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1.
We have jointly applied microwave remote sensing imaging and ground-based geophysical methodologies for investigating ground deformation. In particular, the Differential Interferometric Synthetic Aperture Radar (DInSAR) technique referred to as Small BAseline Subset (SBAS) algorithm and the Electrical Resistivity Tomography (ERT) method have been applied. The former is a tool for investigating large areas, allowing us to detect deformation phenomena and to analyse their spatial patterns and temporal evolution; the latter permits us to reconstruct, with high spatial resolution, the geometry of near-surface geological structures and to estimate the electrical resistivity of outcropping terrains. The starting point of our analysis has been a DInSAR survey carried out on an area of about 400 km2 centred around the town of Potenza (Basilicata region, Italy), for which SAR data acquired by the ERS-1/2 sensors in the time interval 1992–2000 were available. The DInSAR analysis allowed us to detect an unknown ground deformation effect which involves the urban area of Satriano di Lucania, located close to Potenza. An on-site ERT survey was then carried out in order to characterize in detail the physical properties of the terrains involved in the main deformation pattern detected via the DInSAR processing. The integration of the DInSAR and ERT measurements permitted us to investigate areas where the deformation have space-variant characteristics and allowed us to formulate a hypothesis on the origin of the detected displacement processes that, although not fully conclusive, is consistent with the overall DInSAR and ERT analysis.  相似文献   

2.
The European remote sensing satellite (ERS-2) synthetic aperture radar (SAR) data was used for temporal monitoring of soil moisture at Sukhothai, Thailand. Higher correlations were found between the observed soil moisture and the radar backscattering coefficient. The soil moisture distribution shows great variation in space and time due to its stochastic nature. In order to obtain a better understanding of the nature and causes of spatial variation of soil moisture, the extensive soil moisture measurements observed in Thailand and also remotely sensed ERS-2 SAR data were used for geostatistical analysis. The observed soil moisture shows seasonal variations with mean varying from 3.33 %v/v (dry season) to 33.44 %v/v (wet season). The spatial geostatistical structure also shows clear seasonal variations in the geostatistical characteristics such as range and sill. The sills vary from 1.00 (%v/v)2 for the driest day to 107.57 (%v/v)2 for one of the wet days. The range or the correlation lengths varies between 46.5 and 149.8 m for the wettest and driest periods. The nugget effect does not show strong seasonal pattern or trend but the dry periods usually have a smaller nugget effect than the wet periods. The spherical variogram model fits the sample variograms very well in the case of soil moisture observations while the exponential model fits those of the remotely sensed data. The ranges observed from the observed soil moisture data and remotely sensed data at the same resolution are very similar. Resolution degradation affects the geostatistical structure of the data by reducing the sills, and increasing the ranges.  相似文献   

3.
Peatlands are an important multipurpose ecosystem, supporting huge quantities of biomass and peat soil carbon. A time series of Japanese Earth Resource Satellite-1 (JERS-1) L-band Synthetic Aperture Radar (SAR) data was employed to monitor two dynamic ecosystem processes; deforestation and inundation patterns. Using a change detection analysis for three images acquired during dry seasons of 1994, 1997 and 1998, we detected the deforestation that has occurred in the region due to the anthropogenic and natural causes. At a threshold of ±2 dB change in backscattering response, an area of about 98 km2 of these forests was found to have been cleared during 1994–1997 for conversion to cultivatable lands. However, the agricultural crops miserably failed to grow on these cleared lands because of the adverse water and soil chemistry conditions. The deliberate draining of these lands, by laying and extension of a huge network of canals, created congenial ecological conditions for the spread of forest fires, particularly during the 1997 El Niño period. An area of 250 km2 of forests was thus detected to have been destroyed by these fires between September 1997 and January 1998. These deforested lands are rapidly regenerating since their abandonment and the regenerating carbon stocks were simulated using the CENTURY ecosystem dynamics model. Furthermore, the L-band SAR was able to detect the pixel-wise seasonal and spatial inundation information for particular forest types where the transmissivity of the L-band SAR signals was quite significant. These forest types corresponded to comparatively low biomass areas. The SAR derived information about these two important dynamic processes would be useful for improving the accuracy of modelling the spatial and temporal distribution of the carbon and other trace gases in these ecosystems.Edited by D. Boyd  相似文献   

4.
E. G. Mirlin 《Geotectonics》2006,40(4):282-296
Crustal structural features having a vortical or spiral shape were discovered in the first third of the 20th century. Since then, such features of various ranks, but similar appearance, have been revealed in different geotectonic settings; however, an adequate tectonic interpretation has not been offered. With allowance for the specific character of vortical movement, the evolution of the structural geometry of the North Atlantic basins and different segments of the global system of mid-ocean ridges is considered in this paper. It is shown that vortical movements do take place in the solid Earth during ocean formation and create scale-invariant rifting and spreading systems, where the spreading axis tends to undergo whirling. The size of these systems differs by more than two orders of magnitude. Many geotectonic phenomena that accompany the formation of oceans, including segmentation of the ocean floor and passive continental margins, folding of the sedimentary cover at these margins, and tectonic delamination of the oceanic lithosphere, may be explained by vortical movements of different ranks. In addition, the vortical structures on continents are variable in size and related to lithotectonic complexes of different ages. The vortical structural units of the Mediterranean Belt are considered as an example. Being driven by the same physical mechanism, the vortical movements depend on the dynamics of different geospheres. These movements are realized only in a nonlinear, nonequilibrium medium. Hence, only nonlinear and nonequilibrium thermodynamics will serve as a theoretical basis for a new concept, which is coming currently to take the place of plate tectonics.  相似文献   

5.
本文介绍了一种新的星载合成孔径雷达干涉测量数据处理技术（GeoWatch InSAR技术）,具有下述特点和优势：1.对城市和郊区农村全面连续覆盖,不仅包括建筑物,而且包括路面、广场、飞机跑道等其他地物和半植被覆盖的自然地区;2.合成处理多景/多波段/多模式/多极化/多轨道/多卫星平台的数据,从而缩短观测时间,提高精度和覆盖;3.所有结果为真正射投影图像,支持各种比例尺和范围的面状连续监测;4.支持ERS-1＆2、ENVISAT、ALOS PALSAR、JERS-1、RADARSAT-1＆2、TerraSAR、COSMO-SkyMed（CSK）和将来中国的HJ1小雷达卫星群。用此技术处理了天津地区的ENVISAT数据,得到了范围（抽样间隔）分别为100km×100km（50m×50m）、天津市（20m×20m）、廊坊市（15m×15m）及胜芳镇（7m×7m）的全面连续的地面沉降率图像,显示了它在地面沉降监测中的独特优势和应用前景。  相似文献   

6.
This paper illustrates the capabilities of L-band satellite SAR interferometry for the investigation of landslide displacements. SAR data acquired by the L-band JERS satellite over the Italian and Swiss Alps have been analyzed together with C-band ERS-1/2 SAR data and in situ information. The use of L-band SAR data with a wavelength larger than the usual C-band, generally considered for ground motion measurements, reduces some of the limitations of differential SAR interferometry, in particular, signal decorrelation induced by vegetation cover and rapid displacements. The sites of the Alta Val Badia region in South Tyrol (Italy), Ruinon in Lombardia (Italy), Saas Grund in Valais (Switzerland) and Campo Vallemaggia in Ticino (Switzerland), representing a comprehensive set of different mass wasting phenomena in various environments, are considered. The landslides in the Alta Val Badia region are good examples for presenting the improved performance of L-band in comparison to C-band for vegetated areas, in particular concerning open forest. The landslides of Ruinon, Saas Grund, and Campo Vallemaggia demonstrate the strength of L-band in observing moderately fast displacements in comparison to C-band. This work, performed with historical SAR data from a satellite which operated until 1998, demonstrates the capabilities of future planned L-band SAR missions, like ALOS and TerraSAR-L, for landslide studies.  相似文献   

7.
二连盆地西部SAR影像与TM影像复合处理及其地质应用   总被引：1，自引：0，他引：1  
针对SAR与TM数据的不同特征,研究了SAR与TM影像的几何校正方法及波谱信息复合方法,将SAR影像与复合图像进行比较,并且分别用SAR图像和复合图像对内蒙二连盆地进行地质解译,发现雷达图像能够较好地反映沙漠覆盖区的隐伏构造信息,而TM与SAR的复合图像能够较好地发挥两种数据的优势,拓宽了遥感的波段范围,对于图像解译和实际应用都有重要的意义。   相似文献   

8.
Airborne imaging spectrometer (also known as hyperspectral) remote sensing has been widely used to characterize mineralogy on mine waste surfaces, which is useful for predicting potential sources of acidity and metal leaching. The most successful applications employ fine spatial resolution—20-m pixels or smaller. Future satellite imaging spectrometer sensors are proposed to provide coarser spatial resolution—30- to 60-m pixels. This study examined the ability to map minerals related to acid mine drainage with visible to shortwave infrared hyperspectral imagery at varying spatial scales (2-, 15-, 30-, 60-m pixels) at the Leviathan mine Superfund site, located in the Eastern Sierra Nevada. Mineral maps were produced using spectral angle mapper and matched filtering algorithms. The 15-m images provided comparable maps to the 2-m images. The 30- and 60-m images lost the ability to identify smaller features; however, they were still able to identify high- and low-priority remediation zones at least 75 m in width. Based on our results, we believe 30-m spatial resolution on a satellite hyperspectral sensor will be sufficient for identifying hazardous surfaces at larger mine waste sites and provide important reconnaissance information that can help prioritize detailed ground-based studies.  相似文献   

9.
Surface marine wind data base from ERS-1 scatterometer has been processed to define the characteristic seasonal distribution of wind-stress curl throughout the southwestern Indian Ocean between January and December 1994. A compact model to obtain satellite-derived wind-stress curl fields on smaller scales than previously available is proposed and evaluated. The results indicate the strong capability of the ERS-1 scatterometer to monitor wind-driven variations in the mesoscale ocean patterns. To cite this article: M. Petit et al., C. R. Geoscience 338 (2006).  相似文献   

10.
Despite the intense attention paid to internal wave (IW) investigation, the most experimentally studied and theoretically described are internal gravitational waves in shelf zones of oceans and tidal seas appearing during the interaction of tidal currents with the margin of the shelf. Information on surface manifestations of internal waves in enclosed seas, such as the Black and Caspian seas, is almost absent. In this paper, the results of study of the peculiarities of generation and propagation of nontidal internal waves are presented; the study is carried out on the basis of combined analysis in data of marine surface radiolocation and data of optical and infrared satellite-borne sensors. The experimental basis of investigation is radar images of the marine surface derived with the help of Synthetic Aperture Radars, onboard the Envisat and ERS-2 satellites. Additionally, the data of the following sensors belonging to the optical and infrared ranges were used for the purpose of radar image interpretation: MODIS (onboard the Aqua/Terra satellite), MERIS (Envisat), and AVHRR (NOAA). Surface manifestations of IWs in the northeastern part of the Black Sea and in the Caspian Sea have been found in radar imagery for the first time, their pattern of spatial and temporal variation has been reconstructed. The possible factors leading to generation of the observed nontidal IWs are determined and suppositions about the corresponding generation mechanisms are made. In particular, the IW manifestations recorded in the northeastern part of the Black Sea are localized in the vicinity of the boundaries of eddies or hydrological fronts; this fact evidences for the frontal mechanism of generation, at which IWs are radiated by a nonstationary (moving and/or inertially oscillating) front. The most probable main sources of generation of IWs detected in the Caspian Sea are longitudinal one-knot seiches, whose knot point is located near the Apsheron sill.  相似文献   

11.
全球变化与地表参数的定量遥感   总被引：17，自引：0，他引：17  
从全球变化研究对遥感获取地表时空多变要素信息的需求 ,论述定量遥感中对地表多尺度空间信息作地学描述的新思路和新方法。在分析了变差图描述方法的特点及其不足的基础上 ,提出了直方变差图的概念 ,通过定义驻点和边界点 ,尝试采用直方变差图分解的方法分析地物空间分布规律 ,并通过一个实验对此方法进行了说明。进而基于对地表空间分布信息的提取 ,将可见光、近红外波段遥感信息用于热红外遥感的地温反演 ,利用地表空间结构和大气温度空间分布模式的差异 ,将热红外遥感图像分为地表贡献和大气贡献两部分 ,通过空间相关性分析 ,寻求从热红外遥感图像中直接分离出大气的空间分布模式的方法 ,以解决地温反演中面临的困难。已有的研究结果说明了在全球变化和定量遥感研究中 ,对地表多尺度空间变化信息作简洁的地学描述的必要性及其重要的应用意义。  相似文献   

12.
Detection of changes in synthetic aperture radar (SAR) images is an important challenge due to the effects of speckle noise on these images. In recent years, appropriate methods for SAR-based-change detection have been developed based on the level set methods (LSM). These methods need to set parameters for defining a proper initial contour. Moreover, the gradient information is only employed in the total energy of these methods for segmentation of the difference image. In this study, a novel method has been proposed for unsupervised change detection of multitemporal SAR images based on the improved fast level set method (IFLSM) initialized with a combination of k-means and Otsu techniques. The proposed method utilizes the discrete wavelet transform (DWT) fusion strategy and edge enhancement to achieve a noise-resistant difference image from the mean-ratio and log-ratio images. Afterward, the generated binary change map (CM) by applying a combination of k-means and Otsu techniques on the difference image is used as the initial contour to achieve a final CM on difference image using the IFLSM. To check advantages of the proposed method, experiments are applied on two sets of multitemporal SAR images corresponding to artificial Chitgar Lake (under reconstruction) in Tehran (Iran) taken by TerraSAR-X satellite in 2011 and 2012, and corresponding to San Pablo and Briones reservoirs in California (USA) acquired by ERS-2 satellite in 2003 and 2004. Results of proposed method were compared with results of some well-known unsupervised change detection methods. Experimental results prove the sufficiency of the proposed method in unsupervised change detection in terms of accuracy, implementation time, and computational complexity.  相似文献   

13.
Bad weather conditions usually limit the acquisition of optical remote sensing images, while all day and all weather synthetic aperture radar (SAR) shows the ability of providing timely remote sensing data for emergency response and rescue works after earthquake. Because SAR is sensitive to the surface changes caused by earthquake, the modified electromagnetic behaviour by geological disasters and the collapse of buildings can be recorded in SAR images as backscattering intensity changes. Absolute radiometric calibration was performed to SAR products to derive backscattering coefficient sigma nought from image digital number (DN). Based on change detection methods, Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) data and TerraSAR-X data acquired for the Ms 8.0 Wenchuan earthquake were used to extract earthquake damage information. This study revealed that landslides showed stronger backscattering and barrier lakes showed lower backscattering in post-earthquake 10 m ALOS PALSAR images comparing to pre-earthquake, and collapsed buildings showed lower backscattering compared to un-collapsed buildings in 1 m TerraSAR-X image. Results showed that SAR data with different spatial resolutions are useful for different earthquake damage information extraction: medium spatial resolution SAR data, e.g. 10 m ALOS PALSAR data, were efficient for secondary geological disaster extraction; high-resolution SAR data, e.g. 1 m TerraSAR-X data, with the help of ancillary GIS data or high-resolution optical data, could be used to extract building collapse information in urban areas. This study indicates that SAR remote sensing data can provide earthquake damage information at early emergency stage and assist the field surveying, further damage assessment and post-earthquake reconstruction.  相似文献   

14.
This paper describes the use of the Stable Point Network technique, a Persistent Scatterer Interferometry SAR technique, for the analysis of the Portalet landslide area (Central Pyrenees, Spain). For this purpose, different SAR datasets acquired by ERS-1, ERS-2, ENVISAT and TerraSAR-X satellites have been analysed. The use of different SAR images acquired by satellite radar sensors operating at different microwave lengths has allowed for a comparative assessment and illustration of the advantages and disadvantages of these satellites for landslide detection and monitoring. In the introduction, differential interferometry and the study area are briefly described. Then the specifics of the SPN processing and the results of the different datasets are described and compared. In Analysis of the results: the Portalet landslide area, the Portalet landslide area is introduced and the radar displacement measurements are analysed with available geo-information data. Additionally, X-band measurements are compared with those gathered by a ground-based SAR for a previous project. Finally, the most relevant conclusions of this work are discussed.  相似文献   

15.
简单介绍了SAR图像的纹理特征以及正交小波变换纹理提取方法。论述了SAR图像的纹理特征参与分类的重要性。以长白山天池火山为例,通过对ERS2SAR图像进行纹理分析,提取了SAR图像两个层次的尺度变化、时频局部化和方向性纹理特征。并将SAR纹理特征与TM图像及DEM进行复合,利用多源信息各自的优势,进行了BP神经元网络分类,从较大范围对长白山天池火山735±15aB.P.大喷发的喷发物空间分布进行评价。获取了长白山天池火山近代喷发物的空间分布及规模。这对长白山天池火山未来喷发危险性初步评价、火山地质制图及火山灾害预测有重要意义。  相似文献   

16.
Within the SLAM project (Service for Landslide Monitoring), launched in 2003 by the European Space Agency (ESA) the Permanent Scatterers (PS) technique, a multi-image interferometric approach, coupled with the interpretation of aerial-photos and optical satellite images, was carried out for landslide investigations. The PS analysis was applied at a regional scale as support for landslide inventory mapping and at local scale for the monitoring of single well-known slope movements. For the integration of the PS measurements within a landslide inventory the Arno river basin (Italy) was chosen as test site for the presence of a high number of mass movements (to date about 300 areas at high landslide risk and more than 27,000 individual landslides mapped by the institutional authorities). About 350 SAR images have been interferometrically processed by means of the PS technique, with the detection of about 600,000 PS. The use of optical images contributed spatial meaning to the point-wise information provided by the PS, making it easier to identify terrain features related to slope instability and the landslide boundaries. Here we describe the employed methodology and its impact in the updating of a preexisting landslide inventory. 6.8% of the total number of landslides were characterized by ground displacement measurements from the PS: 6.1% of already mapped landslides and 0.8% of new unstable areas detected through the PS analysis. Moreover, most of the PS are located in urban areas, showing that the proposed methodology is suitable for landslide mapping in areas with a quite high density of urbanization, but that over vegetated areas it still suffers from the limitations induced by the current space-borne SAR missions (e.g. temporal de-correlation). On the other hand, the use of InSAR for the monitoring of single slow landslides threatening built-up areas has provided satisfactory results, allowing the measurement of superficial deformations with high accuracy on the landslide sectors characterized by a good radar reflectivity and coherence.  相似文献   

17.
基于PS-InSAR的 1995-2000 年苏州地面沉降监测   总被引：1，自引：0，他引：1  
永久散射体(PS)技术在传统差分干涉测量(D-InSAR)中引入时间维,分析长时间内保持稳定的像元集相位变化,获得毫米级的地面测量精度,但是该技术要求处理的范围较小.采用分块处理的方法,通过PS差分干涉测量处理,得到1995-2000 年苏州地区地面沉降场的测量值.地面水准测量数据的验证分析表明,雷达差分干涉测量精度可达5mm(以水准测量代表地面形变的真实情况),基于分块处理的 PS-InSAR 技术在进行城市地面沉降监测和时空演化特征研究中具有很大的优势.  相似文献   

18.
Sea surface manifestations of internal waves (IW) in the shallow continental shelf waters of North Bay of Bengal have been observed in almost all seasons imaged by Synthetic Aperture Radar (SAR) images of ERS1/2 and Envisat ASAR missions during the period 1993–2004. Shoreward propagating short-period IW packets are observed particularly in summer stratified coastal waters Off Chilka region. In summer waters, prominent short-period shoreward propagating internal waves of consecutive imageries of ERS-1/2 SAR (12th and 13th April 1996) are studied. On 4th October 2003, Envisat ASAR imaged strong surface manifestations of huge internal wave group wavelengths and those propagations were discussed in detail. In the research, we also made an attempt for temporal distribution of IW signatures on SAR in North Bay of Bengal.  相似文献   

19.
Grid system for flood extent extraction from satellite images   总被引：4，自引：2，他引：2  
Floods are among the most devastating natural hazards in the world, affecting more people and causing more property damage than any other natural phenomena. One of the important problems associated with flood monitoring is a flood extent extraction from satellite imagery, since it is impractical to acquire the flood area through field observations. This paper presents a new method to the flood extent extraction from synthetic-aperture radar (SAR) images that is based on intelligent computations. In particular, we apply artificial neural networks, self-organizing Kohonen’s maps (SOMs), for SAR image segmentation and classification. We implemented our approach in a Grid system that was used to process data from three different satellite sensors: ERS-2/SAR during the flooding on the river Tisza, Ukraine and Hungary (2001), ENVISAT/ASAR WSM (Wide Swath Mode) and RADARSAT-1 during the flooding on the river Huaihe, China (2007).  相似文献   

20.
Landslide activity responds to rapid environmental changes and represents a relevant geoindicator in mountainous or hilly areas. This paper discusses the socio-economic relevance of landslide hazard in Italy and the problems encountered in establishing relationships between landslide frequency, climate and vegetation changes at different time scales. Landslides blocking a river channel have been carefully taken into account because they are usually characterized by high intensities (with regard to the involved masses and movement velocities) and their occurrences are often datable via radiocarbon dating. This is due to the recovery of organic matter in the landslide dammed lakes. For these reasons they can be considered important geoindicators in the wider category of slope failures. The marked effects of the anthropogenic activity on slope instability processes in the last 50 years are discussed with reference to two case histories: the Chianti hills in Tuscany and the Cinque Terre National Park in Liguria. Finally, two novel techniques of remote sensing are proposed as tools for a systematic monitoring of slope instability at different time and spatial scales. Both techniques are based on the interferometric synthetic aperture radar (SAR) technology and differ on the type of platform (satellite and ground-based) used to acquire data.  相似文献   

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