涉测量中的永久散射体,综合考虑永久散射体对雷达波的强反射特性和散射的稳定性,本文提出了三重阈值自动探测算法,即时序相关系数、振幅离差和振幅指数三重阈值串行结合的算法.该方法首先考虑回波信号的高信噪比特性,用平均相干系数和振幅两道阈值挑选出永久散射体候选点,然后考虑永久散射体强稳定性,用振幅...  相似文献   

Extended imaging conditions for wave‐equation migration     

Paul Sava  Ivan Vasconcelos 《Geophysical Prospecting》2011,59(1):35-55

Wavefield‐based migration velocity analysis using the semblance principle requires computation of images in an extended space in which we can evaluate the imaging consistency as a function of overlapping experiments. Usual industry practice is to assemble those seismic images in common‐image gathers that represent reflectivity as a function of depth and extensions, e.g., reflection angles. We introduce extended common‐image point (CIP) gathers constructed only as a function of the space‐ and time‐lag extensions at sparse and irregularly distributed points in the image. Semblance analysis using CIP's constructed by this procedure is advantageous because we do not need to compute gathers at regular surface locations and we do not need to compute extensions at all depth levels. The CIP's also give us the flexibility to distribute them in the image at irregular locations aligned with the geologic structure. Furthermore, the CIP's remove the depth bias of common‐image gathers constructed as a function of the depth axis. An interpretation of the CIP's using the scattering theory shows that they are scattered wavefields associated with sources and receivers inside the subsurface. Thus, when the surface wavefields are correctly reconstructed, the extended CIP's are characterized by focused energy at the origin of the space‐ and time‐lag axes. Otherwise, the energy defocuses from the origin of the lag axes proportionally with the cumulative velocity error in the overburden. This information can be used for wavefield‐based tomographic updates of the velocity model, and if the velocity used for imaging is correct, the coordinate‐independent CIP's can be a decomposed as a function of the angles of incidence.  相似文献   

Accounting for image uncertainty in SAR-based flood mapping     

《International Journal of Applied Earth Observation and Geoinformation》2015

Operational flood mitigation and flood modeling activities benefit from a rapid and automated flood mapping procedure. A valuable information source for such a flood mapping procedure can be remote sensing synthetic aperture radar (SAR) data. In order to be reliable, an objective characterization of the uncertainty associated with the flood maps is required.This work focuses on speckle uncertainty associated with the SAR data and introduces the use of a non-parametric bootstrap method to take into account this uncertainty on the resulting flood maps. From several synthetic images, constructed through bootstrapping the original image, flood maps are delineated. The accuracy of these flood maps is also evaluated w.r.t. an independent validation data set, obtaining, in the two test cases analyzed in this paper, F-values (i.e. values of the Jaccard coefficient) comprised between 0.50 and 0.65. This method is further compared to an image segmentation method for speckle analysis, with which similar results are obtained. The uncertainty analysis of the ensemble of bootstrapped synthetic images was found to be representative of image speckle, with the advantage that no segmentation and speckle estimations are required.Furthermore, this work assesses to what extent the bootstrap ensemble size can be reduced while remaining representative of the original ensemble, as operational applications would clearly benefit from such reduced ensemble sizes.  相似文献