Long term monitoring of urban subsidence by Permanent Scatterer DInSAR

When using differential SAR interferometry (DInSAR) to monitor the surface deformation over a long time scale, it is often strongly affected by the spatial and temporal decorrelations and atmospheric dishomogeneities. The recently developed Permanent Scatterers (PS) technique proposed by Fertti et al. can overcome these difficulties by interpreting time-series of interferometric phase only at coherent point scatterers. In this study, we apply this PS technique using 25 ERS-1/2 scenes from 1992 to 2000 to monitor the subsidence in Suzhou. By using the linear deformation model, the deformation map in Suzhou urban area over the eight years is obtained. And the calculated results are in good agreement with the measurements of leveling.     

Long term monitoring of urban subsidence by Permanent Scatterer DInSAR

When using differential SAR interferometry (DInSAR) to monitor the surface deformation over a long time scale, it is often strongly affected by the spatial and temporal decorrelations and atmospheric dishomogeneities. The recently developed Permanent Scatterers (PS) technique proposed by Fertti et al. can overcome these difficulties by interpreting time-series of interferometric phase only at coherent point scatterers. In this study, we apply this PS technique using 25 ERS-1/2 scenes from 1992 to 2000 to monitor the subsidence in Suzhou. By using the linear deformation model, the deformation map in Suzhou urban area over the eight years is obtained. And the calculated results are in good agreement with the measurements of leveling.     

PSInSAR公共主图像优化选取方法研究

在综合考虑空间垂直基线、时间基线和多普勒质心频率基线对干涉图去相关影响的基础上,分析和研究了时序SAR图像中优化选取一幅或多幅公共主图像的两种实用模型;结合具体的ERS-1／2SLCSAR图像,开展了PS InSAR公共主图像的优化选取试验,提出了利用基于DESCW和综合相关系数γ^m的公共主图像优化选取方法在一系列时序SAR图像中优化选取一幅或多幅公共主图像的实甩化数据处理流程。理论分析和计算数据充分表明,该数据处理流程是可行的。     

Earthquake monitoring in australia using satellite radar interferometry

Are there any earthquakes in Australia? Although most Australians are not as familiar with earthquakes as citizens in countries such as Japan, there are some quakes on the Australian continent every year. Differential Synthetic Aperture Radar Interferometry (DInSAR) has been widely used in recent years for monitoring crustal deformation due to earthquakes, volcanoes, underground mining, oil extraction, and so on. Hence the follow-on question is, can repeat-pass satellite DInSAR be used in Australian regions to monitor earthquakes? Nine ERS-1 and ERS-2 radar images of the Burakin region in Western Australia were used to form the InSAR pairs. Twenty-two InSAR pairs were formed and were used to study the temporal decorrelation characteristics in the Burakin area. It was found that good coherence could be maintained all over the full scene for a pair spanning 211 d. The repeat cycles of RADARSAT and ERS (all C-band SAR missions) are 24 and 35 d respectively, Furthermore it is easier to maintain good coherence in L-band SAR images (e.g. the JERS-1 mission has a 44 d repeat cycle). Therefore the authors are confident that repeat-pass differential InSAR can be used to monitor ground deformation due to earthquakes in the Burakin region.     

Ground settlement of Chek Lap Kok Airport, Hong Kong, detected by satellite synthetic aperture radar interferometry

Satellite synthetic aperture radar (SAR) interferometry is used to investigate the slowly accumulating ground settlement at the new Chek Lap Kok Airport in Hong Kong. Most of the land occupied by the airport was reclaimed from the sea and therefore certain ground settlement in the area has been expected. A pair of ERS-2 SAR images spanning nearly a year is used in the study. The high spatial resolution (20 mx20 m) ground settlement map derived indicates that the settlement that occurred in the area over the time period is as large as 50 mm. The SAR measurement results agree with the levelling measurements at some benchmarks in the area to well within 1 cm(rms error), and the overall correlation between the two types of results is 0.89. The paper presents some brief background of interferometric SAR, and outlines the data processing methods and results.     

SAR差分干涉测量技术在地震区域形变测量中的应用研究

合成孔径雷达(SAR)差分干涉测量是一种最新的大地形变测量遥感技术方法.利用欧洲空间局1996年4月15日获取的地球资源卫星ERS-1数据和4月16日获取的ERS-2数据,以及1997年12月2日获取的ERS-2数据,应用差分干涉测量技术对发生于1997年11月8日的西藏玛尼地震进行了提取区域形变场的应用研究.从得到的变化检测条纹图中可识别出地表破裂带,并可定量推算震中周围和两条断裂带附近的变形情况.分析结果表明:断裂为左行平移性质,断裂带南侧水平错动的最大变形量至少超过2.8 m,北侧水平错动的最大变形量至少超过1.75 m.差分干涉测量分析结果与地面调查及已有的相关研究资料符合得很好.     

基于小基线集时序干涉雷达分析武汉中心城区地表沉降时空特征

利用2015—2016年期间获取的15景Sentinel-1A TOPS SAR影像,采用小基线集时序干涉雷达(interferometric syn-thetic aperture radar,InSAR)分析方法,研究了武汉中心城区的地表沉降特征,分析并建立了该地区地表沉降与城市建设、降雨量和长江水位变化等因素的关系.采用32个水准点数据验证了基于Sentinel-1A反演的地表沉降结果,精度为5.82 mm/a.研究区域内不均沉降明显,其地表沉降速率范围为-81.5～18.2 mm/a,且探测到的最大沉降速率位于后湖地区;地表沉降时间序列呈伴随有明显季节变化的非线性沉降.地表沉降与影响因子的对比分析表明,沉降漏斗与工程建设施工区位置分布具有较高的空间相关性;地表沉降中的季节性变化与水位变化和降雨量有关;研究区域地表沉降主要由人为活动、土层压缩性以及地下水过度开采等造成.研究结果给出了武汉中心城区地表沉降时空特征和地表沉降与其影响因子之间的相互关系.     

Taiyuan City subsidence observed with Persistent Scatterer InSAR

C- and X-bands Synthetic Aperture Radar（SAR） images acquired from February 2009 to September 2010 were processed with Persistent Scatterer Interferometry（PS-InSAR） algorithm to investigate spatial and temporal variations in deformation over Taiyuan City, China. The spatial pattern of subsidence and the magnitude of subsidence rate are similar in the velocity field maps achieved by the algorithm from these two data sets. It shows that there are four primary subsidence centers in Taiyuan City：Xiayuan, Wujiabao, Xiaodian, Sunjiazhai, which are near the groundwater extraction wells. The maximum subsidence rate is up to 70 mm/year at Sunjiazhai. The locus of maximum subsidence has shifted from its historical location in the north to the south. In view of the severe shortage of water resources and presented features of subsidence over Taiyuan City, we inferred that excessive pumping of groundwater was the dominant reason of land subsidence.     

哨兵-1A合成孔径雷达的深圳围填海区域地面沉降监测

为更好地监测和掌握深圳围填海区域在填海造地工程结束后的地面沉降情况,通过哨兵-1A影像和时间序列合成孔径雷达干涉测量方法研究了深圳围填海区域2016-2019年的地面形变.结果 表明:深圳围填海区域的地面形变速率为-19.85～ 15.60 mm/a,深圳东部宝安区和西部福田区的地面沉降相对稳定,南山区监测到大面积的地面沉降;和年均降雨量的对比分析显示了南山区的地面沉降存在明显的季节变化规律;靠近海岸的形变点目标受降雨的影响明显大于其他点,与深圳的沉积层厚度存在较为显著的相关性.     

一种适用于时序InSAR的同质像元加权干涉相位滤波方法

为了有效地利用多时相InSAR的时间维度信息, 并保证滤波窗口内像元的同质性, 提出一种同质像元加权干涉相位滤波方法。首先采用拟合优度检验, 对多时相SAR 图像的同质像元进行识别, 然后在同质像元之间进行加权干涉相位滤波, 以保证中心像元在滤波过程中不受周边非同质像元干扰。基于真实干涉SAR图像的实验结果表明, 与经典Goldstein滤波及Lee滤波相比, 该滤波方法在目视效果、相位残差点数量及相位导数标准差3个指标上具有优势, 实现滤波器的设计初衷。     

The coseismic displacement field of the Zhangbei-Shangyi earthquake mapped by differential radar interferometry

The coseismic deformation produced by 1998 earthquake (M_s = 6.2) in Zhangbei-Shangyi of northern China is measured by the differential synthetic aperture radar interferometry (D-InSAR) technique using the European Remote Sensing satellite (ERS) SAR data. Interferograms are constructed from the ERS-1/2 SAR data by the three-pass method. The line-of-sight displacement map indicates that the deformation center of the earthquake is located at E114°20′, N40°57′, with the maximum uplift of 25 cm. The extent of the displacement is around 300 km². The focal mechanism and earthquake-induced structures are analyzed based on the spatial distribution of the deformation. The results give new insights into the seismic mechanism study.     

A parametric method of retrieving ocean wave spectra from synthetic aperture radar images

A parametric method that extracts the ocean wave directional spectra from synthetic aperture radar (SAR) image is presented. The 180° ambiguity of SAR image and the loss of information beyond the azimuthal cutoff can be overcome with this method. The ocean wave spectra can be obtained from SAR image directly by using iteration inversion mapping method with forward nonlinear mapping. Some numerical experiments have been made by using ERS-1 satellite SAR imagette data. The ocean wave direction retrieved from SAR imagette data is in agreement with the wind direction from the scatterometer data.     

同步移相干涉术的相位测量原理

同步移相干涉测量术是指在瞬间同时采集三幅以上具有一定移相间隔的干涉图的一种干涉测量技术.本文对一种同步移相干涉测量系统进行了琼斯理论分析,推导出该同步移相干涉仪各帧干涉图对应点的光强表达式,从而确定系统所得的相邻干涉图之间的移相步长为π/2,并得出了对应的波面复原算法.     

基于SBAS技术的天津市地面形变特征分析

地面沉降是一种普遍存在的地质灾害,天津是我国地面沉降较为严重的城市之一,对地面形变特征的研究,有助于了解地面沉降分布,合理进行城市规划。基于覆盖天津地区的Sentinel-1升轨和降轨数据,使用改进的小基线时序干涉测量方法获取卫星视线向（line of sight,LOS）向形变速率场,针对沿海地区大气影响严重等问题,引用InSAR通用大气校正在线服务（Generic Atmospheric Correction Online Service for InSAR , GACOS）模型去除大气误差影响。从获取的天津地区形变速度场可以看出,天津市区内形变量相对较小,市区周边的静海区、西青区存在一定的形变漏斗,最大LOS向形变量约-40mm/a;武清区和北辰区形变量最大,有一个范围和形变量级都较大的形变漏斗,形变漏斗中心为武清区王庆坨镇,其最大LOS向形变量在升轨和降轨结果中分别为80mm/a和99.2mm/a,结合该区域土地利用情况,发现主要是由于产业园密集建设,导致工业和生活用水过度导致地下水超采。从形变结果可以看出,后续需要对存在形变漏斗的区域进行科学用水管理和合理城市规划,从而有效改善区域形变的影响。     

Uplift, thermal unrest and magma intrusion at Yellowstone caldera

The Yellowstone caldera, in the western United States, formed approximately 640,000 years ago when an explosive eruption ejected approximately 1,000 km3 of material. It is the youngest of a series of large calderas that formed during sequential cataclysmic eruptions that began approximately 16 million years ago in eastern Oregon and northern Nevada. The Yellowstone caldera was largely buried by rhyolite lava flows during eruptions that occurred from approximately 150,000 to approximately 70,000 years ago. Since the last eruption, Yellowstone has remained restless, with high seismicity, continuing uplift/subsidence episodes with movements of approximately 70 cm historically to several metres since the Pleistocene epoch, and intense hydrothermal activity. Here we present observations of a new mode of surface deformation in Yellowstone, based on radar interferometry observations from the European Space Agency ERS-2 satellite. We infer that the observed pattern of uplift and subsidence results from variations in the movement of molten basalt into and out of the Yellowstone volcanic system.     

工矿区地表沉陷D-InSAR监测试验研究

基于差分合成孔径雷达干涉测量(D-InSAR)中相位构成因素的分析,选择中国东部典型工矿区(唐山市及开滦矿区)为试验区进行了矿区地表沉陷D-InSAR监测试验研究.利用该地区1997-1998年两个时相获取的5景ERS1/2卫星SAR单视复数据(SLC),分别采用“2轨法”和“3轨法”进行差分干涉处理,得到了间隔时间超过半年的地下采矿及采水引起的雷达视线向(LOS)形变图.通过将LOS形变图转换成地表下沉分量,分析了试验区沉陷的扩展及演变过程.在此基础上,对D-InSAR技术中存在的时间去相干、空间去相干等误差因素进行了分析和讨论.试验表明:作为数字矿山的关键技术之一,可以利用多时相D-InS...     

廊坊城区地面沉降与地下水漏斗响应关系

通过收集廊坊城区水文地质条件、地面沉降监测等资料,分析地下水漏斗变化和地面沉降发展情况,研究廊坊城区地面沉降与地下水漏斗响应关系。首先,深层地下水是廊坊城区的主要水源,2001—2015年供水量呈整体上升趋势,其中生产用水和家庭用水占主要部分,长期开采深层地下水形成地下水漏斗,漏斗断面呈"V"字形。其次,基于合成孔径雷达干涉(interferometric synthetic aperture radar,InSAR)技术,廊坊市城区大部沉降速率60 mm/a,局部达80 mm/a。再者,地下水漏斗变化和地面沉降响应关系显示,地下水漏斗与地面沉降中心基本吻合,地下水位开采量增加,造成深层水位下降,导致地面沉降速率不断变大,影响范围亦增大,地下水位下降成为该区地面层沉降主要影响因素,同时建筑群荷载增加对地面沉降亦产生不利影响。因此,开展地面沉降与地下水漏斗响应关系研究可为地面沉降灾害防治提供理论依据。     

基于时序InSAR技术的近距离多煤层参数反演方法

近距离多煤层开采引起的采空区地面沉降在当前工矿区沉陷中占有较大的比例,而天基InSAR技术在工矿区大范围形变监测方面具有显著优势.以2018年1月至2019年8月间的43景C波段Sentinel-1B SAR数据为基础,通过时序InSAR技术对近距离多煤层开采的康平煤田进行了大范围沉降监测.以Okada模型为基础,结合近距离多煤层分布特征,采用叠加理论的原则,提出了一种基于多源模型的近距离多煤层参数反演方法.通过定量计算弹性半空间下双源模型和三源模型近距离多煤层参数反演的精度,发现三源模型精度更高,更符合小康矿近距离多煤层开采的实际特征.本研究可以为基于InSAR技术的近距离多煤层开采沉降监测及参数反演提供参考.     

短基线DInSAR法长江漫滩区大面积沉降监测研究

南京河西地区属近代长江退移形成的河漫滩地,固结沉降一直持续发展.提出利用短基线DInSAR新方法监测长江漫滩区大面积地表沉降的新思路,利用多幅差分干涉图序列进行时间序列分析,获取大面积地表沉降的演变过程.南京河西长江漫滩区1996年到2000年短基线DInSAR法沉降监测试验结果表明,该区大部分存在不同程度地面沉降,最大累积沉降量达12 cm.与精密水准检测结果在空间分布上的一致性证明了该方法的正确性.     

Precision ERS-2 orbit determination combining multiple tracking techniques

Both of the oceanographic research by using altimetry and the application of InSAR of ERS-2 satellite need the precise ephemerides of the satellite. In this note, the ERS-2 orbit is precisely determined by using SLR and PRARE observations to take advantage of the high accuracy of SLR and the widespread data coverage of PRARE. Based on the software system SODS-VCE established by us, the ERS-2 orbits in 1997 are calculated. The evaluation from tracking data fits, endpoint consistency of orbital arcs and comparison with independent orbit implies an orbit accuracy of 5–6 cm in radial component which can satisfy the requirement of being better than 10 cm in oceanographic research by altimetry, being less than 20 cm in cross-track component which can meet the requirement of InSAR. In orbit computation, the method of variance component estimation is employed to weight the SLR, PRARE range and Doppler measurements properly. The results indicate that the application of the method can improve the computation accuracy efficiently.