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Sample records for advanced sar asar

  1. Land Use/Land Cover Classification of Urban SAR Scenes: An Envisat/ASAR and HJ-1 Joint Approach

    NASA Astrophysics Data System (ADS)

    Aldrighi, M.; Gamba, P.; Lisini, G.

    2013-01-01

    The classification of urban areas in terms of Land-Use/Land-Cover (LULC) maps is a challenging as well as essential task in order to monitor how the urban sprawl is changing the environment. In many case, this phenomenon leads to dramatic changes, since in many parts of the world commercial as well as residential areas are replacing natural environments, such as crops and forests. In this work we present the description of a novel procedure designed to exploit coarse resolution SAR images and obtain both the built-up area extents and a LULC map of the individuated urban area. Moreover, a data fusion approach, able to combine optical (HJ-1) and SAR (ENVISAT/ASAR) data, has been introduced in order to obtain a better vegetation assessment by means of the Normalized Difference Vegetation Index (NDVI). An experimental result is presented using a data set of the Beijing megacity acquired by ENVISAT/ASAR and HJ-1.

  2. Temporal Stability of Soil Moisture and Radar Backscatter Observed by the Advanced Synthetic Aperture Radar (ASAR)

    PubMed Central

    Wagner, Wolfgang; Pathe, Carsten; Doubkova, Marcela; Sabel, Daniel; Bartsch, Annett; Hasenauer, Stefan; Blöschl, Günter; Scipal, Klaus; Martínez-Fernández, José; Löw, Alexander

    2008-01-01

    The high spatio-temporal variability of soil moisture is the result of atmospheric forcing and redistribution processes related to terrain, soil, and vegetation characteristics. Despite this high variability, many field studies have shown that in the temporal domain soil moisture measured at specific locations is correlated to the mean soil moisture content over an area. Since the measurements taken by Synthetic Aperture Radar (SAR) instruments are very sensitive to soil moisture it is hypothesized that the temporally stable soil moisture patterns are reflected in the radar backscatter measurements. To verify this hypothesis 73 Wide Swath (WS) images have been acquired by the ENVISAT Advanced Synthetic Aperture Radar (ASAR) over the REMEDHUS soil moisture network located in the Duero basin, Spain. It is found that a time-invariant linear relationship is well suited for relating local scale (pixel) and regional scale (50 km) backscatter. The observed linear model coefficients can be estimated by considering the scattering properties of the terrain and vegetation and the soil moisture scaling properties. For both linear model coefficients, the relative error between observed and modelled values is less than 5 % and the coefficient of determination (R2) is 86 %. The results are of relevance for interpreting and downscaling coarse resolution soil moisture data retrieved from active (METOP ASCAT) and passive (SMOS, AMSR-E) instruments.

  3. Leaf Area Index and Biomass Assessment over Tropical Peatland Forest Ecosystem Using ALOS PalSAR and Envisat ASAR Data

    NASA Astrophysics Data System (ADS)

    Wijaya, Arief; Susanti, Ari; Liesenberg, Veraldo; Wardhana, Wahyu; Yanto, Edi; Soeprijadi, Djoko; McFarlane, Craig; Qomar, Nurul

    2011-03-01

    Provision of accurate forest parameter properties is important as a basis for forest resources monitoring and carbon cycle assessment. The present study aims to model leaf area index (LAI), above ground biomass and carbon stocks over tropical peatland forests using single polarization SAR, full polarimetry SAR (PolSAR) data. Single band ALOS Palsar data (HH band, acquired on November 17, 2008) and polarimetric data (HH, VV, HV and VH, collected on April 4 and May 5, 2007) are used for the study. A series of ENVISAT ASAR data (5 datasets) collected in 2004 - 2005 are also used to model the forest properties. Landsat ETM data collected on January 22, 2009 is also used as a reference. The relationship between forest parameters and normalized radar backscattering is estimated using empirical models, and preliminary results show that Polarimetric SAR data has better correlations with the LAI and biomass than single polarimetry SAR data. The field data were collected during field work in March - April 2009 and the reliability of identified forest classes was also assessed from available Landsat ETM data. Analysis will be conducted on the basis of statistical correlations between radar data and modeled forest properties, such as LAI, biomass and tree age. This study focuses on a unique tropical peatland ecosystem in Kampar Peninsula, Sumatera, Indonesia, which has great potentials as carbon sinks and/or sources. Only few studies have been conducted in the study area due to limited satellite and field observation data.

  4. Synergistic Usage of ERS, ASAR and PALSAR Data for PS InSAR Based Mining Induced Subsidence Monitoring

    NASA Astrophysics Data System (ADS)

    Thiel, C. J.; Salepci, N., Jr.; Schmullius, C.; Kuehl, A., Jr.

    2014-12-01

    For the derivation of the temporal evolution and the spatial pattern of the mining induced subsidence in Sondershausen, Germany, this study employs persistent scatterer interferometry (PSI) to multiple sets of SAR scenes from different sensors. The work is a part of the ongoing INFLUINS project funded by the German Federal Ministry of Education and Research. In order to improve the model of subsidence derived from a single sensor, a novel methodology for integration of multiple PSI data sets is introduced. The proposed approach allows the combination of subsidence information derived from different SAR data sets with different temporal coverage and/or spatial resolution. After long and intensive mining activities, the subsidence rate in Sondershausen has gradually increased almost to a rate of 250 mm/year reaching its maximum in the early 1990s. However, since 1996 the mine is backfilled leading to a gradual decrease in the subsidence rate in the undermined part of the city. The SAR scenes cover the period of backfilling between 1995 and 2010. The displacement rates for the first ten years (1995 -2005) are derived by ERS-1/2 scenes and by an ENVISAT-ASAR stack for the following years (2004-2010). In addition, for the span of 3 years from 2007 to 2010 an ALOS-PALSAR stack is processed in order to exploit the different information provided by different sensors. The vertical linear deformation rates derived by PSI clearly indicate the regions of subsidence in each set. Furthermore, they confirm the influence of backfilling, i.e. gradual decreasing of subsidence rates. These results are compared and validated with leveling measurements collected by the mine management company during 1995-2010. After the validation, the results are integrated in order to improve the quality of the subsidence model for the entire time span. With the objective of spatially refining the model derived from a single sensor, the approach exploits the PS points available in the other stacks by

  5. Interferometry With ENVISAT ASAR Alternating Polarization Mode Data

    NASA Astrophysics Data System (ADS)

    Zhou, Xiao; Zeng, Qiming; Liang, Cunren; Cui, Xiai; Jiao, Jian

    2010-10-01

    The Environmental Satellite Advanced Synthetic Aperture Radar (ASAR) sensor has been designed to provide enhanced capabilities for interferometric applications [?]. Different types of interferometric products can be obtained by combining the various ASAR modes, most of which are stripmap [image mode (IM)] and ScanSAR [wide swath (WS) mode]. However, the Alternating Polarization [AP mode] has been rarely used for interferometric experiments. This letter deals with the possibility of using AP mode data to produce two kinds of differential interferograms (HH/HH and HH/VV). We propose a complete processing chain of AP mode interferometry and the results are encouraging, of which the specialty of meaning is explained. The data is processed by the newly developed Peking University Multi-mode SAR Interferometry Processing Kit (PUMSIP v1.0), supported by ROI_PAC of JPL/Caltech.

  6. The EnviSAT ASAR Mission: A Look Back At 10 Years Of Operation

    NASA Astrophysics Data System (ADS)

    Miranda, N.; Rosich, B.; Meadows, P. J.; Haria, K.; Small, D.; Schubert, A.; Lavalle, M.; Collard, F.; Johnsen, H.; Guarnieri, A. Monti; D'Aria, D.

    2013-12-01

    The Advanced Synthetic Aperture Radar (ASAR) on- board Envisat operated successfully for just over 10 years until the failure of Envisat in April 2012. ASAR was ESA's very first deployment of a C-band phased- array antenna, allowing extended imaging capacity in comparison to its ERS SAR predecessors. As such it operated in various acquisition modes - Image (IM), Alternating Polarisation (AP), Wide Swath (WS), Global Monitoring (GM), and Wave (WV). For IM and AP modes there was a selection of 7 swaths with swath width from 100 km to 56 km: IM was single- polarisation, while AP was dual-pol, offering a choice from HH&VV, HH&HV, or VV&VH. WS and GM modes had a total swath width of 405 km based on the combination of 5 sub-swaths. WV acquired imagettes of 10 km by 10 km every 100 km along the satellite track. This paper is a look back to the 10 years of ASAR operations, covering topics such as the ASAR Instrument (characteristics, acquisition modes, product tree and observation scenario), Instrument Calibration and Performance Verification (including instrument stability, internal calibration, external calibration, absolute radiometric calibration, localisation accuracy, absolute geolocation accuracy, performance verification and product calibration), ASAR specific missions (wave and polarimetric), particular ASAR events such as antenna resets, burst synchronisation, AP swath modifications and the Envisat orbit change in October 2010.

  7. Pseudo-thermal bar in poorly salted autumnal waters of the Gulf of Finland from satellite-airborne SAR/ASAR/ALSAR survey

    NASA Astrophysics Data System (ADS)

    Melentyev, Vladimir; Bobylev, Leonid; Tsepelev, Valery; Melentyev, Konstantin; Bednov, Petr

    2010-05-01

    The thermal bar (TB) was disclosed at the end of XIX century by F.A. Forel - world-famed founder of limnology, who studied different processes in Lake Leman from point of view ecology and hydrobiology. Forel supposed that TB arises in temperate large lakes for short period in spring in presence windless calm weather. Well-directed investigations of TB were recommenced in the beginning 1950-s at the Institute of Lake Research Russian Academy of Sciences by Dr A.I. Tikhomirov who had described also specific features of this phenomenon in fall. At the end of 1960-s we began examination thermal and ice regime of fresh and saltish inland water bodies with using remote sensing including multi-spectral airborne-satellite SLR/SAR/ASAR/ALSAR survey. And as result the possibility revealing TB parameters in fall season by low-frequency radar (ALSAR) installed onboard research aircraft was fixed documentally in the Lake Ladoga [Melentyev et. al., 2002]. According to [Tikhomirov, 1959] TB represents convergence zone around temperature of maximum density of fresh water + 4 °C (3, 98 °C, really). This narrow vertical "curtain" appears in littoral in spring owing to heating coastal waters, in fall - due to its cooling. TB divides large lakes and artificial reservoirs on two unequal thermic zones - heat-active (HAZ) and heat-inert (HIZ) that has different stratification of water temperature. Possible existence of TB in poorly salted sea waters was predicted by outstanding Russian oceanographer professor N. Zubov. Obviously firstly it was disclosed but without explanation the physics by [Bychkova, 1987]. Our own sub-satellite studies onboard nuclear icebreaker "Jamal" in western Arctic in fall 1996 allows reveal the TB on saltish waters in north-eastern "corner" of the Yenisei Gulf in mixing zone of marine and river waters. Long-lived converged zone that we call as pseudo-thermal bar (PTB) was marked by stationary banding narrow continuous rough strip that could be destroyed by

  8. Synergy of ASAR and RADARSAT-2 ultra-fine acquisitions for ground deformation monitoring by means of DInSAR and PSI

    NASA Astrophysics Data System (ADS)

    Elias, Panagiotis; Briole, Pierre; Sykioti, Olga

    2010-05-01

    consideration the raised seismisity of the area. The Psathopyrgos fault zone as well as the Rion-Patras transfer fault zone are investigated for any detectable ground deformations that could be indications/precursors or inter-seismic accumulation processes before a main event. The city of Patras are investigated for any detectable ground/buildings deformation due to human interventions or geophysical processes. The potential of Rion-Antirion bridge monitoring for any detectable deformation as well as the surrounding ground on the two edges of it, are also investigated and assessed. The study area presents major difficulties for DInSAR/PSI applications, due to its intense vegetation coverage and high topography presenting various facets, varying high slopes and shadowing effects. Moreover its intense topography in conjunction with its location between Aegean and Ionian seas is leading to high precipitation rates and extend cloud coverage. All these characteristics of the study area contribute to high decorrelation of the interferometric products. For the estimation of the ocuured deformations a series of ASAR/ENVISAT (image swath 2) data are processed by means of PSI and DInSAR techniques, but RADARSAT-2 (ultra-fine beam mode) data are processed only by means of DInSAR technique due to its lack of historical data. The processing will be carried out exploiting commercial and in-house software. The medium and high ground resolution added value products of the acquired data are combined in the thematic level.

  9. Advanced digital SAR processing study

    NASA Technical Reports Server (NTRS)

    Martinson, L. W.; Gaffney, B. P.; Liu, B.; Perry, R. P.; Ruvin, A.

    1982-01-01

    A highly programmable, land based, real time synthetic aperture radar (SAR) processor requiring a processed pixel rate of 2.75 MHz or more in a four look system was designed. Variations in range and azimuth compression, number of looks, range swath, range migration and SR mode were specified. Alternative range and azimuth processing algorithms were examined in conjunction with projected integrated circuit, digital architecture, and software technologies. The advaced digital SAR processor (ADSP) employs an FFT convolver algorithm for both range and azimuth processing in a parallel architecture configuration. Algorithm performace comparisons, design system design, implementation tradeoffs and the results of a supporting survey of integrated circuit and digital architecture technologies are reported. Cost tradeoffs and projections with alternate implementation plans are presented.

  10. Advanced antennas for SAR spacecraft

    NASA Technical Reports Server (NTRS)

    Gail, William B.

    1993-01-01

    Single and multi-frequency antenna concepts were developed to evaluate the feasibility of building large aperture polarimetric synthetic aperture radar (SAR) systems to be launched in low cost vehicles such as the Delta 2. The antennas are 18.9 m long by 2.6 m wide (L-band) and achieve single polarization imaging to an incidence angle of 55 degrees and dual/quad imaging to 42 degrees. When combined with strawman spacecraft designs, both concepts meet the mass and volume constraints imposed by a Delta 2 launch.

  11. Land cover in the Guayas Basin using SAR images from low resolution ASAR Global mode to high resolution Sentinel-1 images

    NASA Astrophysics Data System (ADS)

    Bourrel, Luc; Brodu, Nicolas; Frappart, Frédéric

    2016-04-01

    Remotely sensed images allow a frequent monitoring of land cover variations at regional and global scale. Recently launched Sentinel-1 satellite offers a global cover of land areas at an unprecedented spatial (20 m) and temporal (6 days at the Equator). We propose here to compare the performances of commonly used supervised classification techniques (i.e., k-nearest neighbors, linear and Gaussian support vector machines, naive Bayes, linear and quadratic discriminant analyzes, adaptative boosting, loggit regression, ridge regression with one-vs-one voting, random forest, extremely randomized trees) for land cover applications in the Guayas Basin, the largest river basin of the Pacific coast of Ecuator (area ~32,000 km²). The reason of this choice is the importance of this region in Ecuatorian economy as its watershed represents 13% of the total area of Ecuador where 40% of the Ecuadorian population lives. It also corresponds to the most productive region of Ecuador for agriculture and aquaculture. Fifty percents of the country shrimp farming production comes from this watershed, and represents with agriculture the largest source of revenue of the country. Similar comparisons are also performed using ENVISAT ASAR images acquired in global mode (1 km of spatial resolution). Accuracy of the results will be achieved using land cover map derived from multi-spectral images.

  12. Operational Quality Control of SAR Data under the IDEAS Contract

    NASA Astrophysics Data System (ADS)

    Griffiths, Emma; Haria, Kajal; Meadowws, Peter; Miranda, Nuno

    2010-12-01

    Operational Quality Control (QC) of ERS-1/2 Synthetic Aperture Radar (SAR), Envisat's Advanced Synthetic Aperture Radar (ASAR) and the Phased-Array L-band SAR (PALSAR) on board JAXA's Advanced Land Observing Satellite (ALOS) is currently carried out under the Image Data quality Evaluation and Analysis Service (IDEAS). This paper introduces the concept of IDEAS as it applies to SAR QC including the daily and long-term analysis and shows the interaces to related services, including ESA's user-facing Earth Observation (EO) Help Desk

  13. Recent Advances in Radar Polarimetry and Polarimetric SAR Interferometry

    NASA Technical Reports Server (NTRS)

    Boerner, Wolfgang-Martin

    2005-01-01

    The development of Radar Polarimetry and Radar Interferometry is advancing rapidly, and these novel radar technologies are revamping Synthetic Aperture Radar Imaging decisively. In this exposition the successive advancements are sketched; beginning with the fundamental formulations and high-lighting the salient points of these diverse remote sensing techniques. Whereas with radar polarimetry the textural fine-structure, target-orientation and shape, symmetries and material constituents can be recovered with considerable improvements above that of standard amplitude-only Polarization Radar ; with radar interferometry the spatial (in depth) structure can be explored. In Polarimetric-Interferometric Synthetic Aperture Radar (POL-IN-SAR) Imaging it is possible to recover such co-registered textural plus spatial properties simultaneously. This includes the extraction of Digital Elevation Maps (DEM) from either fully Polarimetric (scattering matrix) or Interferometric (dual antenna) SAR image data takes with the additional benefit of obtaining co-registered three-dimensional POL-IN-DEM information. Extra-Wide-Band POL-IN-SAR Imaging - when applied to Repeat-Pass Image Overlay Interferometry - provides differential background validation and measurement, stress assessment, and environmental stress-change monitoring capabilities with hitherto unattained accuracy, which are essential tools for improved global biomass estimation. More recently, by applying multiple parallel repeat-pass EWB-POL-D(RP)-IN-SAR imaging along stacked (altitudinal) or displaced (horizontal) flight-lines will result in Tomographic (Multi- Interferometric) Polarimetric SAR Stereo-Imaging , including foliage and ground penetrating capabilities. It is shown that the accelerated advancement of these modern EWB-POL-D(RP)-IN-SAR imaging techniques is of direct relevance and of paramount priority to wide-area dynamic homeland security surveillance and local-to-global environmental ground-truth measurement

  14. Validation of significant wave height product from Envisat ASAR using triple collocation

    NASA Astrophysics Data System (ADS)

    Wang, H.; Shi, C. Y.; Zhu, J. H.; Huang, X. Q.; Chen, C. T.

    2014-03-01

    Nowadays, spaceborne Synthetic Aperture Radar (SAR) has become a powerful tool for providing significant wave height. Traditionally, validation of SAR derived ocean wave height has been carried out against buoy measurements or model outputs, which only yield a inter-comparison, but not an 'absolute' validation. In this study, the triple collocation error model has been introduced in the validation of Envisat ASAR level 2 data. Significant wave height data from ASAR were validated against in situ buoy data, and wave model hindcast results from WaveWatch III, covering a period of six years. The impact of the collocation distance on the error of ASAR wave height was discussed. From the triple collocation validation analysis, it is found that the error of Envisat ASAR significant wave height product is linear to the collocation distance, and decrease with the decreasing collocation distance. Using the linear regression fit method, the absolute error of Envisat ASAR wave height was obtained with zero collocation distance. The absolute Envisat ASAR wave height error of 0.49m is presented in deep and open ocean from this triple collocation validation work.

  15. Global monitoring of wetlands--the value of ENVISAT ASAR Global mode.

    PubMed

    Bartsch, A; Wagner, W; Scipal, K; Pathe, C; Sabel, D; Wolski, P

    2009-05-01

    This paper elaborates on recent advances in the use of ScanSAR technologies for wetland-related research. Applications of active satellite radar systems include the monitoring of inundation dynamics as well as time series analyses of surface soil wetness. For management purposes many wetlands, especially those in dry regions, need to be monitored for short and long-term changes. Another application of these technologies is monitoring the impact of climate change in permafrost transition zones where peatlands form one of the major land cover types. Therefore, examples from boreal and subtropical environments are presented using the analysed ENVISAT ASAR Global mode (GM, 1 km resolution) data acquired in 2005 and 2006. In the case of the ENVISAT ASAR instrument, data availability of the rather coarse Global Mode depends on request priorities of other competing modes, but acquisition frequency may still be on average fortnightly to monthly depending on latitude. Peatland types covering varying permafrost regimes of the West Siberian Lowlands can be distinguished from each other and other land cover by multi-temporal analyses. Up to 75% of oligotrophic bogs can be identified in the seasonal permafrost zone in both years. The high seasonal and inter-annual dynamics of the subtropic Okavango Delta can also be captured by GM time series. Response to increased precipitation in 2006 differs from flood propagation patterns. In addition, relative soil moisture maps may provide a valuable data source in order to account for external hydrological factors of such complex wetland ecosystems.

  16. Evaluating the value of ENVISAT ASAR Data for the mapping and monitoring of peatland water table depths

    NASA Astrophysics Data System (ADS)

    Bechtold, Michel; Schlaffer, Stefan

    2015-04-01

    The Advanced Synthetic Aperture Radar (ASAR) onboard ENVISAT collected C-Band microwave backscatter data from 2005 to 2012. Backscatter in the C-Band depends to a large degree on the roughness and the moisture status of vegetation and soil surface with a penetration depth of ca. 3 cm. In wetlands with stable high water levels, the annual soil surface moisture dynamics are very distinct compared to the surrounding areas, which allows the monitoring of such environments with ASAR data (Reschke et al. 2012). Also in drained peatlands, moisture status of vegetation and soil surface strongly depends on water table depth due to high hydraulic conductivities of many peat soils in the low suction range (Dettmann et al. 2014). We hypothesize that this allows the characterization of water table depths with ASAR data. Here we analyze whether ASAR data can be used for the spatial and temporal estimation of water table depths in different peatlands (natural, near-natural, agriculturally-used and rewetted). Mapping and monitoring of water table depths is of crucial importance, e.g. for upscaling greenhouse gas emissions and evaluating the success of peatland rewetting projects. Here, ASAR data is analyzed with a new map of water table depths for the organic soils in Germany (Bechtold et al. 2014) as well as with a comprehensive data set of monitored peatland water levels from 1100 dip wells and 54 peatlands. ASAR time series from the years 2005-2012 with irregular temporal sampling intervals of 3-14 days were processed. Areas covered by snow were masked. Primary results about the accuracy of spatial estimates show significant correlations between long-term backscatter statistics and spatially-averaged water table depths extracted from the map at the resolution of the ASAR data. Backscatter also correlates with long-term averages of point-scale water table depth data of the monitoring wells. For the latter, correlation is highest between the dry reference backscatter values and

  17. ASAR images a diverse set of deformation patterns at Kilauea volcano, Hawai'i

    USGS Publications Warehouse

    Poland, Michael P.

    2007-01-01

    Since 2003, 27 independent look angles have been acquired by ENVISAT’s Advanced Synthetic Aperture Radar (ASAR) instrument over the island of Hawai`i, allowing for the formation of thousands of interferograms showing deformation of the ground surface. On Kīlauea volcano, a transition from minor to broad-scale summit inflation was observed by interferograms that span 2003 to 2006. In addition, radar interferometry (InSAR) observations of Kīlauea led to the discovery of several previously unknown areas of localized subsidence in the caldera and along the volcano’s east rift zone. These features are probably caused by the cooling and contraction of accumulated lavas. After November 2005, a surface instability near the point that lava entered the ocean on the south flank of Kīlauea was observed in interferograms. The motion is most likely a result of unbuttressing of a portion of the coast following the collapse of a large lava delta in November 2005. InSAR data can also be used to map lava flow development over time, providing ~30 m spatial resolution maps at approximately monthly intervals. Future applications of InSAR to Kīlauea will probably result in more discoveries and insights, both as the style of volcano deformation changes and as data from new instruments are acquired.

  18. A Modular and Configurable Instrument Electronics Architecture for "MiniSAR"- An Advanced Smallsat SAR Instrument

    NASA Astrophysics Data System (ADS)

    Gomez, Jaime; Pastena, Max; Bierens, Laurens

    2013-08-01

    MiniSAR is a Dutch program focused on the development of a commercial smallsat featuring a SAR instrument, led by SSBV as prime contractor. In this paper an Instrument Electronics (IEL) system concept to meet the MiniSAR demands is presented. This system has several specificities wrt similar initiatives in the European space industry, driven by our main requirement: keep it small.

  19. Using the MicroASAR on the NASA SIERRA UAS in the Characterization of Arctic Sea Ice Experiment

    NASA Technical Reports Server (NTRS)

    Zaugg, Evan; Long, David; Edwards, Matthew; Fladeland, Matthew; Kolyer, Richard; Crocker, Ian; Maslanik, James; Herzfeld, Ute; Wallin, Bruce

    2010-01-01

    The MicroASAR is a flexible, robust SAR system built on the successful legacy of the BYU microSAR. It is a compact LFM-CW SAR system designed for low-power operation on small, manned aircraft or UAS. The NASA SIERRA UAS was designed to test new instruments and support flight experiments. NASA used the MicroASAR on the SIERRA during a science field campaign in 2009 to study sea ice roughness and break-up in the Arctic and high northern latitudes. This mission is known as CASIE-09 (Characterization of Arctic Sea Ice Experiment 2009). This paper describes the MicroASAR and its role flying on the SIERRA UAS platform as part of CASIE-09.

  20. Tunnel monitoring with an advanced InSAR technique

    NASA Astrophysics Data System (ADS)

    Rabus, Bernhard; Eppler, Jayson; Sharma, Jayanti; Busler, Jennifer

    2012-06-01

    The detection and monitoring of subsurface excavations has a variety of applications in both the civil and defense domains. We have developed a novel InSAR method (Homogenous Distributed Scatterer (HDS)-InSAR) that exploits both persistent point and coherent distributed scatterers by using adaptive multilooking of statistically homogenous pixel neighborhoods. In order to enhance the detection of small scale structures in low SNR environments a matched parametric spatio-temporal model is fit to the deformation signal. We illustrate the performance of our new method for the city of Vancouver over the last nine years using InSAR stacks of RADARSAT-1 and RADARSAT-2 data.

  1. MATLAB tools for EnviSAT ASAR data visualization and image enhancement

    NASA Astrophysics Data System (ADS)

    Wen, Bihan; Lu, Yilong

    2011-10-01

    Advanced synthetic aperture radar (ASAR) is an all-weather, day-and-night and high-resolution imaging instrument carried out by EnviSat. Planetary missions related to Earth surface observation benefit from ASAR. Conventionally, EnviView is used to decode ASAR data and display ASAR data information and images. However, EnviView has very limited functions and is unable to export meaningful images when the data was acquired in some bad weather condition such as after heavy rain as the data is distorted by various factors such as the soil moisture. Furthermore, EnviView is not user friendly and not flexible to use. This paper presents a user-friendly ASAR data visualization and image enhancement toolbox based on the very popular MATLAB software environment. The image enhancement is important for meaningful image analysis and accurate target identification of poor data due to weather or other environment factors. A case study is presented with image enhancement for a poor ASAR data.

  2. Interferometric processing of C-band SAR data for the improvement of stand age estimation in rubber plantation

    NASA Astrophysics Data System (ADS)

    Trisasongko, Bambang H.; Paull, David J.; Panuju, Dyah R.

    2015-01-01

    Rubber ranks the second largest plantation in Indonesia after oil palm. While oil palm plantations have been exploited mainly by large companies, many rubber plantations are still managed by peasant farmers who maintain its biodiversity. Due to its broad and scattered location, monitoring tropical rubber plantation is a crucial application of active remote sensing. In this paper, the backscatter coefficient of Envisat Advanced Synthetic Aperture Radar (ASAR) is compared to interferometric coherence to study the relationship between stand age and SAR parameters. It is shown that VV polarized C-band SAR achieves its saturation level in plantations aged about 5-10 years. Extension of saturation level can be achieved by processing an interferometric pair of ASAR data, which results in interferometric coherence. In this paper, coherence can take up to 20 years stand age to achieve prior to saturation. Since stand age is highly related to biomass, this finding argues that the biomass can be best estimated using coherence.

  3. SBAS-InSAR analysis of surface deformation at Mauna Loa and Kilauea volcanoes in Hawaii

    USGS Publications Warehouse

    Casu, F.; Lanari, Riccardo; Sansosti, E.; Solaro, G.; Tizzani, Pietro; Poland, M.; Miklius, Asta

    2009-01-01

    We investigate the deformation of Mauna Loa and K??lauea volcanoes, Hawai'i, by exploiting the advanced differential Synthetic Aperture Radar Interferometry (InSAR) technique referred to as the Small BAseline Subset (SBAS) algorithm. In particular, we present time series of line-of-sight (LOS) displacements derived from SAR data acquired by the ASAR instrument, on board the ENVISAT satellite, from the ascending (track 93) and descending (track 429) orbits between 2003 and 2008. For each coherent pixel of the radar images we compute time-dependent surface displacements as well as the average LOS deformation rate. Our results quantify, in space and time, the complex deformation of Mauna Loa and K??lauea volcanoes. The derived InSAR measurements are compared to continuous GPS data to asses the quality of the SBAS-InSAR products. ??2009 IEEE.

  4. Atmospheric Phenomena Observed Over The South China Sea By The Advanced Synthetic Aperture Radar Onboard the ENVISAT Satellite

    NASA Astrophysics Data System (ADS)

    Alpers, Werner; Huang, Weigen; Chan, Pak Wai; Wong, Wai Kin; Cheng, Cho Ming; Mouche, Alexis

    2010-10-01

    Atmospheric phenomena often leave fingerprints on the sea surface, which are detectable by synthetic aperture radar (SAR). Here we present some representative examples of SAR images acquired by the Advanced Synthetic Aperture Radar (ASAR) onboard the Envisat satellite over the South China Sea (SCS) which show radar signatures of atmospheric gravity waves (AGWs) and of coastal wind fields. On SAR images of the SCS also often radar signatures of oceanic internal waves (OIWs) are visible which have similar spatial scales as the ones originating from AGWs. Therefore we first present criteria how to distinguish between them by analyzing the structure of the radar signatures. Then we present two examples of ASAR images which show radar signatures of AGWs over the SCS. Furthermore, we present a SAR image showing radar signatures of a northerly Winter Monsoon surge event over the coastal area south of Hong Kong and compare it with a cloud image and a weather radar image. From the ASAR image we retrieve the near-surface wind field and compare it with the wind field simulated by the AIR model of the Hong Kong Observatory. The comparison shows that the AIR model can simulate quite well the wind speed as well as the position and shape of the frontal line measured by ASAR.

  5. Spaceborne SAR data for global urban mapping at 30 m resolution using a robust urban extractor

    NASA Astrophysics Data System (ADS)

    Ban, Yifang; Jacob, Alexander; Gamba, Paolo

    2015-05-01

    With more than half of the world population now living in cities and 1.4 billion more people expected to move into cities by 2030, urban areas pose significant challenges on local, regional and global environment. Timely and accurate information on spatial distributions and temporal changes of urban areas are therefore needed to support sustainable development and environmental change research. The objective of this research is to evaluate spaceborne SAR data for improved global urban mapping using a robust processing chain, the KTH-Pavia Urban Extractor. The proposed processing chain includes urban extraction based on spatial indices and Grey Level Co-occurrence Matrix (GLCM) textures, an existing method and several improvements i.e., SAR data preprocessing, enhancement, and post-processing. ENVISAT Advanced Synthetic Aperture Radar (ASAR) C-VV data at 30 m resolution were selected over 10 global cities and a rural area from six continents to demonstrate the robustness of the improved method. The results show that the KTH-Pavia Urban Extractor is effective in extracting urban areas and small towns from ENVISAT ASAR data and built-up areas can be mapped at 30 m resolution with very good accuracy using only one or two SAR images. These findings indicate that operational global urban mapping is possible with spaceborne SAR data, especially with the launch of Sentinel-1 that provides SAR data with global coverage, operational reliability and quick data delivery.

  6. The development of advanced spread spectrum LFM waveforms for enhanced SAR and GMTI

    NASA Astrophysics Data System (ADS)

    Kirk, John C.; Darden, Scott; Majumder, Uttam K.; Minardi, Michael J.; Bell, Mark R.

    2016-05-01

    Advanced spread spectrum linear frequency modulated (LFM) waveforms are being developed for advanced capability synthetic aperture radar (SAR) and ground moving target indication (GMTI) applications. We have demonstrated by analysis and simulation the feasibility of these new type waveforms and are now in the process of implementing them in hardware. The basic approach is to combine a traditional LFM radar waveform with a direct sequence spread spectrum (DSSS) waveform, and then on receive to de-spread the return and capture the resultant LFM return for traditional matched filter processing and enhanced SAR and GMTI. We show the analysis, simulation and some preliminary hardware results.

  7. Advanced InSAR imaging for dune mapping

    NASA Astrophysics Data System (ADS)

    Havivi, Shiran; August, Yitzhak; Blumberg, Dan G.; Rotman, Stanley R.

    2015-04-01

    Aeolian morphologies are formed in the presence of sufficient wind energy and available particles. These processes occur naturally or are further enhanced or reduced by human intervention. The dimensions of change are dependent primarily on the wind energy and surface properties. Since the 1970's, remote sensing imagery both optical and radar, are used for documentation and interpretation of the geomorphologic changes of sand dunes. Remote sensing studies of Aeolian morphologies is mostly useful to document major changes, yet, subtle changes, occurring in a period of days or months in scales of centimeters, are very difficult to detect in imagery. Interferometric Synthetic Aperture Radar (InSAR) is an imaging technique for measuring Earth's surface topography and deformation. InSAR images are produced by measuring the radar phase difference between two separated antennas that view the same surface area. Classical InSAR is based on high coherence between two images or more. The output (interferogram) can show subtle changes with an accuracy of several millimeters to centimeters. Very little work has been done on measuring or identifying the changes in dunes using InSAR. The reason is that dunes tend to be less coherent than firm, stable, surfaces. This research aims to demonstrate how interferometric decorrelation, or, coherence change detection, can be used for identifying dune instability. We hypothesize and demonstrate that the loss of radar coherence over time on dunes can be used as an indication of the dune's instability. When SAR images are acquired at sufficiently close intervals one can measure the time it takes to lose coherence and associate this time with geomorphic stability. To achieve our goals, the Nitzanim coastal dunes along the Mediterranean, 40 km south of Tel-Aviv, Israel, were chosen as a case study. The dunes in this area are of varying levels of stability and vegetation cover and have been monitored meteorologically, geomorphologically and

  8. Advanced SAR simulator with multi-beam interferometric capabilities

    NASA Astrophysics Data System (ADS)

    Reppucci, Antonio; Márquez, José; Cazcarra, Victor; Ruffini, Giulio

    2014-10-01

    State of the art simulations are of great interest when designing a new instrument, studying the imaging mechanisms due to a given scenario or for inversion algorithm design as they allow to analyze and understand the effects of different instrument configurations and targets compositions. In the framework of the studies about a new instruments devoted to the estimation of the ocean surface movements using Synthetic Aperture Radar along-track interferometry (SAR-ATI) an End-to-End simulator has been developed. The simulator, built in a high modular way to allow easy integration of different processing-features, deals with all the basic operations involved in an end to end scenario. This includes the computation of the position and velocity of the platform (airborne/spaceborne) and the geometric parameters defining the SAR scene, the surface definition, the backscattering computation, the atmospheric attenuation, the instrument configuration, and the simulation of the transmission/reception chains and the raw data. In addition, the simulator provides a inSAR processing suit and a sea surface movement retrieval module. Up to four beams (each one composed by a monostatic and a bistatic channel) can be activated. Each channel provides raw data and SLC images with the possibility of choosing between Strip-map and Scansar modes. Moreover, the software offers the possibility of radiometric sensitivity analysis and error analysis due atmospheric disturbances, instrument-noise, interferogram phase-noise, platform velocity and attitude variations. In this paper, the architecture and the capabilities of this simulator will be presented. Meaningful simulation examples will be shown.

  9. COMPUTATIONAL TOXICOLOGY ADVANCES: EMERGING CAPABILITIES FOR DATA EXPLORATION AND SAR MODEL DEVELOPMENT

    EPA Science Inventory

    Computational Toxicology Advances: Emerging capabilities for data exploration and SAR model development
    Ann M. Richard and ClarLynda R. Williams, National Health & Environmental Effects Research Laboratory, US EPA, Research Triangle Park, NC, USA; email: richard.ann@epa.gov

  10. Comparison of Envisat ASAR and Submarine Sea Ice Thickness Statistics

    NASA Astrophysics Data System (ADS)

    Hughes, Nicolas E.; Rodrigues, Joao; Wadhams, Peter

    2010-12-01

    In April 2004 and March 2007 the Royal Navy sent the submarine HMS Tireless on missions into the Arctic Ocean. On both occasions the submarine traversed the area of remaining multi-year sea ice at latitude 85°N north of Greenland acquiring ice draft measurements using upward-looking sonar. The area is outside of the "Gore Box" used for the release of U.S. Submarine data and was beyond the latitude range of the radar altimeter satellites available at that time. This paper compares ice draft statistics with contemporary data from Envisat ASAR to evaluate the level of correlation between SAR backscatter and sea ice thickness. The decline in sea ice volume over the past decade has predominantly been caused by the loss of old multi-year ice due to increased outflow through Fram Strait. Although Tireless found little decrease in the overall ice thickness between 2004 and 2007, the ice rheology was significantly changed with greatly increased quantities of first- and second-year ice in 2007 than had been encountered in 2004. These are evident in changes to the ice draft probability density functions (PDFs) and the ice appearance as seen by the SAR, and presented here.

  11. Snow density retrieval using SAR data: algorithm validation and applications in part of North Western Himalaya

    NASA Astrophysics Data System (ADS)

    Thakur, P. K.; Garg, R. D.; Aggarwal, S. P.; Garg, P. K.; Snehmani; Shi, J.

    2013-05-01

    The current study has been done using Polarimetric Synthetic Aperture Radar (SAR) data to estimate the dry snow density in Manali sub-basin of Beas River located in state of Himachal Pradesh, India. SAR data from Radarsat-2 (RS2), Environmental Satellite (ENVISAT), Advanced Synthetic Aperture Radar (ASAR) and Advanced Land Observing Satellite (ALOS)-Phased Array type L-band Synthetic Aperture Radar (PALSAR) have been used. The SAR based inversion models were implemented separately for fully polarimetric RS2, PALSAR and dual polarimetric ASAR Alternate polarization System (APS) datasets in Mathematica and MATLAB software and have been used for finding out dry snow dielectric constant and snow density. Masks for forest, built area, layover and shadow were considered in estimating snow parameters. Overall accuracy in terms of R2 value and Root Mean Square Error (RMSE) was calculated as 0.85 and 0.03 g cm-3 for snow density based on the ground truth data. The retrieved snow density is highly useful for snow avalanche and snowmelt runoff modeling related studies of this region.

  12. EPOSAR: an innovative service to provide EPOS community with advanced DInSAR products

    NASA Astrophysics Data System (ADS)

    Manunta, Michele; De Luca, Claudio; Elefante, Stefano; Lanari, Riccardo; Pepe, Antonio; Zinno, Ivana; Casu, Francesco

    2015-04-01

    The quantitative evaluation of ground deformation is traditionally based on in-situ surveying techniques that, through the intensive use of GPS stations, automatic total stations and levelling benchmarks, can measure up to sub-centimetre displacements. In the last decades, the extensive use of satellite remote sensing data, such as Synthetic Aperture Radar (SAR) images, has represented an important breakthrough in the context of non-invasive ground deformation analyses over large areas, thanks to their large spatial coverage and relatively short revisit time, as well as to their medium-high ground resolution. In such a context, the well-known Differential SAR Interferometry (DInSAR) technique allows us to map and measure deformation phenomena due to both natural and man-made causes with centimetre to millimetre accuracy. The Earth Science community has a wide interest in the use of DInSAR displacement maps both for crisis management and risk mitigation activities, and for surveillance, monitoring and analysis of geophysical phenomena. In areas characterized by high level of hazards the availability of routinely generated advanced DInSAR products would allow a fast analysis of their current status, providing a near real time monitoring. Similarly, an on-demand service would allow the customization of the products by selecting the area of interest, the SAR data to be processed, and other processing parameters to be set by the users to edit/correct/improve the final products. In this work we discuss the Satellite Data Thematic Core Service of EPOS and we present the EPOSAR service. In particular, the EPOSAR service, based on the well-known DInSAR approach referred to as Small Baseline Subset (SBAS), accomplishes a shared and synergic Earth Observation (EO) service aimed at designing, implementing and harmonizing efficient satellite data processing chains capable of ingesting the significantly increased data stream expected from the ESA Sentinel-1 satellites. EPOSAR

  13. Evidence of a topographic signal in surface soil moisture derived from ENVISAT ASAR wide swath data

    NASA Astrophysics Data System (ADS)

    Mason, D. C.; Garcia-Pintado, J.; Cloke, H. L.; Dance, S. L.

    2016-03-01

    The susceptibility of a catchment to flooding is affected by its soil moisture prior to an extreme rainfall event. While soil moisture is routinely observed by satellite instruments, results from previous work on the assimilation of remotely sensed soil moisture into hydrologic models have been mixed. This may have been due in part to the low spatial resolution of the observations used. In this study, the remote sensing aspects of a project attempting to improve flow predictions from a distributed hydrologic model by assimilating soil moisture measurements are described. Advanced Synthetic Aperture Radar (ASAR) Wide Swath data were used to measure soil moisture as, unlike low resolution microwave data, they have sufficient resolution to allow soil moisture variations due to local topography to be detected, which may help to take into account the spatial heterogeneity of hydrological processes. Surface soil moisture content (SSMC) was measured over the catchments of the Severn and Avon rivers in the South West UK. To reduce the influence of vegetation, measurements were made only over homogeneous pixels of improved grassland determined from a land cover map. Radar backscatter was corrected for terrain variations and normalized to a common incidence angle. SSMC was calculated using change detection. To search for evidence of a topographic signal, the mean SSMC from improved grassland pixels on low slopes near rivers was compared to that on higher slopes. When the mean SSMC on low slopes was 30-90%, the higher slopes were slightly drier than the low slopes. The effect was reversed for lower SSMC values. It was also more pronounced during a drying event. These findings contribute to the scant information in the literature on the use of high resolution SAR soil moisture measurement to improve hydrologic models.

  14. Inhibitors for the hepatitis C virus RNA polymerase explored by SAR with advanced machine learning methods.

    PubMed

    Weidlich, Iwona E; Filippov, Igor V; Brown, Jodian; Kaushik-Basu, Neerja; Krishnan, Ramalingam; Nicklaus, Marc C; Thorpe, Ian F

    2013-06-01

    Hepatitis C virus (HCV) is a global health challenge, affecting approximately 200 million people worldwide. In this study we developed SAR models with advanced machine learning classifiers Random Forest and k Nearest Neighbor Simulated Annealing for 679 small molecules with measured inhibition activity for NS5B genotype 1b. The activity was expressed as a binary value (active/inactive), where actives were considered molecules with IC50 ≤0.95 μM. We applied our SAR models to various drug-like databases and identified novel chemical scaffolds for NS5B inhibitors. Subsequent in vitro antiviral assays suggested a new activity for an existing prodrug, Candesartan cilexetil, which is currently used to treat hypertension and heart failure but has not been previously tested for anti-HCV activity. We also identified NS5B inhibitors with two novel non-nucleoside chemical motifs. PMID:23608107

  15. Inhibitors for the hepatitis C virus RNA polymerase explored by SAR with advanced machine learning methods

    PubMed Central

    Weidlich, Iwona E.; Filippov, Igor V.; Brown, Jodian; Kaushik-Basu, Neerja; Krishnan, Ramalingam; Nicklaus, Marc C.; Thorpe, Ian F.

    2013-01-01

    Hepatitis C virus (HCV) is a global health challenge, affecting approximately 200 million people worldwide. In this study we developed SAR models with advanced machine learning classifiers Random Forest and k Nearest Neighbor Simulated Annealing for 679 small molecules with measured inhibition activity for NS5B genotype 1b. The activity was expressed as a binary value (active/inactive), where actives were considered molecules with IC50 ≤ 0.95 μM. We applied our SAR models to various drug-like databases and identified novel chemical scaffolds for NS5B inhibitors. Subsequent in vitro antiviral assays suggested a new activity for an existing prodrug, Candesartan cilexetil, which is currently used to treat hypertension and heart failure but has not been previously tested for anti-HCV activity. We also identified NS5B inhibitors with two novel non-nucleoside chemical motifs. PMID:23608107

  16. A joint method to retrieve directional ocean wave spectra from SAR and wave spectrometer data

    NASA Astrophysics Data System (ADS)

    Ren, Lin; Yang, Jingsong; Zheng, Gang; Wang, Juan

    2016-07-01

    This paper proposes a joint method to simultaneously retrieve wave spectra at different scales from spaceborne Synthetic Aperture Radar (SAR) and wave spectrometer data. The method combines the output from the two different sensors to overcome retrieval limitations that occur in some sea states. The wave spectrometer sensitivity coefficient is estimated using an effective significant wave height (SWH), which is an average of SAR-derived and wave spectrometer-derived SWH. This averaging extends the area of the sea surface sampled by the nadir beam of the wave spectrometer to improve the accuracy of the estimated sensitivity coefficient in inhomogeneous sea states. Wave spectra are then retrieved from SAR data using wave spectrometer-derived spectra as first guess spectra to complement the short waves lost in SAR data retrieval. In addition, the problem of 180° ambiguity in retrieved spectra is overcome using SAR imaginary cross spectra. Simulated data were used to validate the joint method. The simulations demonstrated that retrieved wave parameters, including SWH, peak wave length (PWL), and peak wave direction (PWD), agree well with reference parameters. Collocated data from ENVISAT advanced SAR (ASAR), the airborne wave spectrometer STORM, the PHAROS buoy, and the European Centre for Medium-Range Weather Forecasting (ECMWF) were then used to verify the proposed method. Wave parameters retrieved from STORM and two ASAR images were compared to buoy and ECMWF wave data. Most of the retrieved parameters were comparable to reference parameters. The results of this study show that the proposed joint retrieval method could be a valuable complement to traditional methods used to retrieve directional ocean wave spectra, particularly in inhomogeneous sea states.

  17. Using the ESA's ASAR GM radar instrument to map physical soil properties (case study over Australia)

    NASA Astrophysics Data System (ADS)

    Doubkova, Marcela; van Dijk, Albert; Bauer-Marschallinger, Bernhard

    2010-05-01

    A quantitative and qualitative comparison was made between a suite of physical soil parameters derived from the Australian Soil Resources Information System (ASRIS) and backscattering characteristics calculated from the Advanced Synthetic Aperture radar Global Mode (ASAR GM) on ESA's ENVISAT satellite. Based on the results opportunities were identified to map soil physical properties over areas with limited vegetation cover, and to further improve the retrieval of soil moisture content from radar remote sensing.

  18. Analysis of Envisat Orbit Maintenance Strategies to Improve/Increase Envisat ASAR Interferometry Opportunities

    NASA Technical Reports Server (NTRS)

    Kuijper, D.; Matatoros, Garcia

    2007-01-01

    The biggest and most advanced Earth Observation Satellite in-orbit, developed by the European Space Agency (ESA) and its member states, is Envisat. It was launched on March 1, 2002 by an Ariane V from French Guyana and holds a total of 10 multi-disciplinary Earth observation instruments, among which an Advanced Synthetic Aperture Radar (ASAR). The ASAR user community requested the Flight Dynamics division of the European Space Operations Centre (ESOC) to investigate how the orbit control maintenance strategy for Envisat could be changed to optimize ASAR interferometry opportunities overall and in addition support the International Polar Year 2007/2008 initiative. The Polar Regions play a pivotal role in understanding our planet and our impact on it as they are recognized as sensitive barometers of environmental change. One of the main themes of the International Polar Year 2007/2008 is therefore the study of Earth s changing ice and snow, and its impact on our planet and our lives. Naturally, ESA would like to support this very important initiative. This paper presents the investigations that have been conducted to support these requests in the best possible way. It discusses the orbit maintenance strategy that has been in place since its launch, ensuring the actual orbit to be within 1 km of a so-called reference orbit, and presents the new orbit maintenance strategy that is aimed at improving/increasing the opportunities for Envisat ASAR interferometry, while preserving the fuel on board the spacecraft. The hydrazine on-board Envisat happens to be a precious resource as only approximately 300 kg of it was available at launch, like ERS-2. The difference being however that the mass of Envisat is approximately 3.2 times that of ERS-2.

  19. Object-oriented approach to oil spill detection using ENVISAT ASAR images

    NASA Astrophysics Data System (ADS)

    Konik, M.; Bradtke, K.

    2016-08-01

    The growing importance of oil spill detection as part of a rapid response system to oil pollution requires the ongoing development of algorithms. The aim of this study was to create a methodology for improving manual classification at the scale of entire water bodies, focusing on its repeatability. This paper took an object-oriented approach to radar image analysis and put particular emphasis on adaptation to the specificity of seas like the Baltic. Pre-processing using optimised filters enhanced the capability of a multilevel hierarchical segmentation, in order to detect spills of different sizes, forms and homogeneity, which occur as a result of shipping activities. Confirmed spills detected in ENVISAT/ASAR images were used to create a decision-tree procedure that classifies every distinct dark object visible in SAR images into one out of four categories, which reflect growing probability of the oil spill presence: look-alikes, dubious spots, blurred spots and potential oil spills. Our objective was to properly mark known spills on ASAR scenes and to reduce the number of false-positives by eliminating (classifying as background or look-alike) as many objects as possible from the vast initial number of objects appearing on full-scale images. A number of aspects were taken into account in the classification process. The method's performance was tested on a group of 26 oil spills recorded by HELCOM: 96.15% of them were successfully identified. The final target group was narrowed down to about 4% of dark objects extracted from ASAR images. Although a specialist is still needed to supervise the whole process of oil spill detection, this method gives an initial view, substantial for further evaluation of the scenes and risk estimation. It may significantly accelerate the pace of manual image analysis and enhance the objectivity of assessments, which are key aspects in operational monitoring systems.

  20. Spaceborne SAR Imaging Algorithm for Coherence Optimized.

    PubMed

    Qiu, Zhiwei; Yue, Jianping; Wang, Xueqin; Yue, Shun

    2016-01-01

    This paper proposes SAR imaging algorithm with largest coherence based on the existing SAR imaging algorithm. The basic idea of SAR imaging algorithm in imaging processing is that output signal can have maximum signal-to-noise ratio (SNR) by using the optimal imaging parameters. Traditional imaging algorithm can acquire the best focusing effect, but would bring the decoherence phenomenon in subsequent interference process. Algorithm proposed in this paper is that SAR echo adopts consistent imaging parameters in focusing processing. Although the SNR of the output signal is reduced slightly, their coherence is ensured greatly, and finally the interferogram with high quality is obtained. In this paper, two scenes of Envisat ASAR data in Zhangbei are employed to conduct experiment for this algorithm. Compared with the interferogram from the traditional algorithm, the results show that this algorithm is more suitable for SAR interferometry (InSAR) research and application. PMID:26871446

  1. Spaceborne SAR Imaging Algorithm for Coherence Optimized.

    PubMed

    Qiu, Zhiwei; Yue, Jianping; Wang, Xueqin; Yue, Shun

    2016-01-01

    This paper proposes SAR imaging algorithm with largest coherence based on the existing SAR imaging algorithm. The basic idea of SAR imaging algorithm in imaging processing is that output signal can have maximum signal-to-noise ratio (SNR) by using the optimal imaging parameters. Traditional imaging algorithm can acquire the best focusing effect, but would bring the decoherence phenomenon in subsequent interference process. Algorithm proposed in this paper is that SAR echo adopts consistent imaging parameters in focusing processing. Although the SNR of the output signal is reduced slightly, their coherence is ensured greatly, and finally the interferogram with high quality is obtained. In this paper, two scenes of Envisat ASAR data in Zhangbei are employed to conduct experiment for this algorithm. Compared with the interferogram from the traditional algorithm, the results show that this algorithm is more suitable for SAR interferometry (InSAR) research and application.

  2. Spaceborne SAR Imaging Algorithm for Coherence Optimized

    PubMed Central

    Qiu, Zhiwei; Yue, Jianping; Wang, Xueqin; Yue, Shun

    2016-01-01

    This paper proposes SAR imaging algorithm with largest coherence based on the existing SAR imaging algorithm. The basic idea of SAR imaging algorithm in imaging processing is that output signal can have maximum signal-to-noise ratio (SNR) by using the optimal imaging parameters. Traditional imaging algorithm can acquire the best focusing effect, but would bring the decoherence phenomenon in subsequent interference process. Algorithm proposed in this paper is that SAR echo adopts consistent imaging parameters in focusing processing. Although the SNR of the output signal is reduced slightly, their coherence is ensured greatly, and finally the interferogram with high quality is obtained. In this paper, two scenes of Envisat ASAR data in Zhangbei are employed to conduct experiment for this algorithm. Compared with the interferogram from the traditional algorithm, the results show that this algorithm is more suitable for SAR interferometry (InSAR) research and application. PMID:26871446

  3. EnviSAT ASAR Monitoring Of The Natural And Archaeological Landscape Of Nasca, Peru

    NASA Astrophysics Data System (ADS)

    Cigna, Francesca; Tapete, Deodato; Lasaponara, Rosa; Masini, Nicola

    2013-12-01

    We exploit the 4year-long archive of ENVISAT ASAR IS2 C-band imagery available through ESA Cat-1 project id.11073 over Nasca (Southern Peru), to reconstruct the temporal evolution of the Rio Grande drainage basin and its impacts on the natural and cultural heritage preserved within this region, well- known for the evidences of the ancient Paracas and Nasca Civilizations who flourished between the 4th century BC and the 6th century AD. Inferences about the recent changes of the cultural landscapes and the main landforms in 2003-2007 were retrieved based on SAR backscattering (σ0) time series. Ancient aqueduct systems (the so-called puquios) and the famous geoglyphs ('Nasca Lines') were detected, even at a medium-resolution scale provided by ENVISAT images.

  4. High-spatial-resolution mapping of precipitable water vapour using SAR interferograms, GPS observations and ERA-Interim reanalysis

    NASA Astrophysics Data System (ADS)

    Tang, Wei; Liao, Mingsheng; Zhang, Lu; Li, Wei; Yu, Weimin

    2016-09-01

    A high spatial and temporal resolution of the precipitable water vapour (PWV) in the atmosphere is a key requirement for the short-scale weather forecasting and climate research. The aim of this work is to derive temporally differenced maps of the spatial distribution of PWV by analysing the tropospheric delay "noise" in interferometric synthetic aperture radar (InSAR). Time series maps of differential PWV were obtained by processing a set of ENVISAT ASAR (Advanced Synthetic Aperture Radar) images covering the area of southern California, USA from 6 October 2007 to 29 November 2008. To get a more accurate PWV, the component of hydrostatic delay was calculated and subtracted by using ERA-Interim reanalysis products. In addition, the ERA-Interim was used to compute the conversion factors required to convert the zenith wet delay to water vapour. The InSAR-derived differential PWV maps were calibrated by means of the GPS PWV measurements over the study area. We validated our results against the measurements of PWV derived from the Medium Resolution Imaging Spectrometer (MERIS) which was located together with the ASAR sensor on board the ENVISAT satellite. Our comparative results show strong spatial correlations between the two data sets. The difference maps have Gaussian distributions with mean values close to zero and standard deviations below 2 mm. The advantage of the InSAR technique is that it provides water vapour distribution with a spatial resolution as fine as 20 m and an accuracy of ˜ 2 mm. Such high-spatial-resolution maps of PWV could lead to much greater accuracy in meteorological understanding and quantitative precipitation forecasts. With the launch of Sentinel-1A and Sentinel-1B satellites, every few days (6 days) new SAR images can be acquired with a wide swath up to 250 km, enabling a unique operational service for InSAR-based water vapour maps with unprecedented spatial and temporal resolution.

  5. Advanced DInSAR analysis at Campi Flegrei and Vesuvius, Italy

    NASA Astrophysics Data System (ADS)

    Tiampo, K. F.; Camacho, A. G.; Fernandez, J.; Gonzalez, P. J.; Samsonov, S. V.

    2015-12-01

    Geodetic data, the spatial and temporal surface expression of complex geophysical processes in the earth, is being acquired today at unprecedented rates and accuracies. Differential interferometric synthetic aperture radar (DInSAR) is a satellite remote sensing technique used extensively today for mapping ground deformation with high spatial resolution and sub-centimeter precision over large areas that is particularly useful for volcanic monitoring [Massonnet and Feigl, 1998; Rosen et al., 2000]. Here we apply the advanced Multidimensional Small Baseline Subset (MSBAS) InSAR algorithm [Samsonov and d'Oreye, 2012] to several thousand Envisat and RADARSAT-2 images from 1993-2013 and compute time series of ground deformation over the Naples Bay region of Italy. Vesuvius and Campi Flegrei are located in this area in close proximity to the densely populated city of Naples and, as a result, it is one of the most hazardous volcanic areas in the world. We obtain time series of ground deformation at high spatial and temporal resolution that span, for the first time, twenty years. Campi Flegrei underwent continuous subsidence through 1999. Uplift began in 2005, reaching approximately 13 cm by 2013. We model the observed deformation to determine source parameters for subsidence and uplift epochs [Samsonov et al., 2014]. In addition, a typical DInSAR image can contain significant signals from with several different, nonvolcanic sources. For example, we clearly observe decade-long elevation-dependent seasonal oscillations of the vertical displacement component at Vesuvius that are substantially larger than the long-term deformation rate (<0.6 cm/yr). As a result, we employ an eigenpattern decomposition technique known as Karhunen-Loeve expansion (KLE) analysis in order to identify the unique, finite set of correlated deformation patterns associated with volcanic sources at different depths [Tiampo et al., 2004; Tiampo et al., 2012]. Both the inflation and deflation mechanisms

  6. Feature Analysis of Ocean Waves in North Central Pacific Ocean Based ASAR Wave Spectral Data and Wave Model

    NASA Astrophysics Data System (ADS)

    Wang, Jichao; Zhang, Jie; Yang, Jungang; Meng, Junmin

    2013-01-01

    Directional Spectrum of the ocean waves could be obtained form Envisat advanced synthetic aperture radar (ASAR) wave spectral data. The wave model WAVEWATCH III (WW3) is applied to simulate the ocean wave field. Study area is 185°E-215°E and 15°N-30°N, time range is from 1 January 2008 to 31 December 2008. Based on ASAR and buoy data, the wave numerical simulation and assimilation of the north central Pacific Ocean is carried out. The validation and assessment of ASAR ocean wave spectra products is performed. The optimal interpolation (OI) algorithm is used in model WW3 for assimilating ASAR wave spectra data. Based on the result of the simulation and assimilation, mean waves direction (MWD), significant wave height (SWH) and mean wave period (MWP) are analysed. SWH and MWP are larger in winter and SWH reach to more than 2.5 meters. Seasonal change of SWH and MWP are significant.

  7. New perspectives and advanced approaches on effectively processing Big InSAR data: from long term ERS archives to new Sentinel-1 massive data flow

    NASA Astrophysics Data System (ADS)

    Casu, Francesco; De Luca, Claudio; Elefante, Stefano; Lanari, Riccardo; Manunta, Michele; Zinno, Ivana

    2015-04-01

    Advanced differential Synthetic Aperture Radar (SAR) Interferometry (InSAR) usually identifies a set of algorithms, tools and methodologies for the generation of Earth's surface deformation maps and time series computed from a sequence of multi-temporal differential SAR interferograms. Such techniques found their success on the large availability of SAR data archives acquired over time by several satellite systems. Indeed, the current radar Earth Observation (EO) scenario takes advantage of the widely diffused long-term C-band ESA (e.g. ERS-1, ERS-2 and ENVISAT) and Canadian (RADARSAT-1/2) SAR data archives, which have been acquired during the last 20 years, as well as of data sequences provided by the X-band generation SAR sensors, such as the COSMO-SkyMed (CSK) and TerraSAR-X (TSX) constellations. Moreover, a massive and ever increasing data flow will be further supplied by the recently launched (April 2014) Copernicus (European Union) SENTINEL-1A SAR satellite, which will also be paired during 2016 with the SENTINEL-1B twin system that will allow halving the constellation revisit time (from 12 to 6 days). In this context, the massive exploitation of these Big InSAR Data archives for the generation of advanced products will open new research perspectives to understand Earth's surface deformation dynamics at global scale. However, to reach this ambitious goal, Big InSAR Data has to be effectively exploited to generate accurate advanced products in short time frames. Therefore the need of new InSAR processing approaches, efficient algorithms and high performance computing facilities represents the basis for fully benefiting from such a Big Data. In this work we first present the recently proposed Parallel Small BAseline Subset (P-SBAS) InSAR algorithm that has been designed to process big volumes of InSAR data in short times and unsupervised manner by exploiting High Performance Computing (HPC) facilities. Then, we show how the P-SBAS approach is well suitable for

  8. Analysis of ASAR Wide Swath Mode time series for the retrieval of soil moisture in mountainous areas

    NASA Astrophysics Data System (ADS)

    Greifeneder, Felix; Notarnicola, Claudia; Cuozzo, Giovanni; Spindler, Nadine; Bertoldi, Giacomo; Della Chiesa, Stefano; Niedrist, Georg; Stamenkovic, Jelena; Wagner, Wolgang

    2014-05-01

    Soil moisture is a key element in the global cycles of water, energy, and carbon. Knowledge on the spatial and temporal distribution of the soil moisture content (SMC) is therefore essential for a number of hydrological applications as well as earth sciences like meteorology or climatology (Heathman et al., 2003). In the last few years there has been an increasing interest towards the estimation of SMC at local scales using active microwave sensors (Barret et al., 2009). Compared to passive microwave sensors, SAR offers the potential to provide data at high spatial resolution (modern sensors can acquire images with up to approximately 1 m), which is particularly important in mountainous areas. So far, these areas have been considered only marginally in research and only pioneer studies can be found in the literature (Brocca et al., 2012; Bertoldi et al. 2013). In this work we analyzed the temporal and spatial dynamics of the surface SMC (0 - 5 cm depth) on the basis of ground data collected by fixed meteorological stations located in the emerging Long-Term Ecological Research (LTER) site Mazia Valley (Province of Bolzano, South Tyrol, Italy), SAR data from ENVISATs ASAR sensor, wide swath (WS) mode (acquired between 2005 and 2012), and SMC estimates from the hydrological model GEOtop (Endrizzi et al., 2013). The SMC retrieval process was based on the support vector regression (SVR) method introduced by Pasolli et al. (2011). The training of the algorithm was based on data acquired in 2010. Furthermore, the SAR backscatter and derived SMC have been compared with time-series derived from the distributed hydrological model GEOtop. The differences in terms of temporal and spatial dynamic have been analyzed. The main goal of this work is to evaluate the spatial and temporal patterns of SAR derived SMC at field scale and to correlate them with ground information. This is a preparatory study to establish a methodology for the retrieval of SMC with high spatial and

  9. FAST TRACK PAPER: An advanced slip model for the Umbria-Marche earthquake sequence: coseismic displacements observed by SAR interferometry and model inversion

    NASA Astrophysics Data System (ADS)

    Crippa, B.; Crosetto, M.; Biescas, E.; Troise, C.; Pingue, F.; de Natale, G.

    2006-01-01

    We report an improved slip model for the 1997 September-October Umbria-Marche earthquake sequence in central Italy. The model is based on coseismic displacements estimated by differential synthetic aperture radar (DInSAR) interferometry using an advanced inverse modelling approach that enables the characteristics of the SAR data, especially their dense spatial sampling, to be fully exploited. The paper first looks at DInSAR analysis using the simplest configuration, that is, a single-image pair that temporally covers the earthquake sequence. Yet, given that this DInSAR configuration is often used for coseismic studies and the limited availability of SAR data, we duly consider the limitations of the DInSAR results and discuss the rigorous DInSAR procedure carried out, highlighting key errors associated with such observations. We then focus on the inversion of the estimated DInSAR displacements and on our advanced heterogeneous slip model for this earthquake sequence's main shocks, emphasizing its most significant features.

  10. Change detection of polarimetric SAR images based on the KummerU Distribution

    NASA Astrophysics Data System (ADS)

    Chen, Quan; Zou, Pengfei; Li, Zhen; Zhang, Ping

    2014-11-01

    In the society of PolSAR image segmentation, change detection and classification, the classical Wishart distribution has been used for a long time, but it especially suit to low-resolution SAR image, because in traditional sensors, only a small number of scatterers are present in each resolution cell. With the improving of SAR systems these years, the classical statistical models can therefore be reconsidered for high resolution and polarimetric information contained in the images acquired by these advanced systems. In this study, SAR image segmentation algorithm based on level-set method, added with distance regularized level-set evolution (DRLSE) is performed using Envisat/ASAR single-polarization data and Radarsat-2 polarimetric images, respectively. KummerU heterogeneous clutter model is used in the later to overcome the homogeneous hypothesis at high resolution cell. An enhanced distance regularized level-set evolution (DRLSE-E) is also applied in the later, to ensure accurate computation and stable level-set evolution. Finally, change detection based on four polarimetric Radarsat-2 time series images is carried out at Genhe area of Inner Mongolia Autonomous Region, NorthEastern of China, where a heavy flood disaster occurred during the summer of 2013, result shows the recommend segmentation method can detect the change of watershed effectively.

  11. A User-Oriented Methodology for DInSAR Time Series Analysis and Interpretation: Landslides and Subsidence Case Studies

    NASA Astrophysics Data System (ADS)

    Notti, Davide; Calò, Fabiana; Cigna, Francesca; Manunta, Michele; Herrera, Gerardo; Berti, Matteo; Meisina, Claudia; Tapete, Deodato; Zucca, Francesco

    2015-11-01

    Recent advances in multi-temporal Differential Synthetic Aperture Radar (SAR) Interferometry (DInSAR) have greatly improved our capability to monitor geological processes. Ground motion studies using DInSAR require both the availability of good quality input data and rigorous approaches to exploit the retrieved Time Series (TS) at their full potential. In this work we present a methodology for DInSAR TS analysis, with particular focus on landslides and subsidence phenomena. The proposed methodology consists of three main steps: (1) pre-processing, i.e., assessment of a SAR Dataset Quality Index (SDQI) (2) post-processing, i.e., application of empirical/stochastic methods to improve the TS quality, and (3) trend analysis, i.e., comparative implementation of methodologies for automatic TS analysis. Tests were carried out on TS datasets retrieved from processing of SAR imagery acquired by different radar sensors (i.e., ERS-1/2 SAR, RADARSAT-1, ENVISAT ASAR, ALOS PALSAR, TerraSAR-X, COSMO-SkyMed) using advanced DInSAR techniques (i.e., SqueeSAR™, PSInSAR™, SPN and SBAS). The obtained values of SDQI are discussed against the technical parameters of each data stack (e.g., radar band, number of SAR scenes, temporal coverage, revisiting time), the retrieved coverage of the DInSAR results, and the constraints related to the characterization of the investigated geological processes. Empirical and stochastic approaches were used to demonstrate how the quality of the TS can be improved after the SAR processing, and examples are discussed to mitigate phase unwrapping errors, and remove regional trends, noise and anomalies. Performance assessment of recently developed methods of trend analysis (i.e., PS-Time, Deviation Index and velocity TS) was conducted on two selected study areas in Northern Italy affected by land subsidence and landslides. Results show that the automatic detection of motion trends enhances the interpretation of DInSAR data, since it provides an objective

  12. Assessing sinkhole activity in the Ebro Valley mantled evaporite karst using advanced DInSAR

    NASA Astrophysics Data System (ADS)

    Galve, Jorge Pedro; Castañeda, Carmen; Gutiérrez, Francisco; Herrera, Gerardo

    2015-01-01

    Sinkholes in karst areas may cause subsidence damage in transportation infrastructures, demolition of buildings and even the loss of human lives when they occur in a catastrophic way. Differential Interferometry (DInSAR) is a promising technology for detecting and characterizing sinkholes, as well as for reducing the associated risk when combined with other sources of data such as a sinkhole inventory. In this work, the usefulness of InSAR techniques and data for sinkhole risk management has been analyzed through the comparison of three DInSAR-derived velocity maps with a comprehensive sinkhole inventory in the Ebro Valley, NE Spain. The DInSAR maps have contributed to improve the sinkhole inventory in different ways: (1) detection of non-inventoried sinkholes; (2) revision of sinkhole areas previously classified as inactive as active; and (3) refinement of underestimated sinkhole boundaries. The obtained results suggest that DInSAR products are suitable for analyzing active dissolution-induced subsidence. The application of these techniques may help in recognizing and better characterizing previously unknown karst subsidence problems and in preventing personal and property losses. However, the analysis reveals that the available DInSAR maps combined overlook about 70% of the previously mapped active sinkholes mainly due to decorrelation.

  13. Landslide Monitoring in Three Gorges Area Using D-InSAR and PS-InSAR

    NASA Astrophysics Data System (ADS)

    Tantianuparp, Peraya; Shi, Xuguo; Liao, Mingsheng; Zhang, Lu; Balz, Timo

    2013-01-01

    Landslides are a major hazard in steep mountainous area, like the Three Gorges area. The Three Gorges dam was built on a geologically unstable zone. The geological pressures from the rising water level caused by the dam and the deforestation have further increased the possibility for landslides in the area. Many landslide monitoring techniques are applied to analysis, forecast, and control landslides in this area. D-InSAR and PS-InSAR, the time series InSAR analysis, are used for terrain motion detection and to estimate displacement trends. In this paper, SAR data from systems with different wavelengths, like the C-band ASAR, the L-band PALSAR, and the high-resolution TerraSAR-X X-band data, are used.

  14. Landslide Monitoring in Three Gorges Area Using D-InSAR and PS-InSAR

    NASA Astrophysics Data System (ADS)

    Tantianuparp, Peraya; Shi, Xuguo; Liao, Mingsheng; Zhang, Lu; Balz, Timo

    2013-01-01

    Landslides are a major hazard in steep mountainous area. The Three Gorges dam was built on a geologically unstable zone. The geological pressures from the rising water level caused by the dam and the deforestation have increased the possibility for landslides in the area. Many landslide monitoring techniques are applied to analysis, forecast, and control land-slides in this area. D-InSAR and PS-InSAR, the time series InSAR analysis, are used for terrain motion detection and to estimate displacement trends. In this paper, SAR data from systems with different wavelengths, like the C-band ASAR, the L-band ALOS, and the high-resolution TerraSAR-X X-band data, are used.

  15. Study of Discrimination Between Plantation and Dense Scrub Based on Backscattering Behavior of C Band SAR Data

    NASA Astrophysics Data System (ADS)

    Iyyappan, M.; Ramakrishnan, S. S.; Srinivasa Raju, K.

    2014-11-01

    The study about on landuse and landcover classification using multi polarization and multi temporal C-band Synthetic Aperture Radar (SAR) data of recently launched multi-mode of RISAT-1 (Radar Imaging Satellite) by Indian Space Research Organization (ISRO) and European satellite, Envisat ASAR data. The backscattering coefficient were extracted for various land features from Cband SAR data. The training sample collecting from satellite optical imagery of study and field visit for verification. The training samples are used for the supervised classification technique of maximum Likelihood (ML) algorithms, Neural Network (NN) and Support Vector Machine (SVM) algorithms were applied for fourteen different polarizations combination of multi temporal and multiple polarizations. The previous study was carried only four band combination of RISAT 1 data, the continuation of work both SAR data were used in this study. The Classification results are verified with confusion matrix. The pixel based classification gives the good results in the dual polarization of CRS - HH and HV of RISAT -1 compared to dual polarization Envisat ASAR data. Meanwhile the quad Polarization combination of Envisat ASAR data got better classification accuracy. The SVM classifiers has given better classification results for all band combination followed by ML and NN. The Scrub are better identified in EnviSat ASAR - VV & VH Polarization and Plantation are better identified in EnviSat ASAR - HH, HH-HV & HV Polarization. The classification accuracy of both Scrub and Plantation is about 80 % in EnviSat ASAR - HH, VH & VV Polarization combination.

  16. Recent Advances in Highly Accurate Range Measurements with TerraSAR-X

    NASA Astrophysics Data System (ADS)

    Eineder, Michael; Balss, Ulrich; Gisinger, Christoph; Cong, Xiao Ying; Brcic, Ramon; Steigenberger, Peter

    2013-04-01

    Earth surface displacement measurement from space using Synthetic Aperture Radar (SAR) imagery is an interesting alternative to SAR interferometry (InSAR). The advantages are that 2D information can be retrieved (InSAR only 1D), absolute displacements can be retrieved (no reference point required) and it is very robust (phase unwrapping not required). On the other hand, the accuracy is limited by the pixel resolution, the object contrast, the orbit accuracy, by wave propagation distortion and by geodetic effects. Therefore the accuracy was more in the meter / decimeter level in the past, compared to millimeter accuracy of InSAR. During the recent years our team established a test and validation site at the geodetic observatory Wettzell, Germany and developed compensation methods to reduce the overall error of absolute range measurements from decimeters to only one centimeter. The methods include correction of dry and wet atmospheric delays, ionospheric corrections, solid earth tides, continental drift, atmospheric pressure loading and ocean tidal loading. For more one year a radar reflector was monitored and each image evaluated. Our presentation gives and overview of methods and achieved results. Futhermore, examples of real world applications and an outlook on more applications is given such as phase unwrapping augmentation.

  17. SAR Product Control Software

    NASA Astrophysics Data System (ADS)

    Meadows, P. J.; Hounam, D.; Rye, A. J.; Rosich, B.; Börner, T.; Closa, J.; Schättler, B.; Smith, P. J.; Zink, M.

    2003-03-01

    As SAR instruments and their operating modes become more complex, as new applications place more and more demands on image quality and as our understanding of their imperfections becomes more sophisticated, there is increasing recognition that SAR data quality has to be controlled more completely to keep pace. The SAR product CONtrol software (SARCON) is a comprehensive SAR product control software suite tailored to the latest generation of SAR sensors. SARCON profits from the most up-to-date thinking on SAR image performance derived from other spaceborne and airborne SAR projects and is based on the newest applications. This paper gives an overview of the structure and the features of this new software tool, which is a product of a co-operation between teams at BAE SYSTEMS Advanced Technology Centre and DLR under contract to ESA (ESRIN). Work on SARCON began in 1999 and is continuing.

  18. Study strong wind events with erosional effect at coastal areas in Southern Italy comparing SAR vs METMAST vs High Resolution Mesoscale Model Output

    NASA Astrophysics Data System (ADS)

    Calaudi, Rosamaria; Avolio, Elenio; Gullì, Daniel; Lo Feudo, Teresa; Calidonna, Claudia

    2015-04-01

    This study focus on evaluating the use of Synthetic Aperture Radar (SAR) together with experimental data, and output of High Resolution Mesoscale Model for evaluation of coastal erosional effect in Southern Mediterranean areas, where spatial wind information is only provided by sparse buoys, often with long periods of missing data. Since in Mediterranean seas there are limited offshore experimental data, we have performed a qualitative analysis of satellite observations comparing SAR with the available experimental data from the Calabrian Regional Environmental Protection Agency (Functional Multirisk Center) for the case study of Lamezia Terme for the period of 2011-2012. Wind climate for the coastal waters off South Italy were made based on images from March 2002 to April 2012 of the Advanced Synthetic Aperture Radar (ASAR) onboard the ENVISAT satellite. Wind speed fields were derived from the SAR images using the Johns Hopkins University, Applied Physics Laboratory (JHU/APL) software APL/NOAA SAR Wind Retrieval System (ANSWRS version 2.0) with the geophysical model function CMOD5.N. Mean wind speed and energy density were estimated using the Weibull distribution function. This new technique is seen as a supplement to classical wind sampling and modelling efforts, not as a stand-alone alternative. Some evidence on test cases of wind storm, in the considered region, will be described regarding some events happened in winter 2011-2012 comparing data from SAR, Metmast and Output of High Resolution Mesoscale Model.

  19. Advanced Unsupervised Classification Methods to Detect Anomalies on Earthen Levees Using Polarimetric SAR Imagery

    PubMed Central

    Marapareddy, Ramakalavathi; Aanstoos, James V.; Younan, Nicolas H.

    2016-01-01

    Fully polarimetric Synthetic Aperture Radar (polSAR) data analysis has wide applications for terrain and ground cover classification. The dynamics of surface and subsurface water events can lead to slope instability resulting in slough slides on earthen levees. Early detection of these anomalies by a remote sensing approach could save time versus direct assessment. We used L-band Synthetic Aperture Radar (SAR) to screen levees for anomalies. SAR technology, due to its high spatial resolution and soil penetration capability, is a good choice for identifying problematic areas on earthen levees. Using the parameters entropy (H), anisotropy (A), alpha (α), and eigenvalues (λ, λ1, λ2, and λ3), we implemented several unsupervised classification algorithms for the identification of anomalies on the levee. The classification techniques applied are H/α, H/A, A/α, Wishart H/α, Wishart H/A/α, and H/α/λ classification algorithms. In this work, the effectiveness of the algorithms was demonstrated using quad-polarimetric L-band SAR imagery from the NASA Jet Propulsion Laboratory’s (JPL’s) Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR). The study area is a section of the lower Mississippi River valley in the Southern USA, where earthen flood control levees are maintained by the US Army Corps of Engineers. PMID:27322270

  20. Advanced Unsupervised Classification Methods to Detect Anomalies on Earthen Levees Using Polarimetric SAR Imagery.

    PubMed

    Marapareddy, Ramakalavathi; Aanstoos, James V; Younan, Nicolas H

    2016-01-01

    Fully polarimetric Synthetic Aperture Radar (polSAR) data analysis has wide applications for terrain and ground cover classification. The dynamics of surface and subsurface water events can lead to slope instability resulting in slough slides on earthen levees. Early detection of these anomalies by a remote sensing approach could save time versus direct assessment. We used L-band Synthetic Aperture Radar (SAR) to screen levees for anomalies. SAR technology, due to its high spatial resolution and soil penetration capability, is a good choice for identifying problematic areas on earthen levees. Using the parameters entropy (H), anisotropy (A), alpha (α), and eigenvalues (λ, λ₁, λ₂, and λ₃), we implemented several unsupervised classification algorithms for the identification of anomalies on the levee. The classification techniques applied are H/α, H/A, A/α, Wishart H/α, Wishart H/A/α, and H/α/λ classification algorithms. In this work, the effectiveness of the algorithms was demonstrated using quad-polarimetric L-band SAR imagery from the NASA Jet Propulsion Laboratory's (JPL's) Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR). The study area is a section of the lower Mississippi River valley in the Southern USA, where earthen flood control levees are maintained by the US Army Corps of Engineers.

  1. Advanced Unsupervised Classification Methods to Detect Anomalies on Earthen Levees Using Polarimetric SAR Imagery.

    PubMed

    Marapareddy, Ramakalavathi; Aanstoos, James V; Younan, Nicolas H

    2016-01-01

    Fully polarimetric Synthetic Aperture Radar (polSAR) data analysis has wide applications for terrain and ground cover classification. The dynamics of surface and subsurface water events can lead to slope instability resulting in slough slides on earthen levees. Early detection of these anomalies by a remote sensing approach could save time versus direct assessment. We used L-band Synthetic Aperture Radar (SAR) to screen levees for anomalies. SAR technology, due to its high spatial resolution and soil penetration capability, is a good choice for identifying problematic areas on earthen levees. Using the parameters entropy (H), anisotropy (A), alpha (α), and eigenvalues (λ, λ₁, λ₂, and λ₃), we implemented several unsupervised classification algorithms for the identification of anomalies on the levee. The classification techniques applied are H/α, H/A, A/α, Wishart H/α, Wishart H/A/α, and H/α/λ classification algorithms. In this work, the effectiveness of the algorithms was demonstrated using quad-polarimetric L-band SAR imagery from the NASA Jet Propulsion Laboratory's (JPL's) Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR). The study area is a section of the lower Mississippi River valley in the Southern USA, where earthen flood control levees are maintained by the US Army Corps of Engineers. PMID:27322270

  2. Advances in Digital Calibration Techniques Enabling Real-Time Beamforming SweepSAR Architectures

    NASA Technical Reports Server (NTRS)

    Hoffman, James P.; Perkovic, Dragana; Ghaemi, Hirad; Horst, Stephen; Shaffer, Scott; Veilleux, Louise

    2013-01-01

    Real-time digital beamforming, combined with lightweight, large aperture reflectors, enable SweepSAR architectures, which promise significant increases in instrument capability for solid earth and biomass remote sensing. These new instrument concepts require new methods for calibrating the multiple channels, which are combined on-board, in real-time. The benefit of this effort is that it enables a new class of lightweight radar architecture, Digital Beamforming with SweepSAR, providing significantly larger swath coverage than conventional SAR architectures for reduced mass and cost. This paper will review the on-going development of the digital calibration architecture for digital beamforming radar instrument, such as the proposed Earth Radar Mission's DESDynI (Deformation, Ecosystem Structure, and Dynamics of Ice) instrument. This proposed instrument's baseline design employs SweepSAR digital beamforming and requires digital calibration. We will review the overall concepts and status of the system architecture, algorithm development, and the digital calibration testbed currently being developed. We will present results from a preliminary hardware demonstration. We will also discuss the challenges and opportunities specific to this novel architecture.

  3. Monitoring duration and extent of storm-surge and flooding in Western Coastal Louisiana marshes with Envisat ASAR data

    USGS Publications Warehouse

    Ramsey, E.; Lu, Zhiming; Suzuoki, Y.; Rangoonwala, A.; Werle, D.

    2011-01-01

    Inundation maps of coastal marshes in western Louisiana were created with multitemporal Envisat Advanced Synthetic Aperture (ASAR) scenes collected before and during the three months after Hurricane Rita landfall in September 2005. Corroborated by inland water-levels, 7 days after landfall, 48% of coastal estuarine and palustrine marshes remained inundated by storm-surge waters. Forty-five days after landfall, storm-surge inundated 20% of those marshes. The end of the storm-surge flooding was marked by an abrupt decrease in water levels following the passage of a storm front and persistent offshore winds. A complementary dramatic decrease in flood extent was confirmed by an ASAR-derived inundation map. In nonimpounded marshes at elevations 80cm during the first month after Rita landfall. After this initial period, drainage from marshes-especially impounded marshes-was hastened by the onset of offshore winds. Following the abrupt drops in inland water levels and flood extent, rainfall events coinciding with increased water levels were recorded as inundation re-expansion. This postsurge flooding decreased until only isolated impounded and palustrine marshes remained inundated. Changing flood extents were correlated to inland water levels and largely occurred within the same marsh regions. Trends related to incremental threshold increases used in the ASAR change-detection analyses seemed related to the preceding hydraulic and hydrologic events, and VV and HH threshold differences supported their relationship to the overall wetland hydraulic condition. ?? 2010 IEEE.

  4. Advanced InSAR techniques for the management and characterization of geothermal resources

    NASA Astrophysics Data System (ADS)

    Bellotti, F.; Falorni, G.; Morgan, J.; Rucci, A.; Ferretti, A.

    2012-04-01

    InSAR is a remote sensing tool that has applications in both geothermal exploitation and in the management of producing fields. The technique has developed rapidly in recent years and the most evolved algorithms, now capable of providing precise ground movement measurements with unprecedented spatial density over large areas, allow the monitoring of the effects of fluid injection and extraction on surface deformation and the detection of active faults. Multi-interferogram approaches have been used at several geothermal sites in different stages of development. SqueeSAR™, which represents the latest breakthrough in InSAR technology, provides a significant increase in the spatial density of measurement points by exploiting signal returns from both point-like and distributed scatterers. Furthermore, recent satellite radar sensors have a higher spatial resolution (down to 1 m), as well as a higher temporal frequency of image acquisitions (down to a few days). The coupling of the new algorithm with this new generation of satellites provides a valuable tool for monitoring the different phases of geothermal production and in support of the decision making process. Some examples from the US are presented here: the first case study involves the use of InSAR within a suite of tools for exploration of the San Emidio geothermal field in Nevada. This project aimed to develop geophysical techniques to identify and map large aperture fractures for the placement of new production/exploration wells. The second and third examples examine two zones in California: the Salton Sea area, where multi-interferogram InSAR provided an overview of surface deformation at a producing geothermal reservoir. Surface deformation in this area was complex, and the added detail provided insight into the interplay of tectonics and production activities. Additional InSAR studies have also been carried out at the Geysers field in order to evaluate the behavior of an Enhanced Geothermal System (EGS) in

  5. Texture of Wetland in Single-Band and Single-Polarization ENVISAT ASAR Image

    NASA Astrophysics Data System (ADS)

    Jiag, Liaxiang; Zhang, Jie; Ma, Yi

    2010-10-01

    Texture is an inherent property of virtually all surfaces. It contains important information about the structural arrangement of surfaces and the relationships with the surrounding environment. Image texture is a kind of important feature for object recognition. The paper has taken the ENVISAT ASAR image in the Yellow River Delta as an example, and analyzed four typical wetland types (aquaculture, salt field, tidal flat, and reservoir) and two other land-use categories(farmland and sea) based on gray level co-occurrence matrix(GLCM). We ascertained the factors of GLCM on SAR wetland image such as orientation, displacement, quantization, and window size. The optimum orientation was average of the four orientations of 0°, 45°, 90° and 135°. The optimum quantization in these texture parameters was 64-level. The optimum window size was 13×13. With regard of the displacement, the optimum was 6. The textural analysis results indicated that reservoirs had lower gray value, marked boundary and the difference of texture curve between it and other wetland types; salt field and aquaculture had similarity on spatial structure and gray value, so their texture curve were close. Because the image had not been filtered before texture analysis, there were noise, the texture of sea was close to that of tidal flat. Farmland has a feature of higher gray value, complex spatial structure and confused orientation, so it was easy to distinguish it from others, although its texture feature was close to others.

  6. Adaptive Algorithm for Soil Mosture Retrieval in Agricultural and Mountainous Areas with High Resolution ASAR Images

    NASA Astrophysics Data System (ADS)

    Notarnicola, C.; Paloscia, S.; Pettinato, S.; Preziosa, G.; Santi, E.; Ventura, B.

    2010-12-01

    In this paper, extensive data sets of SAR images and related ground truth on three areas characterized by very different surface features have been analyzed in order to understand the ENVISAT/ASAR responses to different soil, environmental and seasonal conditions. The comparison of the backscattering coefficients in dependence of soil moisture values for all the analyzed datasets indicates the same sensitivity to soil moisture variations but with different biases, which may depend on soil characteristics, vegetation presence and roughness effect. A further comparison with historical data collected on bare soils with comparable roughness at the same frequency, polarization and incidence angle, confirmed that the different surface features affect the bias of the relationship, while the backscattering sensitivity to the SMC remains quite constant. These different biases values have been used to determine an adaptive term to be added in the electromagnetic formulation of the backscattering responses from natural surfaces, obtained by using the Integral Equation Model (IEM). The simulated data from this model have been then used to train a neural network as inversion algorithm. The paper will present the results from this new technique in comparison to neural network and Bayesian algorithms trained on one area and then tested on the other ones.

  7. Advanced Interferometric Synthetic Aperture Imaging Radar (InSAR) for Dune Mapping

    NASA Astrophysics Data System (ADS)

    Havivi, Shiran; Amir, Doron; Schvartzman, Ilan; August, Yitzhak; Mamman, Shimrit; Rotman, Stanely R.; Blumberg, Dan G.

    2016-04-01

    Aeolian morphologies are formed in the presence of sufficient wind energy and available lose particles. These processes occur naturally or are further enhanced or reduced by human intervention. The dimensions of change are dependent primarily on the wind energy and surface properties. Since the 1970s, remote sensing imagery, both optical and radar, have been used for documentation and interpretation of the geomorphologic changes of sand dunes. Remote sensing studies of aeolian morphologies is mostly useful to document major changes, yet, subtle changes, occurring in a period of days or months in scales of centimeters, are very difficult to detect in imagery. Interferometric Synthetic Aperture Radar (InSAR) is an imaging technique for measuring Earth's surface topography and deformation. InSAR images are produced by measuring the radar phase difference between two separated antennas that view the same surface area. Classical InSAR is based on high coherence between two or more images. The output (interferogram) can show subtle changes with an accuracy of several millimeters to centimeters. Very little work has been done on measuring or identifying the changes in dunes using InSAR methods. The reason is that dunes tend to be less coherent than firm, stable, surfaces. This work aims to demonstrate how interferometric decorrelation can be used for identifying dune instability. We hypothesize and demonstrate that the loss of radar coherence over time on dunes can be used as an indication of the dune's instability. When SAR images are acquired at sufficiently close intervals one can measure the time it takes to lose coherence and associate this time with geomorphic stability. To achieve our goals, the coherence change detection method was used, in order to identify dune stability or instability and the dune activity level. The Nitzanim-Ashdod coastal dunes along the Mediterranean, 40 km south of Tel-Aviv, Israel, were chosen as a case study. The dunes in this area are of

  8. A time series deformation estimation in the NW Himalayas using SBAS InSAR technique

    NASA Astrophysics Data System (ADS)

    Kumar, V.; Venkataraman, G.

    2012-12-01

    A time series land deformation studies in north western Himalayan region has been presented in this study. Synthetic aperture radar (SAR) interferometry (InSAR) is an important tool for measuring the land displacement caused by different geological processes [1]. Frequent spatial and temporal decorrelation in the Himalayan region is a strong impediment in precise deformation estimation using conventional interferometric SAR approach. In such cases, advanced DInSAR approaches PSInSAR as well as Small base line subset (SBAS) can be used to estimate earth surface deformation. The SBAS technique [2] is a DInSAR approach which uses a twelve or more number of repeat SAR acquisitions in different combinations of a properly chosen data (subsets) for generation of DInSAR interferograms using two pass interferometric approach. Finally it leads to the generation of mean deformation velocity maps and displacement time series. Herein, SBAS algorithm has been used for time series deformation estimation in the NW Himalayan region. ENVISAT ASAR IS2 swath data from 2003 to 2008 have been used for quantifying slow deformation. Himalayan region is a very active tectonic belt and active orogeny play a significant role in land deformation process [3]. Geomorphology in the region is unique and reacts to the climate change adversely bringing with land slides and subsidence. Settlements on the hill slopes are prone to land slides, landslips, rockslides and soil creep. These hazardous features have hampered the over all progress of the region as they obstruct the roads and flow of traffic, break communication, block flowing water in stream and create temporary reservoirs and also bring down lot of soil cover and thus add enormous silt and gravel to the streams. It has been observed that average deformation varies from -30.0 mm/year to 10 mm/year in the NW Himalayan region . References [1] Massonnet, D., Feigl, K.L.,Rossi, M. and Adragna, F. (1994) Radar interferometry mapping of

  9. How operational Advanced-DInSAR Analysis can improve knowledge on natural and anthropogenic deformations for Nuclear Power Plant areas

    NASA Astrophysics Data System (ADS)

    Vollrath, Andreas; Zucca, Francesco; Stramondo, Salvatore; Bignami, Christian; Roeder, Johannes

    2015-04-01

    The application of Advanced Differential Interferometric Synthetic Aperture Radar (A-DINSAR) techniques has strongly emerged in the last two decades and became an important part in georelated fields. State-of-the-art A-DInSAR methods, such as Persistent Scatterer Interferometry (PSI) or the Small BASeline (SBAS) approach have demonstrated their usefulness in monitoring urban areas and single buildings, up to critical infrastructures. Combined with additional data from GPS networks or levelling, it could prove its large potential for an operational, cost-effective mapping of surface deformations. Given a reasonable amount of images, changes in surface deformation can be detected down to 1 mm/y. Compared to point-wise field measurements it offers a spatially consistent mapping approach from local to regional scales. In this review we want to provide a synopsis how A-DInSAR can be utilized in the framework of Nuclear Power Plant safety. Indeed, A-DInSAR is able to provide a detailed spatial analysis of slow movements occurring at NPP structures directly, as well as within the surrounding areas of the NPPs. Different phenomena of surface motion can be subject of such a monitoring. Natural causes, like active tectonics and terrain instability of slope which lead to landslides, as well as human-induced subsidence phenomena due to heavy construction or water pumping can be detected. We start by presenting techniques to determine the feasibility of the analysis for a given area and show its limitations. Then we propose a short insight into state-of-the-art studies where landslides, interseismic and human-induced deformation of the surface were mapped by A-DInSAR, to point out the relevance of a consequent analysis over an area of a NPP. Furthermore we present results of case studies from international projects (TERRAFIRMA) as well as preliminary results from the Krsko NPP in Slovenia. Finally, we provide a outlook into present and future trends concerning the use of freely

  10. Applications Of EnviSAT SAR For The Identification Of Seasonally Flooded Areas In Archaeological Semi-Arid Contexts

    NASA Astrophysics Data System (ADS)

    Conesa, C. F.; Devanthery, N.; Balbo, A.; Madella, M.; Rondelli, B.

    2013-12-01

    This work explores the potential of amplitude information from advanced ENVISAT ASAR C-band data for understanding surface and near-surface water dynamics in the semi-arid archaeological landscape of North Gujarat (India). Research is done within the framework of an explorative Earth Observation project (ESA) proposal between the North Gujarat Archaeological Project (NoGAP) and the Active Remote Sensing Unit from the Institute of Geomatics. The amplitude component of multi-temporal ASAR Single Look Complex (SLC) images from pre-monsoon, monsoon and post-monsoon seasons have been used. The mean extent of floodable areas has been estimated by comparing the mean amplitude of seasonal periods. The integration of SAR data and geoarchaeological data has provided new insights to understand present-day landscape dynamics affecting archaeological preservation and visibility. Furthermore, preliminary results suggest a good correlation between Mid- Holocene settlement patterns and the distribution and extension of seasonal floodable areas, opening interesting inroads to study settlement distribution and resource availability in past socio-ecological systems in semi-arid areas.

  11. Recent advances and plans in processing and geocoding of SAR data at the DFD

    NASA Technical Reports Server (NTRS)

    Noack, W.

    1993-01-01

    Because of the needs of future projects like ENVISAT and the experiences made with the current operational ERS-1 facilities, a radical change in the synthetic aperture radar (SAR) processing scenarios can be predicted for the next years. At the German PAF several new developments were initialized which are driven mainly either by user needs or by system and operational constraints ('lessons learned'). At the end there will be a major simplification and uniformation of all used computer systems. Especially the following changes are likely to be implemented at the German PAF: transcription before archiving, processing of all standard products with high throughput directly at the receiving stations, processing of special 'high-valued' products at the PAF, usage of a single type of processor hardware, implementation of a large and fast on-line data archive, and improved and unified fast data network between the processing and archiving facilities. A short description of the current operational SAR facilities as well as the future implementations are given.

  12. InSAR Detection of Ground Deformation in Megalopolises of Pearl River Delta

    NASA Astrophysics Data System (ADS)

    Zhao, Qing

    Megalopolises in the Pearl River Delta, including Guangzhou and Hong Kong, have experienced various degree of ground subsidence. The causes can be divided into two categories: natural subsidence and the human-induced subsidence. Monitoring the ground subsidence can not only help people to find out the distributions in both spatial and temporal fields, but also guide people to minimize the hazard ahead. Thus, it is significant to monitor the ground subsidence accurately, timely and frequently. This dissertation research uses the Environmental Satellite Advanced Synthetic Aperture Radar (ENVISAT ASAR) data received at the Chinese University of Hong Kong Satellite Remote Sensing Receiving Station and SAR Interferometry (InSAR) technology as a powerful tool for large-scale ground deformation monitoring in Guangzhou and Hong Kong areas. Persistent Scatterer Interferometry (PSI) method is used to detect ground deformation in the urban area of Guangzhou city. A ground deformation rate map with scattered distribution of point targets shows the maximum subsidence (rise) rate as high as -26 to -20 mma-1 (16-21 mma-1 ), implying that the study area is an active zone for ground deformation. Based on the point target map, a contour ground deformation rate map is generated. All the six ground collapse accidents that occurred in 2007-2008 fall within the subsidence zones, qualitatively validating the IPTA results. Ground subsidence and geological conditions on Datansha Island are examined. The results indicate that the local geological conditions and underground engineering projects are responsible for ground subsidence and ground collapse accidents occurred there. To interpret the distribution of active ground subsidence zones, a local geological map is used as a reference for generating a series of thematic maps. The results show that geological faults, rock distribution, over-development, and underground engineering projects may be four factors leading to the distribution of

  13. Envisat ASAR Polarimetric Data for Soil Moisture Mapping

    NASA Astrophysics Data System (ADS)

    Rao, Y. S.; Singh, A. K.; Sharma, S.; Venkataraman, G.

    2007-03-01

    ENVISAT ASAR Data acquired over four test sites were analyzed for soil moisture mapping using various models. The polarimetric data covers dual polarized HH/VV, HH/HV and single polarized VV in swaths IS2, IS2, IS4, IS5 and IS6. SIR-C L- and C-band data were also used for the verification of models. Dubois et al. empirical and linear regression equations were used for soil moisture estimation. The test sites cover bare, rice, sugarcane, corn, etc. fields. Using the SIR-C data, we found that Dubois et al. model overestimates soil moisture at C-band compared to L-band. The difference is about 5%. The linear regressions equations developed by Baghdadi et al. predict soil moisture with reasonable accuracy for bare fields using ENVISAT ASAR data. However, these regression equations are site specific and do not take into account surface roughness and vegetation cover. More groundtruth data are needed for the verification of these relations.

  14. Long term volcano monitoring by using advanced Persistent Scatterer SAR Interferometry technique: A case study at Unimak Island, Alaska

    NASA Astrophysics Data System (ADS)

    Gong, W.; Meyer, F. J.; Freymueller, J. T.; Lu, Z.

    2012-12-01

    Unimak Island, the largest island in the eastern Aleutians of Alaska, is home to three major active volcanoes: Shishaldin, Fisher, and Westdahl. Shishaldin and Westdahl erupted within the past 2 decades and Fisher has shown persistent hydrothermal activity (Mann and Freymueller, 2003). Therefore, Unimak Island is of particular interest to geoscientists. Surface deformation on Unimak Island has been studied in several previous efforts. Lu et al. (2000, 2003) applied conventional InSAR techniques to study surface inflation at Westdahl during 1991 and 2000. Mann and Freymueller (2003) used GPS measurements to analyze inflation at Westdahl and subsidence at Fisher during 1998-2001. Moran et al., ( 2006) reported that Shishaldin, the most active volcano in the island , experienced no significant deformation during the 1993 to 2003 period bracketing two eruptions. In this paper, we present deformation measurements at Unimak Islank during 2003-2010 using advanced persistent scatterer InSAR (PSI). Due to the non-urban setting in a subarctic environment and the limited data acquisition, the number of images usable for PSI processing is limited to about 1-3 acquisitions per year. The relatively smaller image stack and the irregular acquisition distribution in time pose challenges in the PSI time-series processing. Therefore, we have developed a modified PSI technique that integrates external atmospheric information from numerical weather predication models to assist in the removal of atmospheric artifacts [1]. Deformation modeling based on PSI results will be also presented. Our new results will be combined with previous findings to address the magma plumbing system at Unimak Island. 1) W. Gong, F. J. Meyer (2012): Optimized filter design for irregular acquired data stack in Persistent Scatterers Synthetic Aperture Radar Interferometry, Proceeding of Geosciences and Remote Sensing Symposium (IGARSS), 2012 IEEE International, Munich, Germany.

  15. Analysis of ASAR Wide Swath Mode time series for the retrieval of soil moisture in mountainous areas

    NASA Astrophysics Data System (ADS)

    Greifeneder, Felix; Notarnicola, Claudia; Cuozzo, Giovanni; Spindler, Nadine; Bertoldi, Giacomo; Della Chiesa, Stefano; Niedrist, Georg; Stamenkovic, Jelena; Wagner, Wolgang

    2014-05-01

    Soil moisture is a key element in the global cycles of water, energy, and carbon. Knowledge on the spatial and temporal distribution of the soil moisture content (SMC) is therefore essential for a number of hydrological applications as well as earth sciences like meteorology or climatology (Heathman et al., 2003). In the last few years there has been an increasing interest towards the estimation of SMC at local scales using active microwave sensors (Barret et al., 2009). Compared to passive microwave sensors, SAR offers the potential to provide data at high spatial resolution (modern sensors can acquire images with up to approximately 1 m), which is particularly important in mountainous areas. So far, these areas have been considered only marginally in research and only pioneer studies can be found in the literature (Brocca et al., 2012; Bertoldi et al. 2013). In this work we analyzed the temporal and spatial dynamics of the surface SMC (0 - 5 cm depth) on the basis of ground data collected by fixed meteorological stations located in the emerging Long-Term Ecological Research (LTER) site Mazia Valley (Province of Bolzano, South Tyrol, Italy), SAR data from ENVISATs ASAR sensor, wide swath (WS) mode (acquired between 2005 and 2012), and SMC estimates from the hydrological model GEOtop (Endrizzi et al., 2013). The SMC retrieval process was based on the support vector regression (SVR) method introduced by Pasolli et al. (2011). The training of the algorithm was based on data acquired in 2010. Furthermore, the SAR backscatter and derived SMC have been compared with time-series derived from the distributed hydrological model GEOtop. The differences in terms of temporal and spatial dynamic have been analyzed. The main goal of this work is to evaluate the spatial and temporal patterns of SAR derived SMC at field scale and to correlate them with ground information. This is a preparatory study to establish a methodology for the retrieval of SMC with high spatial and

  16. Advanced Algorithms and High-Performance Testbed for Large-Scale Site Characterization and Subsurface Target Detecting Using Airborne Ground Penetrating SAR

    NASA Technical Reports Server (NTRS)

    Fijany, Amir; Collier, James B.; Citak, Ari

    1997-01-01

    A team of US Army Corps of Engineers, Omaha District and Engineering and Support Center, Huntsville, let Propulsion Laboratory (JPL), Stanford Research Institute (SRI), and Montgomery Watson is currently in the process of planning and conducting the largest ever survey at the Former Buckley Field (60,000 acres), in Colorado, by using SRI airborne, ground penetrating, Synthetic Aperture Radar (SAR). The purpose of this survey is the detection of surface and subsurface Unexploded Ordnance (UXO) and in a broader sense the site characterization for identification of contaminated as well as clear areas. In preparation for such a large-scale survey, JPL has been developing advanced algorithms and a high-performance restbed for processing of massive amount of expected SAR data from this site. Two key requirements of this project are the accuracy (in terms of UXO detection) and speed of SAR data processing. The first key feature of this testbed is a large degree of automation and a minimum degree of the need for human perception in the processing to achieve an acceptable processing rate of several hundred acres per day. For accurate UXO detection, novel algorithms have been developed and implemented. These algorithms analyze dual polarized (HH and VV) SAR data. They are based on the correlation of HH and VV SAR data and involve a rather large set of parameters for accurate detection of UXO. For each specific site, this set of parameters can be optimized by using ground truth data (i.e., known surface and subsurface UXOs). In this paper, we discuss these algorithms and their successful application for detection of surface and subsurface anti-tank mines by using a data set from Yuma proving Ground, A7, acquired by SRI SAR.

  17. Advanced algorithms and high-performance testbed for large-scale site characterization and subsurface target detection using airborne ground-penetrating SAR

    NASA Astrophysics Data System (ADS)

    Fijany, Amir; Collier, James B.; Citak, Ari

    1999-08-01

    A team of US Army Corps of Engineers, Omaha District and Engineering and Support Center, Huntsville, JPL, Stanford Research Institute (SRI), and Montgomery Watson is currently in the process of planning and conducting the largest ever survey at the Former Buckley Field, in Colorado, by using SRI airborne, ground penetrating, SAR. The purpose of this survey is the detection of surface and subsurface Unexploded Ordnance (UXO) and in a broader sense the site characterization for identification of contaminated as well as clear areas. In preparation for such a large-scale survey, JPL has been developing advanced algorithms and a high-performance testbed for processing of massive amount of expected SAR data from this site. Two key requirements of this project are the accuracy and speed of SAR data processing. The first key feature of this testbed is a large degree of automation and maximum degree of the need for human perception in the processing to achieve an acceptable processing rate of several hundred acres per day. For accuracy UXO detection, novel algorithms have been developed and implemented. These algorithms analyze dual polarized SAR data. They are based on the correlation of HH and VV SAR data and involve a rather large set of parameters for accurate detection of UXO. For each specific site, this set of parameters can be optimized by using ground truth data. In this paper, we discuss these algorithms and their successful application for detection of surface and subsurface anti-tank mines by using a data set from Yuma Proving Ground, AZ, acquired by SRI SAR.

  18. Development and Validation of New Advanced Ocean Altimetry Products From Cryosat-2 in Conventional and in SAR Mode

    NASA Astrophysics Data System (ADS)

    Cotton, D.; Gommenginger, C.; Andersen, O. B.; Boy, F.; Cancet, M.; Egido, A.; Fernandes, J.; Moreau, T.; Naeije, M.; Garcia, P.; Dinardo, S.; Benveniste, J.

    2013-12-01

    The ESA CryoSat-2 mission is the first space mission to carry a radar altimeter that can operate in Synthetic Aperture Radar (SAR) mode, as well as the more conventional Low Rate Mode (LRM), and also the SAR Interferometric mode (SARIN). Although the prime mission objective of CryoSat-2 is to monitor land and marine ice, the SAR mode capability of the CryoSat-2 SIRAL altimeter also presents the opportunity of demonstrating significant potential benefits of SAR altimetry for ocean applications. Expected performance enhancements of SAR mode include improved range precision, finer along track spatial resolution, and an improved ability to provide measurements close to the coast. The 'Cryosat Plus for Oceans' (CP4O) project is supported by ESA under the Support To Science Element Programme. CP4O started in June 2012, and will continue to June 2014. The objectives of CP4O are: to build a sound scientific basis for new scientific and operational applications of CryoSat-2 data over the open ocean, polar ocean, coastal seas and for sea-floor mapping. to generate and evaluate new methods and products that will enable the full exploitation of the capabilities of the CryoSat-2 SIRAL altimeter, and extend their application beyond the initial mission objectives. to ensure that the scientific return of the CryoSat-2 mission is maximised. This work is being carried out within four sub-themes: Open Ocean Altimetry, Coastal Zone Altimetry, Polar Ocean Altimetry, and Sea Floor Altimetry. In this presentation we provide a detailed assessment of the capability of SAR altimeter data to provide improved oceanographic measurements over the open ocean, coastal ocean and polar ocean. We describe different processing schemes applied to Cryosat-2 SAR mode data, to carry out full resolution SAR processing and SAR mode retracking, and to construct LRM-type altimeter waveforms from the SAR bursts, - so called Reduced SAR mode (RDSAR). The latter processing is important to determine if it is

  19. SAR Wave Mode Processing- Improvements Towards Sentinel-1 Mission

    NASA Astrophysics Data System (ADS)

    Johnsen, Harald; Collard, Fabrice

    2013-03-01

    The Sentinel-1 level-2 (L2) ocean product (OCN) has been designed to deliver geophysical parameters related to the wind, waves and surface velocity to a large panel of end-users. Each L2 OCN product contains up to three geophysical components: the radial velocity (RVL), the ocean surface wind field (OWI) and the ocean swell wave spectra (OSW) components. The Sentinel-1 Level 2 OSW component is the two-dimensional ocean surface wave spectra estimated from a Sentinel-1 Level 1 Single-Look Complex (SLC) SAR image by inversion of the corresponding image cross-spectra. The cross spectra are computed by performing inter-looking in azimuth followed by co- and cross-spectra estimation among the detected individual look images. The image from which a single OSW is computed can be a SLC vignette from the WV mode, or a co-polarized subimage extracted from a SM SLC image. The experiences with ASAR have shown the need to improve the modulation transfer functions (MTF), especially the wind dependency in the RAR MTF. The OSW processing scheme is an upgraded version of the ASAR WM Level 2 processing accounting for these findings. The Sentinel-1 Level 2 OSW processing has been evaluated using ASAR WM and ASAR SM data, and preliminary key results are presented in this paper.

  20. Soil moisture monitoring over a semiarid region using Envisat ASAR data

    NASA Astrophysics Data System (ADS)

    Amriche, Atef A. E.; Guerfi, Mokhtar

    2012-09-01

    Soil moisture (SM) is of fundamental importance to many agricultural, hydrological and climate studies. In this paper, a simple approach for mapping near-surface SM from Envisat ASAR data was developed. Four high-resolution images covering a semiarid region in Algeria were acquired with the same sensor configuration. We performed the pretreatment using the Basic Envisat SAR Toolbox of the European Space Agency. Then, we extracted the backscattering coefficient σ0 (dB) from the filtered and calibrated images. On the other hand, five training sites with different soil physical properties and vegetation cover were selected for monitoring SM. The field campaigns were conducted concurrent to satellite image acquisitions to measure soil water content in the top five centimeters using the gravimetric method. The study of linear regressions associated to the change detection approach allowed the expression of the backscattering coefficient as a function of volumetric soil moisture (σ0 = a*θ + b). The coefficients "a" and "b" of the equation slightly differ from one site to another and also from one season to the next. This difference is mainly due to the effects of surface roughness and vegetation biomass variations. Our study confirms a good agreement between the volumetric nearsurface SM and the radar backscattering coefficient for all the test fields. The comparison between measured and estimated SM proves the accuracy of the inversion models used here with a mean average error of less than 5%. At the end, high resolution maps of soil moisture distribution were obtained from the acquired radar images.

  1. An operational soil moisture product from ENVISAT ASAR GM for Australia

    NASA Astrophysics Data System (ADS)

    Doubkova, M.; Bartsch, A.; Sabel, D.; Wagner, W.

    2009-04-01

    Soil moisture is a key element in the global cycles of water, energy and carbon and belongs to the Essential Climate Variables defined by the Global Climate Observing System (GCOS). Soil moisture represents a switch that controls the proportion of rainfall that percolates, runs off, or evaporates from land. Its quantitative representation can bring further improvement in hydrological monitoring and modelling. Since 1970's the microwave technology dominated the soil moisture retrieval. A variety of coarse resolution datasets became available from active and passive microwave systems (ERS-1/2, METOP ASCAT or AMSR-E) and the potential of these datasets for improvement in hydrological, climatological, and vegetation studies has been amply demonstrated. To address the needs of the hydrological community for medium resolution soil moisture dataset an approach developed at the TU WIEN for the coarse resolution ERS/METOP datasets has been transferred to medium resolution SAR data. This work was performed within the ESA Tiger Innovator project SHARE. The used sensor is the ENVISAR ASAR. Its Global Mode with 1 km spatial resolution provides frequent data coverage which allows for detection of the highly variable soil moisture patterns. The original product is available for the region of the Southern African Development Community (SADC) since June 2007 and is regularly updated (www.ipf.tuwien.ac.at/radar/share). In June 2008 a similar service has been implemented for the entire Australian continent with exception of Tasmania. The new dataset provides twice weekly measurements for 92% of the continent leaving the reminding regions with at least 1 acquisition a week. The datasets also allow for downscaling of the coarser resolution datasets (ERS, ASCAT) for operational applications.

  2. Subway Subsidence Monitoring and Analysis in Beijing through Envisat-Asar and Terrasar-X DATA

    NASA Astrophysics Data System (ADS)

    Duan, G.; Gong, H.; Chen, B.; Li, X.

    2014-12-01

    Subway plays a significant role in public transport in Beijing, China. The safe operation of such underground rail transports are serious threatened by ground subsidence that mainly caused by groundwater over-exploitation. It is necessary to carry out a continuous observation and analysis of the surface deformation along the newly built rails. The paper mainly studied four subways which were built in different periods(see attachment). Envisat-ASAR and Terrasar-X images of the study area were selected to measure the ground deformation. Interferometric Point Target Analysis method was gathered to process the SAR data. The method is developed based on the idea of the Permanent Scatterers SAR Interferometry method which can overcome the decorrelation and atmospheric effect to gain more precise estimation of the ground deformation. The master image can be selected according to the perpendicular, Doppler and temporal baselines to minimize the potential decorrelation. After the registration of all slave images to the master image, the PS candidates would be detected on the basis of the scattering properties of the images. A complex operation of the PSs was conducted to obtain the interferometric phase which was composed of terrain phase, atmospheric phase, deformation phase and noise. A model used for the evaluation of the contribution of each component was built by means of the least squares method. The deformation phase would be the remaining of the interferometric phase minus disturbance terms. Deformation information that came from two different kinds of data was jointly analyzed to reveal the temporal character of the rails before, during and after they were built. The regional LOS(line-of-sight) velocity around a special subway station shows that the rail has suffered from a serious uneven settlement along the rail during the observation period. In addition, time series data revealed the characteristic stages of each PS point. There is a clear accelerating trend of

  3. Archaeological prospection of cultural heritage in the Nasca region, Peru, by coupling ENVISAT ASAR 2003-2007 and optical-VHR time series

    NASA Astrophysics Data System (ADS)

    Tapete, Deodato; Cigna, Francesca; Masini, Nicola; Lasaponara, Rosa

    2013-04-01

    We present the radar-interpretation of a 4year-long stack of ENVISAT ASAR imagery, integrated and cross-validated with optical-Very High Resolution (VHR) data from QuickBird2, GeoEye and WorldView-1/2, and carried out over the cultural and natural heritage of the Nasca region in Southern Peru. This research is performed thanks to the provision of free-access archive SAR data from the European Space Agency (ESA) through the Cat-1 project 11073, and is supporting the activities of the Italian mission of heritage Conservation and Archaeogeophysics (ITACA), which directly involve researchers from the Institute for Archaeological and Monumental Heritage (IBAM) and the Institute of Methodologies for Environmental Analysis (IMAA), National Research Council (CNR) of Italy. The whole ENVISAT ASAR imagery archive, consisting of 8 ASAR IS2 scenes acquired in descending mode between 04/02/2003 and 15/11/2005 and 5 images in ascending mode between 24/07/2005 and 11/11/2007, was processed by exploiting and analyzing SAR amplitude information and change detection to reconstruct the temporal evolution of radar signatures and related backscattering coefficient (σ0) of the targets on the ground in the monitoring period 2003-2007. The selection of a SAR amplitude-based change detection method was made to explore its actual potentials for archaeological prospection and monitoring purposes, complementarily to approaches of interferometric coherence used by other scholars over the same region of investigation. The novel contribution to heritage studies over Nasca includes remote sensing insights into the renowned UNESCO-WHL Nasca geoglyphs and archaeological mounds of the adobe Ceremonial Centre of Cahuachi, as well as the ancient puquios within the Rio Grande drainage basin. The latter are prehispanic underground aqueducts, and nowadays represent not only important cultural features to preserve, but also a potential driver to revitalize waterways and oases in such a dry region

  4. Application of small baseline subsets D-InSAR technique to estimate time series land deformation of Jinan area, China

    NASA Astrophysics Data System (ADS)

    Liu, Xiangtong; Cao, Qiuxiang; Xiong, Zhuguo; Yin, Haitao; Xiao, Genru

    2016-04-01

    Jinan, located in the South of the North China Plain, is an area where underground water has been exploited excessively. However, land deformation surveys only focus on the small district obtained by GPS and Leveling. Here, we use interferometric synthetic aperture radar (InSAR) time-series of ASAR data to resolve land subsidence in the entire Jinan region. In our research, we get 20 interferograms with a temporal threshold of 700 days and spatial-baseline threshold of 300 m from 14 ASAR satellite images on a descending orbit, and then get the surface displacement using Small Baseline InSAR (SBAS D-InSAR) retrained with a periodic model. Meanwhile, the accuracy of our work is proved by the results of GPS measurements. Finally, several settlement funnels are observed with extreme values of -20 cm, and their generation is related to massive groundwater extraction.

  5. Application of small baseline subsets D-InSAR technique to estimate time series land deformation of Jinan area, China

    NASA Astrophysics Data System (ADS)

    Liu, Xiangtong; Cao, Qiuxiang; Xiong, Zhuguo; Yin, Haitao; Xiao, Genru

    2016-04-01

    Jinan, located in the South of the North China Plain, is an area where underground water has been exploited excessively. However, land deformation surveys only focus on the small district obtained by GPS and Leveling. Here, we use interferometric synthetic aperture radar (InSAR) time-series of ASAR data to resolve land subsidence in the entire Jinan region. In our research, we get 20 interferograms with a temporal threshold of 700 days and spatial-baseline threshold of 300 m from 14 ASAR satellite images on a descending orbit, and then get the surface displacement using Small Baseline InSAR (SBAS D-InSAR) retrained with a periodic model. Meanwhile, the accuracy of our work is proved by the results of GPS measurements. Finally, several settlement funnels are observed with extreme values of -20 cm, and their generation is related to massive groundwater extraction.

  6. New evidence for active tectonics at the boundary of the Kashi Depression, China, from time series InSAR observations

    NASA Astrophysics Data System (ADS)

    He, Ping; Wen, Yangmao; Xu, Caijun; Liu, Yang; Fok, H. S.

    2015-06-01

    Kashi Depression is one of the most complex active tectonic areas in the southern flank of Tianshan, China. Due to the lack of ground observations, the boundary of basin mountain transition zone and the interseismic activity of the Tianshan have not been clearly determined. In this study, 48 Envisat Advanced Synthetic Aperture Radar (ASAR) imagery acquired from 2003 to 2010 are used to construct interferograms for measuring high-resolution interseismic deformation in the Kashi Depression area. A global atmospheric model ERA-Interim provided by the European Center for Medium Range Weather Forecast (ECMWF) and a global network orbital correction are applied to remove atmospheric effect, and the long-wavelength orbital errors, respectively, for the interferograms. Interferometric SAR time series with Atmospheric Estimation Model (InSAR TS + AEM) are then used to obtain a deformation rate map for the Kashi Depression area. The InSAR rate map indicates that the north part of South Atushi Fault has ~ 3 mm/year uplift relative to that of the south part. This result manifests the main tectonic deformation potentially occurs along the Southern Atushi Fault. Based on a simple edge dislocation model, the dip angle of 31 ± 0.6°, slip rate of 2.3 ± 0.1 mm/year, and locking depth of 10.6 ± 0.4 km for the Southern Atushi Fault between Tianshan Orogenic Belt and the Kashi Depression are obtained. This modeling result shows in good agreement with the InSAR derived rates. Our results show that the Southern Atushi Fault is the main active fault in block boundary region between the south of Tianshan and the Tarim Basin.

  7. Active anthropogenic and surface salt deformation measured by InSAR, northwestern China

    NASA Astrophysics Data System (ADS)

    Colon, C.; Webb, A. G.; Lasserre, C.; Doin, M. P.

    2014-12-01

    Despite the global occurrence of salt, very few salt bodies outcrop and are presently preserved at the surface. Because of this much of our knowledge on salt structures is sourced from subsurface imaging and modeling and less from field based studies. Using interferometry of synthetic aperture radar (InSAR) we monitor surface displacements across four surface salt outcrops in the western margin of the Kuqa fold-thrust belt of Xinjiang Province, China. An InSAR time series was constructed from 40 Envisat ASAR C-band images between June 2003 and October 2010. Interferometric processing was completed using the New Small Baseline Algorithm Subset (NSBAS). These poorly studied salt structures provide a fresh opportunity to study how salt behaves on the surface. The salt bodies outcrop along an active intracontinental thrust system between the Tian Shan and Tarim basin to the south. The four surface namakiers (salt glaciers) were analyzed in this study include: the Quele, Awate, Bozidun, and an unnamed structure referred to as the Western namakier. The ~35 km long Quele namakier is a line-sourced structure advancing along the Quele salt thrust. The other three namakiers range between ~1-3 km long and are point-sourced structures. The namakiers studied display non-steady deformation with rates of displacement varying between uplifts of up to +4 cm/yr and subsidence rates of -4 cm/yr. Additionally, the Kuqa fold-thrust belt hosts a number of hydrocarbon fields and InSAR measurements detect significant anthropogenic deformation associated with hydrocarbon extraction and fluid injection.

  8. Advanced InSAR and GPS measurements for the detection of surface movements along the Alto Tiberina (Italy) normal fault system: data modeling and future perspectives

    NASA Astrophysics Data System (ADS)

    Anderlini, L.; Polcari, M.; Bignami, C.; Pepe, A.; Solaro, G.; Serpelloni, E.; Moro, M.; Albano, M.; Chiaraluce, L.; Stramondo, S.

    2014-12-01

    The Alto Tiberina fault (ATF) is a low-angle (east-dipping at 15°), 70 km long normal fault (LANF) located in the Umbria-Marche Apennines (central Italy), an area characterized by a SW-NE oriented extension occurring at rates of ~2 mm/yr. Active extension is precisely measured by a dense distribution of GPS stations belonging to several networks, thanks also to additional sites recently installed in the framework of the INGV national RING network and of the ATF observatory. Advanced Interferometry SAR (A-InSAR) techniques play today a key role in Earth Sciences thanks to their capability to detect and monitor slow surface movements over wide areas. A-InSAR techniques, along with in-situ ground measurements, can provide suitable information on the causes of interseismic (seismic, creep) movements. Large datasets of SAR images of European (ERS 1-2 and ENVISAT) and Italian (COSMO-SKyMed) satellites have been used to retrieve surface velocity maps and relevant time series from 1992 to 2014, along both ascending and descending orbits. A network of artificial Corner Reflectors has also been deployed in the proximity of some GPS sites in order to calibrate the processing results of the COSMO-SkyMed SAR data-set and to derive velocity maps. We use an elastic Block Modeling (BM) approach in order to model GPS data by considering the major fault systems as bounds of rotating blocks, while estimating geodetic fault slip-rates.,Thanks to the latest imaging of its deep structure obtained from seismic profiles, the ATF is represented as a complex rough surface with the goal of evaluating the distribution of interseismic fault coupling. The preliminary results obtained show firstly that the observed extension is partially accommodated by interseismic deformation on the ATF, highlighting the important role of this LANF inside an active tectonic contest. Secondarily, using the ATF surface "topography", we found for the resolved areas an interesting correlation between

  9. Long-term and wide-area subsidence pattern from time series of Envisat Asar Data in Konya Basin, Turkey

    NASA Astrophysics Data System (ADS)

    Ustun, Aydin

    2016-04-01

    Konya Basin as a sub-part of Konya Closed Basin is dominated by the Neogene and Quaternary sediments that are largely fluvial and lacustrine characteristic. The wide plains cultivated over the last 10000 years are the remnants of the Pluvial lake basin during wet and humid climate environment after the last glacial period. With the form of isolated depression-block, the geomorphological landscape has been mainly driven by the neotectonic activity of striking normal fault systems of the region. Konya that has doubled in size over the last two and half decades is both expanding into the agricultural areas and increasing its building expansion in the city center. The level observations recorded at the monitoring stations indicate that groundwater resources have been exploited permanently or seasonally in some parts where water demand exceeds supply. In this study, a long-term and wide area subsidence pattern in Konya Basin has been analyzed by stacking the deformation interferograms for time series. The study area that covers approximately 7500 km squared was investigated through a large number of the raw images of Asar sensor onboard Envisat from December 2002 to October 2010. Almost a hundred SAR scenes imaged over three tracks in both ascending and descending modes have been used to create a set of 127 differential interferograms using GMTSAR processing system. A continuous deformation map on the basinwide scale has been produced by combining the stacked interferograms. The average contour map shows that the DInSAR detected line of sight subsidence (or uplift) rates vary between 0.6 and -3.3 cm/yr throughout 8 years. The subsidence pattern significantly is correlated with the land and groundwater use within the basin and it states that the anthropogenic effect is much greater than the identified geological and hydrogeological processes.

  10. Preliminary results of ESA Category-1 Project 5834 "Application of DInSAR technique to areas of active ground deformations"

    NASA Astrophysics Data System (ADS)

    Massa, B.; D'Auria, L.

    2009-04-01

    We have established a processing chain of Synthetic Aperture Radar (SAR) data for identification and parametrisation of deformation sources in areas of active ground deformation (e.g. seismogenic areas, volcanic districts). SAR data from European Space Agency (ESA) satellites ERS-2 and ENVISAT are used. SAR and InSAR data processing LEVEL 0 SAR data are focussed to Single Look Complex (SLC) through ROI_PAC (Copyright 2002-2008, Caltech/Jet Propulsion Laboratory). We perform an advanced data processing using Doris (Kampes and Usai, 1999) a single program that can do most common steps of the interferometric radar processing starting from SLC data to generation of interferometric products and geocoding. Unwrapping of interferometric phase is performed using the public domain software snaphu (Chen and Zebker, 2001). Modeling of deformation sources We propose a novel inversion approach base on non-linear inversion. The forward modeling is provided by the semi-analytic deformation model for point sources and finite faults. The parameters of the fault (center position, width, height, rake and seismic moment) are inverted using a combination of non-linear optimization algorithms (as Monte-Carlo, Nelder&Mead Simplex and Simulated Annealing). The misfit function defined for the optimization is based on the L2 norm of the error weighted by the coherence of the considered spatial point. Test datasets To test our modeling procedure we chose three different study areas, refer to mainly strike-slip seismogenic sources with different orientation to respect satellite Line Of Sight (LOS): December 26 2003 Iranian earthquake (Bam e.), data from both ascending and descending passes of ENVISAT ASAR narrow swath IS2 (RAW and SLCs); August 17 1999 Turkey earthquake (Izmit e.), data from both ascending and descending passes of ERS-2 AMI SAR (SLCs); June 17-21 2000 Iceland earthquakes, data from both ascending and descending passes of ERS-2 AMI SAR (SLCs). Tests carried over real

  11. Comparison Of Optical And SAR Data In Tropical Land CoverClassification For REDD+

    NASA Astrophysics Data System (ADS)

    Sirro, Laura; Hame, Tuomas; Rauste, Yrjo; Antropov, Oleg; Hamalainen, Jarno; Lativa-Kayra, Petri; Paz, Fernando; de Jong, Bernardus

    2013-12-01

    A comparison study was performed to evaluate the applicability of optical and SAR data for land cover classification for REDD+ services on a test site in Chiapas State in Mexico. The accuracy of the maps was assessed using an independent data set that was collected from very high resolution optical data. The overall accuracy of the maps varied between 79 % of ENVISAT ASAR and 94 % of RapidEye for the forest - non-forest classifications. The accuracies for the six IPCC compliant classes were from 5 to 9 percentage units lower. Results that were obtained with the optical data were somewhat better than the results using the SAR data. However, the difference between the optical and SAR results was fairly small when L-band SAR data were used. L-band SAR data seem to be competitive alternative for optical data particularly in the areas with frequent cloud cover.

  12. Multi-Temporal SAR Interferometry for Landslide Monitoring

    NASA Astrophysics Data System (ADS)

    Dwivedi, R.; Narayan, A. B.; Tiwari, A.; Dikshit, O.; Singh, A. K.

    2016-06-01

    In the past few years, SAR Interferometry specially InSAR and D-InSAR were extensively used for deformation monitoring related applications. Due to temporal and spatial decorrelation in dense vegetated areas, effectiveness of InSAR and D-InSAR observations were always under scrutiny. Multi-temporal InSAR methods are developed in recent times to retrieve the deformation signal from pixels with different scattering characteristics. Presently, two classes of multi-temporal InSAR algorithms are available- Persistent Scatterer (PS) and Small Baseline (SB) methods. This paper discusses the Stanford Method for Persistent Scatterer (StaMPS) based PS-InSAR and the Small Baselines Subset (SBAS) techniques to estimate the surface deformation in Tehri dam reservoir region in Uttarkhand, India. Both PS-InSAR and SBAS approaches used sixteen ENVISAT ASAR C-Band images for generating single master and multiple master interferograms stack respectively and their StaMPS processing resulted in time series 1D-Line of Sight (LOS) mean velocity maps which are indicative of deformation in terms of movement towards and away from the satellites. From 1D LOS velocity maps, localization of landslide is evident along the reservoir rim area which was also investigated in the previous studies. Both PS-InSAR and SBAS effectively extract measurement pixels in the study region, and the general results provided by both approaches show a similar deformation pattern along the Tehri reservoir region. Further, we conclude that StaMPS based PS-InSAR method performs better in terms of extracting more number of measurement pixels and in the estimation of mean Line of Sight (LOS) velocity as compared to SBAS method. It is also proposed to take up a few major landslides area in Uttarakhand for slope stability assessment.

  13. SAR observation and model tracking of an oil spill event in coastal waters.

    PubMed

    Cheng, Yongcun; Li, Xiaofeng; Xu, Qing; Garcia-Pineda, Oscar; Andersen, Ole Baltazar; Pichel, William G

    2011-02-01

    Oil spills are a major contributor to marine pollution. The objective of this work is to simulate the oil spill trajectory of oil released from a pipeline leaking in the Gulf of Mexico with the GNOME (General NOAA Operational Modeling Environment) model. The model was developed by NOAA (National Oceanic and Atmospheric Administration) to investigate the effects of different pollutants and environmental conditions on trajectory results. Also, a Texture-Classifying Neural Network Algorithm (TCNNA) was used to delineate ocean oil slicks from synthetic aperture radar (SAR) observations. During the simulation, ocean currents from NCOM (Navy Coastal Ocean Model) outputs and surface wind data measured by an NDBC (National Data Buoy Center) buoy are used to drive the GNOME model. The results show good agreement between the simulated trajectory of the oil spill and synchronous observations from the European ENVISAT ASAR (Advanced Synthetic Aperture Radar) and the Japanese ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array L-band Synthetic Aperture Radar) images. Based on experience with past marine oil spills, about 63.0% of the oil will float and 18.5% of the oil will evaporate and disperse. In addition, the effects from uncertainty of ocean currents and the diffusion coefficient on the trajectory results are also studied.

  14. SAR observation and model tracking of an oil spill event in coastal waters.

    PubMed

    Cheng, Yongcun; Li, Xiaofeng; Xu, Qing; Garcia-Pineda, Oscar; Andersen, Ole Baltazar; Pichel, William G

    2011-02-01

    Oil spills are a major contributor to marine pollution. The objective of this work is to simulate the oil spill trajectory of oil released from a pipeline leaking in the Gulf of Mexico with the GNOME (General NOAA Operational Modeling Environment) model. The model was developed by NOAA (National Oceanic and Atmospheric Administration) to investigate the effects of different pollutants and environmental conditions on trajectory results. Also, a Texture-Classifying Neural Network Algorithm (TCNNA) was used to delineate ocean oil slicks from synthetic aperture radar (SAR) observations. During the simulation, ocean currents from NCOM (Navy Coastal Ocean Model) outputs and surface wind data measured by an NDBC (National Data Buoy Center) buoy are used to drive the GNOME model. The results show good agreement between the simulated trajectory of the oil spill and synchronous observations from the European ENVISAT ASAR (Advanced Synthetic Aperture Radar) and the Japanese ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array L-band Synthetic Aperture Radar) images. Based on experience with past marine oil spills, about 63.0% of the oil will float and 18.5% of the oil will evaporate and disperse. In addition, the effects from uncertainty of ocean currents and the diffusion coefficient on the trajectory results are also studied. PMID:21067783

  15. Interseismic strain accumulation across an active thrust system: an InSAR case study in the Himalaya

    NASA Astrophysics Data System (ADS)

    Grandin, R.; Doin, M.; Ducret, G.; Bollinger, L.; Pinel-Puysségur, B.; Lasserre, C.; Jolivet, R.

    2011-12-01

    The major active thrust system underlying the Himalayan range produces recurrent large earthquakes, posing a significant threat to the densely populated Indo-Gangetic basin. Measuring the interseismic deformation associated with this fault system could provide important constraints on the geometry of the locked faults that are bound to rupture in future great earthquakes. This has so far been considered out of reach of InSAR techniques, due to decorrelation, prominent topographic features, and unfavourable climatic conditions. However, preliminary tests carried out with the archived ASAR data provided by ESA's ENVISAT satellite since 2002 have shown that recent advances in InSAR processing may now allow geodesists to tackle most of these perturbations. In this context, applying these advanced techniques to the case of the Himalayas is both a challenging and necessary task. We will present the methodology and the first results of an InSAR study of interseismic strain accumulation across the Himalayas. Small-baseline processing of ENVISAT data using a combination of ROI_PAC software, NSBAS processing chain and MulSAR technique yields a sufficient number of coherent interferograms to compute a preliminary average velocity map of interseismic uplift. Time-space variations of stratified tropospheric delay observed in these interferogrames are mitigated using a prediction deduced from outputs of the ECMWF global meteorological reanalysis ERA-Interim. Finally, a correction of DEM errors from the wrapped InSAR data set further improves the coherence of interferograms with a large perpendicular baseline. Comparison of the InSAR LOS velocity maps with microseismic activity detected near the transition zone at the base of the seismogenic portion of the Main Himalayan Thrust is expected to provide constraints on the process of elastic strain accumulation during the interseismic period. This will help in understanding the interaction between the construction of topography

  16. Comparison and Analysis of Geometric Correction Models of Spaceborne SAR.

    PubMed

    Jiang, Weihao; Yu, Anxi; Dong, Zhen; Wang, Qingsong

    2016-01-01

    Following the development of synthetic aperture radar (SAR), SAR images have become increasingly common. Many researchers have conducted large studies on geolocation models, but little work has been conducted on the available models for the geometric correction of SAR images of different terrain. To address the terrain issue, four different models were compared and are described in this paper: a rigorous range-doppler (RD) model, a rational polynomial coefficients (RPC) model, a revised polynomial (PM) model and an elevation derivation (EDM) model. The results of comparisons of the geolocation capabilities of the models show that a proper model for a SAR image of a specific terrain can be determined. A solution table was obtained to recommend a suitable model for users. Three TerraSAR-X images, two ALOS-PALSAR images and one Envisat-ASAR image were used for the experiment, including flat terrain and mountain terrain SAR images as well as two large area images. Geolocation accuracies of the models for different terrain SAR images were computed and analyzed. The comparisons of the models show that the RD model was accurate but was the least efficient; therefore, it is not the ideal model for real-time implementations. The RPC model is sufficiently accurate and efficient for the geometric correction of SAR images of flat terrain, whose precision is below 0.001 pixels. The EDM model is suitable for the geolocation of SAR images of mountainous terrain, and its precision can reach 0.007 pixels. Although the PM model does not produce results as precise as the other models, its efficiency is excellent and its potential should not be underestimated. With respect to the geometric correction of SAR images over large areas, the EDM model has higher accuracy under one pixel, whereas the RPC model consumes one third of the time of the EDM model. PMID:27347973

  17. Comparison and Analysis of Geometric Correction Models of Spaceborne SAR

    PubMed Central

    Jiang, Weihao; Yu, Anxi; Dong, Zhen; Wang, Qingsong

    2016-01-01

    Following the development of synthetic aperture radar (SAR), SAR images have become increasingly common. Many researchers have conducted large studies on geolocation models, but little work has been conducted on the available models for the geometric correction of SAR images of different terrain. To address the terrain issue, four different models were compared and are described in this paper: a rigorous range-doppler (RD) model, a rational polynomial coefficients (RPC) model, a revised polynomial (PM) model and an elevation derivation (EDM) model. The results of comparisons of the geolocation capabilities of the models show that a proper model for a SAR image of a specific terrain can be determined. A solution table was obtained to recommend a suitable model for users. Three TerraSAR-X images, two ALOS-PALSAR images and one Envisat-ASAR image were used for the experiment, including flat terrain and mountain terrain SAR images as well as two large area images. Geolocation accuracies of the models for different terrain SAR images were computed and analyzed. The comparisons of the models show that the RD model was accurate but was the least efficient; therefore, it is not the ideal model for real-time implementations. The RPC model is sufficiently accurate and efficient for the geometric correction of SAR images of flat terrain, whose precision is below 0.001 pixels. The EDM model is suitable for the geolocation of SAR images of mountainous terrain, and its precision can reach 0.007 pixels. Although the PM model does not produce results as precise as the other models, its efficiency is excellent and its potential should not be underestimated. With respect to the geometric correction of SAR images over large areas, the EDM model has higher accuracy under one pixel, whereas the RPC model consumes one third of the time of the EDM model. PMID:27347973

  18. Comparison and Analysis of Geometric Correction Models of Spaceborne SAR.

    PubMed

    Jiang, Weihao; Yu, Anxi; Dong, Zhen; Wang, Qingsong

    2016-06-25

    Following the development of synthetic aperture radar (SAR), SAR images have become increasingly common. Many researchers have conducted large studies on geolocation models, but little work has been conducted on the available models for the geometric correction of SAR images of different terrain. To address the terrain issue, four different models were compared and are described in this paper: a rigorous range-doppler (RD) model, a rational polynomial coefficients (RPC) model, a revised polynomial (PM) model and an elevation derivation (EDM) model. The results of comparisons of the geolocation capabilities of the models show that a proper model for a SAR image of a specific terrain can be determined. A solution table was obtained to recommend a suitable model for users. Three TerraSAR-X images, two ALOS-PALSAR images and one Envisat-ASAR image were used for the experiment, including flat terrain and mountain terrain SAR images as well as two large area images. Geolocation accuracies of the models for different terrain SAR images were computed and analyzed. The comparisons of the models show that the RD model was accurate but was the least efficient; therefore, it is not the ideal model for real-time implementations. The RPC model is sufficiently accurate and efficient for the geometric correction of SAR images of flat terrain, whose precision is below 0.001 pixels. The EDM model is suitable for the geolocation of SAR images of mountainous terrain, and its precision can reach 0.007 pixels. Although the PM model does not produce results as precise as the other models, its efficiency is excellent and its potential should not be underestimated. With respect to the geometric correction of SAR images over large areas, the EDM model has higher accuracy under one pixel, whereas the RPC model consumes one third of the time of the EDM model.

  19. Space-borne polarimetric SAR sensors or the golden age of radar polarimetry

    NASA Astrophysics Data System (ADS)

    Pottier, E.

    2010-06-01

    SAR Polarimetry represents an active area of research in Active Earth Remote Sensing. This interest is clearly supported by the fact that nowadays there exists, or there will exist in a very next future, a non negligible quantity of launched Polarimetric SAR Spaceborne sensors. The ENVISAT satellite, developed by ESA, was launched on March 2002, and was the first Spaceborne sensor offering an innovative dualpolarization Advanced Synthetic Aperture Radar (ASAR) system operating at C-band. The second Polarimetric Spaceborne sensor is ALOS, a Japanese Earth-Observation satellite, developed by JAXA and was launched in January 2006. This mission includes an active L-band polarimetric radar sensor (PALSAR) whose highresolution data may be used for environmental and hazard monitoring. The third Polarimetric Spaceborne sensor is TerraSAR-X, a new German radar satellite, developed by DLR, EADS-Astrium and Infoterra GmbH, was launched on June 2007. This sensor carries a dual-polarimetric and high frequency X-Band SAR sensor that can be operated in different modes and offers features that were not available from space before. At least, the Polarimetric Spaceborne sensor, developed by CSA and MDA, and named RADARSAT-2 was launched in December 2007 The Radarsat program was born out the need for effective monitoring of Canada’s icy waters, and some Radarsat-2 capabilities that benefit sea- and river ice applications are the multi-polarization options that will improve ice-edge detection, ice-type discrimination and structure information. The many advances in these different Polarimetric Spaceborne platforms were developed to respond to specific needs for radar data in environmental monitoring applications around the world, like : sea- and river-ice monitoring, marine surveillance, disaster management, oil spill detection, snow monitoring, hydrology, mapping, geology, agriculture, soil characterisation, forestry applications (biomass, allometry, height…), urban mapping etc

  20. SARS Basics

    MedlinePlus

    ... waiting room or office. Top of Page CDC’s response to SARS during the 2003 outbreak CDC worked ... Center to provide round-the-clock coordination and response. Committed more than 800 medical experts and support ...

  1. Two scales of inflation at Lastarria-Cordon del Azufre volcanic complex, central Andes, revealed from ASAR-ENVISAT interferometric data

    NASA Astrophysics Data System (ADS)

    Froger, J.-L.; Remy, D.; Bonvalot, S.; Legrand, D.

    2007-03-01

    ASAR-ENVISAT Interferometric Synthetic Aperture Radar (InSAR) data collected over the Lastarria-Cordon del Azufre complex (Chile-Argentina) between March 2003 and May 2005 show the persistence of the large wavelength ground inflation revealed by Pritchard and Simons in 2002 from the analysis of ERS InSAR data [Nature 418 (2002) 167-170]. After reducing the tropospheric contribution in the interferograms using a combination of data network adjustment and analysis of MODIS images, we produced an accurate interferometric time series showing a 2 yr long temporal evolution of the ground displacements patterns. Two distinct inflating signals are detected. The main signal covers an elliptical area with a 45 km NNE-SSW major axis and a 37 km minor axis. It is correlated with a regional topographic dome. We estimated its maximum inflation rate to ˜ 2.5 cm yr - 1 . We inverted the InSAR data for a range of source geometries (spherical, prolate ellipsoids, penny-shaped cracks). The inferred source parameters for 2003-2005 period are consistent with an over-pressured reservoir at shallow to intermediate crustal depths (7-15 km), with an average volumetric rate of inflation of about 14 × 10 6 m 3 yr - 1 . In addition to this main signal a new feature highlighted by the ASAR data is short wavelength inflation (6 km wide) at the location of Lastarria volcano on the northern margin of the large wavelength signal. We explain this short wavelength signal by a spherical over-pressured source lying 1000 m below the summit of Lastarria volcano. We estimate the average volumetric rate of inflation during the observation period to be ˜ 35 × 10 3 m 3 yr - 1 . It is remarkable that both volumetric variations for the large and small inflations exhibit the same evolution during the 2003-2005 period, suggesting that both processes could be related. On the basis of the inversion results and of arguments provided by field evidences and a morpho-structural analysis of the Digital Elevation

  2. Sea ice concentration and sea ice drift for the Arctic summer using C- and L-band SAR

    NASA Astrophysics Data System (ADS)

    Johansson, Malin; Berg, Anders; Eriksson, Leif

    2014-05-01

    The decreasing amount of sea ice and changes from multi-year ice to first year ice within the Arctic Ocean opens up for increased maritime activities. These activities include transportation, fishing and tourism. One of the major threats for the shipping is the presence of sea ice. Should an oil spill occur, the search and rescue is heavily dependent on constant updates of sea ice movements, both to enable a safer working environment and to potentially prevent the oil from reaching the sea ice. It is therefore necessary to have accurate and updated sea ice charts for the Arctic Ocean during the entire year. During the melt season that ice is subject to melting conditions making satellite observations of sea ice more difficult. This period coincides with the peak in marine shipping activities and therefore requires highly accurate sea ice concentration estimates. Synthetic Aperture Radar (SAR) are not hindered by clouds and do not require daylight. The continuous record and high temporal resolution makes C-band data preferable as input data for operational sea ice mapping. However, with C-band SAR it is sometimes difficult to distinguish between a wet sea ice surface and surrounding open water. L-band SAR has a larger penetration depth and has been shown to be less sensitive to less sensitive than C-band to the melt season. Inclusion of L-band data into sea chart estimates during the melt season in particular could therefore improve sea ice monitoring. We compare sea ice concentration melt season observations using Advanced Land Observing Satellite (ALOS) L-band images with Envisat ASAR C-band images. We evaluate if L-band images can be used to improve separation of wet surface ice from open water and compare with results for C-band.

  3. Alteration zone Mapping in the Meiduk and Sar Cheshmeh Porphyry Copper Mining Districts of Iran using Advanced Land Imager (ALI) Satellite Data

    NASA Astrophysics Data System (ADS)

    Beiranvand Pour, A.; Hashim, M.

    2015-10-01

    This study evaluates the capability of Earth Observing-1 (EO1) Advanced Land Imager (ALI) data for hydrothermal alteration mapping in the Meiduk and Sar Cheshmeh porphyry copper mining districts, SE Iran. Feature-oriented principal components selection, 4/2, 8/9, 5/4 band ratioing were applied to ALI data for enhancing the hydrothermally altered rocks associated with porphyry copper mineralization, lithological units and vegetation. Mixture-tuned matched-filtering (MTMF) was tested to discriminate the hydrothermal alteration areas of porphyry copper mineralization from surrounding environment using the shortwave infrared bands of ALI. Results indicate that the tested methods are able to yield spectral information for identifying vegetation, iron oxide/hydroxide and clay minerals, lithological units and the discrimination of hydrothermally altered rocks from unaltered rocks using ALI data.

  4. Long-range ground deformation monitoring by InSAR analysis

    NASA Astrophysics Data System (ADS)

    Rokugawa, S.; Nakamura, T.

    2015-11-01

    InSAR (Interferometric Synthetic Aperture Radar) analysis is an effective technique to map 3-dimensional surface deformation with high spatial resolution. The aim of this study was to evaluate the capability of InSAR analysis when applied to ground monitoring of an environmental disaster. We performed a time series InSAR analysis using ENVISAT/ASAR and ALOS/PALSAR data and commercial software to investigate subsidence around the Kanto District of Japan. We also investigated techniques for efficient early detection of landslides in Kyushu using time series analysis that incorporated synthetic aperture radar (SAR) images. ENVISAT/ASAR data acquired from 2003-2010 and ALOS/PALSAR data acquired from 2006-2011 were used to detect poorly expressed geomorphological deformation by conducting time series analyses of periodically acquired SAR data. In addition, to remove noise caused by geographical feature stripes or phase retardation, we applied median filtering, histogram extraction processing, and clarification of the displacement with a Laplacian filter. The main functions of the InSAR time series analysis are the calculation of phase differences between two images and the inversion with smoothness constraint for the estimation of deformation along the line of sight. The results enabled us to establish criteria for the selection of suitable InSAR data pairs, and provided the final error estimation of the derived surface deformation. The results of the analysis in the Kanto District suggested that localized areas of uplift and subsidence have occurred at irregular intervals in this area. Furthermore, the method offers the possibility of early warning of environmental disasters such as landslide and abrupt subsidence. Our results confirm the effectiveness of InSAR analysis for the monitoring of ground deformation over wide areas via the detection of localized subsidence and landslides.

  5. ERS-1 SAR data processing

    NASA Technical Reports Server (NTRS)

    Leung, K.; Bicknell, T.; Vines, K.

    1986-01-01

    To take full advantage of the synthetic aperature radar (SAR) to be flown on board the European Space Agency's Remote Sensing Satellite (ERS-1) (1989) and the Canadian Radarsat (1990), the implementation of a receiving station in Alaska is being studied to gather and process SAR data pertaining in particular to regions within the station's range of reception. The current SAR data processing requirement is estimated to be on the order of 5 minutes per day. The Interim Digital Sar Processor (IDP) which was under continual development through Seasat (1978) and SIR-B (1984) can process slightly more than 2 minutes of ERS-1 data per day. On the other hand, the Advanced Digital SAR Processore (ADSP), currently under development for the Shuttle Imaging Radar C (SIR-C, 1988) and the Venus Radar Mapper, (VMR, 1988), is capable of processing ERS-1 SAR data at a real time rate. To better suit the anticipated ERS-1 SAR data processing requirement, both a modified IDP and an ADSP derivative are being examined. For the modified IDP, a pipelined architecture is proposed for the mini-computer plus array processor arrangement to improve throughout. For the ADSP derivative, a simplified version is proposed to enhance ease of implementation and maintainability while maintaing real time throughput rates. These processing systems are discussed and evaluated.

  6. A novel approach for the characterization of tundra wetland regions with C-band SAR satellite data

    PubMed Central

    Widhalm, Barbara; Bartsch, Annett; Heim, Birgit

    2015-01-01

    A circumpolar representative and consistent wetland map is required for a range of applications ranging from upscaling of carbon fluxes and pools to climate modelling and wildlife habitat assessment. Currently available data sets lack sufficient accuracy and/or thematic detail in many regions of the Arctic. Synthetic aperture radar (SAR) data from satellites have already been shown to be suitable for wetland mapping. Envisat Advanced SAR (ASAR) provides global medium-resolution data which are examined with particular focus on spatial wetness patterns in this study. It was found that winter minimum backscatter values as well as their differences to summer minimum values reflect vegetation physiognomy units of certain wetness regimes. Low winter backscatter values are mostly found in areas vegetated by plant communities typically for wet regions in the tundra biome, due to low roughness and low volume scattering caused by the predominant vegetation. Summer to winter difference backscatter values, which in contrast to the winter values depend almost solely on soil moisture content, show expected higher values for wet regions. While the approach using difference values would seem more reasonable in order to delineate wetness patterns considering its direct link to soil moisture, it was found that a classification of winter minimum backscatter values is more applicable in tundra regions due to its better separability into wetness classes. Previous approaches for wetland detection have investigated the impact of liquid water in the soil on backscatter conditions. In this study the absence of liquid water is utilized. Owing to a lack of comparable regional to circumpolar data with respect to thematic detail, a potential wetland map cannot directly be validated; however, one might claim the validity of such a product by comparison with vegetation maps, which hold some information on the wetness status of certain classes. It was shown that the Envisat ASAR-derived classes

  7. Estimating subtle long-wavelength deformation with InSAR: Application to the Chaman Fault

    NASA Astrophysics Data System (ADS)

    Fattahi, H.; Amelung, F.

    2012-12-01

    While it's difficult to discriminate the tectonic deformation from the effects of orbital error in the single interferogram due to their similar spatial pattern, but their different temporal behavior is an opportunity to measure the tectonic deformation from the InSAR time-series. Considering the fact that the long-wavelength tectonic signal is correlated in time (in most cases linearly) whereas orbital errors have random distribution, theoretically we should be able to extract tectonic deformation signal from the InSAR time-series results. However in practice, systematic errors from various sources, usually misinterpreted as the orbital error, are the main obstacles to use current SAR archives for estimating long-wavelength deformation. In this presentation we will introduce a temporal systematic error in Envisat-ASAR data limiting our ability in using these data for estimating long-wavelength deformation and propose a processing strategy to correct it's effects in the time-series results. We will show using simulated data that the linear velocity map calculated from the InSAR time-series is not affected by the random orbital error. However in practice the velocity map of InSAR time-series from Envisat ASAR data is always affected by an approximately 1.5 cm/yr ramp in the range direction. This constant ramp in the results from Envisat should not be misinterpreted as the random orbital error but it's a result of systematic temporal error with possible sources from the radar hardware, processing parameters or softwares. Being aware of this systematic effect in the Envisat data enables us to propose a new processing strategy to correct the error without removing the long-wavelength deformation. We have examined this strategy to estimate the velocity map over Southern San Andreas Fault. These results show that the obtained velocity map using only Envisat InSAR data is very well comparable with other recent studies attempting to use GPS to correct the InSAR orbital

  8. Unsupervised SBAS-DInSAR time series generation: a small brick for building a Supersites ecosystem

    NASA Astrophysics Data System (ADS)

    Casu, F.; De Luca, C.; Elefante, S.; Imperatore, P.; Lanari, R.; Manunta, M.; Zinno, I.; Farres, J.; Lengert, W.

    2013-12-01

    Differential SAR Interferometry (DInSAR) is an effective tool to detect and monitor ground displacements with centimeter accuracy. The geoscience communities, as well as those related to hazard monitoring and risk mitigation, make extensively use of DInSAR. They take advantage from the current huge amount of SAR data and will benefit the incoming big data stream of Sentinel 1 system. The availability of this information makes possible the generation of Earth's surface displacement maps and time series with large spatial coverage and long time span and, often in conjunction to in-situ data, fosters advances in science. However, the managing, processing and analysis of such a huge amount of data is expected to be the major bottleneck, particularly when crisis phases occur. The emerging need of creating a common ecosystem in which data (space born and in-situ), results and processing tools are shared, is envisaged to be a successful way to address such a problem and contribute to information and knowledge spreading. The Supersites initiative as well as the ESA SuperSites Exploitation Platform (SSEP), through the ESA Grid Processing On Demand (G-POD) and Cloud Computing Operational Pilot (CIOP) projects, provide effective answers to this need. The existent tools for querying and analysing SAR data are required to be redesigned for both processing big data and for quickly replying to simultaneous user requests, mainly during emergency situations. These requirements push for the development of automatic and unsupervised processing tools as well as of scalable, widely accessible and high performance computing capabilities. The cloud-computing environment successfully responds to these objectives, particularly in case of spike and peak requests of processing resources linked to disaster events. In this work we present a parallel computational model for the Small BAseline Subset (SBAS) DInSAR algorithm as it was implemented within the computing environment provided by the

  9. Multibaseline POLInSAR Module for SAR Data Processing and Analysis in RAT (Radar Tools)

    NASA Astrophysics Data System (ADS)

    Neumann, M.; Reiber, A.; Jäger, M.; Guillaso, S.; Hellwich, O.

    2007-03-01

    The combination of SAR Polarimetry (POL- SAR) and SAR Interferometry (InSAR) into Polarimetric SAR Interferometry (POLInSAR) has shown great potential for information extraction from SAR data. Applications have been developed and validated theoretically for POLInSAR data. But due to different reasons these methods are difficult to apply on real data. The SAR observables have to be increased, and the utilization of multiple baselines (MB) is one of the possibilities. There will be a need for data processing and analysis methods and tools to work effectively with multibaseline datasets. In this paper we present the newly developed module for the software package RAT (Radar Tools), which provides these abilities for multibaseline polarimetric interferometric SAR data. It is the first available package of tools for working with MBSAR data. RAT (RAdar Tools [1], [2]) is a collection of tools for advanced image processing of SAR remote sensing data, originally started as a student's project and currently under further development at the Department of Computer Vision and Remote Sensing of the Technical University of Berlin. It is programmed in IDL (Interactive Data Language) and uses IDL widgets as graphical user interface. The purpose of this paper is also to give an overview of the current development status of RAT through addressing the newest structural improvements in RAT as well as recently implemented methods for SAR polarimetry and interferometry.

  10. Influence of the external DEM on PS-InSAR processing and results on Northern Appennine slopes

    NASA Astrophysics Data System (ADS)

    Bayer, B.; Schmidt, D. A.; Simoni, A.

    2014-12-01

    We present an InSAR analysis of slow moving landslide in the Northern Appennines, Italy, and assess the dependencies on the choice of DEM. In recent years, advanced processing techniques for synthetic aperture radar interferometry (InSAR) have been applied to measure slope movements. The persistent scatterers (PS-InSAR) approach is probably the most widely used and some codes are now available in the public domain. The Stanford method of Persistent Scatterers (StamPS) has been successfully used to analyze landslide areas. One problematic step in the processing chain is the choice of an external DEM that is used to model and remove the topographic phase in a series of interferograms in order to obtain the phase contribution caused by surface deformation. The choice is not trivial, because the PS InSAR results differ significantly in terms of PS identification, positioning, and the resulting deformation signal. We use four different DEMs to process a set of 18 ASAR (Envisat) scenes over a mountain area (~350 km2) of the Northern Appennines of Italy, using StamPS. Slow-moving landslides control the evolution of the landscape and cover approximately 30% of the territory. Our focus in this presentation is to evaluate the influence of DEM resolution and accuracy by comparing PS-InSAR results. On an areal basis, we perform a statistical analysis of displacement time-series to make the comparison. We also consider two case studies to illustrate the differences in terms of PS identification, number and estimated displacements. It is clearly shown that DEM accuracy positively influences the number of PS, while line-of-sight rates differ from case to case and can result in deformation signals that are difficult to interpret. We also take advantage of statistical tools to analyze the obtained time-series datasets for the whole study area. Results indicate differences in the style and amount of displacement that can be related to the accuracy of the employed DEM.

  11. Progress Toward Demonstrating SAR Monitoring of Chinese Seas

    NASA Astrophysics Data System (ADS)

    Huang, Weigen; Johannessen, Johnny; Alpers, Werner; Yang, Jingsong

    2010-12-01

    "Demonstrating SAR monitoring of Chinese seas" is a project of the ESA-MOST Dragon 2 program. This paper presents the progress of the project. Retrieval algorithms for SAR monitoring of sea surface currents, oceanic internal waves, sea surface winds, oil spills and ships have been advanced. SAR monitoring of Chinese seas in near-real-time is now in demonstration phase.

  12. TerraSAR-X mission

    NASA Astrophysics Data System (ADS)

    Werninghaus, Rolf

    2004-01-01

    The TerraSAR-X is a German national SAR- satellite system for scientific and commercial applications. It is the continuation of the scientifically and technologically successful radar missions X-SAR (1994) and SRTM (2000) and will bring the national technology developments DESA and TOPAS into operational use. The space segment of TerraSAR-X is an advanced high-resolution X-Band radar satellite. The system design is based on a sound market analysis performed by Infoterra. The TerraSAR-X features an advanced high-resolution X-Band Synthetic Aperture Radar based on the active phased array technology which allows the operation in Spotlight-, Stripmap- and ScanSAR Mode with various polarizations. It combines the ability to acquire high resolution images for detailed analysis as well as wide swath images for overview applications. In addition, experimental modes like the Dual Receive Antenna Mode allow for full-polarimetric imaging as well as along track interferometry, i.e. moving target identification. The Ground Segment is optimized for flexible response to (scientific and commercial) User requests and fast image product turn-around times. The TerraSAR-X mission will serve two main goals. The first goal is to provide the strongly supportive scientific community with multi-mode X-Band SAR data. The broad spectrum of scientific application areas include Hydrology, Geology, Climatology, Oceanography, Environmental Monitoring and Disaster Monitoring as well as Cartography (DEM Generation) and Interferometry. The second goal is the establishment of a commercial EO-market in Europe which is driven by Infoterra. The commercial goal is the development of a sustainable EO-business so that the e.g. follow-on systems can be completely financed by industry from the profit. Due to its commercial potential, the TerraSAR-X project will be implemented based on a public-private partnership with the Astrium GmbH. This paper will describe first the mission objectives as well as the

  13. Environmental evolution of the Rio Grande drainage basin and Nasca region (Peru) in 2003-2007 using ENVISAT ASAR and ASTER time series

    NASA Astrophysics Data System (ADS)

    Cigna, Francesca; Tapete, Deodato; Lasaponara, Rosa; Masini, Nicola

    2013-04-01

    Recent palaeo-environmental studies and remote sensing investigations demonstrated that the Rio Grande drainage basin in Southern Peru is a still evolving landscape, and impacts due to its changes have implications for the preservation of both the natural and cultural features of the Nasca region, well-known for the evidences of the ancient Paracas and Nasca Civilizations, who flourished from the 4th century BC to the 6th century AD. To image the modifications occurred in the last decade, we exploited the entire 4year-long stack of ENVISAT ASAR C-band archive imagery available over the region, which was provided by the European Space Agency (ESA) via the Cat-1 project 11073. The latter supports the activities of the Italian mission of heritage Conservation and Archaeogeophysics (ITACA), which directly involve researchers from the Institute for Archaeological and Monumental Heritage (IBAM) and the Institute of Methodologies for Environmental Analysis (IMAA), National Research Council (CNR) of Italy. With the aim of reconstructing the temporal evolution of the Rio Grande drainage basin and its effects and implications for the heritage of the region, we processed 8 ASAR Image Mode IS2 scenes acquired in descending mode between 04/02/2003 and 15/11/2005 and 5 images in ascending mode between 24/07/2005 and 11/11/2007, and focused on SAR backscattering information, amplitude change detection methods and extraction of ASAR-derived time series of the backscattering coefficient over target areas of interest. The ASAR 2003-2007 analysis was coupled and integrated with NDVI-based soil moisture and vegetation change assessment performed by using ASTER multi-spectral data acquired during the same time frame of the ASAR stacks, on 30/05/2003, 01/06/2004 and 10/06/2007. The research was performed both at the regional scale over the entire Rio Grande drainage basin, with particular focus on its tributaries Rio Ingenio, Rio Nazca and Rio Taruga, and at the local scale over the

  14. Assimilation of ASAR-ENVISAT directional wave spectra in wave model WAM

    NASA Astrophysics Data System (ADS)

    Aouf, L.; Lefevre, J.-M.; Hauser, D.; Chapron, B.

    2003-04-01

    Better understanding and prediction of sea state are an essential need for many application domains, such as navigation and security of ships, off-shore industrial activities and the survey of the coastal zone... etc. In the framework of SWIMSAT (Surface wave investigations and monitoring from satellite, proposition to spatial mission to European Space Agency), we have shown the significant contribution induced by the assimilation of directional wave spectra in wave model WAM (Aouf et al, 2002). These results can be summarized in one hand by the improvement of the estimation of wave parameters (significant wave height, wave period and direction). In the other hand the duration of the assimilation impact in the forecast period is significantly larger regarding to the assimilation of altimeter data (wave height only). In order to prepare the assimilation scheme for operational use, assimilation tests in wave model WAM are performed with real wave spectra from the radar ASAR of the satellite ENVISAT. In this study, assimilation parameters (estimation of the covariance matrix, cross-assignement and selection of wave trains) are well adapted and the partitioning procedure in the scheme is improved in such a way that the limitation in frequency concerning the observed wave spectra (frequency cut-off of 0.1 Hz) is taken into account. The results show that the assimilation is efficient and works correctly. Furthermore, the root mean square of the analyzed wave parameters (wave height, direction and frequency) is significantly reduced and the impact of the assimilation stays effective in the forecast period. Also it has been shown that the ASAR wave spectra affect much more the low frequency wave parameters (swell). More complete and validated ASAR data will be assimilated and compared with other data sources such as RA2, buoy and RAR as part of VALPARAISO experiment.

  15. Detecting Agricultural Practices Using Envisat ASAR DualPol and RADARSAT-2 QadPol Data

    NASA Astrophysics Data System (ADS)

    Weydahl, Dan Johan; Eggestad, Hans Olav; Oygarden, Lillian; Sorensen, Kai

    2010-12-01

    Satellite SAR images may be used to detect tillage practices over agricultural fields at times of the year where optical imaging is hampered by cloud conditions. Analysis of multitemporal SAR data sets show that ploughing may be detected using ERS, ENVISAT or Radarsat-2 images. A combination of temporal SAR data sets together with polarimetric data acquired at times with high soil moisture, will increase the detection probability.

  16. Next generation SAR demonstration on space station

    SciTech Connect

    Edelstein, Wendy; Kim, Yunjin; Freeman, Anthony; Jordan, Rolando

    1999-01-22

    This paper describes the next generation synthetic aperture radar (SAR) that enables future low cost space-borne radar missions. In order to realize these missions, we propose to use an inflatable, membrane, microstrip antenna that is particularly suitable for low frequency science radar missions. In order to mitigate risks associated with this revolutionary technology, the space station demonstration will be very useful to test the long-term survivability of the proposed antenna. This experiment will demonstrate several critical technology challenges associated with space-inflatable technologies. Among these include space-rigidization of inflatable structures, controlled inflation deployment, flatness and uniform separation of thin-film membranes and RF performance of membrane microstrip antennas. This mission will also verify the in-space performance of lightweight, high performance advanced SAR electronics. Characteristics of this SAR instrument include a capability for high resolution polarimetric imaging. The mission will acquire high quality scientific data using this advanced SAR to demonstrate the utility of these advanced technologies. We will present an inflatable L-band SAR concept for commercial and science applications and a P-band design concept to validate the Biomass SAR mission concept. The ionospheric effects on P-band SAR images will also be examined using the acquired data.

  17. Estimation of surface soil moisture and roughness from multi-angular ASAR imagery in the Watershed Allied Telemetry Experimental Research (WATER)

    NASA Astrophysics Data System (ADS)

    Wang, S. G.; Li, X.; Han, X. J.; Jin, R.

    2011-05-01

    Radar remote sensing has demonstrated its applicability to the retrieval of basin-scale soil moisture. The mechanism of radar backscattering from soils is complicated and strongly influenced by surface roughness. Additionally, retrieval of soil moisture using AIEM (advanced integrated equation model)-like models is a classic example of underdetermined problem due to a lack of credible known soil roughness distributions at a regional scale. Characterization of this roughness is therefore crucial for an accurate derivation of soil moisture based on backscattering models. This study aims to simultaneously obtain surface roughness parameters (standard deviation of surface height σ and correlation length cl) along with soil moisture from multi-angular ASAR images by using a two-step retrieval scheme based on the AIEM. The method firstly used a semi-empirical relationship that relates the roughness slope, Zs (Zs = σ2/cl) and the difference in backscattering coefficient (Δσ) from two ASAR images acquired with different incidence angles. Meanwhile, by using an experimental statistical relationship between σ and cl, both these parameters can be estimated. Then, the deduced roughness parameters were used for the retrieval of soil moisture in association with the AIEM. An evaluation of the proposed method was performed in an experimental area in the middle stream of the Heihe River Basin, where the Watershed Allied Telemetry Experimental Research (WATER) was taken place. It is demonstrated that the proposed method is feasible to achieve reliable estimation of soil water content. The key challenge is the presence of vegetation cover, which significantly impacts the estimates of surface roughness and soil moisture.

  18. SAR wind retrieval: from Singlecore to Multicore and GPU computing

    NASA Astrophysics Data System (ADS)

    Myasoedov, Alexander; Monzikova, Anna

    The large spatial coverage and high resolution of spaceborne synthetic aperture radars (SAR) offers a unique opportunity to derive mesoscale wind fields over the ocean surface, providing high resolution wind fields near the shore. On the other hand, due to the large size of SAR images their processing might be a headache when dealing with operational tasks or doing long-period statistical analysis. Algorithms for satellite image processing often offer many possibilities for parallelism (e.g., pixel-by-pixel processing) which makes them good candidates for execution on high-performance parallel computing hardware such as Multicore CPUs and modern graphic processing units (GPUs). In this study we implement different SAR wind speed retrieval algorithms (e.g. CMOD4, CMOD5) for Singlecore and Multicore systems, including GPUs. For this purpose both serial and parallelized versions of CMOD algorithms were written in Matlab, Python, CPython and PyOpenCL. We apply these algorithms to an Envisat ASAR image, compare the results received with different versions of the algorithms executed on both Intel CPU and a Tesla GPU. As a result of our experiments we not only show the up to 400 times speedup of GPU comparing to CPU but also try to give some advises on how much time we have spent and efforts were made for writing the same algorithm using different programming languages. We hope that our experience will help other scientist to achieve all the goodness from the GPU/Multicore computing.

  19. Aoutomatic Oil Spill Detection Using TerraSAR-X Data

    NASA Astrophysics Data System (ADS)

    Zulipiye, Kaiyoumu; Balik Sanli, Fusun

    2016-07-01

    Oil release into the ocean may affect marine ecosystems and cause environmental pollution. Thus, oil spill detection and identification becomes critical important. Characterized by synoptic view over large regions, remote sensing has been proved to be a reliable tool for oil spill detection. Synthetic Aperture Radar (SAR) imagery shows returned signal that clearly distinguish oil from oil-free surface under optimal wind conditions, which makes it the most frequent used remote sensing technique in oil spill detection. Algorithms of automatic oil spill detection has already been developed for different SAR sensors, including RADARSAT and ENVISAT. In this study, we want to apply automatic oil spill detection algorithms on TerraSAR-X data which is previously developed for ASAR data. The applied methodology includes two steps as segmentation and classification. First segmentation algorithms compiled by C# have been applied under a Bayesian framework adopting a multi-level logistic. After segmentation different classification methods such as feature selection, filter, and embedded selection have been applied. As a result the used classifiers for oil spill detection will be compared, and the complete processing chain will be evaluated.

  20. Development of an Advanced Technique to Correct Along-Track InSAR-Derived Surface Current Fields for Contributions of Wave Motions

    NASA Astrophysics Data System (ADS)

    Smith, C.; Romeiser, R.; Reniers, A.; MacMahan, J.

    2014-12-01

    The feasibility of surface current measurements by airborne and spaceborne along-track interferometric synthetic aperture radar (along-track InSAR) has been demonstrated on a number of occasions. Since the Doppler shifts detected by the radar include contributions of surface wave motions, a correction for these contributions has to be applied, which is often estimated as a mean correction for the entire current field on the basis of a simple theoretical model. In coastal areas and river estuaries with complex current and wave patterns, this approach is not adequate because one has to account for spatial variations in the wave field and in the corresponding corrections for the current field, which can be on the same order of magnitude as the actual surface currents of interest. Here we test the ability of a numerical near-shore hindcast model (Delft3D) to produce a wave field to be used for more appropriate computations of corrections for the along-track InSAR data. Our study was conducted at the mouth of the Columbia River on the West Coast of the U.S. during the spring of 2013. Over the course of the experiment, seven TerraSAR-X along-track InSAR images were acquired as well as a variety of in-situ data sets, such as trajectories of GPS-equipped Lagrangian drifters and velocity profiles from acoustic Doppler current profilers (ADCP). We use the in-situ data to validate our Delft3D model results, and we try to relate spatially varying differences between the measured and simulated surface currents and the TerraSAR-X derived Doppler velocities to the wave spectra obtained from Delft3D and to wave patterns observed in the SAR images. The long-term objective of this work is to derive the wave information and the corresponding velocity corrections from signatures contained in the along-track InSAR data set itself, such that a completely self-consistent correction of along-track InSAR-derived surface current fields for the contributions of spatially varying wave motions

  1. On the application of DInSAR to deformation monitoring in desert areas

    NASA Astrophysics Data System (ADS)

    Chang, Xiao-Tao; Guo, Jin-Yun; Zhang, Yong-Hong; Wang, Xiao-Qing

    2011-03-01

    The DInSAR technique is used for monitoring the desert height changes to study sandstorms. Hunshandake Sandy Land, as the test area, is one of the main sources of sandstorms in Beijing. In order to study the sandstorm source and its impact, a pair of EnviSat ASAR images of Oct. 11, 2005, and Oct. 26, 2004, is processed on the basis of analysis of six ERS-2 and EnviSat radar images. After the image configuration, flat earth effect correction, data filtering, phase unwrapping, and geo-coding, a deformation model over Hunshandake desert is built. According to the results, the height decreased in most areas and increased in a few areas, which basically coincides with the strong sandstorm appearing in Beijing in the Spring of 2005. The results show DInSAR has an important role in monitoring of desert surface deformation.

  2. Using SAR and GPS for Hazard Management and Response: Progress and Examples from the Advanced Rapid Imaging and Analysis (ARIA) Project

    NASA Astrophysics Data System (ADS)

    Owen, S. E.; Simons, M.; Hua, H.; Yun, S. H.; Agram, P. S.; Milillo, P.; Sacco, G. F.; Webb, F.; Rosen, P. A.; Lundgren, P.; Milillo, G.; Manipon, G. J. M.; Moore, A. W.; Liu, Z.; Polet, J.; Cruz, J.

    2014-12-01

    ARIA is a joint JPL/Caltech project to automate synthetic aperture radar (SAR) and GPS imaging capabilities for scientific understanding, hazard response, and societal benefit. We have built a prototype SAR and GPS data system that forms the foundation for hazard monitoring and response capability, as well as providing imaging capabilities important for science studies. Together, InSAR and GPS have the ability to capture surface deformation in high spatial and temporal resolution. For earthquakes, this deformation provides information that is complementary to seismic data on location, geometry and magnitude of earthquakes. Accurate location information is critical for understanding the regions affected by damaging shaking. Regular surface deformation measurements from SAR and GPS are useful for monitoring changes related to many processes that are important for hazard and resource management such as volcanic deformation, groundwater withdrawal, and landsliding. Observations of SAR coherence change have a demonstrated use for damage assessment for hazards such as earthquakes, tsunamis, hurricanes, and volcanic eruptions. These damage assessment maps can be made from imagery taken day or night and are not affected by clouds, making them valuable complements to optical imagery. The coherence change caused by the damage from hazards (building collapse, flooding, ash fall) is also detectable with intelligent algorithms, allowing for rapid generation of damage assessment maps over large areas at fine resolution, down to the spatial scale of single family homes. We will present the progress and results we have made on automating the analysis of SAR data for hazard monitoring and response using data from the Italian Space Agency's (ASI) COSMO-SkyMed constellation of X-band SAR satellites. Since the beginning of our project with ASI, our team has imaged deformation and coherence change caused by many natural hazard events around the world. We will present progress on our

  3. Investigating the Creeping Segment of the San Andreas Fault using InSAR time series analysis

    NASA Astrophysics Data System (ADS)

    Rolandone, Frederique; Ryder, Isabelle; Agram, Piyush S.; Burgmann, Roland; Nadeau, Robert M.

    2010-05-01

    We exploit the advanced Interferometric Synthetic Aperture Radar (InSAR) technique referred to as the Small BAseline Subset (SBAS) algorithm to analyze the creeping section of the San Andreas Fault in Central California. Various geodetic creep rate measurements along the Central San Andreas Fault (CSAF) have been made since 1969 including creepmeters, alignment arrays, geodolite, and GPS. They show that horizontal surface displacements increase from a few mm/yr at either end to a maximum of up to ~34 mm/yr in the central portion. They also indicate some discrepancies in rate estimates, with the range being as high as 10 mm/yr at some places along the fault. This variation is thought to be a result of the different geodetic techniques used and of measurements being made at variable distances from the fault. An interferometric stack of 12 interferograms for the period 1992-2001 shows the spatial variation of creep that occurs within a narrow (<2 km) zone close to the fault trace. The creep rate varies spatially along the fault but also in time. Aseismic slip on the CSAF shows several kinds of time dependence. Shallow slip, as measured by surface measurements across the narrow creeping zone, occurs partly as ongoing steady creep, along with brief episodes with slip from mm to cm. Creep rates along the San Juan Bautista segment increased after the 1989 Loma Prieta earthquake and slow slip transients of varying duration and magnitude occurred in both transition segments The main focus of this work is to use the SBAS technique to identify spatial and temporal variations of creep on the CSAF. We will present time series of line-of-sight (LOS) displacements derived from SAR data acquired by the ASAR instrument, on board the ENVISAT satellite, between 2003 and 2009. For each coherent pixel of the radar images we compute time-dependent surface displacements as well as the average LOS deformation rate. We compare our results with characteristic repeating microearthquakes that

  4. Deformation monitoring in Hanyuan reservoir resettlement of Pubugou Hydropower Station using PS-InSAR

    NASA Astrophysics Data System (ADS)

    He, Min; He, Xiufeng

    2011-10-01

    Interferometric synthetic aperture radar (InSAR) is a very effective technique for measuring surface deformation, but the temporal and geometrical decorrelation and atmospheric disturbances can strongly compromise the accuracy of the results. Persistent scatterer InSAR (PS-InSAR) overcomes the decorrelation and atmospheric disturbances problem by identifying resolution elements whose echo is dominated by a single scatterer in a series of interferograms. The results obtained by PS-InSAR technique are not the field deformation information but persistent scatterers deformation. In this paper, PS-InSAR is used to investigate surface deformation caused by landslide hazards in Hanyuan reservoir resettlement, China. The subsidence map derived from Envisat ASAR data between May 2008 and Oct 2009 reveals the spatial extent of the deformations and subsidence velocity. The experimental results show that there are instable areas which are located in the Middle of new Hanyuan county. The average deformation rate of the instable areas is over - 20mm. The Upper right and Lower left of new Hanyuan county are relatively stable.

  5. Evaluation Of A Sea Ice Algorithm For SAR Data From The Bay Of Bothnia

    NASA Astrophysics Data System (ADS)

    Berg, Anders; Eriksson, Leif

    2010-04-01

    A sea ice drift algorithm published by M. Thomas et. al. (2008) has been implemented and evaluated. Input to the algorithm is Synthetic Aperture Radar (SAR) images, which are processed using phase correlation in a multi-resolution processing system. The algorithm has been tested with horizontally co-polarized (HH) ENVISAT ASAR Wide Swath images and RADARSAT-2 ScanSAR images. The possible benefits of using cross-polarized (HV) RADARSAT-2 ScanSAR data are investigated, and initial testing of the algorithm for L-band SAR data from ALOS PALSAR has been done. The validity of the produced motion fields has been tested in three different ways. Most of the SAR images in this analysis were acquired over the Bay of Bothnia. Five meteorological stations located in this region have been collecting wind data with a temporal resolution of three hours. It is confirmed that the wind data correlates with the derived sea ice motion. Another source of validation data that has been used is the daily ice charts published by the Swedish Meteorological and Hydrological Institute (SMHI). The third method used for validation is straightforward, visual tracking of sea ice features. The algorithm is facing some difficulties when it comes to ice tracking close to the shoreline, in archipelagoes etc, since the motionless solution will be favoured. It can however be suppressed by filtering areas of land. This addition gives a more robust algorithm.

  6. An Analysis of Surface Subsidence in Chiba Using PSInSAR Technique

    NASA Astrophysics Data System (ADS)

    Li, R. H.; Zhao, Z.; Duan, M. Y.; Wang, Z. Y.; Wang, P.

    2015-06-01

    Currently, surface subsidence has become an important problem what we are facing. Because of complex topography, uneven distribution of rainfall, and the fast development of urbanization, many cities of the world have undergone surface subsidence disaster, such as Chiba, Paris, Tokyo, Beijing. The surface subsidence has occurred in Chiba since the early twenty-first century. The surface subsidence seriously threatens the safety of human life and property. In order to monitor surface subsidence, people have done a lot of research, and time-series InSAR technique with its better coverage, lower cost and high measurement accuracy advantages shows great potentiality for monitoring surface subsidence. Time-series InSAR technique can be applied for analysis of subtle surface subsidence which occurred consistently for a long term period. This paper uses time-series InSAR technique, Permanent Scatterers Interferometric SAR (PSInSAR), to monitor surface subsidence of Chiba. The used dataset consists of thirty-four Envisat ASAR images from September 2006 to August 2010. For the experimental results, this paper uses GPS data to verify the reliability of the results, and the results can provide information for local government to prevent the occurrence of surface subsidence.

  7. SAR change detection MTI

    NASA Astrophysics Data System (ADS)

    Scarborough, Steven; Lemanski, Christopher; Nichols, Howard; Owirka, Gregory; Minardi, Michael; Hale, Todd

    2006-05-01

    This paper examines the theory, application, and results of using single-channel synthetic aperture radar (SAR) data with Moving Reference Processing (MRP) to focus and geolocate moving targets. Moving targets within a standard SAR imaging scene are defocused, displaced, or completely missing in the final image. Building on previous research at AFRL, the SAR-MRP method focuses and geolocates moving targets by reprocessing the SAR data to focus the movers rather than the stationary clutter. SAR change detection is used so that target detection and focusing is performed more robustly. In the cases where moving target returns possess the same range versus slow-time histories, a geolocation ambiguity results. This ambiguity can be resolved in a number of ways. This paper concludes by applying the SAR-MRP method to high-frequency radar measurements from persistent continuous-dwell SAR observations of a moving target.

  8. Climate change effects on Glacier recession in Himalayas using Multitemporal SAR data and Automatic Weather Station observations

    NASA Astrophysics Data System (ADS)

    Kumar, V.; Singh, S. K.; Venkataraman, G.

    2009-04-01

    The Himalaya is the highest but the youngest mountain belt (20 to 60 million years B.P.) of the earth running in arc shape for about 2500 km. It has more than 90 peaks above 6000 m and contains about 50% of all glaciers outside of the polar environments (Bahadur, 1993). All glaciers in this region are in general recession since last 150 years (Paul et al.,1979). Gangotri, Siachen, Bara Shigri and Patsio are major glaciers in this region which are showing retreat with different rates and their respective tributary glaciers are completely disconnected from main body of glaciers. Spaceborne synthetic aperture radar data provide an important tool for monitoring the fluctuation of the glaciers. In this paper attempt has been made for quantifying the glacier retreat using multitemporal synthetic aperture radar (SAR) data. SAR intensity and phase information will be exploited separately under SAR intensity tracking and interferometric SAR (InSAR) coherence tracking (Strozzi et al., 2002) respectively. Glacier retreat study have been done using time series coregistered multi temporal SAR images. Simultaneously InSAR coherence thresholding is applied for tracking the snout of Gangotri glacier. It is observed that glacier is retreating at the rate of 21 m/a. Availability of high resolution spotlight mode TerraSAR-X SAR data will supplement the ENVISAT ASAR and ERS-1/2 based observations. The observatory in the proximity of Gangotri glacier has been made functional at Bhojbasa and all weather parameters viz. Snow fall, temperature, pressure, air vector, column water vapor and humidity are recorded twice a day as per WMO standards manually and automatically. Three Automatic Weather Stations (AWS) have been established in the glacier area at Bhojbasa , Kalindipass and Nandaban. Since Himalayan environment is presently under great stress of decay and degeneration, AWS data will be analyzed in the context of climate change effects on fluctuation of glaciers. References 1.Jagdish

  9. Non-invasive deformation analysis of historical buildings through the advanced SBAS-DInSAR technique: the case of the city of Roma (Italy)

    NASA Astrophysics Data System (ADS)

    Manunta, Michele; Bonano, Manuela; Marsella, Maria; Lanari, Riccardo

    2010-05-01

    The monitoring of urban areas and man-made structures is of key importance for the preservation of artistic, archaeological and architectural heritage. In this context, the remote sensing techniques may allow non-invasive analysis of large areas by exploiting long time series of satellite data. Among these techniques, the Synthetic Aperture Radar (SAR) Interferometry (InSAR) has already demonstrated to be an effective tool for monitoring the displacements occurring in the historical and artistic heritage located in the historical city centers. As a matter of fact, the InSAR technique allows producing spatially dense deformation maps with centimeter to millimeter accuracy, by exploiting the phase difference (interferogram) of temporally separated SAR images relevant to the same analyzed area. In order to guarantee the monitoring of urban area displacements, it is strategic to provide very long term deformation time series by also exploiting SAR data acquired by different sensors. Accordingly, ERS/ENVISAT data archive, providing acquisitions spanning the 1992-2010 time period, might allow us generating very long term deformation time-series. However, an ERS/ENVISAT data combination is limited by the two sensors slightly different carrier frequencies: 5.331 GHz for the ENVISAT sensor and 5.3 GHz for the ERS one. Therefore, because the interferometric phase is dependent on the radiation wavelength, the generation of conventional ERS/ENVISAT cross-interferograms is strongly affected by the induced decorrelation effects. In this work we show the effectiveness of the Small BAseline Subset (SBAS) (Berardino et al., 2002; Lanari et al., 2004) approach for the conservation, monitoring and risk prevention of cultural heritage. Indeed, the SBAS technique allows us to produce deformation time series at the scale of the single building by processing very long sequences of ERS-1/2 and ENVISAT (IS2 swath) SAR data, acquired with the same illumination geometry. In particular, the

  10. Different scale land subsidence and ground fissure monitoring with multiple InSAR techniques over Fenwei basin, China

    NASA Astrophysics Data System (ADS)

    Zhao, C.; Zhang, Q.; Yang, C.; Zhang, J.; Zhu, W.; Qu, F.; Liu, Y.

    2015-11-01

    Fenwei basin, China, composed by several sub-basins, has been suffering severe geo-hazards in last 60 years, including large scale land subsidence and small scale ground fissure, which caused serious infrastructure damages and property losses. In this paper, we apply different InSAR techniques with different SAR data to monitor these hazards. Firstly, combined small baseline subset (SBAS) InSAR method and persistent scatterers (PS) InSAR method is used to multi-track Envisat ASAR data to retrieve the large scale land subsidence covering entire Fenwei basin, from which different land subsidence magnitudes are analyzed of different sub-basins. Secondly, PS-InSAR method is used to monitor the small scale ground fissure deformation in Yuncheng basin, where different spatial deformation gradient can be clearly discovered. Lastly, different track SAR data are contributed to retrieve two-dimensional deformation in both land subsidence and ground fissure region, Xi'an, China, which can be benefitial to explain the occurrence of ground fissure and the correlation between land subsidence and ground fissure.

  11. Investigation of ionospheric effects on SAR Interferometry (InSAR): A case study of Hong Kong

    NASA Astrophysics Data System (ADS)

    Zhu, Wu; Ding, Xiao-Li; Jung, Hyung-Sup; Zhang, Qin; Zhang, Bo-Chen; Qu, Wei

    2016-08-01

    Synthetic Aperture Radar Interferometry (InSAR) has demonstrated its potential for high-density spatial mapping of ground displacement associated with earthquakes, volcanoes, and other geologic processes. However, this technique may be affected by the ionosphere, which can result in the distortions of Synthetic Aperture Radar (SAR) images, phases, and polarization. Moreover, ionospheric effect has become and is becoming further significant with the increasing interest in low-frequency SAR systems, limiting the further development of InSAR technique. Although some research has been carried out, thorough analysis of ionospheric influence on true SAR imagery is still limited. Based on this background, this study performs a thorough investigation of ionospheric effect on InSAR through processing L-band ALOS-1/PALSAR-1 images and dual-frequency Global Positioning System (GPS) data over Hong Kong, where the phenomenon of ionospheric irregularities often occurs. The result shows that the small-scale ionospheric irregularities can cause the azimuth pixel shifts and phase advance errors on interferograms. Meanwhile, it is found that these two effects result in the stripe-shaped features in InSAR images. The direction of the stripe-shaped effects keep approximately constant in space for our InSAR dataset. Moreover, the GPS-derived rate of total electron content change index (ROTI), an index to reflect the level of ionospheric disturbances, may be a useful indicator for predicting the ionospheric effect for SAR images. This finding can help us evaluate the quality of SAR images when considering the ionospheric effect.

  12. Potential contribution of ENVISAT ASAR alternating polarisation and Wide-Swath modes images for crop discrimination at the regional scale

    NASA Astrophysics Data System (ADS)

    Blaes, X.; Holeck, F.; Defourny, P.

    2002-01-01

    This experimental study was carried out in the framework of the DUP project "Dedicated Remote Sensing Product Generation for the Agro-Industry: Cereal Case" leaded by Synoptics b.v. (NL). The main objective is to investigate the potential contribution of the ENVISAT images for the discrimination of the main crops at a regional scale. ASAR Alternating Polarisation (AP and Wide Swath (WS) modes have been simulated from 15 ERS images over Belgium. A quantitative approach was completed using 791 parcels corresponding to the following crops: winter wheat, winter barley, spring wheat, spring barley, grasses, sugar beet, maize and potato. The impact of the spatial resolution of the ASAR sensor is assessed through the comparison of the results obtained for the AP (30m) and WS (150m) modes with regards to the field size. Both pixel-based and parcel-based unsupervised classification approaches have been applied. Dedicated interpretation schemes were developed for specific crop discrimination. The promising results obtained from the 150-m ASAR signal are expected to be further enhanced by the very high acquisition rate of the WS mode, i.e. an acquisition every 3 to 5 days.

  13. Federated query services provided by the Seamless SAR Archive project

    NASA Astrophysics Data System (ADS)

    Baker, S.; Bryson, G.; Buechler, B.; Meertens, C. M.; Crosby, C. J.; Fielding, E. J.; Nicoll, J.; Youn, C.; Baru, C.

    2013-12-01

    The NASA Advancing Collaborative Connections for Earth System Science (ACCESS) seamless synthetic aperture radar (SAR) archive (SSARA) project is a 2-year collaboration between UNAVCO, the Alaska Satellite Facility (ASF), the Jet Propulsion Laboratory (JPL), and OpenTopography at the San Diego Supercomputer Center (SDSC) to design and implement a seamless distributed access system for SAR data and derived data products (i.e. interferograms). A major milestone for the first year of the SSARA project was a unified application programming interface (API) for SAR data search and results at ASF and UNAVCO (WInSAR and EarthScope data archives) through the use of simple web services. A federated query service was developed using the unified APIs, providing users a single search interface for both archives (http://www.unavco.org/ws/brokered/ssara/sar/search). A command line client that utilizes this new service is provided as an open source utility for the community on GitHub (https://github.com/bakerunavco/SSARA). Further API development and enhancements added more InSAR specific keywords and quality control parameters (Doppler centroid, faraday rotation, InSAR stack size, and perpendicular baselines). To facilitate InSAR processing, the federated query service incorporated URLs for DEM (from OpenTopography) and tropospheric corrections (from the JPL OSCAR service) in addition to the URLs for SAR data. This federated query service will provide relevant QC metadata for selecting pairs of SAR data for InSAR processing and all the URLs necessary for interferogram generation. Interest from the international community has prompted an effort to incorporate other SAR data archives (the ESA Virtual Archive 4 and the DLR TerraSAR-X_SSC Geohazard Supersites and Natural Laboratories collections) into the federated query service which provide data for researchers outside the US and North America.

  14. Real time SAR processing

    NASA Technical Reports Server (NTRS)

    Premkumar, A. B.; Purviance, J. E.

    1990-01-01

    A simplified model for the SAR imaging problem is presented. The model is based on the geometry of the SAR system. Using this model an expression for the entire phase history of the received SAR signal is formulated. From the phase history, it is shown that the range and the azimuth coordinates for a point target image can be obtained by processing the phase information during the intrapulse and interpulse periods respectively. An architecture for a VLSI implementation for the SAR signal processor is presented which generates images in real time. The architecture uses a small number of chips, a new correlation processor, and an efficient azimuth correlation process.

  15. Ionospheric Specifications for SAR Interferometry (ISSI)

    NASA Technical Reports Server (NTRS)

    Pi, Xiaoqing; Chapman, Bruce D; Freeman, Anthony; Szeliga, Walter; Buckley, Sean M.; Rosen, Paul A.; Lavalle, Marco

    2013-01-01

    The ISSI software package is designed to image the ionosphere from space by calibrating and processing polarimetric synthetic aperture radar (PolSAR) data collected from low Earth orbit satellites. Signals transmitted and received by a PolSAR are subject to the Faraday rotation effect as they traverse the magnetized ionosphere. The ISSI algorithms combine the horizontally and vertically polarized (with respect to the radar system) SAR signals to estimate Faraday rotation and ionospheric total electron content (TEC) with spatial resolutions of sub-kilometers to kilometers, and to derive radar system calibration parameters. The ISSI software package has been designed and developed to integrate the algorithms, process PolSAR data, and image as well as visualize the ionospheric measurements. A number of tests have been conducted using ISSI with PolSAR data collected from various latitude regions using the phase array-type L-band synthetic aperture radar (PALSAR) onboard Japan Aerospace Exploration Agency's Advanced Land Observing Satellite mission, and also with Global Positioning System data. These tests have demonstrated and validated SAR-derived ionospheric images and data correction algorithms.

  16. Forest and Forest Change Mapping with C- and L-band SAR in Liwale, Tanzania

    NASA Astrophysics Data System (ADS)

    Haarpaintner, J.; Davids, C.; Hindberg, H.; Zahabu, E.; Malimbwi, R. E.

    2015-04-01

    As part of a Tanzanian-Norwegian cooperation project on Monitoring Reporting and Verification (MRV) for REDD+, 2007-2011 Cand L-band synthetic aperture radar (SAR) backscatter data from Envisat ASAR and ALOS Palsar, respectively, have been processed, analysed and used for forest and forest change mapping over a study side in Liwale District in Lindi Region, Tanzania. Land cover observations from forest inventory plots of the National Forestry Resources Monitoring and Assessment (NAFORMA) project have been used for training Gaussian Mixture Models and k-means classifier that have been combined in order to map the study region into forest, woodland and non-forest areas. Maximum forest and woodland extension masks have been extracted by classifying maximum backscatter mosaics in HH and HV polarizations from the 2007-2011 ALOS Palsar coverage and could be used to map efficiently inter-annual forest change by filtering out changes in non-forest areas. Envisat ASAR APS (alternate polarization mode) have also been analysed with the aim to improve the forest/woodland/non-forest classification based on ALOS Palsar. Clearly, the combination of C-band SAR and L-band SAR provides useful information in order to smooth the classification and especially increase the woodland class, but an overall improvement for the wall-to-wall land type classification has yet to be confirmed. The quality assessment and validation of the results is done with very high resolution optical data from WorldView, Ikonos and RapidEye, and NAFORMA field observations.

  17. Advanced DInSAR analysis for building damage assessment in large urban areas: an application to the city of Roma, Italy

    NASA Astrophysics Data System (ADS)

    D'Aranno, Peppe J. V.; Marsella, Maria; Scifoni, Silvia; Scutti, Marianna; Sonnessa, Alberico; Bonano, Manuela

    2015-10-01

    Remote sensing data play an important role for the environmental monitoring because they allow to provide systematic information on very large areas and for a long period of time. Such information must be analyzed, validated and incorporated into proper modeling tools in order to become useful for performing risk assessment analysis. These approaches has been already applied in the field of natural hazard evaluation (i.e. for monitoring seismic, volcanic areas and landslides). However, not enough attention has been devoted to the development of validated methods for implementing quantitative analysis on civil structures. This work is dedicated to the comprehensive utilization of ERS / ENVISAT data store ESA SAR used to detect deformation trends and perform back-analysis of the investigated structures useful to calibrate the damage assessment models. After this preliminary analysis, SAR data of the new satellite mission (ie Cosmo SkyMed) were adopted to monitor the evolution of existent surface deformation processes and to detect new occurrence. The specific objective was to set up a data processing and data analysis chain tailored on a service that sustains the safe maintenance of the built-up environment, including critical construction such as public (schools, hospital, etc), strategic (dam, highways, etc) and also the cultural heritage sites. The analysis of the test area, in the southeastern sector of Roma, has provided three different levels and sub-levels of products from metropolitan area scale (territorial analysis), settlement scale (aggregated analysis) to single structure scale (damage degree associated to the structure).

  18. Complex faulting in the Quetta Syntaxis: fault source modeling of the October 28, 2008 earthquake sequence in Baluchistan, Pakistan, based on ALOS/PALSAR InSAR data

    NASA Astrophysics Data System (ADS)

    Usman, Muhammad; Furuya, Masato

    2015-09-01

    The Quetta Syntaxis in western Baluchistan, Pakistan, is the result of an oroclinal bend of the western mountain belt and serves as a junction for different faults. As this area also lies close to the left-lateral strike-slip Chaman fault, which marks the boundary between the Indian and Eurasian plates, the resulting seismological behavior of this regime is very complex. In the region of the Quetta Syntaxis, close to the fold and thrust belt of the Sulaiman and Kirthar Ranges, an earthquake with a magnitude of 6.4 (Mw) occurred on October 28, 2008, which was followed by a doublet on the very next day. Six more shocks associated with these major events then occurred (one foreshock and five aftershocks), with moment magnitudes greater than 4. Numerous researchers have tried to explain the source of this sequence based on seismological, GPS, and Environmental Satellite (ENVISAT)/Advanced Synthetic Aperture Radar (ASAR) data. Here, we used Advanced Land Observing Satellite (ALOS)/Phased Array-type L-band Synthetic Aperture Radar (PALSAR) InSAR data sets from both ascending and descending orbits that allow us to more completely detect the deformation signals around the epicentral region. The results indicated that the shock sequence can be explained by two right-lateral and two left-lateral strike-slip faults that also included reverse slip. The right-lateral faults have a curved geometry. Moreover, whereas previous studies have explained the aftershock crustal deformation with a different fault source, we found that the same left-lateral segment of the conjugate fault was responsible for the aftershocks. We thus confirmed the complex surface deformation signals from the moderate-sized earthquake. Intra-plate crustal bending and shortening often seem to be accommodated as conjugate faulting, without any single preferred fault orientation. We also detected two possible landslide areas along with the crustal deformation pattern.

  19. Land Subsidence Detection in Agricultural Areas of Konya Closed Basin by PS-InSAR and GNSS Observations

    NASA Astrophysics Data System (ADS)

    Canaslan Comut, Fatma; Lazecky, Milan; Ustun, Aydin; Yalvack, Sefa

    2015-05-01

    The aim of this study is to determine and to monitor the areas affected by land subsidence caused by the decrease of groundwater, by using geodetic methods in Konya Closed Basin, Turkey. The GPS and InSAR techniques which complement each other perfectly will be used to deduce spatial deformations caused by the land subsidence. The land subsidence activity in the area of Küçükköy situated at the Konya Closed Basin (KCB) of the Central Anatolia Region in Turkey has been studied using the Stanford Method for Persistent Scatterers (StaMPS) InSAR technique. Significant movements of land subsidence ranging from mm to cm per year were detected with ENVISAT ASAR data between 2003 and 2010 above the city center. Results are also compared with GNSS measurements. Estimated deformation rate of KCKY GPS station is approximately - 2 cm/yr.

  20. SAR image registration in absolute coordinates using GPS carrier phase position and velocity information

    SciTech Connect

    Burgett, S.; Meindl, M.

    1994-09-01

    It is useful in a variety of military and commercial application to accurately register the position of synthetic aperture radar (SAR) imagery in absolute coordinates. The two basic SAR measurements, range and doppler, can be used to solve for the position of the SAR image. Imprecise knowledge of the SAR collection platform`s position and velocity vectors introduce errors in the range and doppler measurements and can cause the apparent location of the SAR image on the ground to be in error by tens of meters. Recent advances in carrier phase GPS techniques can provide an accurate description of the collection vehicle`s trajectory during the image formation process. In this paper, highly accurate carrier phase GPS trajectory information is used in conjunction with SAR imagery to demonstrate a technique for accurate registration of SAR images in WGS-84 coordinates. Flight test data will be presented that demonstrates SAR image registration errors of less than 4 meters.

  1. Local interpolation of coseismic displacements measured by InSAR

    NASA Astrophysics Data System (ADS)

    Yaseen, M.; Hamm, N. A. S.; Woldai, T.; Tolpekin, V. A.; Stein, A.

    2013-08-01

    Coseismic displacements play a significant role in characterizing earthquake causative faults and understanding earthquake dynamics. They are typically measured from InSAR using pre- and post-earthquake images. The displacement map produced by InSAR may contain missing coseismic values due to the decorrelation of ASAR images. This study focused on interpolating missing values in the coseismic displacement map of the 2003 Bam earthquake using geostatistics with the aim of running a slip distribution model. The gaps were grouped into 23 patches. Variograms of the patches showed that the displacement data were spatially correlated. The variogram prepared for ordinary kriging (OK) indicated the presence of a trend and thus justified the use of universal kriging (UK). Accuracy assessment was performed in 3 ways. First, 11 patches of equal size and with an equal number of missing values generated artificially, were kriged and validated. Second, the four selected patches results were validated after shifting them to new locations without missing values and comparing them with the observed values. Finally, cross validation was performed for both types of patch at the original and shifted locations. UK results were better than OK in terms of kriging variance, mean error (ME) and root mean square error (RMSE). For both OK and UK, only 4 out of 23 patches (1, 5, 11 and 21) showed ME and RMSE values that were substantially larger than for the other patches. The accuracy assessment results were found to be satisfactory with ME and RMSE values close to zero. InSAR data inversion demonstrated the usefulness of interpolation of the missing coseismic values by improving a slip distribution model. It is therefore concluded that kriging serves as an effective tool for interpolating the missing values on a coseismic displacement map.

  2. Monitoring and analyzing surface subsidence based on SBAS-InSAR in Beijing region, China

    NASA Astrophysics Data System (ADS)

    Zhou, L.; Guo, J. M.; Li, X.

    2015-12-01

    Surface subsidence is the main regional environmental geological disaster in plain area in China. The rapid growth of population, the over-exploitation of groundwater and the rapid development of urbanization impacts the occurrence and development of surface subsidence to some extent. The city of Beijing, located in the Beijing Plain, is one of international metropolis in China that experiences the severe surface subsidence. Because of conventional measurement methods with low spatial resolution, differential interferometric synthetic aperture radar(D-InSAR) is susceptible to signal decorrelation and atmospheric delay, persistent scatterer interferometric synthetic aperture radar(PS-InSAR) is based on a large number of SAR images, but small baseline subset interferometric synthetic aperture radar (SBASInSAR) only needs a small number of images and performs better than PS-InSAR for obtaining nonlinear deformation information, in this paper, SBAS-InSAR was used to obtain the high resolution surface subsidence information in Beijing region, China. A spatial-temporal analysis of the surface subsidence in Beijing region during the years of 2007- 2010 was performed utilizing eighteen C-band ENVISAT ASAR images (from August 1, 2007 to September 29, 2010). The results show that subsidence in Beijing region is severe uneven, subsidence funnels appear in Changping District, Shunyi District, Tongzhou District, Daxing District, etc., and many subsidence funnels are interconnected and have an eastward expansion trend; during the period of 2007 to 2010, the subsidence velocities are in the range of -158.5 mm/year to 12.4 mm/year and the maximum subsidence of subsidence center is over 400 mm; surface subsidence is influenced by groundwater exploitation and urbanization significantly.

  3. On the assessment of re-assimilation of ASAR Wave Spectra in the ERA-Interim Reanalysis

    NASA Astrophysics Data System (ADS)

    Bué, Isabel; Semedo, Alvaro; Aouf, Lotfi; Catalão, João

    2016-04-01

    The Sentinel-1A satellite, launched on April 3 2014, is the first of the new European Spatial Agency (ESA) missions developed for the Copernicus initiative. The European Earth observations program Copernicus will offer vital environmental information for the global monitoring of climate, for meteorological forecast, as well as for new security aspects concerning environment catastrophes. The Sentinel-1 platform will ensure the continuity of global wave spectra measurements from space, already available since 1991 with ERS-1, ERS-2 and ENVISAT/ASAR, thanks to one mode of acquisition that is dedicated to swell measurements in open ocean, the wave mode. This satellite constellation comprises two polar orbiting satellites, operating in a tandem mode, with the second (the Sentinel 1B), sharing the same orbital plane with a 180° orbital phasing difference, being launched during 2016. The satellites will perform as a C-band ASAR imagers and will operate day and night, regardless of the weather. In this study significant wave height (SWH) comparisons between wave altimetry measurements from ERS-2 and ENVISAT and several wave buoy measurements in the North Atlantic, and the ECMWF (European Centre for Medium-Range Weather Forecasts) ERA-Interim reanalysis, are presented trough the triple-collocation method. The triple collocation method is needed to use all the different data (due to the different acquisitions, resolutions, time and space positioning), having the buoy positions as the key element for the positioning of all measurements. The triple collocated data will then be compared with SWH computed from the wave spectra retrievals from the ENVISAT ASAR wave mode. After that the ERA-Interim wave spectra is statistically corrected with the ENVISAT measured spectra, with an evaluation of the gains of this process.

  4. SAR calibration technology review

    NASA Technical Reports Server (NTRS)

    Walker, J. L.; Larson, R. W.

    1981-01-01

    Synthetic Aperture Radar (SAR) calibration technology including a general description of the primary calibration techniques and some of the factors which affect the performance of calibrated SAR systems are reviewed. The use of reference reflectors for measurement of the total system transfer function along with an on-board calibration signal generator for monitoring the temporal variations of the receiver to processor output is a practical approach for SAR calibration. However, preliminary error analysis and previous experimental measurements indicate that reflectivity measurement accuracies of better than 3 dB will be difficult to achieve. This is not adequate for many applications and, therefore, improved end-to-end SAR calibration techniques are required.

  5. Monitoring Structure and Regional-Level Displacements for Lisbon Using Mltitemporal InSAR Techniques

    NASA Astrophysics Data System (ADS)

    Roque, Dora; Perissin, Daniele Falcao, Ana Paula; Fonseca, Ana Maria; Henriques, Maria Joao

    2015-05-01

    The city of Lisbon is the capital of Portugal and has been devastated by catastrophic events in the past, such as earthquakes and tsunamis. This study provides a regional analysis of displacements for the city and its neighbourhoods, between 2008 and 2010, through the application of mutitemporal InSAR techniques on Envisat ASAR images. Smaller areas with identified problems were subjected to a more refined processing. Besides, the behaviour of some key infrastructures, such as important buildings or railways, was carefully analysed in order to evaluate their safety. Subsidence was detected at the regional and small areas, in which the highest subsidence rates were verified on industrial parks or on landfills close to the river. Seasonal trends were found for the small areas, mainly related with structure thermal expansion or variations in underground water.

  6. Characteristics of short-period internal waves in the Kara Sea inferred from satellite SAR data

    NASA Astrophysics Data System (ADS)

    Kozlov, I. E.; Kudryavtsev, V. N.; Zubkova, E. V.; Zimin, A. V.; Chapron, B.

    2015-12-01

    In this paper we present the results of short-period internal wave (SIW) observations in the Kara Sea on the basis of satellite ENVISAT ASAR data between July and October 2007. Altogether, 248 internal wave (IW) packets and solitons are identified in 89 SAR images. Detailed spatial statistics of IW signatures and their properties in the Kara Sea is presented. The primary regions of IW activity are the areas near the Kara Gates Strait, the southeastern part of the Novaya Zemlya Trough, and in the vicinity of Cape Zhelaniya. We identify the regions where large IW packets are observed with wavelengths up to 2-3 km and the front length exceeding 200 km. The mean interpacket distance for observed IWs is about 20 km, but it may reach 50-60 km. Consequent IW packets are observed to travel up to 500 km from the presumed generation points. The results of satellite observations are compared with results of previous studies.

  7. Mapping tillage operations over peri-urban croplands using a synchronous SPOT4/ASAR ENVISAT pair and soil roughness measurements

    NASA Astrophysics Data System (ADS)

    Vaudour, Emmanuelle; Baghdadi, Nicolas; Gilliot, Jean-Marc

    2014-05-01

    Tillage operations (TOs) affect nutrient uptake, carbon sequestration, water and CO2 exchanges in soil, and therefore impact soil ecology together with biophysical processes such as soil erosion, leaching, run-off and infiltration. They are critical for parameterizing complex dynamic models of carbon and nitrogen. This study done in the framework of the Prostock-Gessol3 project presents an approach for mapping TOs of bare agricultural fields over a peri-urban area characterized by conventional tillage system in the western suburbs of Paris (France), combining synchronous SPOT4 and ENVISAT/ASAR images (HH and HV polarizations). Spatial modeling relied on 57 reference within-field areas named 'reference zones' (RZs) homogeneous for their soil properties, constructed in the vicinity of 57 roughness measurement locations and spread across 20 agricultural fields for which TOs were known. Soil roughness expressed as the standard deviation of surface height (Hrms) was estimated on the ground with a fully automatic photogrammetric method based on the processing of a set of overlapping pictures taken from different viewpoints from a simple digital camera all around a rectangular frame. The relationship was studied between the mean backscattering coefficient of the ASAR image and Hrms choosing a limited set of 28 RZs, on which successive random selections of training/validating RZs were then performed; the remaining 29 RZs were kept for validating the final map results. Six supervised per-pixel classifiers were used in order to map 2 TOs classes (seedbed&harrowed and late winter plough) in addition to 4 landuse classes (forest, urban,crops and grass, water bodies): support vector machine with polynomial kernel (pSVM), SVM with radial basis kernel (rSVM), artificial neural network (ANN), Maximum Likelihood (ML), regression tree (RT), and random forests (RF). All 6 classifiers were implemented in a bootstrapping approach in order to assess the uncertainty of map results. The

  8. A novel multi-band SAR data technique for fully automatic oil spill detection in the ocean

    NASA Astrophysics Data System (ADS)

    Del Frate, Fabio; Latini, Daniele; Taravat, Alireza; Jones, Cathleen E.

    2013-10-01

    With the launch of the Italian constellation of small satellites for the Mediterranean basin observation COSMO-SkyMed and the German TerraSAR-X missions, the delivery of very high-resolution SAR data to observe the Earth day or night has remarkably increased. In particular, also taking into account other ongoing missions such as Radarsat or those no longer working such as ALOS PALSAR, ERS-SAR and ENVISAT the amount of information, at different bands, available for users interested in oil spill analysis has become highly massive. Moreover, future SAR missions such as Sentinel-1 are scheduled for launch in the very next years while additional support can be provided by Uninhabited Aerial Vehicle (UAV) SAR systems. Considering the opportunity represented by all these missions, the challenge is to find suitable and adequate image processing multi-band procedures able to fully exploit the huge amount of data available. In this paper we present a new fast, robust and effective automated approach for oil-spill monitoring starting from data collected at different bands, polarizations and spatial resolutions. A combination of Weibull Multiplicative Model (WMM), Pulse Coupled Neural Network (PCNN) and Multi-Layer Perceptron (MLP) techniques is proposed for achieving the aforementioned goals. One of the most innovative ideas is to separate the dark spot detection process into two main steps, WMM enhancement and PCNN segmentation. The complete processing chain has been applied to a data set containing C-band (ERS-SAR, ENVISAT ASAR), X-band images (Cosmo-SkyMed and TerraSAR-X) and L-band images (UAVSAR) for an overall number of more than 200 images considered.

  9. Detecting Moorland Wildfire Scars and their Persistence in the Landscape using Synthetic Aperture Radar (SAR) in the Peak District National Park, UK

    NASA Astrophysics Data System (ADS)

    Millin-chalabi, G. R.; McMorrow, J.; Agnew, C.

    2012-12-01

    The overall aim of this research is to assess the ability of SAR to detect moorland wildfire scars and their persistence in the landscape using the Peak District National Park (PDNP) in the UK as a case study. Spatially-robust data to monitor wildfire scar size and severity in UK moorlands is currently rare. Fires can burn deep into peat soils and contribute to the release of carbon dioxide into the atmosphere and may also affect the water quality of nearby streams. Information on fire extent would be useful for conservation organisations such as Moors For The Future who are trying to preserve the delicate peatland environment. Knowing the size and location of fire scars would help the Fire and Rescue Service to plan future response to moorland fires. Fire scar boundaries can be mapped in the field using Global Positioning Systems (GPS), however this is labour intensive. Indeed in the PDNP wildfire scar mapping is conducted by park rangers which provides essential ground truth data for assessing against the SAR data. Therefore this particular area provides a unique opportunity for testing an alternative SAR technique for monitoring wildfire scars in the moorland landscape. Previous research shows that SAR has been successfully applied for wildfire scar detection in other types of environments such as boreal (Bourgeau-Chavez et al, 1997) and the tropics (Huang and Siegert, 2004). This research presents some of the first results of the project which tests the capability of ERS 2; ASAR (C-band) and PALSAR (L-band) data to detect several wildfire scars from 2003 - 2008 of various spatial scales and fire severity. Some of the key areas of interest the paper will explore are at Bleaklow and the Kinder plateau. The Bleaklow peat fire of 18th April 2003 was larger (7km2) and more severe than at Kinder, which burned between 26-29th May 2008 and covered an area of 10 ha. All the wildfire scars were GPS, mapped just after the fire event. Archival time-series SAR imagery was

  10. The Accuratre Signal Model and Imaging Processing in Geosynchronous SAR

    NASA Astrophysics Data System (ADS)

    Hu, Cheng

    With the development of synthetic aperture radar (SAR) application, the disadvantage of low earth orbit (LEO) SAR becomes more and more apparent. The increase of orbit altitude can shorten the revisit time and enlarge the coverage area in single look, and then satisfy the application requirement. The concept of geosynchronous earth orbit (GEO) SAR system is firstly presented and deeply discussed by K.Tomiyasi and other researchers. A GEO SAR, with its fine temporal resolution, would overcome the limitations of current imaging systems, allowing dense interpretation of transient phenomena as GPS time-series analysis with a spatial density several orders of magnitude finer. Until now, the related literatures about GEO SAR are mainly focused in the system parameter design and application requirement. As for the signal characteristic, resolution calculation and imaging algorithms, it is nearly blank in the related literatures of GEO SAR. In the LEO SAR, the signal model analysis adopts the `Stop-and-Go' assumption in general, and this assumption can satisfy the imaging requirement in present advanced SAR system, such as TerraSAR, Radarsat2 and so on. However because of long propagation distance and non-negligible earth rotation, the `Stop-and-Go' assumption does not exist and will cause large propagation distance error, and then affect the image formation. Furthermore the long propagation distance will result in the long synthetic aperture time such as hundreds of seconds, therefore the linear trajectory model in LEO SAR imaging will fail in GEO imaging, and the new imaging model needs to be proposed for the GEO SAR imaging processing. In this paper, considering the relative motion between satellite and earth during signal propagation time, the accurate analysis method for propagation slant range is firstly presented. Furthermore, the difference between accurate analysis method and `Stop-and-Go' assumption is analytically obtained. Meanwhile based on the derived

  11. Ground deformation monitoring using small baseline DInSAR technique: A case study in Taiyuan City from 2003 to 2009

    USGS Publications Warehouse

    Wu, H.-A.; Zhang, Y.-H.; Chen, X.-Y.; Lu, T.; Du, J.; Sun, Z.-H.; Sun, G.-T.

    2011-01-01

    DInSAR technique based on time series of SAR images has been very popular to monitor ground stow deformation in recent years such as permanent scatterers (PS) method small baseline subsets (SBAS) method and coherent targets (CT) method. By taking advantage of PS method and CT method in this paper small baseline DTnSAR technique is used to investigate the ground deformation of Taiyuan City Shanxi Province from 2003 to 2009 by using 23 ENVISAT ASAR images. The experiment results demonstrate that: (1) during this period four significant subsidence centers have been developed in Taiyuan namely Xiayuan Wujiabu Xiaodian Sunjiazhai. The largest subsidence center is Sunjiazhai with an average subsidence rate of -77. 28 mm/a; (2) The subsidence of the old center Wanbolin has sHowed down. And the subsidence in the northern region has stopped and some areas even rebounded. (3) The change of subsidence centers indicates that the control measures of "closing wells and reducing exploitation" taken by the Taiyuan government has achieved initial effects. (4) The experiment results have been validated with leveling data and the acouracy is 2. 90 mm which shows that the small baseline DInSAR technique can be used to monitor urban ground deformation.

  12. Sentinel-3 SAR Altimetry Toolbox

    NASA Astrophysics Data System (ADS)

    Benveniste, Jerome; Lucas, Bruno; DInardo, Salvatore

    2015-04-01

    The prime objective of the SEOM (Scientific Exploitation of Operational Missions) element is to federate, support and expand the large international research community that the ERS, ENVISAT and the Envelope programmes have build up over the last 20 years for the future European operational Earth Observation missions, the Sentinels. Sentinel-3 builds directly on a proven heritage of ERS-2 and Envisat, and CryoSat-2, with a dual-frequency (Ku and C band) advanced Synthetic Aperture Radar Altimeter (SRAL) that provides measurements at a resolution of ~300m in SAR mode along track. Sentinel-3 will provide exact measurements of sea-surface height along with accurate topography measurements over sea ice, ice sheets, rivers and lakes. The first of the two Sentinels is expected to be launched in early 2015. The current universal altimetry toolbox is BRAT (Basic Radar Altimetry Toolbox) which can read all previous and current altimetry mission's data, but it does not have the capabilities to read the upcoming Sentinel-3 L1 and L2 products. ESA will endeavour to develop and supply this capability to support the users of the future Sentinel-3 SAR Altimetry Mission. BRAT is a collection of tools and tutorial documents designed to facilitate the processing of radar altimetry data. This project started in 2005 from the joint efforts of ESA (European Space Agency) and CNES (Centre National d'Etudes Spatiales), and it is freely available at http://earth.esa.int/brat. The tools enable users to interact with the most common altimetry data formats, the BratGUI is the front-end for the powerful command line tools that are part of the BRAT suite. BRAT can also be used in conjunction with Matlab/IDL (via reading routines) or in C/C++/Fortran via a programming API, allowing the user to obtain desired data, bypassing the data-formatting hassle. BRAT can be used simply to visualise data quickly, or to translate the data into other formats such as netCDF, ASCII text files, KML (Google Earth

  13. PHARUS airborne SAR concept

    NASA Astrophysics Data System (ADS)

    Snoeij, Paul; Pouwels, Henk; Koomen, Peter J.; Hoogeboom, Peter

    1995-11-01

    PHARUS (phased array universal SAR) is an airborne SAR concept which is being developed in the Netherlands. The PHARUS system differs from other airborne SARs by the use of a phased array antenna, which provides both for the flexibility in the design as well as for a compact, light-weight instrument that can be carried on small aircraft. The concept allows for the construction of airborne SAR systems on a common generic basis but tailored to specific user needs and can be seen as a preparation for future spaceborne SAR systems using solid state transmitters with electronically steerable phased array antenna. The whole approach is aimed at providing an economic and yet technically sophisticated solution to remote sensing or surveying needs of a specific user. The solid state phased array antenna consists of a collection of radiating patches; the design flexibility for a large part resides in the freedom to choose the number of patches, and thereby the essential radar performance parameters such as resolution and swath width. Another consequence of the use of the phased array antenna is the system's compactness and the possibility to rigidly mount it on a small aircraft. The use of small aircraft of course considerably improves the cost/benefit ratio of the use of airborne SAR. Flight altitude of the system is flexible between about 7,000 and 40,000 feet, giving much operational freedom within the meteo and airspace control limits. In the PHARUS concept the airborne segment is complemented by a ground segment, which consists of a SAR processor, possibly extended by a matching image processing package. (A quick look image is available in real-time on board the aircraft.) The SAR processor is UNIX based and runs on easily available hardware (SUN station). Although the additional image processing software is available, the SAR processing software is nevertheless designed to be able to interface with commercially available image processing software, as well as being able

  14. Landslide risk assessment with multi pass DInSAR analysis and error suppressing approach

    NASA Astrophysics Data System (ADS)

    yun, H.; Kim, J.; Lin, S.; Choi, Y.

    2013-12-01

    ) which was newly developed for extracting the reliable deformation values even with the presence of error terms and two pass DInSAR with the error term compensation based on the external weather information using L band ALOS PALSAR and C band ENVISAT ASAR. Since MERIS Reduced Resolution (RR) coverage over target areas includes a few cloud free scenes, the water vapor map constructions were feasible with 1.2km spatial resolutions in two pass DInSAR pairs and enable to assess the deformation measurement of StaMPS/MTI by the inter comparison. Although the correlation between deformation patterns from two pass DInSAR and StaMPS was not very clearly identified in this study, the deformation values and the landslide triggering factors showed some agreements. Thus the quantitative landslide monitoring scheme is supposedly feasible on the condition that the high accuracy atmospheric error map and the methodology effectively compensating it from DInSAR interferograms are available. The scheme in this study will be further upgraded for the application of future C, X and L band SAR by incorporating the spaceborne radiometer and/or weather forecasting model to establish electromagnetic wave delay map.

  15. Hybrid polarity SAR architecture

    NASA Astrophysics Data System (ADS)

    Raney, R. Keith

    2009-05-01

    A space-based synthetic aperture radar (SAR) designed to provide quantitative information on a global scale implies severe requirements to maximize coverage and to sustain reliable operational calibration. These requirements are best served by the hybrid-polarity architecture, in which the radar transmits in circular polarization, and receives on two orthogonal linear polarizations, coherently, retaining their relative phase. This paper summarizes key attributes of hybrid-polarity dual- and quadrature-polarized SARs, reviews the associated advantages, formalizes conditions under which the signal-to-noise ratio is conserved, and describes the evolution of this architecture from first principles.

  16. Polarization effects and multipolarization SAR

    NASA Technical Reports Server (NTRS)

    Freeman, Anthony

    1992-01-01

    Imaging radar polarimeters are usually implemented using a Synthetic Aperture Radar (SAR) approach to give a high resolution image in two dimensions: range and azimuth. For each pixel in the image a polarimetric SAR gives sufficient information to characterize the polarimetric scattering properties of the imaged area (or target) as seen by the radar. Using a polarimetric SAR system as opposed to a single-polarization SAR system provides significantly more information about the target scattering mechanisms and allows better discrimination between different types of surfaces. In these notes a brief overview of SAR polarimetry is offered. The notes are intended as a text to accompany a lecture on SAR polarimetry as part of an AGARD-NATO course. Covered in the notes are the following: the polarization properties of electromagnetic waves; the concepts of radar scattering and measuring radar backscatter with a SAR; polarization synthesis; scattering matrix, Stokes matrix, and covariance matrix representations of polarimetric SAR data; polarization signature plots; design and calibration of polarimetric SAR systems; polarization filtering for target detection; fitting a simple model to polarimetric SAR measurements of naturally occurring features; and supervised classification of polarimetric SAR data.

  17. Bistatic SAR: Proof of Concept.

    SciTech Connect

    Yocky, David A.; Doren, Neall E.; Bacon, Terry A.; Wahl, Daniel E.; Eichel, Paul H.; Jakowatz, Charles V,; Delaplain, Gilbert G.; Dubbert, Dale F.; Tise, Bertice L.; White, Kyle R.

    2014-10-01

    Typical synthetic aperture RADAR (SAR) imaging employs a co-located RADAR transmitter and receiver. Bistatic SAR imaging separates the transmitter and receiver locations. A bistatic SAR configuration allows for the transmitter and receiver(s) to be in a variety of geometric alignments. Sandia National Laboratories (SNL) / New Mexico proposed the deployment of a ground-based RADAR receiver. This RADAR receiver was coupled with the capability of digitizing and recording the signal collected. SNL proposed the possibility of creating an image of targets the illuminating SAR observes. This document describes the developed hardware, software, bistatic SAR configuration, and its deployment to test the concept of a ground-based bistatic SAR. In the proof-of-concept experiments herein, the RADAR transmitter will be a commercial SAR satellite and the RADAR receiver will be deployed at ground level, observing and capturing RADAR ground/targets illuminated by the satellite system.

  18. Monitoring of land subsidence and ground fissures in Xian, China 2005-2006: Mapped by sar Interferometry

    USGS Publications Warehouse

    Zhao, C.Y.; Zhang, Q.; Ding, X.-L.; Lu, Zhiming; Yang, C.S.; Qi, X.M.

    2009-01-01

    The City of Xian, China, has been experiencing significant land subsidence and ground fissure activities since 1960s, which have brought various severe geohazards including damages to buildings, bridges and other facilities. Monitoring of land subsidence and ground fissure activities can provide useful information for assessing the extent of, and mitigating such geohazards. In order to achieve robust Synthetic Aperture Radar Interferometry (InSAR) results, six interferometric pairs of Envisat ASAR data covering 2005-2006 are collected to analyze the InSAR processing errors firstly, such as temporal and spatial decorrelation error, external DEM error, atmospheric error and unwrapping error. Then the annual subsidence rate during 2005-2006 is calculated by weighted averaging two pairs of D-InSAR results with similar time spanning. Lastly, GPS measurements are applied to calibrate the InSAR results and centimeter precision is achieved. As for the ground fissure monitoring, five InSAR cross-sections are designed to demonstrate the relative subsidence difference across ground fissures. In conclusion, the final InSAR subsidence map during 2005-2006 shows four large subsidence zones in Xian hi-tech zones in western, eastern and southern suburbs of Xian City, among which two subsidence cones are newly detected and two ground fissures are deduced to be extended westward in Yuhuazhai subsidence cone. This study shows that the land subsidence and ground fissures are highly correlated spatially and temporally and both are correlated with hi-tech zone construction in Xian during the year of 2005-2006. ?? Springer-Verlag 2008.

  19. Satellite SAR data assessment for Silk Road archaeological prospection

    NASA Astrophysics Data System (ADS)

    Chen, Fulong; Lasaponara, Rosa; Masini, Nicola; Yang, Ruixia

    2015-04-01

    direction of observed targets is beneficial for improved detection of potential linear remains (e.g. Great Wall in Han-dynasty surrounding the Yumen Frontier Pass) owing to the formation of dihedral and helix scatterings based on the theory of radar physics. Morevorer, spatial resolution of multi-mode SAR images for archaeology was compared in the sites of Niya, Yumen Frontier Pass and suspected protectorate of the western regions. Results indicated that high resolution tended to easier detection of ancient targets through the identification of backscattering anomalies. Finally, interferometric analysis was also evaluated to provide complementary information rather than the backscattering. The variation of coherence is closely related to the physical parameters of observed surface, e.g. soil moisture, mild-relief as well as materials; and consequently it is useful for the relic feature enhancement and identification, validated by the PALSAR coherence images in Niya site. Acknowledgement This research was performed within the framework of the project "Smart management of cultural heritage sites in Italy and China: Earth Observation and pilot projects", funded by the Italian Ministry of Foreign Affairs and the Hundred Talents Program of the Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences (Y2ZZ27101B). The PALSAR data were provided by the European Space Agency to the authors through the Category-1 Project Id. 28640. Reference [1] Lasaponara R., Masini N. 2013, Satellite Synthetic Aperture Radar in Archaeology and Cultural Landscape: An Overview. Archaeological Prospection, 20, 71-78, doi: 10.1002/arp.1452 [2] Chen F., Masini N., Yang R., Milillo P., Feng D., Lasaponara R., 2015 A Space View of Radar Archaeological Marks: First Applications of COSMO-SkyMed X-Band Data. Remote Sens. 2015, 7, 24-50; doi:10.3390/rs70100024. [3] Cigna, F.; Tapete, D.; Lasaponara, R.; Masini, N. Amplitude change detection with Envisat ASAR to image the cultural landscape

  20. A Study of Linear Approximation Techniques for SAR Azimuth Processing

    NASA Technical Reports Server (NTRS)

    Martinson, L. W.; Perry, R. P.; Liu, B.

    1979-01-01

    The application of the step transform subarray processing techniques to synthetic aperture radar (SAR) was studied. The subarray technique permits the application of efficient digital transform computational techniques such as the fast Fourier transform to be applied while offering an effective tool for range migration compensation. Range migration compensation is applied at the subarray level, and with the subarray size based on worst case range migration conditions, a minimum control system is achieved. A baseline processor was designed for a four-look SAR system covering approximately 4096 by 4096 SAR sample field every 2.5 seconds. Implementation of the baseline system was projected using advanced low power technologies. A 20 swath is implemented with approximately 1000 circuits having a power dissipation of from 70 to 195 watts. The baseline batch step transform processor is compared to a continuous strip processor, and variations of the baseline are developed for a wide range of SAR parameters.

  1. Soil moisture estimation using synergy of optical, SAR, and topographic data with Gaussian Process Regression

    NASA Astrophysics Data System (ADS)

    Stamenkovic, J.; Notarnicola, C.; Spindler, N.; Cuozzo, G.; Bertoldi, G.; Della Chiesa, S.; Niedrist, G.; Greifeneder, F.; Tuia, D.; Borgeaud, M.; Thiran, J.-Ph.

    2014-10-01

    In this work we address the synergy of optical, SAR (Synthetic Aperture Radar) and topographic data in soil moisture retrieval over an Alpine area. As estimation technique, we consider Gaussian Process Regression (GPR). The test area is located in South Tyrol, Italy where the main land types are meadows and pastures. Time series of ASAR Wide Swath - SAR, optical, topographic and ancillary data (meteorological information and snow cover maps) acquired repetitively in 2010 were examined. Regarding optical data, we used both, daily MODIS reflectances, and daily NDVI, interpolated from the 16-day MODIS composite. Slope, elevation and aspect were extracted from a 2.5 m DEM (Digital Elevation Model) and resampled to 10 m. Daily soil moisture measurements were collected in the three fixed stations (two located in meadows and one located in pasture). The snow maps were used to mask the points covered by snow. The best performance was obtained by adding MODIS band 6 at 1640 nm to SAR and DEM features. The corresponding coefficient of determination, R2, was equal to 0.848, and the root mean square error, RMSE, to 5.4 % Vol. Compared to the case when no optical data were considered, there was an increase of ca. 0.05 in R2 and a decrease in RMSE of ca. 0.7 % Vol. This work showed that the joint use of NDVI or water absorption reflectance with SAR and topographic data can improve the estimation of soil moisture in specific Alpine area and that GPR is an effective method for estimation.

  2. A study of mining-induced subsidence in Hebi coalfield based on D-InSAR

    NASA Astrophysics Data System (ADS)

    Ma, Chao

    2014-11-01

    The aim of obtaining a continuous space distribution of mining-induced subsidence in a large scale, damage intensity, and its dynamic evolution, furthermore understanding the rule of the subsidence, is extracts finally the surface movement parameters of the mining-induced subsidence. Using 9 issues of ENVISAT ASAR data over 2009 year and by both of DInSAR processing algorithms, an atmospheric effect can eliminate and real subsidence region can be determined by a cumulative phase 2 PASS D-InSAR, and a temporal decoherence effect can be reduced and each stage deformation can be extracted by an adjacent phase 2 PASS D-InSAR. Results are as follows: (1) 8 phase variation regions according with the criterion of mining subsidence are extracted from 70 phase variation regions with the two methods of D-InSAR. (2) 16 main profiles (along with the strike, dip) of subsidence contained in 8 typical subsidence basins are obtained. Annual maximum subsidence reaches -210.0mm during the period of image acquisitions, from Jan. to Sep. 2009, the maximum rate is ±1.2 mm/d, and the average daily subsidence rate is ±0.60mm/d. (3) Sampling the minimum Standard Deviation (SD) is ± 4.3 mm, maximum SD is ± 8.1mm, and the total SD Mean is ± 5.9mm. Root Mean Square Error (RMSE) of data processing is ± 0.41 mm, the maximum RMSE is ± 0.74 mm, total average RMSE of observations is ± 0.55mm. The monitoring accuracy is self-consistent at sub-centimeter level, and it can reveal the rule of mining subsidence and extract partly parameters of mining damage. The result presents also that mine surface by the impact of mining activities are frequent and severe, deterioration of surface stability, and the risk of collapse, slip or mudslides is higher than outside coalfield.

  3. 3D SAR approach to IF SAR processing

    NASA Astrophysics Data System (ADS)

    Doerry, Armin W.; Bickel, Doug

    2000-08-01

    Interferometric SAR (IFSAR) can be shown to be a special case of 3-D SAR image formation. In fact, traditional IFSAR processing results in the equivalent of merely a super- resolved, under-sampled, 3-D SAR image. However, when approached as a 3-D SAR problem, a number of IFSAR properties and anomalies are easily explained. For example, IFSAR decorrelation with height is merely ordinary migration in 3-D SAR. Consequently, treating IFSAR as a 3-D SAR problem allows insight and development of proper motion compensation techniques and image formation operations to facilitate optimal height estimation. Furthermore, multiple antenna phase centers and baselines are easily incorporated into this formulation, providing essentially a sparse array in the elevation dimension. This paper shows the Polar Format image formation algorithm extended to 3 dimensions, and then proceeds to apply it to the IFSAR collection geometry. This suggests a more optimal reordering of the traditional IFSAR processing steps.

  4. Terrain-Corrected Gamma: Improved Thematic Land-Cover Retrieval for SAR with Robust Radiometric Terrain Correction

    NASA Astrophysics Data System (ADS)

    Small, David; Miranda, Nuno; Zuberbuhler, Lukas; Schubert, Adrian; Meier, Erich

    2010-12-01

    In regions with significant terrain variations, the modulation of SAR backscatter by mountain slopes can dominate interpretation of the radar imagery unless effective countermeasures are first applied. We first demonstrate deficiencies in conventional radiometric treatments. Geocoded-terrain-corrected (GTC) products assume an ellipsoid-model for the radiometry, even if they improve upon geocoded-ellipsoid-corrected (GEC) imagery by properly compensating for the effects of terrain variations on image geometry. Both the sigma nought and gamma nought radiometric normalisation conventions as applied to distributed targets have an ellipsoidal Earth assumption at their core. Simply using a local-incidence-angle-mask (LIM) to normalise image radiometry fails to adequately model the image formation process. We prefer to use instead a product that we refer to as terrain-corrected gamma for backscatter analysis. The product makes use of SAR image simulation, incorporating shadow checks and proper accounting of local illuminated area in foreshortened and even layover areas: the result is a substantially improved sensor model in comparison to LIM-based backscatter retrieval. Use of terrain- corrected gamma in a radiometrically terrain-corrected (RTC) product enables multi-track and even multi- sensor image overlays, as terrain-induced backscatter variations are normalised using the available DEM. By properly normalising the hills and mountains, the growing availability of SAR images from diverse sensors can be compared on a Ò level playing fieldÓ . Time series analysis of hundreds of multi-track ASAR wide swath images covering Switzerland is shown to benefit when comparisons are made using terrain-corrected gamma rather than GTC or LIM- normalised SAR backscatter retrievals. We show how the spring snow melt period can be followed well using multi-track ASAR WS data only if terrain-corrected gamma backscatter values are used as the basis for comparison. Finally, we recommend

  5. Modified Multilook Cross Correlation technique for Doppler centroid estimation in SAR image signal processing

    NASA Astrophysics Data System (ADS)

    Bee Cheng, Sew

    Synthetic Aperture Radar (SAR) is one of the widely used remote sensing sensors which produces high resolution image by using advance signal processing technique. SAR managed to operate in all sorts of weather and cover wide range of area. To produce a high-quality image, accurate parameters such as Doppler centroid are required for precise SAR signal processing. In the azimuth matched filtering of SAR signal processing, Doppler centroid is an important azimuth parameter that helps to focus the image pixels. Doppler centroid has always been overlooked during SAR signal processing. It is due to the fact that estimation of Doppler centroid involved complicated calculation and increased computational load. Therefore, researcher used to apply only the approximate Doppler value which is not precise and cause defocus effort in the generated SAR image. In this study, several conventional Doppler centroid estimation algorithms are reviewed and developed using Matlab software program to extract the Doppler parameter from received SAR data, namely Spectrum Fit Algorithm, Wavelength Diversity Algorithm (WDA), Multilook Cross Correlation Algorithm (MLCC), and Multilook Beat Frequency Algorithm (MLBF). Two sets of SAR data are employed to evaluate the performance of each estimator, i.e. simulated point target data and RADARSAT-1 Vancouver scene raw data. These experiments gave a sense of accuracy for the estimated results together with computational time consumption. Point target is simulated to generate ideal case SAR data with pre-defined SAR system parameters.

  6. Hospital Preparedness and SARS

    PubMed Central

    Wallington, Tamara; Rutledge, Tim; Mederski, Barbara; Rose, Keith; Kwolek, Sue; McRitchie, Donna; Ali, Azra; Wolff, Bryan; White, Diane; Glassman, Edward; Ofner, Marianna; Low, Don E.; Berger, Lisa; McGeer, Allison; Wong, Tom; Baron, David; Berall, Glenn

    2004-01-01

    On May 23, 2003, Toronto experienced the second phase of a severe acute respiratory syndrome (SARS) outbreak. Ninety cases were confirmed, and >620 potential cases were managed. More than 9,000 persons had contact with confirmed or potential case-patients; many required quarantine. The main hospital involved during the second outbreak was North York General Hospital. We review this hospital’s response to, and management of, this outbreak, including such factors as building preparation and engineering, personnel, departmental workload, policies and documentation, infection control, personal protective equipment, training and education, public health, management and administration, follow-up of SARS patients, and psychological and psychosocial management and research. We also make recommendations for other institutions to prepare for future outbreaks, regardless of their origin. PMID:15200807

  7. SAR peculiarities, ambiguities and constraints

    NASA Astrophysics Data System (ADS)

    Keydel, Wolfgang

    1992-08-01

    A synthetic aperture radar (SAR) is basically a coherent scatterometer that employs a coherent real aperture radar with highly sophisticated data evaluation and image processing capabilities. Therefore, the coherence of the system is very important; furthermore, the keypoints for SAR are data storage, evaluation, and processing. These facts entail peculiarities of SAR and special ambiguities which are different from those arising with real aperture radar (RAR). The objective of this paper is to point out the special peculiarities and ambiguities of SAR in comparison to the corresponding properties of RAR. Main topics in this connection are as follows: basic peculiarities like range dependency of signal to noise ratio; azimuth resolution; influence of platform velocity; range and azimuth ambiguities; pulse repetition frequency limitations; velocity effects; and phase error influence, on SAR-image, that can cause motion compensation problems. All these effects will be explained together with different contrast-equations between the target and clutter signals of SAR and RAR.

  8. [Spatial-temporal evolution characterization of land subsidence by multi-temporal InSAR method and GIS technology].

    PubMed

    Chen, Bei-Bei; Gong, Hui-Li; Li, Xiao-Juan; Lei, Kun-Chao; Duan, Guang-Yao; Xie, Jin-Rong

    2014-04-01

    Long-term over-exploitation of underground resources, and static and dynamic load increase year by year influence the occurrence and development of regional land subsidence to a certain extent. Choosing 29 scenes Envisat ASAR images covering plain area of Beijing, China, the present paper used the multi-temporal InSAR method incorporating both persistent scatterer and small baseline approaches, and obtained monitoring information of regional land subsidence. Under different situation of space development and utilization, the authors chose five typical settlement areas; With classified information of land-use, multi-spectral remote sensing image, and geological data, and adopting GIS spatial analysis methods, the authors analyzed the time series evolution characteristics of uneven settlement. The comprehensive analysis results suggests that the complex situations of space development and utilization affect the trend of uneven settlement; the easier the situation of space development and utilization, the smaller the settlement gradient, and the less the uneven settlement trend. PMID:25007621

  9. [Spatial-temporal evolution characterization of land subsidence by multi-temporal InSAR method and GIS technology].

    PubMed

    Chen, Bei-Bei; Gong, Hui-Li; Li, Xiao-Juan; Lei, Kun-Chao; Duan, Guang-Yao; Xie, Jin-Rong

    2014-04-01

    Long-term over-exploitation of underground resources, and static and dynamic load increase year by year influence the occurrence and development of regional land subsidence to a certain extent. Choosing 29 scenes Envisat ASAR images covering plain area of Beijing, China, the present paper used the multi-temporal InSAR method incorporating both persistent scatterer and small baseline approaches, and obtained monitoring information of regional land subsidence. Under different situation of space development and utilization, the authors chose five typical settlement areas; With classified information of land-use, multi-spectral remote sensing image, and geological data, and adopting GIS spatial analysis methods, the authors analyzed the time series evolution characteristics of uneven settlement. The comprehensive analysis results suggests that the complex situations of space development and utilization affect the trend of uneven settlement; the easier the situation of space development and utilization, the smaller the settlement gradient, and the less the uneven settlement trend.

  10. Circular SAR GMTI

    NASA Astrophysics Data System (ADS)

    Page, Douglas; Owirka, Gregory; Nichols, Howard; Scarborough, Steven

    2014-06-01

    We describe techniques for improving ground moving target indication (GMTI) performance in multi-channel synthetic aperture radar (SAR) systems. Our approach employs a combination of moving reference processing (MRP) to compensate for defocus of moving target SAR responses and space-time adaptive processing (STAP) to mitigate the effects of strong clutter interference. Using simulated moving target and clutter returns, we demonstrate focusing of the target return using MRP, and discuss the effect of MRP on the clutter response. We also describe formation of adaptive degrees of freedom (DOFs) for STAP filtering of MRP processed data. For the simulated moving target in clutter example, we demonstrate improvement in the signal to interference plus noise (SINR) loss compared to more standard algorithm configurations. In addition to MRP and STAP, the use of tracker feedback, false alarm mitigation, and parameter estimation techniques are also described. A change detection approach for reducing false alarms from clutter discretes is outlined, and processing of a measured data coherent processing interval (CPI) from a continuously orbiting platform is described. The results demonstrate detection and geolocation of a high-value target under track. The endoclutter target is not clearly visible in single-channel SAR chips centered on the GMTI track prediction. Detections are compared to truth data before and after geolocation using measured angle of arrival (AOA).

  11. Wetland InSAR

    NASA Astrophysics Data System (ADS)

    Wdowinski, S.; Kim, S.; Amelung, F.; Dixon, T.

    2006-12-01

    Wetlands are transition zones where the flow of water, the nutrient cycling, and the sun energy meet to produce a unique and very productive ecosystem. They provide critical habitat for a wide variety of plant and animal species, including the larval stages of many ocean fish. Wetlands also have a valuable economical importance, as they filter nutrients and pollutants from fresh water used by human and provide aquatic habitats for outdoor recreation, tourism, and fishing. Globally, many such regions are under severe environmental stress, mainly from urban development, pollution, and rising sea level. However, there is increasing recognition of the importance of these habitats, and mitigation and restoration activities have begun in a few regions. A key element in wetlands conservation, management, and restoration involves monitoring its hydrologic system, as the entire ecosystem depends on its water supply. Heretofore, hydrologic monitoring of wetlands are conducted by stage (water level) stations, which provide good temporal resolution, but suffer from poor spatial resolution, as stage station are typically distributed several, or even tens of kilometers, from one another. Wetland application of InSAR provides the needed high spatial resolution hydrological observations, complementing the high temporal resolution terrestrial observations. Although conventional wisdom suggests that interferometry does not work in vegetated areas, several studies have shown that both L- and C-band interferograms with short acquisition intervals (1-105 days) can maintain excellent coherence over wetlands. In this study we explore the usage of InSAR for detecting water level changes in various wetland environments around the world, including the Everglades (south Florida), Louisiana Coast (southern US), Chesapeake Bay (eastern US), Pantanal (Brazil), Okavango Delta (Botswana), and Lena Delta (Siberia). Our main study area is the Everglades wetland (south Florida), which is covered by

  12. Fusion of LADAR with SAR for precision strike

    SciTech Connect

    Cress, D.H.; Muguira, M.R.

    1995-03-01

    This paper presents a concept for fusing 3-dimensional image reconnaissance data with LADAR imagery for aim point refinement. The approach is applicable to fixed or quasi-fixed targets. Quasi-fixed targets are targets that are not expected to be moved between the time of reconnaissance and the time of target engagement. The 3-dimensional image data is presumed to come from standoff reconnaissance assets tens to hundreds of kilometers from the target area or acquisitions prior to hostilities. Examples are synthetic aperture radar (SAR) or stereoprocessed satellite imagery. SAR can be used to generate a 3-dimensional map of the surface through processing of data acquired with conventional SAR acquired using two closely spaced, parallel reconnaissance paths, either airborne or satellite based. Alternatively, a specialized airborne SAR having two receiving antennas may be used for data acquisition. The data sets used in this analysis are: (1) LADAR data acquired using a Hughes-Danbury system flown over a portion of Kirtland AFB during the period September 15--16, 1993; (2) two pass interferometric SAR data flown over a terrain-dominated area of Kirtland AFB; (3) 3-dimensional mapping of an urban-dominated area of the Sandia National Laboratories and adjacent cultural area extracted from aerial photography by Vexcel Corporation; (4) LADAR data acquired at Eglin AFB under Wright Laboratory`s Advanced Technology Ladar System (ATLAS) program using a 60 {mu}J, 75 KHz Co{sub 2} laser; and (5) two pass interferometric SAR data generated by Sandia`s STRIP DCS (Data Collection System) radar corresponding to the ATLAS LADAR data. The cultural data set was used in the urban area rather than SAR because high quality interferometric SAR data were not available for the urban-type area.

  13. FlexSAR, a high quality, flexible, cost effective, prototype SAR system

    NASA Astrophysics Data System (ADS)

    Jensen, Mark; Knight, Chad; Haslem, Brent

    2016-05-01

    The FlexSAR radar system was designed to be a high quality, low-cost, flexible research prototype instrument. Radar researchers and practitioners often desire the ability to prototype new or advanced configurations, yet the ability to enhance or upgrade existing radar systems can be cost prohibitive. FlexSAR answers the need for a flexible radar system that can be extended easily, with minimal cost and time expenditures. The design approach focuses on reducing the resources required for developing and validating new advanced radar modalities. Such an approach fosters innovation and provides risk reduction since actual radar data can be collected in the appropriate mode, processed, and analyzed early in the development process. This allows for an accurate, detailed understanding of the corresponding trade space. This paper is a follow-on to last years paper and discusses the advancements that have been made to the FlexSAR system. The overall system architecture is discussed and presented along with several examples illustrating the system utility.

  14. Dual frequency Synthetic Aperture Radar (SAR) mission for monitoring our dynamic planet

    NASA Technical Reports Server (NTRS)

    Hilland, J.; Bard, S.; Key, R.; Kim, Y.; Vaze, P.; Huneycutt, B.

    2000-01-01

    Advances in spaceborne Synthetic Aperture Radar (SAR) remote sensing technology make it possible to acquire global-scale data sets that provide unique information about the Earth's continually changing surface characteristics.

  15. Evaluation of the predicted error of the soil moisture retrieval from C-band SAR by comparison against modelled soil moisture estimates over Australia.

    PubMed

    Doubková, Marcela; Van Dijk, Albert I J M; Sabel, Daniel; Wagner, Wolfgang; Blöschl, Günter

    2012-05-15

    The Sentinel-1 will carry onboard a C-band radar instrument that will map the European continent once every four days and the global land surface at least once every twelve days with finest 5 × 20 m spatial resolution. The high temporal sampling rate and operational configuration make Sentinel-1 of interest for operational soil moisture monitoring. Currently, updated soil moisture data are made available at 1 km spatial resolution as a demonstration service using Global Mode (GM) measurements from the Advanced Synthetic Aperture Radar (ASAR) onboard ENVISAT. The service demonstrates the potential of the C-band observations to monitor variations in soil moisture. Importantly, a retrieval error estimate is also available; these are needed to assimilate observations into models. The retrieval error is estimated by propagating sensor errors through the retrieval model. In this work, the existing ASAR GM retrieval error product is evaluated using independent top soil moisture estimates produced by the grid-based landscape hydrological model (AWRA-L) developed within the Australian Water Resources Assessment system (AWRA). The ASAR GM retrieval error estimate, an assumed prior AWRA-L error estimate and the variance in the respective datasets were used to spatially predict the root mean square error (RMSE) and the Pearson's correlation coefficient R between the two datasets. These were compared with the RMSE calculated directly from the two datasets. The predicted and computed RMSE showed a very high level of agreement in spatial patterns as well as good quantitative agreement; the RMSE was predicted within accuracy of 4% of saturated soil moisture over 89% of the Australian land mass. Predicted and calculated R maps corresponded within accuracy of 10% over 61% of the continent. The strong correspondence between the predicted and calculated RMSE and R builds confidence in the retrieval error model and derived ASAR GM error estimates. The ASAR GM and Sentinel-1 have

  16. Evaluation of the predicted error of the soil moisture retrieval from C-band SAR by comparison against modelled soil moisture estimates over Australia

    PubMed Central

    Doubková, Marcela; Van Dijk, Albert I.J.M.; Sabel, Daniel; Wagner, Wolfgang; Blöschl, Günter

    2012-01-01

    The Sentinel-1 will carry onboard a C-band radar instrument that will map the European continent once every four days and the global land surface at least once every twelve days with finest 5 × 20 m spatial resolution. The high temporal sampling rate and operational configuration make Sentinel-1 of interest for operational soil moisture monitoring. Currently, updated soil moisture data are made available at 1 km spatial resolution as a demonstration service using Global Mode (GM) measurements from the Advanced Synthetic Aperture Radar (ASAR) onboard ENVISAT. The service demonstrates the potential of the C-band observations to monitor variations in soil moisture. Importantly, a retrieval error estimate is also available; these are needed to assimilate observations into models. The retrieval error is estimated by propagating sensor errors through the retrieval model. In this work, the existing ASAR GM retrieval error product is evaluated using independent top soil moisture estimates produced by the grid-based landscape hydrological model (AWRA-L) developed within the Australian Water Resources Assessment system (AWRA). The ASAR GM retrieval error estimate, an assumed prior AWRA-L error estimate and the variance in the respective datasets were used to spatially predict the root mean square error (RMSE) and the Pearson's correlation coefficient R between the two datasets. These were compared with the RMSE calculated directly from the two datasets. The predicted and computed RMSE showed a very high level of agreement in spatial patterns as well as good quantitative agreement; the RMSE was predicted within accuracy of 4% of saturated soil moisture over 89% of the Australian land mass. Predicted and calculated R maps corresponded within accuracy of 10% over 61% of the continent. The strong correspondence between the predicted and calculated RMSE and R builds confidence in the retrieval error model and derived ASAR GM error estimates. The ASAR GM and Sentinel-1 have

  17. Recovering Seasat SAR Data

    NASA Astrophysics Data System (ADS)

    Logan, T. A.; Arko, S. A.; Rosen, P. A.

    2013-12-01

    To demonstrate the feasibility of orbital remote sensing for global ocean observations, NASA launched Seasat on June 27th, 1978. Being the first space borne SAR mission, Seasat produced the most detailed SAR images of Earth from space ever seen to that point in time. While much of the data collected in the USA was processed optically, a mere 150 scenes had been digitally processed by March 1980. In fact, only an estimated 3% of Seasat data was ever digitally processed. Thus, for over three decades, the majority of the SAR data from this historic mission has been dormant, virtually unavailable to scientists in the 21st century. Over the last year, researchers at the Alaska Satellite Facility (ASF) Distributed Active Archive Center (DAAC) have processed the Seasat SAR archives into imagery products. A telemetry decoding system was created and the data were filtered into readily processable signal files. Due to nearly 35 years of bit rot, the bit error rate (BER) for the ASF DAAC Seasat archives was on the order of 1 out of 100 to 1 out of 100,000. This extremely high BER initially seemed to make much of the data undecodable - because the minor frame numbers are just 7 bits and no range line numbers exist in the telemetry even the 'simple' tasks of tracking the minor frame number or locating the start of each range line proved difficult. Eventually, using 5 frame numbers in sequence and a handful of heuristics, the data were successfully decoded into full range lines. Concurrently, all metadata were stored into external files. Recovery of this metadata was also problematic, the BER making the information highly suspect and, initially at least, unusable in any sort of automated fashion. Because of the BER, all of the single bit metadata fields proved unreliable. Even fields that should be constant for a data take (e.g. receiving station, day of the year) showed high variability, each requiring a median filter to be usable. The most challenging, however, were the

  18. Analytical SAR-GMTI principles

    NASA Astrophysics Data System (ADS)

    Soumekh, Mehrdad; Majumder, Uttam K.; Barnes, Christopher; Sobota, David; Minardi, Michael

    2016-05-01

    This paper provides analytical principles to relate the signature of a moving target to parameters in a SAR system. Our objective is to establish analytical tools that could predict the shift and smearing of a moving target in a subaperture SAR image. Hence, a user could identify the system parameters such as the coherent processing interval for a subaperture that is suitable to localize the signature of a moving target for detection, tracking and geolocating the moving target. The paper begins by outlining two well-known SAR data collection methods to detect moving targets. One uses a scanning beam in the azimuth domain with a relatively high PRF to separate the moving targets and the stationary background (clutter); this is also known as Doppler Beam Sharpening. The other scheme uses two receivers along the track to null the clutter and, thus, provide GMTI. We also present results on implementing our SAR-GMTI analytical principles for the anticipated shift and smearing of a moving target in a simulated code. The code would provide a tool for the user to change the SAR system and moving target parameters, and predict the properties of a moving target signature in a subaperture SAR image for a scene that is composed of both stationary and moving targets. Hence, the SAR simulation and imaging code could be used to demonstrate the validity and accuracy of the above analytical principles to predict the properties of a moving target signature in a subaperture SAR image.

  19. Atypical SARS in Geriatric Patient

    PubMed Central

    Oh, Helen M.L.; Hui, K.P.; Lien, Christopher T.C.; Narendran, K.; Heng, B.H.; Ling, A.E.

    2004-01-01

    We describe an atypical presentation of severe acute respiratory syndrome (SARS) in a geriatric patient with multiple coexisting conditions. Interpretation of radiographic changes was confounded by cardiac failure, with resolution of fever causing delayed diagnosis and a cluster of cases. SARS should be considered even if a contact history is unavailable, during an ongoing outbreak. PMID:15030694

  20. Review of bats and SARS.

    PubMed

    Wang, Lin-Fa; Shi, Zhengli; Zhang, Shuyi; Field, Hume; Daszak, Peter; Eaton, Bryan T

    2006-12-01

    Bats have been identified as a natural reservoir for an increasing number of emerging zoonotic viruses, including henipaviruses and variants of rabies viruses. Recently, we and another group independently identified several horseshoe bat species (genus Rhinolophus) as the reservoir host for a large number of viruses that have a close genetic relationship with the coronavirus associated with severe acute respiratory syndrome (SARS). Our current research focused on the identification of the reservoir species for the progenitor virus of the SARS coronaviruses responsible for outbreaks during 2002-2003 and 2003-2004. In addition to SARS-like coronaviruses, many other novel bat coronaviruses, which belong to groups 1 and 2 of the 3 existing coronavirus groups, have been detected by PCR. The discovery of bat SARS-like coronaviruses and the great genetic diversity of coronaviruses in bats have shed new light on the origin and transmission of SARS coronaviruses.

  1. Review of Bats and SARS

    PubMed Central

    Shi, Zhengli; Zhang, Shuyi; Field, Hume; Daszak, Peter; Eaton, Bryan T.

    2006-01-01

    Bats have been identified as a natural reservoir for an increasing number of emerging zoonotic viruses, including henipaviruses and variants of rabies viruses. Recently, we and another group independently identified several horseshoe bat species (genus Rhinolophus) as the reservoir host for a large number of viruses that have a close genetic relationship with the coronavirus associated with severe acute respiratory syndrome (SARS). Our current research focused on the identification of the reservoir species for the progenitor virus of the SARS coronaviruses responsible for outbreaks during 2002–2003 and 2003–2004. In addition to SARS-like coronaviruses, many other novel bat coronaviruses, which belong to groups 1 and 2 of the 3 existing coronavirus groups, have been detected by PCR. The discovery of bat SARS-like coronaviruses and the great genetic diversity of coronaviruses in bats have shed new light on the origin and transmission of SARS coronaviruses. PMID:17326933

  2. Bistatic SAR: Imagery & Image Products.

    SciTech Connect

    Yocky, David A.; Wahl, Daniel E.; Jakowatz, Charles V,

    2014-10-01

    While typical SAR imaging employs a co-located (monostatic) RADAR transmitter and receiver, bistatic SAR imaging separates the transmitter and receiver locations. The transmitter and receiver geometry determines if the scattered signal is back scatter, forward scatter, or side scatter. The monostatic SAR image is backscatter. Therefore, depending on the transmitter/receiver collection geometry, the captured imagery may be quite different that that sensed at the monostatic SAR. This document presents imagery and image products formed from captured signals during the validation stage of the bistatic SAR research. Image quality and image characteristics are discussed first. Then image products such as two-color multi-view (2CMV) and coherent change detection (CCD) are presented.

  3. Some thoughts on error-contributions to reconstruct 3D coseismic displacement field using the model of combining multiple independent InSAR

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Zhang, Jingfa; Luo, Yi

    2012-07-01

    Interferometric Synthetic Aperture Radar (InSAR) has proved an immensely powerful tool in studying earthquakes with millimetre-scale accuracy at a high spatial resolution. However, each interferogram records only the component of displacement in the direction of the satellite line of sight (LOS). Thus previous InSAR studies of displacement due to earthquakes were generally limited to one or two components of the surface displacement field. Three- dimensional (3D) surface displacement maps can provide a more comprehensive understanding of source geometry associated with earthquake. By combining interferograms from multiple look angles, it is possible to constrain the three-dimensional components of displacement [Jung et al., 2011; Wright, et al., 2004; Hong et al., 2010]. In this work, we take 2008 Gaize Ms6.9 earthquake (Tibet) for example, derive LOS surface displacement from several paths of ENVISAT ASAR images (Image mode: Track 348, descending pass; Track 341, 427, and 155, ascending pass. ScanSAR mode: Track 341, 112, 155, and 384, ascending pass), and reconstruct the 3D coseismic displacement field with the model named multiple independent InSAR with different viewing angles. Because it is difficult to distinguish tectonic signal from phase noise (eg. orbital errors, atmospheric errors, and unwrapping errors), these error-contributions may be propagated to the 3D coseismic components (vertical, north, east). In addition, for ENVISAT ASAR, it is worth notice that the radar antenna is fixed with respect to the current satellite, which may lead to different LOS observations with nearly identical viewing angles in parallel passes. Thus, when inverting 3D components with least square solution, InSAR observation errors may be magnified by the ill-conditioned system of equations in the solution. Although the ill-conditioned system of equations may result in bad solution, some InSAR observation errors can be detected by the system. In our study, we will introduce the

  4. Optimizing deep hyperthermia treatments: are locations of patient pain complaints correlated with modelled SAR peak locations?

    NASA Astrophysics Data System (ADS)

    Canters, R. A. M.; Franckena, M.; van der Zee, J.; van Rhoon, G. C.

    2011-01-01

    During deep hyperthermia treatment, patient pain complaints due to heating are common when maximizing power. Hence, there exists a good rationale to investigate whether the locations of predicted SAR peaks by hyperthermia treatment planning (HTP) are correlated with the locations of patient pain during treatment. A retrospective analysis was performed, using the treatment reports of 35 patients treated with deep hyperthermia controlled by extensive treatment planning. For various SAR indicators, the average distance from a SAR peak to a patient discomfort location was calculated, for each complaint. The investigated V0.1 closest (i.e. the part of the 0.1th SAR percentile closest to the patient complaint) performed the best, and leads to an average distance between the SAR peak and the complaint location of 3.9 cm. Other SAR indicators produced average distances that were all above 10 cm. Further, the predicted SAR peak location with V0.1 provides a 77% match with the region of complaint. The current study demonstrates that HTP is able to provide a global indication of the regions where hotspots during treatment will most likely occur. Further development of this technology is necessary in order to use HTP as a valuable toll for objective and advanced SAR steering. The latter is especially valid for applications that enable 3D SAR steering.

  5. Optimizing deep hyperthermia treatments: are locations of patient pain complaints correlated with modelled SAR peak locations?

    PubMed

    Canters, R A M; Franckena, M; van der Zee, J; van Rhoon, G C

    2011-01-21

    During deep hyperthermia treatment, patient pain complaints due to heating are common when maximizing power. Hence, there exists a good rationale to investigate whether the locations of predicted SAR peaks by hyperthermia treatment planning (HTP) are correlated with the locations of patient pain during treatment. A retrospective analysis was performed, using the treatment reports of 35 patients treated with deep hyperthermia controlled by extensive treatment planning. For various SAR indicators, the average distance from a SAR peak to a patient discomfort location was calculated, for each complaint. The investigated V(0.1 closest) (i.e. the part of the 0.1th SAR percentile closest to the patient complaint) performed the best, and leads to an average distance between the SAR peak and the complaint location of 3.9 cm. Other SAR indicators produced average distances that were all above 10 cm. Further, the predicted SAR peak location with V(0.1) provides a 77% match with the region of complaint. The current study demonstrates that HTP is able to provide a global indication of the regions where hotspots during treatment will most likely occur. Further development of this technology is necessary in order to use HTP as a valuable toll for objective and advanced SAR steering. The latter is especially valid for applications that enable 3D SAR steering.

  6. Offshore Wind Mapping Mediterranean area using SAR. A case study of retrieval around peninsular regions.

    NASA Astrophysics Data System (ADS)

    Calaudi, Rosamaria; Arena, Felice; Badger, Merete; Sempreviva, Anna Maria

    2013-04-01

    Satellite observations like Scatterometers e.g. QuickScat, and Synthetic Aperture Radars (SAR) of the ocean surface provide information about the spatial wind variability over large areas. This is very valuable, for mapping offshore wind resources for offshore wind farm installation, where the most suitable locations within a given region must be identified using at least 5 year wind data over the whole domain. This is a special issue in the Mediterranean, where spatial information is not readily available because buoys or masts are sparse, with long periods of missing data, and measurements represent only one point. Here, we focus on the SAR images that have the advantage of high spatial resolution (down to 100m) allowing to derive information close to the coast but with the disadvantage of low time resolution causing lack of information on regimes with low time scale. We retrieved SAR (ENVISAT ASAR scenes acquired in Wide Swath Mode-WSM-) wind speed in the Mediterranean from March 2002 to April 2012 using the Johns Hopkins University, Applied Physics Laboratory (JHU/APL) software APL/NOAA SAR Wind Retrieval System (ANSWRS version 2.0) (Monaldo 2000; Monaldo et al. 2006). The ANSWRS software produces per default wind speed fields initialized using wind directions determined by the Navy Operational Global Atmospheric Prediction System (NOGAPS) models interpolated in time and space to match the satellite data. NOGAPS data are available at 6-hour intervals mapped to a 1° latitude/longitude grid. Here, we present a case study in Calabria, a long, narrow and mountainous peninsula in South Italy that causes a significant wind conditions variability from one coast to the other. We considered a 10m mast, measuring hourly wind speed and direction located at the coastline at the harbor of the town Crotone, belonging to the marine network of sensors of ISPRA (Institute for Environmental Protection and Research). Three points of the SAR images were chosen at offshore

  7. Persistent Scatterer InSAR monitoring of Bratislava urban area

    NASA Astrophysics Data System (ADS)

    Bakon, Matus; Perissin, Daniele; Papco, Juraj; Lazecky, Milan

    2014-05-01

    ) technique, covering the target area with 57 Envisat ASAR images from Ascending Track No. 229 (32) and Descending Track No. 265 (25) captured between years 2002 and 2010. Processing involves Sarproz (Copyright (c) 2009 Daniele Perissin) a powerful software solution for obtaining differential interferograms and performing PSInSAR methodology. The area of interest to investigate the deformation phenomena is covering approximately 16 by 16 kilometers (256 sqkm). For evaluation of PSInSAR potential to detect and monitor ground displacements, PS derived time series of deformation signal were compared to the field GNSS data from three GNSS stations coded PIL1, BRAT and GKU4. By the detailed look on the deformation maps the investigated urban area of Bratislava is relatively stable with the deformation rates within the few (±5) millimeters. The comparison of PSInSAR derived time series with GNSS data indicates good correlation and confirms achievable precision and applicability of InSAR measurements for ground stability monitoring purposes. Data for this work were provided by European Space Agency within the Category-1 project ID 9981: "Detection of ground deformation using radar interferometry techniques". The authors are grateful to the Tatrabanka Foundation and The National Scholarship Programme of the Slovak Republic for the opportunity to work together. Data have been processed by the Sarproz (Copyright (c) 2009 Daniele Perissin) and visualised in Google Earth. This paper is also the result of the implementation of the project: the National Centre of Earth's Surface Deformation Diagnostic in the area of Slovakia, ITMS 26220220108 supported by the Research and Development Operational Programme funded by the ERDF and the grant No. 1/0642/13 of the Slovak Grant Agency VEGA.

  8. Multiresolution analysis of SAR data

    NASA Astrophysics Data System (ADS)

    Hummel, Robert

    1993-01-01

    The 'Multiresolution Analysis of SAR Data' program supported research work in five areas. Geometric hashing theory can now be viewed as a Bayesian approach to object recognition. False alarm rates can be greatly reduced by using certain enhancements and modifications developed under this project. Geometric hashing algorithms now exist for the Connection Machine. Recognition of synthetically-produced dot arrays was demonstrated using a model base of 1024 objects. The work represents a substantial advance over existing model-based vision capabilities. Algorithms were developed for determining the translation and rotation of a sensor given only the image flow field data. These are new algorithms, and are much more stable than existing computer vision algorithms for this task. The algorithms might provide independent verification of gyroscopic data, or might be used to compute relative motion with respect to a moving scene object, or may be useful for motion-based segmentation. Our theories explaining the Dempster/Shafer calculus and developing new uncertainty reasoning calculi were extended, and presented at a conference and were incorporated into the Bayesian interpretation of geometric hashing. 'Wavelet Slice Theorem' was developed in several different versions, any of which yields an alternate approach to image formation. The result may well provide a more stable approach to image formation than the standard Fourier-based projection slide theorem, since interpolation of unknown spectra values is better-founded.

  9. Acousto-optic techniques for real SAR imaging

    NASA Technical Reports Server (NTRS)

    Haney, M.; Psaltis, D.

    1985-01-01

    Recent advancements in the development of the Real Time Acousto-optic SAR Processor are presented. In particular, the technique for introducing the azimuth reference function into the processor via an acousto-optic Bragg cell is discussed. This approach permits the reference function to be stored in electronic memory, thus giving the processor the flexibility needed to adapt rapidly to changes in the radar/target geometry. The architecture is described and results are presented which show the applicability of the technique to both spot-light and strip-map SAR.

  10. Flood Extent Mapping for Namibia Using Change Detection and Thresholding with SAR

    NASA Technical Reports Server (NTRS)

    Long, Stephanie; Fatoyinbo, Temilola E.; Policelli, Frederick

    2014-01-01

    A new method for flood detection change detection and thresholding (CDAT) was used with synthetic aperture radar (SAR) imagery to delineate the extent of flooding for the Chobe floodplain in the Caprivi region of Namibia. This region experiences annual seasonal flooding and has seen a recent renewal of severe flooding after a long dry period in the 1990s. Flooding in this area has caused loss of life and livelihoods for the surrounding communities and has caught the attention of disaster relief agencies. There is a need for flood extent mapping techniques that can be used to process images quickly, providing near real-time flooding information to relief agencies. ENVISAT/ASAR and Radarsat-2 images were acquired for several flooding seasons from February 2008 to March 2013. The CDAT method was used to determine flooding from these images and includes the use of image subtraction, decision based classification with threshold values, and segmentation of SAR images. The total extent of flooding determined for 2009, 2011 and 2012 was about 542 km2, 720 km2, and 673 km2 respectively. Pixels determined to be flooded in vegetation were typically <0.5 % of the entire scene, with the exception of 2009 where the detection of flooding in vegetation was much greater (almost one third of the total flooded area). The time to maximum flooding for the 2013 flood season was determined to be about 27 days. Landsat water classification was used to compare the results from the new CDAT with SAR method; the results show good spatial agreement with Landsat scenes.

  11. Anatomy of a SAR impulse response.

    SciTech Connect

    Doerry, Armin Walter

    2007-08-01

    A principal measure of Synthetic Aperture Radar (SAR) image quality is the manifestation in the SAR image of a spatial impulse, that is, the SAR's Impulse Response (IPR). IPR requirements direct certain design decisions in a SAR. Anomalies in the IPR can point to specific anomalous behavior in the radar's hardware and/or software.

  12. Landslide Mapping Using SqueeSAR Data

    NASA Astrophysics Data System (ADS)

    Ferretti, A.; Bellotti, F.; Alberti, S.; Allievi, J.; Del Conte, S.; Tamburini, A.; Broccolato, M.; Ratto, S.; Alberto, W.

    2011-12-01

    SqueeSAR represents the most recent advancement of PSInSAR algorithm. By exploiting signal radar returns both from Permanent and Distributed Scatterers (PS and DS), it is able to detect millimetre displacements over long periods and large areas and to obtain a significant increase in the spatial density of ground measurement points. SqueeSAR analysis is complementary to conventional geological and geomorphological studies in landslide mapping over wide areas, traditionally based on aerial-photo interpretation and field surveys. However, whenever surface displacement rates are low (mm to cm per year), assessing landslide activity is difficult or even impossible without a long-term monitoring tool, as in the case of Deep-seated Gravitational Slope Deformations (DGSD), typically characterized by large areal extent and subtle surface displacement. The availability of surface displacement time series per each measurement point allows one to have both a synoptic overview, at regional scale, as well as an in depth characterization of the instability phenomena analyzed, a meaningful support to the design of traditional monitoring networks and the efficiency testing of remedial works. When data archives are available, SqueeSAR can also provide valuable information before the installation of any terrestrial measurement system. The Italian authorities increasing interest in the application of SqueeSAR as a standard monitoring tool to help hydrogeological risk assessment, resulted in a national project, Piano Straordinario di Telerilevamento (PST), founded by the Ministry of the Environment. The aim of the project was to create the first interferometric database on a national scale for mapping unstable areas. More than 12,000 ERS and ENVISAT radar scenes acquired over Italy were processed spanning the period 1992-2010, proving that, in less than ten years, radar interferometry has become a standard monitoring tool. Recently, many regional governments in Italy have applied

  13. Studies of ice sheet hydrology using SAR

    NASA Technical Reports Server (NTRS)

    Bindschadler, R. A.; Vornberger, P. L.

    1989-01-01

    Analysis of SAR data of the Greenland ice sheet in summer and winter suggest the use of SAR to monitor the temporal hydrology of ice sheets. Comparisons of each SAR data set with summer Landsat TM imagery show an areal-positive correlation with summer SAR data and a negative correlation with winter SAR data. It is proposed that the summer SAR data are most sensitive to the variable concentrations of free water in the surface snow and that the winter SAR data indicate variations in snow grain size.

  14. Synthetic Aperture Radar (SAR) data processing

    NASA Technical Reports Server (NTRS)

    Beckner, F. L.; Ahr, H. A.; Ausherman, D. A.; Cutrona, L. J.; Francisco, S.; Harrison, R. E.; Heuser, J. S.; Jordan, R. L.; Justus, J.; Manning, B.

    1978-01-01

    The available and optimal methods for generating SAR imagery for NASA applications were identified. The SAR image quality and data processing requirements associated with these applications were studied. Mathematical operations and algorithms required to process sensor data into SAR imagery were defined. The architecture of SAR image formation processors was discussed, and technology necessary to implement the SAR data processors used in both general purpose and dedicated imaging systems was addressed.

  15. InSAR Scientific Computing Environment

    NASA Astrophysics Data System (ADS)

    Gurrola, E. M.; Rosen, P. A.; Sacco, G.; Zebker, H. A.; Simons, M.; Sandwell, D. T.

    2010-12-01

    The InSAR Scientific Computing Environment (ISCE) is a software development effort in its second year within the NASA Advanced Information Systems and Technology program. The ISCE will provide a new computing environment for geodetic image processing for InSAR sensors that will enable scientists to reduce measurements directly from radar satellites and aircraft to new geophysical products without first requiring them to develop detailed expertise in radar processing methods. The environment can serve as the core of a centralized processing center to bring Level-0 raw radar data up to Level-3 data products, but is adaptable to alternative processing approaches for science users interested in new and different ways to exploit mission data. The NRC Decadal Survey-recommended DESDynI mission will deliver data of unprecedented quantity and quality, making possible global-scale studies in climate research, natural hazards, and Earth's ecosystem. The InSAR Scientific Computing Environment is planned to become a key element in processing DESDynI data into higher level data products and it is expected to enable a new class of analyses that take greater advantage of the long time and large spatial scales of these new data, than current approaches. At the core of ISCE is both legacy processing software from the JPL/Caltech ROI_PAC repeat-pass interferometry package as well as a new InSAR processing package containing more efficient and more accurate processing algorithms being developed at Stanford for this project that is based on experience gained in developing processors for missions such as SRTM and UAVSAR. Around the core InSAR processing programs we are building object-oriented wrappers to enable their incorporation into a more modern, flexible, extensible software package that is informed by modern programming methods, including rigorous componentization of processing codes, abstraction and generalization of data models, and a robust, intuitive user interface with

  16. Thermal noise removal in hybrid polarimetry SAR data

    NASA Astrophysics Data System (ADS)

    Suneela Mishra, J. V. D.; Misra, Tapan

    2016-05-01

    This paper presents an overview of the estimation of noise, techniques for noise removal in Single Look Complex (SLC) as well as hybrid polarimetry decomposed images and the effects of noise removal in SAR images, using RISAT-1 data. Thermal noise affects the signal to noise ratio as well as radiometry of the SAR images. Different approaches adopted for estimating the thermal noise using onboard noise measurements and from the noise equivalent area of the images like calm reservoirs, lakes, etc., for RISAT-1 SAR are discussed. Subsequent to noise removal, its effect on minimum detectable noise and SNR of the images is addressed. Traditional noise removal methods affect the phase of the data, which in turn affect advanced SAR applications. A brief overview of the hybrid polarimetry configuration of RISAT-1 SAR, one of the emerging trends in polarimetry domain, is given and the effect of using noise removed single look complex (SLC) images for polarimetry decomposition is brought out. Thereby, a new technique for thermal noise removal in polarimetry decomposed data is presented.

  17. Methods of InSAR atmosphere correction for volcano activity monitoring

    USGS Publications Warehouse

    Gong, W.; Meyer, F.; Webley, P.W.; Lu, Zhiming

    2011-01-01

    When a Synthetic Aperture Radar (SAR) signal propagates through the atmosphere on its path to and from the sensor, it is inevitably affected by atmospheric effects. In particular, the applicability and accuracy of Interferometric SAR (InSAR) techniques for volcano monitoring is limited by atmospheric path delays. Therefore, atmospheric correction of interferograms is required to improve the performance of InSAR for detecting volcanic activity, especially in order to advance its ability to detect subtle pre-eruptive changes in deformation dynamics. In this paper, we focus on InSAR tropospheric mitigation methods and their performance in volcano deformation monitoring. Our study areas include Okmok volcano and Unimak Island located in the eastern Aleutians, AK. We explore two methods to mitigate atmospheric artifacts, namely the numerical weather model simulation and the atmospheric filtering using Persistent Scatterer processing. We investigate the capability of the proposed methods, and investigate their limitations and advantages when applied to determine volcanic processes. ?? 2011 IEEE.

  18. Earth observing SAR data processing systems at the Jet Propulsion Laboratory - Seasat to EOS SAR

    NASA Technical Reports Server (NTRS)

    Nichols, David A.; Curlander, John C.

    1991-01-01

    The evolution of SAR digital data processing and management ground systems developed at the JPL for earth science missions is discussed. Attention is given to the SAR ground data system requirements, the early data processing systems, the Seasat SAR system, and the SIR-B data processing system. Special consideration is given to two currently operational SAR data systems: the JPL aircraft SAR processing system that flies on the NASA DC-8 and the Alaska SAR Facility at Fairbanks.

  19. Surface Subsidence Analysis by Multi-Temporal InSAR and GRACE: A Case Study in Beijing

    PubMed Central

    Guo, Jiming; Zhou, Lv; Yao, Chaolong; Hu, Jiyuan

    2016-01-01

    The aim of this study was to investigate the relationship between surface subsidence and groundwater changes. To investigate this relationship, we first analyzed surface subsidence. This paper presents the results of a case study of surface subsidence in Beijing from 1 August 2007 to 29 September 2010. The Multi-temporal Interferometric Synthetic Aperture Radar (multi-temporal InSAR) technique, which can simultaneously detect point-like stable reflectors (PSs) and distributed scatterers (DSs), was used to retrieve the subsidence magnitude and distribution in Beijing using 18 ENVISAT ASAR images. The multi-temporal InSAR-derived subsidence was verified by leveling at an accuracy better than 5 mm/year. Based on the verified multi-temporal InSAR results, a prominent uneven subsidence was identified in Beijing. Specifically, most of the subsidence velocities in the downtown area were within 10 mm/year, and the largest subsidence was detected in Tongzhou, with velocities exceeding 140 mm/year. Furthermore, Gravity Recovery and Climate Experiment (GRACE) data were used to derive the groundwater change series and trend. By comparison with the multi-temporal InSAR-derived subsidence results, the long-term decreasing trend between groundwater changes and surface subsidence showed a relatively high consistency, and a significant impact of groundwater changes on the surface subsidence was identified. Additionally, the spatial distribution of the subsidence funnel was partially consistent with that of groundwater depression, i.e., the former possessed a wider range than the latter. Finally, the relationship between surface subsidence and groundwater changes was determined. PMID:27649183

  20. Surface Subsidence Analysis by Multi-Temporal InSAR and GRACE: A Case Study in Beijing.

    PubMed

    Guo, Jiming; Zhou, Lv; Yao, Chaolong; Hu, Jiyuan

    2016-09-14

    The aim of this study was to investigate the relationship between surface subsidence and groundwater changes. To investigate this relationship, we first analyzed surface subsidence. This paper presents the results of a case study of surface subsidence in Beijing from 1 August 2007 to 29 September 2010. The Multi-temporal Interferometric Synthetic Aperture Radar (multi-temporal InSAR) technique, which can simultaneously detect point-like stable reflectors (PSs) and distributed scatterers (DSs), was used to retrieve the subsidence magnitude and distribution in Beijing using 18 ENVISAT ASAR images. The multi-temporal InSAR-derived subsidence was verified by leveling at an accuracy better than 5 mm/year. Based on the verified multi-temporal InSAR results, a prominent uneven subsidence was identified in Beijing. Specifically, most of the subsidence velocities in the downtown area were within 10 mm/year, and the largest subsidence was detected in Tongzhou, with velocities exceeding 140 mm/year. Furthermore, Gravity Recovery and Climate Experiment (GRACE) data were used to derive the groundwater change series and trend. By comparison with the multi-temporal InSAR-derived subsidence results, the long-term decreasing trend between groundwater changes and surface subsidence showed a relatively high consistency, and a significant impact of groundwater changes on the surface subsidence was identified. Additionally, the spatial distribution of the subsidence funnel was partially consistent with that of groundwater depression, i.e., the former possessed a wider range than the latter. Finally, the relationship between surface subsidence and groundwater changes was determined.

  1. Spatial-temporal heterogeneity of land subsidence evolution in Beijing based on InSAR and cluster analysis

    NASA Astrophysics Data System (ADS)

    Ke, Y.; Li, Y.; Gong, H.; Pan, Y.; Zhu, L.; Chen, B.

    2015-12-01

    Land subsidence is a common natural hazard occurring in extensive areas in the world. In Beijing, the capital city of China, there has been serious land subsidence due to overexploitation of ground water during the recent decades. Five major subsidence tunnels have formed. Across the Beijing plain area, the ground is sinking at the rate of 30-100mm/year. Uneven subsidence leads to ground fissure and building destruction, and has caused great economical and property loss. To better characterize and understand regional land subsidence evolution, it is critical to monitor the time-series dynamics of subsidence, and capture the spatial-temporal heterogeneity of the subsidence evolution. Interferometric SAR technique, as it provides high spatial resolution and wide range of observation, have been successfully used to monitor regional ground deformation. The objective of this study is to derive time-series regional land subsidence dynamics in Beijing, and based on which, analyze and assess the spatial-temporal heterogeneity of the evolution using cluster analysis. First, ENVISAT ASAR (2003-2009 years, 28 scenes, track number: 218) datasets during 2003-2010 covering Beijing plain area were utilized to obtain time-series subsidence rate using Persistent Scatter InSAR (PS-InSAR) technique provided in SARProz software. Second, time-series subsidence characteristics of the PS points were analyzed and the PS points were clustered based on Self-Organization feature Maps (SOM) algorithm considering environmental factors such as groundwater level and lithologic characters. This study demonstrates that based on InSAR measurements and SOMs algorithm, the spatial-temporal heterogeneity of land subsidence evolution can be captured. Each cluster shows unique spatial-temporal evolution pattern. The results of this study will facilitate further land subsidence modeling and prediction at regional spatial scale.

  2. Surface Subsidence Analysis by Multi-Temporal InSAR and GRACE: A Case Study in Beijing.

    PubMed

    Guo, Jiming; Zhou, Lv; Yao, Chaolong; Hu, Jiyuan

    2016-01-01

    The aim of this study was to investigate the relationship between surface subsidence and groundwater changes. To investigate this relationship, we first analyzed surface subsidence. This paper presents the results of a case study of surface subsidence in Beijing from 1 August 2007 to 29 September 2010. The Multi-temporal Interferometric Synthetic Aperture Radar (multi-temporal InSAR) technique, which can simultaneously detect point-like stable reflectors (PSs) and distributed scatterers (DSs), was used to retrieve the subsidence magnitude and distribution in Beijing using 18 ENVISAT ASAR images. The multi-temporal InSAR-derived subsidence was verified by leveling at an accuracy better than 5 mm/year. Based on the verified multi-temporal InSAR results, a prominent uneven subsidence was identified in Beijing. Specifically, most of the subsidence velocities in the downtown area were within 10 mm/year, and the largest subsidence was detected in Tongzhou, with velocities exceeding 140 mm/year. Furthermore, Gravity Recovery and Climate Experiment (GRACE) data were used to derive the groundwater change series and trend. By comparison with the multi-temporal InSAR-derived subsidence results, the long-term decreasing trend between groundwater changes and surface subsidence showed a relatively high consistency, and a significant impact of groundwater changes on the surface subsidence was identified. Additionally, the spatial distribution of the subsidence funnel was partially consistent with that of groundwater depression, i.e., the former possessed a wider range than the latter. Finally, the relationship between surface subsidence and groundwater changes was determined. PMID:27649183

  3. Detecting surface oil slick related to gas hydrate/petroleum on the ocean bed of South China Sea by ENVI/ASAR radar data

    NASA Astrophysics Data System (ADS)

    Wang, Yunpeng; Chen, Duofu; Song, Zhiguang

    2013-03-01

    For exploring the distribution of oil slick related to gas hydrate or petroleum in the northern part of South China Sea and evaluating the potential of ENVI/ASAR radar data for detecting oil slick, this paper tries to detect the oil slick on ocean surface of some potential areas in South China Sea and map oil slick from anomaly area in radar image. Seven surface oil slicks in Qiongdongnan Basin and four potential targets of oil slicks in Taixi-Dongsha Basin were detected and extracted by using ENIV/ASAR data. The anomalies of the radar image representing oil slick are validated by in-site sampling and laboratory analyzing. The Gas Chromatograph (GC) results of the extracted oil from the water samples gathered from the sites of detected oil slick demonstrate a typical composition of oil rather than that of ocean microbial origins, and Total Organic Carbon (TOC) concentrations in two designed vertical profiles keep steady in different depths, showing that the organic contents in water column are steady from the deep area to ocean surface. These results suggest the detected oil slick is a thin floating oil rather than a thick spill. Influencing factors to the results of oil slick detection including wind speed, current, small islands and capes as well as deep-sea petroleum reservoirs are discussed. The results in this study exhibit that extracting the anomaly signals related to oil slick related to oil/gas seeps using image processing techniques from ENVI/ASAR data is helpful to predict anomaly areas as potential targets for further exploration in this area.

  4. [Breeding habitat characteristics of red-crowned crane at Zhalong of Northeast China: a multi-scale approach based on TM and ASAR image data].

    PubMed

    Liu, Chun-Yue; Jiang, Hong-Xing; Zhang, Shu-Qing; Hou, Yun-Qiu; Lu, Jun

    2012-02-01

    Based on the Landsat TM and Envisat ASAR HH/HV imagery data and by using the GPS data of red-crowned crane nesting sites (n = 28) at Zhalong National Nature Reserve of Northeast China, the models of the breeding habitat selection of red-crowned crane at the Reserve were established by binary Logistic regression to identify the key variables for the habitat selection at eight spatial scales (30-240 m). The relative performance of the two models based on the Landsat TM and Envisat ASAR HH/HV databases was compared, and the prediction capacity of the models across the eight scales was approached. The overall precisions of the two models were satisfactory (> or = 69.0%). At scale 30 m, only variable TCA_2 entered with negative value into the model based on Landsat TM database, which indicated that the crane at this scale avoided selecting higher density reed marshes. At scales 60-120 m, the variable PCA_2 entered with positive value into the two models, indicating that the crane at these scales had higher demand of high density reed marshes to improve its concealment. At scale 90 m, the variable HV backward scatting coefficient also entered into the combined model, which indicated that water condition was the important factor for the habitat selection of the crane at this scale. At scales > 120 m, the texture information of the two satellite sensors started to be involved into the two models, indicating that at larger scales, the crane had decreasing demand on the vegetation features for its breeding habitat selection but increasing sensitivity to the anthropogenic disturbance factors. The introduction of ASAR variables into the models increased the prediction accuracy of the models markedly at all scales.

  5. Satellite SAR data assessment for Silk Road archaeological prospection

    NASA Astrophysics Data System (ADS)

    Chen, Fulong; Lasaponara, Rosa; Masini, Nicola; Yang, Ruixia

    2015-04-01

    direction of observed targets is beneficial for improved detection of potential linear remains (e.g. Great Wall in Han-dynasty surrounding the Yumen Frontier Pass) owing to the formation of dihedral and helix scatterings based on the theory of radar physics. Morevorer, spatial resolution of multi-mode SAR images for archaeology was compared in the sites of Niya, Yumen Frontier Pass and suspected protectorate of the western regions. Results indicated that high resolution tended to easier detection of ancient targets through the identification of backscattering anomalies. Finally, interferometric analysis was also evaluated to provide complementary information rather than the backscattering. The variation of coherence is closely related to the physical parameters of observed surface, e.g. soil moisture, mild-relief as well as materials; and consequently it is useful for the relic feature enhancement and identification, validated by the PALSAR coherence images in Niya site. Acknowledgement This research was performed within the framework of the project "Smart management of cultural heritage sites in Italy and China: Earth Observation and pilot projects", funded by the Italian Ministry of Foreign Affairs and the Hundred Talents Program of the Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences (Y2ZZ27101B). The PALSAR data were provided by the European Space Agency to the authors through the Category-1 Project Id. 28640. Reference [1] Lasaponara R., Masini N. 2013, Satellite Synthetic Aperture Radar in Archaeology and Cultural Landscape: An Overview. Archaeological Prospection, 20, 71-78, doi: 10.1002/arp.1452 [2] Chen F., Masini N., Yang R., Milillo P., Feng D., Lasaponara R., 2015 A Space View of Radar Archaeological Marks: First Applications of COSMO-SkyMed X-Band Data. Remote Sens. 2015, 7, 24-50; doi:10.3390/rs70100024. [3] Cigna, F.; Tapete, D.; Lasaponara, R.; Masini, N. Amplitude change detection with Envisat ASAR to image the cultural landscape

  6. Crystal structure of the SarS protein from Staphylococcus aureus.

    PubMed

    Li, Ronggui; Manna, Adhar C; Dai, Shaodong; Cheung, Ambrose L; Zhang, Gongyi

    2003-07-01

    The expression of virulence determinants in Staphylococcus aureus is controlled by global regulatory loci (e.g., sarA and agr). One of these determinants, protein A (spa), is activated by sarS, which encodes a 250-residue DNA-binding protein. Genetic analysis indicated that the agr locus likely mediates spa repression by suppressing the transcription of sarS. Contrary to SarA and SarR, which require homodimer formation for proper function, SarS is unusual within the SarA protein family in that it contains two homologous halves, with each half sharing sequence similarity to SarA and SarR. Here we report the 2.2 A resolution X-ray crystal structure of the SarS protein. SarS has folds similar to those of SarR and, quite plausibly, the native SarA structure. Two typical winged-helix DNA-binding domains are connected by a well-ordered loop. The interactions between the two domains are extensive and conserved. The putative DNA-binding surface is highly positively charged. In contrast, negatively charged patches are located opposite to the DNA-binding surface. Furthermore, sequence alignment and structural comparison revealed that MarR has folds similar to those of SarR and SarS. Members of the MarR protein family have previously been implicated in the negative regulation of an efflux pump involved in multiple antibiotic resistance in many gram-negative species. We propose that MarR also belongs to the winged-helix protein family and has a similar mode of DNA binding as SarR and SarS and possibly the entire SarA protein family member. Based on the structural differences of SarR, SarS, and MarR, we further classified these winged-helix proteins to three subfamilies, SarA, SarS, and MarR. Finally, a possible transcription regulation mechanism is proposed.

  7. Vehicle-mounted SAR-GPR and its evaluation

    NASA Astrophysics Data System (ADS)

    Sato, Motoyuki; Kobayashi, Takao; Takahashi, Kazunori; Fujiwara, Jun; Feng, Xuan

    2006-05-01

    SAR-GPR is a sensor system composed of a GPR and a metal detector for landmine detection. The GPR employs an array antenna for advanced signal processing for better subsurface imaging. This system combined with synthetic aperture radar algorithm, can suppress clutter and can image buried objects in strongly inhomogeneous material. SAR-GPR is a stepped frequency radar system, whose RF component is a newly developed compact vector network analyzers. The size of the system is 30cm x 30cm x 30cm, composed from 6 Vivaldi antennas and 3 vector network analyzers. The weight of the system is less than 30kg, and it can be mounted on a robotic arm on a small unmanned vehicle. In the signal processing of the SAR-GPR has a unique future. It can be used with an algorithm for strong clutter suppression. The sensor has about 10cm offset from the ground surface, and it can even image the ground surface topography. It will be implemented for more advanced imaging algorithm, which can be used for the ground surface with a large roughness. Field tests of SAR-GPR were carried out in March 2005 in Japan. Then after, it was also evaluated in the Netherlands and Croatia. We report the results of these evaluation and demonstration.

  8. InSAR data for monitoring land subsidence: time to think big

    NASA Astrophysics Data System (ADS)

    Ferretti, A.; Colombo, D.; Fumagalli, A.; Novali, F.; Rucci, A.

    2015-11-01

    Satellite interferometric synthetic aperture radar (InSAR) data have proven effective and valuable in the analysis of urban subsidence phenomena based on multi-temporal radar images. Results obtained by processing data acquired by different radar sensors, have shown the potential of InSAR and highlighted the key points for an operational use of this technology, namely: (1) regular acquisition over large areas of interferometric data stacks; (2) use of advanced processing algorithms, capable of estimating and removing atmospheric disturbances; (3) access to significant processing power for a regular update of the information over large areas. In this paper, we show how the operational potential of InSAR has been realized thanks to the recent advances in InSAR processing algorithms, the advent of cloud computing and the launch of new satellite platforms, specifically designed for InSAR analyses (e.g. Sentinel-1a operated by the ESA and ALOS2 operated by JAXA). The processing of thousands of SAR scenes to cover an entire nation has been performed successfully in Italy in a project financed by the Italian Ministry of the Environment. The challenge for the future is to pass from the historical analysis of SAR scenes already acquired in digital archives to a near real-time monitoring program where up to date deformation data are routinely provided to final users and decision makers.

  9. Changes in ice thickness and SAR backscatter in relation to ice deformation in the Bay of Bothnia

    NASA Astrophysics Data System (ADS)

    Casey, J. A.; Haas, C.

    2011-12-01

    Ice conditions in the Bay of Bothnia were heavier than normal in winter 2011 and icebreaker support was in high demand. This research documents the ice conditions (ice thickness and surface roughness) within the Bay of Bothnia as measured with a helicopter-borne electromagnetic induction system (HEM), and compares the HEM measurements to synthetic aperture radar (SAR) data. Emphasis is given to observations acquired over an array of buoys that provided localized ice drift vectors from hourly global positioning system (GPS) locations. The HEM, SAR, and buoy drift data were acquired in the Bay of Bothnia during the Safety of Winter Navigation in Dynamic Ice (SafeWin) 2011 field campaign, carried out onboard the R/V Aranda between February 22 and March 8, 2011. HEM data were acquired each day from March 2 to 7 while stationed at an ice camp at 63.9N, 22.4E (near Kokkola, Finland). Six ENVISAT ASAR Wide Swath Mode images (HH polarization) were acquired during this period. The GPS buoys were deployed in a roughly rectangular array centered on the Aranda ice station. Repeated HEM flights were carried out over the buoy array to document temporal changes in the ice thickness distribution in the vicinity of the ice station. Additionally, four of the ASAR images provide complete coverage of the buoy array. The buoy drift data document periods of both convergent and divergent ice motion, as well as shear along the fast ice edge, which was located just east of the buoy array. Over the observation period the buoy array underwent a net convergent ice motion. Preliminary results from the HEM buoy array flights indicate a reduced frequency of the modal ice thickness and an associated increase in the frequency of thick (>1 m) deformed ice. These results are in agreement with the compression and shear observed in the buoy drift tracks. After applying a correction for incidence angle effects, the mean SAR backscatter over the buoy array fluctuates during the observation period. The

  10. Interferometric SAR to EO image registration problem

    NASA Astrophysics Data System (ADS)

    Rogers, George W.; Mansfield, Arthur W.; Rais, Houra

    2000-08-01

    Historically, SAR to EO registration accuracy has been at the multiple pixel level compared to sub-pixel EO to EO registration accuracies. This is due to a variety of factors including the different scattering characteristics of the ground for EO and SAR, SAR speckle, and terrain induced geometric distortion. One approach to improving the SAR to EO registration accuracy is to utilize the full information from multiple SAR surveys using interferometric techniques. In this paper we will examine this problem in detail with an example using ERS SAR imagery. Estimates of the resulting accuracy based on ERS are included.

  11. Multi-temporal InSAR monitoring of landslides in a tropical urban environment: focus on Bukavu (DR Congo)

    NASA Astrophysics Data System (ADS)

    Nobile, Adriano; Monsieurs, Elise; Dewitte, Olivier; d'Oreyes, Nicolas; Kervyn, Francois

    2016-04-01

    The western branch of the East African Rift System, in Central Africa, is characterized by the presence of several geohazards: earthquakes, volcanoes, and landslides. Every year, landslides cause fatalities, structural and functional damage to infrastructure and private properties with serious disruptions of the organization of societies and severe impact on the populations. These impacts are particularly important in the city of Bukavu (DR Congo) located within the Rift, on the southern shore of Lake Kivu. Large slow-moving landslides continuously affect highly populated slopes in the city. However little is known about their actual kinematics and the processes at play. Here we use multi-temporal InSAR technique to monitor these ground deformations. Using 50 Cosmo-SkyMed SAR images, acquired between March - October 2015 with a revisiting time of 8 days (ascending and descending orbits), we produce displacement-rate maps and ground deformation time series using the PS technique. Movements with a velocity >5cm/yr are detected, which is consistent with field observations. DGPS measurements, taken at 21 benchmarks in the area during the same period, allow validating the results. Similar ground deformation rates are found for the period 2002-2008 using Envisat ASAR images. Furthermore, comparison with rainfall monitoring data acquire on site should help us to understand the influence of water and the tropical seasonality in the slide mechanisms.

  12. Atmospheric correction in time-series SAR interferometry for land surface deformation mapping - A case study of Taiyuan, China

    NASA Astrophysics Data System (ADS)

    Tang, Wei; Liao, Mingsheng; Yuan, Peng

    2016-08-01

    The dominant error source of Synthetic Aperture Radar Interferometry (InSAR) is atmospheric phase screen (APS), resulting in phase delay of the radar signal propagating through the atmosphere. The APS in the atmosphere can be decomposed into stratified and turbulent components. In this paper, we introduced a method to compensate for stratified component in a radar interferogram using ERA-Interim reanalysis products obtained from European Centre for Medium-Range Weather Forecasts (ECMWF). Our comparative results with radiosonde data demonstrated that atmospheric condition from ERA-Interim could produce reasonable patterns of vertical profiles of atmospheric states. The stratified atmosphere shows seasonal changes which are correlated with time. It cannot be properly estimated by temporal high-pass filtering which assumes that atmospheric effects are random in time in conventional persistent scatterer InSAR (PSI). Thus, the estimated deformation velocity fields are biased. Therefore, we propose the atmosphere-corrected PSI method that the stratified delay are corrected on each interferogram by using ERA-Interim. The atmospheric residuals after correction of stratified delay were interpreted as random variations in space and time which are mitigated by using spatial-temporal filtering. We applied the proposed method to ENVISAT ASAR images covering Taiyuan basin, China, to study the ground deformation associated with groundwater withdrawal. Experimental results show that the proposed method significantly mitigate the topography-correlated APS and the estimated ground displacements agree more closely with GPS measurements than the conventional PSI.

  13. InSAR Scientific Computing Environment (Invited)

    NASA Astrophysics Data System (ADS)

    Rosen, P. A.; Gurrola, E. M.; Sacco, G.; Zebker, H. A.; Simons, M.; Sandwell, D. T.

    2009-12-01

    The InSAR Scientific Computing Environment (ISCE) is a new development effort within the NASA Advanced Information Systems and Technology program, with the intent of recasting the JPL/Caltech ROI_PAC repeat-pass interferometry package into a modern, reconfigurable, open-source computing environment. The new capability initiates the next generation of geodetic imaging processing technology for InSAR sensors, providing flexibility and extensibility in reducing measurements from radar satellites and aircraft to new geophysical products. The NRC Decadal Survey recommended DESDynI mission will deliver to the science community data of unprecedented quantity and quality, making possible global-scale studies in climate research, natural hazards, and Earth’s ecosystem. DESDynI will provide time series and multi-image measurements that permit four-dimensional models of Earth surface processes so that, for example, climate-induced changes over time become apparent and quantifiable. In this paper, we describe the Environment, and illustrate how it can facility space-based geodesy from InSAR. The ISCE invokes object oriented scripts to control legacy and new codes, and abstracts and generalizes the data model for efficient manipulation of objects among modules. The module interfaces are suitable for command-line execution or GUI-programming. It exposes users gradually to its levels of capability, allowing novices to apply it readily for simple tasks and for experienced users to mine the data with great facility. The intent of the effort is to encourage user contributions to the code, creating an open source community that will extend its life and utility.

  14. Technology progresses in microelectronics promote on-board imaging of spaceborne SAR

    NASA Astrophysics Data System (ADS)

    Xu, Xinfeng

    2007-11-01

    The realization of spaceborne SAR imaging on-board is a necessary trend for digital avionics in speedily advancing SAR remote sensors. Powerful and efficient application-specific instruction-set processors (ASIPs) play a leading role in this solution to keep data processing system functioning real-time. A few improving methodologies, technologies and advanced EDA tools in microelectronics make it possible to design such a SAR imaging processor easier and faster. Some evident and important delegates of them, including system-level modeling and simulation for SAR imaging algorithm, available IP library designed by experts, ideas of designing domain-specific SoC with multiple processors and the microelectronic ways to ruggedize avionics applied in space radiation-active environment, are presented heuristically in this paper.

  15. Mapping Changes and Damages in Areas of Conflict: From Archive C-Band SAR Data to New HR X-Band Imagery, Towards the Sentinels

    NASA Astrophysics Data System (ADS)

    Tapete, Deodato; Cigna, Francesca; Donoghue, Daniel N. M.; Philip, Graham

    2015-05-01

    On the turn of radar space science with the recent launch of Sentinel-1A, we investigate how to better exploit the opportunities offered by large C-band SAR archives and increasing datasets of HR to VHR X-band data, to map changes and damages in urban and rural areas affected by conflicts. We implement a dual approach coupling multi-interferogram processing and amplitude change detection, to assess the impact of the recent civil war on the city of Homs, Western Syria, and the surrounding semi-arid landscape. More than 280,000 coherent pixels are retrieved from Small BAseline Subset (SBAS) processing of the 8year-long ENVISAT ASAR IS2 archive, to quantify land subsidence due to pre-war water abstraction in rural areas. Damages in Homs are detected by analysing the changes of SAR backscattering (σ0), comparing 3m-resolution StripMap TerraSAR-X pairs from 2009 to 2014. Pre-war alteration is differentiated from war-related damages via operator-driven interpretation of the σ0 patterns.

  16. Land subsidence in the Cerro Prieto Geothermal Field, 1 Baja California, Mexico, from 1994 to 2005. An integrated analysis of DInSAR, levelingand geological data.

    SciTech Connect

    Sarychikhina, O; Glowacka, E; Mellors, R; Vidal, F S

    2011-03-03

    Cerro Prieto is the oldest and largest Mexican geothermal field in operation and has been producing electricity since 1973. The large amount of geothermal fluids extracted to supply steam to the power plants has resulted in considerable deformation in and around the field. The deformation includes land subsidence and related ground fissuring and faulting. These phenomena have produced severe damages to infrastructure such as roads, irrigation canals and other facilities. In this paper, the technique of Differential Synthetic Aperture Radar Interferometry (DInSAR) is applied using C-band ENVISAR ASAR data acquired between 2003 and 2006 to determine the extent and amount of land subsidence in the Mexicali Valley near Cerro Prieto Geothermal Field. The DInSAR results were compared with published data from precise leveling surveys (1994- 1997 and 1997-2006) and detailed geological information in order to improve the understanding of temporal and spatial distributions of anthropogenic subsidence in the Mexicali Valley. The leveling and DInSAR data were modeled to characterize the observed deformation in terms of fluid extraction. The results confirm that the tectonic faults control the spatial extent of the observed subsidence. These faults likely act as groundwater flow barriers for aquifers and reservoirs. The shape of the subsiding area coincides with the Cerro Prieto pull-apart basin. In addition, the spatial pattern of the subsidence as well as changes in rate are highly correlated with the development of the Cerro Prieto Geothermal Field.

  17. Spatio-temporal evolution of aseismic ground deformation in the Mexicali Valley (Baja California, Mexico) from 1993 to 2010, using differential SAR interferometry

    NASA Astrophysics Data System (ADS)

    Sarychikhina, O.; Glowacka, E.

    2015-11-01

    Ground deformation in Mexicali Valley, Baja California, Mexico, the southern part of the Mexicali-Imperial valley, is influenced by active tectonics and human activity, mainly that of geothermal fluid extraction in the Cerro Prieto Geothermal Field. Significant ground deformation, mainly subsidence (~ 18 cm yr-1), and related ground fissures cause severe damage to local infrastructure. The technique of Differential Synthetic Aperture Radar Interferometry (DInSAR) has been demonstrated to be a very effective remote sensing tool for accurately measuring the spatial and temporal evolution of ground displacements over broad areas. In present study ERS-1/2 SAR and ENVISAT ASAR images acquired between 1993 and 2010 were used to perform a historical analysis of aseismic ground deformation in Mexicali Valley, in an attempt to evaluate its spatio-temporal evolution and improve the understanding of its dynamic. For this purpose, the conventional 2-pass DInSAR was used to generate interferograms which were used in stacking procedure to produce maps of annual aseismic ground deformation rates for different periods. Differential interferograms that included strong co-seismic deformation signals were not included in the stacking and analysis. The changes in the ground deformation pattern and rate were identified. The main changes occur between 2000 and 2005 and include increasing deformation rate in the recharge zone and decreasing deformation rate in the western part of the CPGF production zone. We suggested that these changes are mainly caused by production development in the Cerro Prieto Geothermal Field.

  18. Land subsidence in the Cerro Prieto Geothermal Field, Baja California, Mexico, from 1994 to 2005: An integrated analysis of DInSAR, leveling and geological data

    NASA Astrophysics Data System (ADS)

    Sarychikhina, Olga; Glowacka, Ewa; Mellors, Robert; Vidal, Francisco Suárez

    2011-07-01

    Cerro Prieto is the oldest and largest Mexican geothermal field in operation and has been producing electricity since 1973. The large amount of geothermal fluids extracted to supply steam to the power plants has resulted in considerable deformation in and around the field. The deformation includes land subsidence and related ground fissuring and faulting. These phenomena have produced severe damages to the local infrastructure such as roads, irrigation canals and other facilities. In this paper, the technique of Differential Synthetic Aperture Radar Interferometry (DInSAR) is applied using C-band ENVISAR ASAR data acquired between 2003 and 2006 to determine the extent and amount of land subsidence in the Mexicali Valley near Cerro Prieto Geothermal Field. The DInSAR results were compared with published data from precise leveling surveys (1994-1997 and 1997-2006) and detailed geological information in order to improve understanding of the temporal and spatial distributions of anthropogenic subsidence in the Mexicali Valley. The leveling and DInSAR data were modeled to characterize the observed deformation in terms of fluid extraction. The results confirm that the tectonic faults control the spatial extent of the observed subsidence. These faults likely act as groundwater flow barriers for aquifers and reservoirs. The shape of the subsiding area coincides with the Cerro Prieto pull-apart basin. In addition, the changes in spatial pattern and rate of the subsidence are correlated with the development of the Cerro Prieto Geothermal Field.

  19. A TACSAT SAR concept

    NASA Astrophysics Data System (ADS)

    Hall, C. D.; Baker, C. J.; Keyte, G. E.; Murphy, L. M.

    1993-02-01

    The payload concept covered is that of a low cost, high performance radar sensor capable of detecting and recognizing static objects within an imaged scene of the Earth's surface using the Synthetic Aperture Radar (SAR) technique. The overall system is integrated with a TACSAT platform in Low Earth Orbit (LEO) and, although only passing reference is made to this feature, the radar could also have a capability for the detection of Ground Moving Targets (GMTI). A parametric review of such a sensor in the light of the target and background features to be observed is provided. A design concept is included showing the possible hardware realization of a candidate system, as well as budgets for the mass, size, power, and pointing requirements of the instrument. Additional design features considered are the influence that short duration missions may have on hardware redundancy and the effect of short, low duty-cycle observation periods on solar array and battery sizing. The way towards a low cost R and D demonstrator system allowing a practical investigation of the key techniques and technologies is addressed.

  20. Estimation of surface soil moisture and roughness from multi-angular ASAR imagery in the Watershed Allied Telemetry Experimental Research (WATER)

    NASA Astrophysics Data System (ADS)

    Wang, S. G.; Li, X.; Han, X. J.; Jin, R.

    2010-06-01

    Radar remote sensing has demonstrated its applicability to the retrieval of basin-scale soil moisture. The mechanism of radar backscattering from soils is complicated and strongly influenced by surface roughness. Furthermore, retrieval of soil moisture using AIEM-like models is a classic example of the underdetermined problem due to a lack of credible known soil roughness distributions at a regional scale. Characterization of this roughness is therefore crucial for an accurate derivation of soil moisture based on backscattering models. This study aims to directly obtain surface roughness information along with soil moisture from multi-angular ASAR images. The method first used a semi-empirical relationship that connects the roughness slope (Zs) and the difference in backscattering coefficient (Δσ) from ASAR data in different incidence angles, in combination with an optimal calibration form consisting of two roughness parameters (the standard deviation of surface height and the correlation length), to estimate the roughness parameters. The deduced surface roughness was then used in the AIEM model for the retrieval of soil moisture. An evaluation of the proposed method was performed in a grassland site in the middle stream of the Heihe River Basin, where the Watershed Allied Telemetry Experimental Research (WATER) was taken place. It has demonstrated that the method is feasible to achieve reliable estimation of soil water content. The key challenge to surface soil moisture retrieval is the presence of vegetation cover, which significantly impacts the estimates of surface roughness and soil moisture.

  1. SARS Patients and Their Close Contacts

    MedlinePlus

    ... Fact Sheet for SARS Patients and Their Close Contacts Format: Select one PDF [256 KB] Recommend on ... that are not now known. What does "close contact" mean? In the context of SARS, close contact ...

  2. P-3 SAR motion compensation techniques

    NASA Astrophysics Data System (ADS)

    Schwartz, Debra S.; Mansfield, Arthur W.; Roth, Duane; Rais, Houra

    2000-08-01

    The potential of airborne SAR to support the search and rescue mission needs to be investigated. Interferometric SAR (IFSAR) is to process P-3 airborne SAR data to evaluate products such as Coherent Change Detection (CCD) and Digital Elevation Models (DEM). The most crucial step in this process is the precise registration of the two SAR images obtained from separate passes. This paper presents a new technique for this registration step.

  3. Method for removing RFI from SAR images

    DOEpatents

    Doerry, Armin W.

    2003-08-19

    A method of removing RFI from a SAR by comparing two SAR images on a pixel by pixel basis and selecting the pixel with the lower magnitude to form a composite image. One SAR image is the conventional image produced by the SAR. The other image is created from phase-history data which has been filtered to have the frequency bands containing the RFI removed.

  4. SAR-derived gap jet characteristics in the lee of the Philippine Archipelago

    NASA Astrophysics Data System (ADS)

    Gierach, M. M.; Graber, H. C.

    2010-12-01

    Gap jets are ubiquitous features that have been the subject of numerous scientific studies regarding flow within the mountain gap, flow over the ocean, and/or jet-induced ocean responses (i.e., SST cooling, chlorophyll-a enhancement, and eddy generation). None of these studies characterized or quantified gap jet scales, such as jet spreading rate, velocity decay rate, and length at which the gap flow becomes fully developed or self-preserving. Instead, theoretical work and experimental studies provide the basis to understand jet characteristic scales and the respective power laws describing jet variation over the open ocean. Such scales and power laws were applied to high-resolution synthetic aperture radar (SAR) winds to assess the validity of the held scales/laws in Philippine Island wind jets. In the lee of the Philippine Archipelago, wind jets are common during the winter monsoon (November-March) season as a result of steady northeasterly winds that interact with volcanic topography. ENVISAT ASAR images from the winter monsoon were obtained and scales/power laws respective to the Philippine mountain gap jets were derived, and compared to the held scales/power laws.

  5. Monitoring land subsidence rates with permanent scatterers SAR interferometry: a case study of Beijing, China

    NASA Astrophysics Data System (ADS)

    Fan, Jun; Li, Xiaojuan; Yu, Jie; Wang, Yanbing; Wan, Yanyan; An, Zhihui

    2015-12-01

    The ground subsidence phenomenon is more serious in Beijing, large-scale land subsidence seriously threats to urban planning and construction and the safety of residents. In order to study the subsidence condition, it is necessary to monitor land subsidence. Choosing 28 scenes Envisat ASAR images covering Beijing city from December 2003 to March 2009, permanent scatterer SAR interferometry (PSI) technique was applied to obtained time series land subsidence information. Then the trend characteristics and factors of subsidence were analyzed, comparing land subsidence result with the groundwater data and geological structure data. Comparison between the PSI-derived subsidence rates and leveling data obtained shows that the result of PSI is agreed with the leveling data. The results indicate that the PSI technique is capable of providing high-level accuracy subsidence information. The results show that:(1) The deformation rates derived PSI ranging from -45.80 to 4.36mm/a;(2) In the study area, the serious subsidence areas distribute in Chaoyang District, Shunyi District, Tongzhou District and Pinggu District;(3) The subsidence tends to become more and more concentrated in 6 years from 2003 to 2009.

  6. Kronecker STAP and SAR GMTI

    NASA Astrophysics Data System (ADS)

    Greenewald, Kristjan H.; Zelnio, Edmund G.; Hero, Alfred O.

    2016-05-01

    As a high resolution radar imaging modality, SAR detects and localizes non-moving targets accurately, giving it an advantage over lower resolution GMTI radars. Moving target detection is more challenging due to target smearing and masking by clutter. Space-time adaptive processing (STAP) is often used on multiantenna SAR to remove the stationary clutter and enhance the moving targets. In (Greenewald et al., 2016),1 it was shown that the performance of STAP can be improved by modeling the clutter covariance as a space vs. time Kronecker product with low rank factors, providing robustness and reducing the number of training samples required. In this work, we present a massively parallel algorithm for implementing Kronecker product STAP, enabling application to very large SAR datasets (such as the 2006 Gotcha data collection) using GPUs. Finally, we develop an extension of Kronecker STAP that uses information from multiple passes to improve moving target detection.

  7. Monsoon '90 - Preliminary SAR results

    NASA Technical Reports Server (NTRS)

    Dubois, Pascale C.; Van Zyl, Jakob J.; Guerra, Abel G.

    1992-01-01

    Multifrequency polarimetric synthetic aperture radar (SAR) images of the Walnut Gulch watershed near Tombstone, Arizona were acquired on 28 Mar. 1990 and on 1 Aug. 1990. Trihedral corner reflectors were deployed prior to both overflights to allow calibration of the two SAR data sets. During both overflights, gravimetric soil moisture and dielectric constant measurements were made. Detailed vegetation height, density, and water content measurements were made as part of the Monsoon 1990 Experiment. Preliminary results based on analysis of the multitemporal polarimetric SAR data are presented. Only the C-band data (5.7-cm wavelength) radar images show significant difference between Mar. and Aug., with the strongest difference observed in the HV images. Based on the radar data analysis and the in situ measurements, we conclude that these differences are mainly due to changes in the vegetation and not due to the soil moisture changes.

  8. Monsoon 1990: Preliminary SAR results

    NASA Technical Reports Server (NTRS)

    Vanzyl, Jakob J.; Dubois, Pascale; Guerra, Abel

    1991-01-01

    Multifrequency polarimetric synthetic aperture radar (SAR) images of the Walnut Gulch watershed near Tombstone, Arizona were acquired on 28 Mar. 1990 and on 1 Aug. 1990. Trihedral corner reflectors were deployed prior to both overflights to allow calibration of the two SAR data sets. During both overflights, gravimetric soil moisture and dielectric constant measurements were made. Detailed vegetation height, density, and water content measurements were made as part of the Monsoon 1990 Experiment. Preliminary results based on analysis of the multitemporal polarimetric SAR data are presented. Only the C-band data (5.7-cm wavelength) radar images show significant difference between Mar. and Aug., with the strongest difference observed in the HV images. Based on the radar data analysis and the in situ measurements, we conclude that these differences are mainly due to changes in the vegetation and not due to the soil moisture changes.

  9. Registration of interferometric SAR images

    NASA Technical Reports Server (NTRS)

    Lin, Qian; Vesecky, John F.; Zebker, Howard A.

    1992-01-01

    Interferometric synthetic aperture radar (INSAR) is a new way of performing topography mapping. Among the factors critical to mapping accuracy is the registration of the complex SAR images from repeated orbits. A new algorithm for registering interferometric SAR images is presented. A new figure of merit, the average fluctuation function of the phase difference image, is proposed to evaluate the fringe pattern quality. The process of adjusting the registration parameters according to the fringe pattern quality is optimized through a downhill simplex minimization algorithm. The results of applying the proposed algorithm to register two pairs of Seasat SAR images with a short baseline (75 m) and a long baseline (500 m) are shown. It is found that the average fluctuation function is a very stable measure of fringe pattern quality allowing very accurate registration.

  10. InSAR Scientific Computing Environment - The Home Stretch

    NASA Astrophysics Data System (ADS)

    Rosen, P. A.; Gurrola, E. M.; Sacco, G.; Zebker, H. A.

    2011-12-01

    The Interferometric Synthetic Aperture Radar (InSAR) Scientific Computing Environment (ISCE) is a software development effort in its third and final year within the NASA Advanced Information Systems and Technology program. The ISCE is a new computing environment for geodetic image processing for InSAR sensors enabling scientists to reduce measurements directly from radar satellites to new geophysical products with relative ease. The environment can serve as the core of a centralized processing center to bring Level-0 raw radar data up to Level-3 data products, but is adaptable to alternative processing approaches for science users interested in new and different ways to exploit mission data. Upcoming international SAR missions will deliver data of unprecedented quantity and quality, making possible global-scale studies in climate research, natural hazards, and Earth's ecosystem. The InSAR Scientific Computing Environment has the functionality to become a key element in processing data from NASA's proposed DESDynI mission into higher level data products, supporting a new class of analyses that take advantage of the long time and large spatial scales of these new data. At the core of ISCE is a new set of efficient and accurate InSAR algorithms. These algorithms are placed into an object-oriented, flexible, extensible software package that is informed by modern programming methods, including rigorous componentization of processing codes, abstraction and generalization of data models. The environment is designed to easily allow user contributions, enabling an open source community to extend the framework into the indefinite future. ISCE supports data from nearly all of the available satellite platforms, including ERS, EnviSAT, Radarsat-1, Radarsat-2, ALOS, TerraSAR-X, and Cosmo-SkyMed. The code applies a number of parallelization techniques and sensible approximations for speed. It is configured to work on modern linux-based computers with gcc compilers and python

  11. SARS: hospital infection control and admission strategies.

    PubMed

    Ho, Pak-Leung; Tang, Xiao-Ping; Seto, Wing-Hong

    2003-11-01

    Nosocomial clustering with transmission to health care workers, patients and visitors is a prominent feature of severe acute respiratory syndrome (SARS). Hospital outbreaks of SARS typically occurred within the first week after admission of the very first SARS cases when the disease was not recognized and before isolation measures were implemented. In the majority of nosocomial infections, there was a history of close contact with a SARS patient, and transmission occurred via large droplets, direct contact with infectious material or by contact with fomites contaminated by infectious material. In a few instances, potential airborne transmission was reported in association with endotracheal intubation, nebulised medications and non-invasive positive pressure ventilation of SARS patients. In all SARS-affected countries, nosocomial transmission of the disease was effectively halted by enforcement of routine standard, contact and droplet precautions in all clinical areas and additional airborne precautions in the high-risk areas. In Hong Kong, where there are few private rooms for patient isolation, some hospitals have obtained good outcome by having designated SARS teams and separate wards for patient triage, confirmed SARS cases and step-down of patients in whom SARS had been ruled out. In conclusion, SARS represents one of the new challenges for those who are involved in hospital infection control. As SARS might re-emerge, all hospitals should take advantage of the current SARS-free interval to review their infection control programmes, alert mechanisms, response capability and to repair any identified inadequacies.

  12. Antarctic mass budget from 1975-2015 using InSAR, Landsat and RACMO-2

    NASA Astrophysics Data System (ADS)

    Mouginot, J.; Scheuchl, B.; Rignot, E. J.; Li, X.

    2015-12-01

    Ice Sheet Mass balance is measured from the difference between the ice discharge along the coast and surface mass balance of the drainage basins of the glaciers. Precise estimation of the mass balance of each glacier needs an exact delineation of their drainage basin, which, ultimately, is defined by the flow of the ice. The precision of mapping is, however, limited by the precision of the actual maps of ice flow, mainly based on speckle tracking, which is not sufficient to fully capture the direction of flow in slow-moving parts of the ice sheets. Here we revisit prior drainage basins of Antarctica using a new precise velocity map based on the interferometric phase by combining InSAR tracks from ALOS/PALSAR-1, ENVISAT/ASAR, ERS-1/-2 and RADARSAT-1/-2. We map ice flow in the interior of the ice sheet at the meter/year level precision. We discuss differences observed between new divides and topographic divides. In addition, we combine this information with a new bed topography from the mass conservation approach and a time history of glacier velocity from Landsat 1975-2015 and InSAR 1992-2015 to calculate the continental discharge since 1975. The results are combined with RACMO2 output products to reconstruct the mass balance of the ice sheet for the past 40 years. The results indicate a significant increase in mass loss from Antarctica starting in the 1990s. This work was performed at UC Irvine and Caltech's Jet Propulsion Laboratory under a contract with NASA.

  13. Mapping Selective Logging In Tropical Forest With Space-Borne SAR Data

    NASA Astrophysics Data System (ADS)

    Rauste, Yrjo; Antropov, , Oleg; Hame, Tuomas; Ramminger, Gernot; Gomez, Sharon; Seifert, Frank Martin

    2013-12-01

    A technique was developed for the mapping of selective logging in tropical forest using PALSAR imagery acquired before and after the logging operations. The technique is based on automatic detection of new forest roads and unsupervised classification of textural features, which were computed from a backscatter ratio image. The technique was adapted for TerraSAR-X and EN- VISAT/ASAR data. The accuracy of a PALSAR-based map of selective logging was assessed against reference plot data interpreted from GeoEye-1 imagery. The user's accuracy of selective logging was 95 %. The overall accuracy was 70.4 %. This is affected by the limited size of the area, which was chosen to include a large proportion of selectively logged forest. The accuracy of a TerraSAR-X-based map of selective logging was 53.6 %, but the user's accuracy of selective logging was 100 %. ALOS-type L-band radar data could be applied in an operational system over country-wide datasets to map newly constructed roads. The 40 % underestimation does not make direct reliable mapping of the area of selective logging possible. Instead, L-band derived maps of selectively logged area and new roads can be used in a wider system to pin-point areas of recent logging activity (as a proxy for forest degradation). The detected areas can then be covered by satellite or airborne optical data or ground surveys. The L-band map of areas with logging activity can also be used for stratification for sampling in a statistical area assessment.

  14. Hybrid-Polarity SAR Architecture

    NASA Astrophysics Data System (ADS)

    Raney, R. K.; Freeman, A.

    2009-04-01

    A space-based synthetic aperture radar (SAR) designed to provide quantitative information on a global scale implies severe requirements to maximize coverage and to sustain reliable operational calibration. These requirements are best served by the hybrid-polarity architecture, in which the radar transmits in circular polarization, and receives on two orthogonal linear polarizations, coherently, retaining their relative phase. This paper reviews those advantages,summarizes key attributes of hybrid-polarity dual- and quadrature-polarized SARs including conditions under which the signal-to-noise ratio is conserved, and describes the evolution of this architecture from first principles.

  15. Foliage problem in interferometric SAR

    NASA Astrophysics Data System (ADS)

    Rogers, George W.; Mansfield, Arthur W.; Roth, Duane; Poehler, Paul L.; Rais, Houra

    1999-08-01

    Interferometric SAR exploits the coherent nature of multiple synthetic aperture radar images to recover phase (range difference) information and thence terrain evaluation data as well as other phase derivative products such as Coherent Change Detection (CCD). Of the numerous factors that can degrade the coherency of multiple SAR collections, foliage constitutes one of the most challenging. The foliage problem in IFSAR is discussed and an airborne multiple pass collection is used to illustrate some facets of the problem. Resolution as a variable in the tradeoff between the bias and variance of the interferogram is discussed in the context of the example.

  16. Remote sensing measurements of thermokarst subsidence using InSAR

    NASA Astrophysics Data System (ADS)

    Liu, L.; Schaefer, K. M.; Chen, A. C.; Gusmeroli, A.; Zebker, H. A.; Zhang, T.

    2015-09-01

    Thawing of ice-rich permafrost followed by surface subsidence results in irregular, depressed landforms known as thermokarst. Many remote sensing studies have identified thermokarst landforms and mapped their changes. However, the intrinsic dynamic thermokarst process of surface subsidence remains a challenge to quantify and is seldom examined using remote sensing methods. In this study we used spaceborne interferometric synthetic aperture radar (InSAR) data to map surface subsidence trends at a thermokarst landform located near Deadhorse on the North Slope of Alaska. A pipeline access road constructed in the 1970s triggered the thawing of the permafrost, causing subsequent expansion of the thermokarst landform. Using Phased Array type L band Synthetic Aperture Radar images acquired by the Advanced Land Observing Satellite-1, our InSAR analysis reveals localized thermokarst subsidence of 2-8 cm/yr between 2006 and 2010, equivalent to an ice volume loss of about 1.2 × 107 m3/yr. Comparisons between InSAR subsidence trends and lidar microtopography suggest a characteristic time of 8 years of thermokarst development. We also quantitatively explain the difficulty, uncertainties, and possible biases in separating thermokarst-induced, irreversible subsidence from cyclic seasonal deformation. Our study illustrates that InSAR is an effective tool for mapping and studying active thermokarst processes and quantifying ice loss.

  17. sarU, a sarA homolog, is repressed by SarT and regulates virulence genes in Staphylococcus aureus.

    PubMed

    Manna, Adhar C; Cheung, Ambrose L

    2003-01-01

    In searching the Staphylococcus aureus genome, we previously identified sarT, a homolog of sarA, which encodes a repressor for alpha-hemolysin synthesis. Adjacent but transcribed divergently to sarT is sarU, which encodes a 247-residue polypeptide, almost twice the length of SarA. Sequence alignment disclosed that SarU, like SarS, which is another SarA homolog, could be envisioned as a molecule with two halves, with each half being homologous to SarA. SarU, as a member of the SarA family proteins, disclosed conservation of basic residues within the helix-turn-helix motif and within the beta hairpin loop, two putative DNA binding domains within this protein family. The transcription of sarU is increased in a sarT mutant. Gel shift and transcriptional fusion studies revealed that SarT can bind to the sarU promoter region, probably acting as a repressor for sarU transcription. The expression of RNAII and RNAIII of agr is decreased in a sarU mutant. As RNAIII expression is up-regulated in a sarT mutant, we hypothesize that sarT may down regulate agr RNAIII expression by repressing sarU, a positive activator of agr expression. We propose that, in addition to the quorum sensing effect of the autoinducing peptide of agr, the sarT-sarU pathway may represent a secondary amplification loop whereby the expression of agr (e.g., those found in vivo) might repress sarT, leading to increased expression of sarU. Elevated sarU expression would result in additional amplification of the original agr signal.

  18. ENVISAT.MERIS spectral bands and ENVISAT ASAR - discussion on applications of Sentinel 1 and 2 for agriculture in Poland.

    NASA Astrophysics Data System (ADS)

    Dabrowska-Zielinska, K.; Budzynska, M.; Tomaszewska, M.; Bartold, M.; Turlej, K.

    2012-04-01

    Presented studies were based on application of ENVISAT MERIS data for assessment of crop conditions in 04.05.2003; 26.04.2007 and 04.09.2004. Sentinel 2 will have better spatial resolution than MERIS and additionally short wave infrared band, but the results of LAI assessment were presented using various indices from MERIS and the same study will be repeated using Sentinel data. Also the indices derived from MERIS were correlated with the ASAR data to indicate the possibilities of LAI assessment using Sentinel 1. The study has been conducted at agricultural region Wielkopolska located in the West part of Poland - The dominating crops are: winter and spring wheat, winter rye, winter and spring triticale, winter and spring barley, winter rape, corn, alfalfa, and sugar beet. Also, grassland area is presented. For the test area ENVISAT.MERIS images has been obtained for the ESA projects: C1P.1427, AOALO.3677, and C1P.7389. Simultaneously to satellite overpasses ground measurement of various soil-vegetation parameters have been carried out including wet and dry biomass taken from 1 m2 (in the laboratory), LAI using LAI-2000 Plant Canopy Analyser, height of the vegetation, and soil moisture using TRIME-FM. These measurements were applied for statistical analysis of parameters with satellite-derived indices. In this article only data for biomass and Leaf Area Index have been used in order to find the relationship between measured and satellite derived index. There has been found the high correlation between biomass and LAI for each of the studied crops, the highest for beet root and alfalfa (R2=0.95 and R2=0.90), the lowest for rape For the statistical analyses between LAI and satellite data the following indices calculated from Meris have been taken into account: 2/8 (443/681), 5/12 (550/779), 10/5 (754/560), 10/9 (754/709), 12/5 (779/560), and using red edge (10-9)/(10+9), using blue spectrum (10-2)/(10+2), (12-8)/(12+8), (13-7)/(13+7). MERIS blue bands are 1-3, green 4

  19. SARS: a health system's perspective.

    PubMed

    Beard, Leslie; Clark, Caroline

    2003-01-01

    Effective communications with different stakeholders was critical for health systems everywhere during the worldwide SARS outbreak earlier this year. For Capital Health in Edmonton, Alberta, the health system was able to build on its past experiences in dealing with meningococcal outbreaks and its planning for a pandemic flu. PMID:14628532

  20. Further SEASAT SAR coastal ocean wave analysis

    NASA Technical Reports Server (NTRS)

    Kasischke, E. S.; Shuchman, R. A.; Meadows, G. A.; Jackson, P. L.; Tseng, Y.

    1981-01-01

    Analysis techniques used to exploit SEASAT synthetic aperture radar (SAR) data of gravity waves are discussed and the SEASAT SAR's ability to monitor large scale variations in gravity wave fields in both deep and shallow water is evaluated. The SAR analysis techniques investigated included motion compensation adjustments and the semicausal model for spectral analysis of SAR wave data. It was determined that spectra generated from fast Fourier transform analysis (FFT) of SAR wave data were not significantly altered when either range telerotation adjustments or azimuth focus shifts were used during processing of the SAR signal histories, indicating that SEASAT imagery of gravity waves is not significantly improved or degraded by motion compensation adjustments. Evaluation of the semicausal (SC) model using SEASAT SAR data from Rev. 974 indicates that the SC spectral estimates were not significantly better than the FFT results.

  1. Helmand river hydrologic studies using ALOS PALSAR InSAR and ENVISAT altimetry

    USGS Publications Warehouse

    Lu, Zhiming; Kim, J.-W.; Lee, H.; Shum, C.K.; Duan, J.; Ibaraki, M.; Akyilmaz, O.; Read, C.-H.

    2009-01-01

    The Helmand River wetland represents the only fresh-water resource in southern Afghanistan and one of the least mapped water basins in the world. The relatively narrow wetland consists of mostly marshes surrounded by dry lands. In this study, we demonstrate the use of the Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) Interferometric SAR (InSAR) to detect the changes of the Helmand River wetland water level. InSAR images are combined with the geocentric water level measurements from the retracked high-rate (18-Hz) Environmental Satellite (Envisat) radar altimetry to construct absolute water level changes over the marshes. It is demonstrated that the integration of the altimeter and InSAR can provide spatio-temporal measurements of water level variation over the Helmand River marshes where in situ measurements are absent. ?? Taylor & Francis Group, LLC.

  2. Long-Term Monitoring of Water Dynamics in the Sahel Region Using the Multi-Sar

    NASA Astrophysics Data System (ADS)

    Bertram, A.; Wendleder, A.; Schmitt, A.; Huber, M.

    2016-06-01

    Fresh water is a scarce resource in the West-African Sahel region, seasonally influenced by droughts and floods. Particularly in terms of climate change, the importance of wetlands increases for flora, fauna, human population, agriculture, livestock and fishery. Hence, access to open water is a key factor. Long-term monitoring of water dynamics is of great importance, especially with regard to the spatio-temporal extend of wetlands and drylands. It can predict future trends and facilitate the development of adequate management strategies. Lake Tabalak, a Ramsar wetland of international importance, is one of the most significant ponds in Niger and a refuge for waterbirds. Nevertheless, human population growth increased the pressure on this ecosystem, which is now degrading for all uses. The main objective of the study is a long-term monitoring of the Lake Tabalak's water dynamics to delineate permanent and seasonal water bodies, using weather- and daytime-independent multi-sensor and multi-temporal Synthetic Aperture Radar (SAR) data available for the study area. Data of the following sensors from 1993 until 2016 are used: Sentinel-1A, TerraSARX, ALOS PALSAR-1/2, Envisat ASAR, RADARSAT-1/2, and ERS-1/2. All SAR data are processed with the Multi-SAR-System, unifying the different characteristics of all above mentioned sensors in terms of geometric, radiometric and polarimetric resolution to a consistent format. The polarimetric representation in Kennaugh elements allows fusing single-polarized data acquired by older sensors with multi-polarized data acquired by current sensors. The TANH-normalization guarantees a consistent and therefore comparable description in a closed data range in terms of radiometry. The geometric aspect is solved by projecting all images to an earth-fixed coordinate system correcting the brightness by the help of the incidence angle. The elevation model used in the geocoding step is the novel global model produced by the TanDEM-X satellite

  3. DInSAR time series generation within a cloud computing environment: from ERS to Sentinel-1 scenario

    NASA Astrophysics Data System (ADS)

    Casu, Francesco; Elefante, Stefano; Imperatore, Pasquale; Lanari, Riccardo; Manunta, Michele; Zinno, Ivana; Mathot, Emmanuel; Brito, Fabrice; Farres, Jordi; Lengert, Wolfgang

    2013-04-01

    requests of processing resources linked to disaster events. This work aims at presenting a parallel computational model for the widely used DInSAR algorithm named as Small BAseline Subset (SBAS), which has been implemented within the cloud computing environment provided by the ESA-CIOP platform. This activity has resulted in developing a scalable, unsupervised, portable, and widely accessible (through a web portal) parallel DInSAR computational tool. The activity has rewritten and developed the SBAS application algorithm within a parallel system environment, i.e., in a form that allows us to benefit from multiple processing units. This requires the devising a parallel version of the SBAS algorithm and its subsequent implementation, implying additional complexity in algorithm designing and an efficient multi processor programming, with the final aim of a parallel performance optimization. Although the presented algorithm has been designed to work with Sentinel-1 data, it can also process other satellite SAR data (ERS, ENVISAT, CSK, TSX, ALOS). Indeed, the performance analysis of the implemented SBAS parallel version has been tested on the full ASAR archive (64 acquisitions) acquired over the Napoli Bay, a volcanic and densely urbanized area in Southern Italy. The full processing - from the raw data download to the generation of DInSAR time series - has been carried out by engaging 4 nodes, each one with 2 cores and 16 GB of RAM, and has taken about 36 hours, with respect to about 135 hours of the sequential version. Extensive analysis on other test areas significant from DInSAR and geophysical viewpoint will be presented. Finally, preliminary performance evaluation of the presented approach within the Sentinel-1 scenario will be provided.

  4. Controlling Data Collection to Support SAR Image Rotation

    DOEpatents

    Doerry, Armin W.; Cordaro, J. Thomas; Burns, Bryan L.

    2008-10-14

    A desired rotation of a synthetic aperture radar (SAR) image can be facilitated by adjusting a SAR data collection operation based on the desired rotation. The SAR data collected by the adjusted SAR data collection operation can be efficiently exploited to form therefrom a SAR image having the desired rotational orientation.

  5. L-Band SAR Interferometry for Mapping Arctic Landfast Ice

    NASA Astrophysics Data System (ADS)

    Meyer, F. J.; Mahoney, A.; Eicken, H.; Denny, C. L.

    2010-12-01

    Landfast sea ice is a key element of the arctic coastal system. Its presence can mitigate the effect of winter storms on the coast and impact the degree of coastal erosion. Landfast ice is also of great importance to coastal communities who use the ice for travel and to hunt. Furthermore, its presence and stability is of considerable economic importance for offshore oil and gas development in parts of the Arctic. In recent years, there has been a reduced presence of landfast sea ice throughout the Arctic. E.g., along Alaska’s northern coast, although the annual maximum extent has changed little, landfast sea ice appears to forming later and breaking up earlier than it did during the 1970s. As a result of these changes together with increasing commercial interest in coastal areas of the Arctic, it has become important in recent years to be able to identify landfast ice from remote sensing data. In recent years methods have been developed to extract the seaward landfast ice edge from series of remote sensing images, with most of them relying on incoherent change detection in optical, infrared, or radar amplitude imagery. While such approaches provide valuable results, some still lack the required level of robustness and all lack the ability to fully automate the detection and mapping of landfast ice over large areas and long time spans. Furthermore, it is often not so much the presence, but the stability of landfast ice that matters most in practical applications, in particular use of sea ice as a platform. This paper presents an alternative approach to mapping landfast ice extent and assessing ice stability. The method is based on interferometric processing of L-band SAR image pairs acquired by the spaceborne SAR sensor PALSAR on board the Japanese Advanced Land Observing Satellite (ALOS). With interferometric phase and interferometric coherence, SAR interferometry (InSAR) comprises two measurements that have the potential for assessing both landfast ice extent

  6. Applying PolSAR and PolInSAR to Forest Structure Information Extraction

    NASA Astrophysics Data System (ADS)

    Chen, E.; Li, Z.; Li, W.; Feng, Q.; Zhou, W.; Pottier, E.; Hong, W.

    2013-01-01

    The key research activities and achievements in the field of applying PolSAR and PolInSAR to forest structure information extraction in DRAGON 2 are summarized in this paper. The limitation of the ALOS PolInSAR dataset acquired in the Culai test site for forest height extraction because of its long temporal baseline (46 days), and how the PolInSAR coherence optimization methods can help improve the topography inversion accuracy under forest canopy were presented. We have analyzed and evaluated the capability of multiple polarization parameters extracted from different frequency PolSAR data for forest scar mapping in the Shibazhan test site, and developed the land cover classification method based on SVM (Support Vector Machine) using PolSAR data. With the L-band E-SAR PolInSAR data acquired in the test site in Germany, we developed forest above ground biomass (AGB) estimation approach based on polarization coherence tomography (PCT).

  7. 5. SWITCH TOWER AND JUNCTION OF S.A.R. #1 & S.A.R. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. SWITCH TOWER AND JUNCTION OF S.A.R. #1 & S.A.R. #2 TRANSMISSION LINES, MARCH 7, 1916. SCE drawing no. 4932. - Santa Ana River Hydroelectric System, Transmission Lines, Redlands, San Bernardino County, CA

  8. Parallel strategies for SAR processing

    NASA Astrophysics Data System (ADS)

    Segoviano, Jesus A.

    2004-12-01

    This article proposes a series of strategies for improving the computer process of the Synthetic Aperture Radar (SAR) signal treatment, following the three usual lines of action to speed up the execution of any computer program. On the one hand, it is studied the optimization of both, the data structures and the application architecture used on it. On the other hand it is considered a hardware improvement. For the former, they are studied both, the usually employed SAR process data structures, proposing the use of parallel ones and the way the parallelization of the algorithms employed on the process is implemented. Besides, the parallel application architecture classifies processes between fine/coarse grain. These are assigned to individual processors or separated in a division among processors, all of them in their corresponding architectures. For the latter, it is studied the hardware employed on the computer parallel process used in the SAR handling. The improvement here refers to several kinds of platforms in which the SAR process is implemented, shared memory multicomputers, and distributed memory multiprocessors. A comparison between them gives us some guidelines to follow in order to get a maximum throughput with a minimum latency and a maximum effectiveness with a minimum cost, all together with a limited complexness. It is concluded and described, that the approach consisting of the processing of the algorithms in a GNU/Linux environment, together with a Beowulf cluster platform offers, under certain conditions, the best compromise between performance and cost, and promises the major development in the future for the Synthetic Aperture Radar computer power thirsty applications in the next years.

  9. Reflectors for SAR performance testing.

    SciTech Connect

    Doerry, Armin Walter

    2008-01-01

    Synthetic Aperture Radar (SAR) performance testing and estimation is facilitated by observing the system response to known target scene elements. Trihedral corner reflectors and other canonical targets play an important role because their Radar Cross Section (RCS) can be calculated analytically. However, reflector orientation and the proximity of the ground and mounting structures can significantly impact the accuracy and precision with which measurements can be made. These issues are examined in this report.

  10. Representing SAR complex image pixels

    NASA Astrophysics Data System (ADS)

    Doerry, A. W.

    2016-05-01

    Synthetic Aperture Radar (SAR) images are often complex-valued to facilitate specific exploitation modes. Furthermore, these pixel values are typically represented with either real/imaginary (also known as I/Q) values, or as Magnitude/Phase values, with constituent components comprised of integers with limited number of bits. For clutter energy well below full-scale, Magnitude/Phase offers lower quantization noise than I/Q representation. Further improvement can be had with companding of the Magnitude value.

  11. SAR Image Complex Pixel Representations

    SciTech Connect

    Doerry, Armin W.

    2015-03-01

    Complex pixel values for Synthetic Aperture Radar (SAR) images of uniform distributed clutter can be represented as either real/imaginary (also known as I/Q) values, or as Magnitude/Phase values. Generally, these component values are integers with limited number of bits. For clutter energy well below full-scale, Magnitude/Phase offers lower quantization noise than I/Q representation. Further improvement can be had with companding of the Magnitude value.

  12. Bats, civets and the emergence of SARS.

    PubMed

    Wang, L F; Eaton, B T

    2007-01-01

    Severe acute respiratory syndrome (SARS) was the first pandemic transmissible disease of previously unknown aetiology in the twenty-first century. Early epidemiologic investigations suggested an animal origin for SARS-CoV. Virological and serological studies indicated that masked palm civets ( Paguma larvata), together with two other wildlife animals, sampled from a live animal market were infected with SARS-CoV or a closely related virus. Recently, horseshoe bats in the genus Rhinolophus have been identified as natural reservoir of SARS-like coronaviruses. Here, we review studies by different groups demonstrating that SARS-CoV succeeded in spillover from a wildlife reservoir (probably bats) to human population via an intermediate host(s) and that rapid virus evolution played a key role in the adaptation of SARS-CoVs in at least two nonreservoir species within a short period.

  13. Interseismic strain accumulation across the North Anatolian Fault measured using InSAR

    NASA Astrophysics Data System (ADS)

    Walters, R. J.; Parsons, B. E.; Wright, T. J.

    2010-12-01

    The North Anatolian Fault (NAF) is a major feature of Middle Eastern tectonics, facilitating the westwards 'escape' of the Anatolian block away from the Arabia-Eurasia continental collision. In order to understand the role that the NAF plays in regional tectonics it is important to accurately determine the slip rate across the fault. Many slip rate estimates for the NAF have been made over Quaternary and longer time-scales but few geodetic estimates currently exist, especially in eastern Turkey. Here we construct satellite radar interferograms using Envisat ASAR data to measure ground displacements around the NAF and hence estimate the slip rate across it. We make use of SAR data from two satellite tracks, one ascending and one descending, that overlap across the NAF, providing a check on the assumption of horizontal fault-parallel motion that has previously been used in interseismic modelling of the fault. We mitigate the effects of atmospheric errors by constructing multiple interferograms over the fault and summing them, effectively creating a longer timespan interferogram and improving the signal-to-noise ratio. We empirically correct for orbital errors by flattening the radar swaths on the Anatolian Plateau, an area with little expected deformation. Our measurements of rates of displacement are consistent with an interseismic model for the NAF where deformation occurs at depth on a narrow shear zone below a layer in which the fault is locked. We jointly invert data from both satellite tracks to solve for best fitting model parameters, estimating both the slip rate and the depth to which the fault is locked. Our best-fitting model gives a slip rate of 23 mm/yr and a locking depth of 19 km, which is in agreement with a previous estimate made from a single track of ERS SAR data (Wright et al., 2001, GRL 28, 2117-2120), and with existing GPS data. We also construct a velocity field using a combination of InSAR and GPS data for eastern Turkey.

  14. Coastal flood inundation monitoring with Satellite C-band and L-band Synthetic Aperture Radar data

    USGS Publications Warehouse

    Ramsey, Elijah W.; Rangoonwala, Amina; Bannister, Terri

    2013-01-01

    Satellite Synthetic Aperture Radar (SAR) was evaluated as a method to operationally monitor the occurrence and distribution of storm- and tidal-related flooding of spatially extensive coastal marshes within the north-central Gulf of Mexico. Maps representing the occurrence of marsh surface inundation were created from available Advanced Land Observation Satellite (ALOS) Phased Array type L-Band SAR (PALSAR) (L-band) (21 scenes with HH polarizations in Wide Beam [100 m]) data and Environmental Satellite (ENVISAT) Advanced SAR (ASAR) (C-band) data (24 scenes with VV and HH polarizations in Wide Swath [150 m]) during 2006-2009 covering 500 km of the Louisiana coastal zone. Mapping was primarily based on a decrease in backscatter between reference and target scenes, and as an extension of previous studies, the flood inundation mapping performance was assessed by the degree of correspondence between inundation mapping and inland water levels. Both PALSAR- and ASAR-based mapping at times were based on suboptimal reference scenes; however, ASAR performance seemed more sensitive to reference-scene quality and other types of scene variability. Related to water depth, PALSAR and ASAR mapping accuracies tended to be lower when water depths were shallow and increased as water levels decreased below or increased above the ground surface, but this pattern was more pronounced with ASAR. Overall, PALSAR-based inundation accuracies averaged 84% (n = 160), while ASAR-based mapping accuracies averaged 62% (n = 245).

  15. InSAR Forensics: Tracing InSAR Scatterers in High Resolution Optical Image

    NASA Astrophysics Data System (ADS)

    Wang, Yuanyuan; Zhu, XiaoXiang

    2015-05-01

    This paper presents a step towards a better interpretation of the scattering mechanism of different objects and their deformation histories in SAR interferometry (InSAR). The proposed technique traces individual SAR scatterer in high resolution optical images where their geometries, materials, and other properties can be better analyzed and classified. And hence scatterers of a same object can be analyzed in group, which brings us to a new level of InSAR deformation monitoring.

  16. Microstrip antennas for SAR applications

    NASA Technical Reports Server (NTRS)

    Haddad, H. A.

    1983-01-01

    Current and future microstrip antenna technology development for Spaceborne Synthetic Aperture Radars (SAR) are summarized. Some of the electrical and mechanical characteristics of previously and presently developed microstrip SAR antennas are shown. The SEASAT, the SIR-A and presently the SIR-B antennas are all designed for operation at L-band with approximately 22 MHz of bandwidth. The antennas have linear polarization with minimum of 20 dB of polarization purity. Both the SEASAT and SIR-A antennas were designed for a fixed pointing angle of 20.5 deg and 47 deg, respectively. However, the SIR-B has the added feature of mechanical beam steering in elevation (range). With the exception of different mechanical characteristics, it is concluded that present spaceborne SAR antennas have only single frequency and single polarization performance. The lack of large spaceborne antennas operating at the higher degree of fabrication tolerance required for a given performance; and larger feed and radiating element losses.

  17. Building detection in SAR imagery

    SciTech Connect

    Steinbach, Ryan Matthew

    2015-04-01

    Current techniques for building detection in Synthetic Aperture Radar (SAR) imagery can be computationally expensive and/or enforce stringent requirements for data acquisition. I present two techniques that are effective and efficient at determining an approximate building location. This approximate location can be used to extract a portion of the SAR image to then perform a more robust detection. The proposed techniques assume that for the desired image, bright lines and shadows, SAR artifact effects, are approximately labeled. These labels are enhanced and utilized to locate buildings, only if the related bright lines and shadows can be grouped. In order to find which of the bright lines and shadows are related, all of the bright lines are connected to all of the shadows. This allows the problem to be solved from a connected graph viewpoint, where the nodes are the bright lines and shadows and the arcs are the connections between bright lines and shadows. For the first technique, constraints based on angle of depression and the relationship between connected bright lines and shadows are applied to remove unrelated arcs. The second technique calculates weights for the connections and then performs a series of increasingly relaxed hard and soft thresholds. This results in groups of various levels on their validity. Once the related bright lines and shadows are grouped, their locations are combined to provide an approximate building location. Experimental results demonstrate the outcome of the two techniques. The two techniques are compared and discussed.

  18. Study on the properties of the Integrated Precipitable Water (IPW) maps derived by GPS, SAR interferometry and numerical forecasting models

    NASA Astrophysics Data System (ADS)

    Mateus, Pedro; Nico, Giovanni; Tomé, Ricardo; Catalão, João.; Miranda, Pedro

    2010-05-01

    The knowledge of spatial distribution of relative changes in atmospheric Integrated Precipitable Water (IPW) density is important for climate studies and numerical weather forecasting. An increase (or decrease) of the IPW density affects the phase of electromagnetic waves. For this reason, this quantity can be measured by techniques such as GPS and space-borne SAR interferometry (InSAR). The aim of this work is to study the isotropic properties of the IPW maps obtained by GPS and SAR InSAR measurements and derived by a Numerical Weather Forecasting Model. The existence of a power law in their phase spectrum is verified. The relationship between the interferometric phase delay and the topographic height of the observed area is also investigated. The Lisbon region, Portugal, was chosen as a study area. This region is monitored by a network of GPS permanent stations covering an area of about squared kilometers. The network consists of 12 GPS stations of which 4 belonging to the Instituto Geográfico Português (IGP) and 8 to Instituto Geográfico do Exercito (IGEOE). All stations were installed between 1997 and the beginning of 2009. The GAMIT package was used to process GPS data and to estimate the total zenith delay with a temporal sampling of 15 minutes. A set of 25 SAR interferograms with a 35-day temporal baseline were processed using ASAR-ENVISAT data acquired over the Lisbon region during the period from 2003 to 2005 and from 2008 to 2009. These interferograms give an estimate of the variation of the global atmospheric delay. Terrain deformations related to known geological phenomena in the Lisbon area are negligible at this time scale of 35 days. Furthermore, two interferometric SAR images acquired by ERS-1/2 over the Lisbon region on 20/07/1995 and 21/07/1995, respectively, and so with a temporal baseline of just 1 day, were also processed. The Weather Research & Forecasting Model (WRF) was used to generate the three-dimensional fields of temperature

  19. Chirp Scaling Algorithms for SAR Processing

    NASA Technical Reports Server (NTRS)

    Jin, M.; Cheng, T.; Chen, M.

    1993-01-01

    The chirp scaling SAR processing algorithm is both accurate and efficient. Successful implementation requires proper selection of the interval of output samples, which is a function of the chirp interval, signal sampling rate, and signal bandwidth. Analysis indicates that for both airborne and spaceborne SAR applications in the slant range domain a linear chirp scaling is sufficient. To perform nonlinear interpolation process such as to output ground range SAR images, one can use a nonlinear chirp scaling interpolator presented in this paper.

  20. Sea state monitoring over Socotra Rock (Ieodo) by dual polarization SAR image analysis

    NASA Astrophysics Data System (ADS)

    Choi, Y.; Kim, J.; Yun, H.; yun, H.

    2013-12-01

    The application SAR in sea state monitoring have been conducted in the large number of fields such as the vessel tracing using the wake in SAR amplitude, the measurement of sea wave height and the oil spill detection. The true merit of SAR application in sea state monitoring is the full independence from the climate conditions. Hence, it is highly useful to secure safety of the anthropogenic activities in ocean and the understanding of the marine environment. Especially the dual and full polarization modes of new L band and X band SAR such as Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR)'s Fine Beam double Polarization (FDB) and Polarimetry mode (PLR) and terraSAR-X polarization mode provided innovative means to extract sea state information exploiting the different amplitude and phase angle responses by electromagnetic and sea wave interactions. Thus a sample projects for mining the maximum possible sea state information from the ALOS PLASAR FDB SAR/InSAR pairs compared with the in-suit observation of sea state is being conducted. Test site was established over Socotra Rock (Ieodo in Korean), which is located at the Western Sea of Korea. At first, it aimed the measurement of sea waves using ALOS PLASAR multi-polarization images and its doppler-shift analysis. Together with sea state monitoring, auxiliary data analyses to combine the sea state outputs with the other in-orbital sensing image and non image information to trace the influence of sea states in the marine environment are actively undergoing. For instance, MERIS chlorophyll-a products are under investigation to identify the correlation with sea state. However, an significant obstacles to apply SAR interpretation scheme for mining sea state is the temporal gap between SAR image acquisitions in spite of the improved revising time of contemporary in-orbital SAR sensors. To tackle this problem, we are also introducing the multi view angle optical sensor

  1. High resolution SAR applications and instrument design

    NASA Technical Reports Server (NTRS)

    Dionisio, C.; Torre, A.

    1993-01-01

    The Synthetic Aperture Radar (SAR) has viewed, in the last two years, a huge increment of interest from many preset and potential users. The good spatial resolution associated to the all weather capability lead to considering SAR not only a scientific instrument but a tool for verifying and controlling the daily human relationships with the Earth Environment. New missions were identified for SAR as spatial resolution became lower than three meters: disasters, pollution, ships traffic, volcanic eruptions, earthquake effect are only a few of the possible objects which can be effectively detected, controlled and monitored by SAR mounted on satellites. High resolution radar design constraints and dimensioning are discussed.

  2. Bistatic SAR: Signal Processing and Image Formation.

    SciTech Connect

    Wahl, Daniel E.; Yocky, David A.

    2014-10-01

    This report describes the significant processing steps that were used to take the raw recorded digitized signals from the bistatic synthetic aperture RADAR (SAR) hardware built for the NCNS Bistatic SAR project to a final bistatic SAR image. In general, the process steps herein are applicable to bistatic SAR signals that include the direct-path signal and the reflected signal. The steps include preprocessing steps, data extraction to for a phase history, and finally, image format. Various plots and values will be shown at most steps to illustrate the processing for a bistatic COSMO SkyMed collection gathered on June 10, 2013 on Kirtland Air Force Base, New Mexico.

  3. [SARS-CoV infection and pregnancy].

    PubMed

    Ksiezakowska, Kinga; Laszczyk, Magdalena; Wilczyński, Jan; Nowakowska, Dorota

    2008-01-01

    SARS is a highly contagious infection, caused by new coronavirus SARS-CoV. Immunopathological mechanisms responsible for the reaction to SARS-CoV infection have not yet been fully elucidated. Cytokine profile of SARS patients showed marked elevation of Th1 cytokine, interferon gamma, inflammatory cytokines for at least 2 weeks after the onset of the disease. The clinical manifestation of SARS in patients has been of varied nature. Fever of more then 38 degrees C, lasting more then 24 hours, is the most frequently encountered symptom. Other symptoms are non specific and they may include: sore throat, myalgia and nausea. The results of the radiological investigation may appear normal. Infants born to pregnant women with SARS did not appear to have acquired the infection through vertical transmission. However, direct contact with the maternal body fluid which contained SARS-CoV, has put the infants in great danger of perinatal infection. Ribavirin and corticosteroids are usually suggested for the treatment of SARS. However, the ribavirin therapy increases the risk of teratogenic effects in newborns of pregnant women with SARS. Therefore, the usage of this drug is not recommended during pregnancy and lactation. PMID:18510050

  4. Geodetic integration of Sentinel-1A IW data using PSInSAR in Hungary

    NASA Astrophysics Data System (ADS)

    Farkas, Péter; Hevér, Renáta; Grenerczy, Gyula

    2015-04-01

    ESA's latest Synthetic Aperture Radar (SAR) mission Sentinel-1 is a huge step forward in SAR interferometry. With its default acquisition mode called the Interferometric Wide Swath Mode (IW) areas through all scales can be mapped with an excellent return time of 12 days (while only the Sentinel-1A is in orbit). Its operational data policy is also a novelty, it allows scientific users free and unlimited access to data. It implements a new type of ScanSAR mode called Terrain Observation with Progressive Scan (TOPS) SAR. It has the same resolution as ScanSAR but with better signal-to-noise ratio distribution. The bigger coverage is achieved by rotation of the antenna in the azimuth direction, therefore it requires very precise co-registration because even errors under a pixel accuracy can introduce azimuth phase variations caused by differences in Doppler-centroids. In our work we will summarize the benefits and the drawbacks of the IW mode. We would like to implement the processing chain of GAMMA Remote Sensing of such data for mapping surface motion with special attention to the co-registration step. Not only traditional InSAR but the advanced method of Persistent Scatterer InSAR (PSInSAR) will be performed and presented as well. PS coverage, along with coherence, is expected to be good due to the small perpendicular and temporal baselines. We would also like to integrate these measurements into national geodetic networks using common reference points. We have installed trihedral corner reflectors at some selected sites to aid precise collocation. Thus, we aim to demonstrate that Sentinel-1 can be effectively used for surface movement detection and monitoring and it can also provide valuable information for the improvement of our networks.

  5. Pol(In)SAR Soil Moisture Study by using Pi-SAR 2L and GB-SAR Data in Preparation of the upcoming ALOS-2/PALSAR-2 Mission

    NASA Astrophysics Data System (ADS)

    Koyama, C.; Sato, M.

    2013-12-01

    Recently Earth Observation by means of active microwave is advancing rapidly. The evolution started from first-generation classical single-channel systems like JERS (JAXA), ERS (ESA) or Radarsat-1 (CSA). With the launch of ALOS-1 (JAXA), the first fully polarimetric SAR measurements became available followed by Radarsat-2 (CSA) and TerraSAR-X (DLR), making polarimetric L-, C-, and X-band data available. In Japanese fiscal year 2013, the third generation of SAR satellites will begin with the launch of ALOS-2. The JAXA cutting-edge follow-on mission to the highly acclaimed ALOS-1 will carry the state-of-the-art PALSAR-2 sensor aboard. Due to its much better orbital revisit cycle of only 14 days and its very high spatial resolution (3 m) the system will be highly suitable for interferometric analysis of polarimetric data obtained from repeat-pass acquisitions. The combination of polarimetry and interferometry is probably the most promising approach for a better estimation of geophysical parameters from SAR data acquired over natural terrain and thus will greatly improve the capabilities to estimate soil moisture under all kinds of vegetation with high accuracy and with high temporal and spatial resolutions. In advent of the 3rd generation of Japanese SAR EO satellites, our group conducts a variety of fundamental research on low-frequency SAR surface scattering/interactions. Here, we present first results from soil moisture experiments based on fully polarimetric GB-SAR (Tohoku University) and Pi-SAR 2L (JAXA) measurements. These experiments comprise investigations of the effective soil moisture measuring depth of L-band SAR. The experimental set-up consists of an array of receiving di-pole antennas installed in different depths to quantify the penetration (and reflection) capabilities of the incoming EM waves. We use a fully polarimetric GB-SAR system based on a high-end VNA capable of coherent measurement of the [S2] scattering matrix. It uses 2 large horn antennas

  6. InfoTerra/TerraSAR initiative

    NASA Astrophysics Data System (ADS)

    Wahl, Manfred W.

    2004-01-01

    The overarching goal of the InfoTerra/TerraSAR Initiative is to establish a self-sustaining operational/commercial business built on Europe"s know-how and experience in space-borne Synthetic Aperture Radar (SAR) technology, in SAR data processing as well as in SAR applications. InfoTerra stands for a new business concept based on supplying innovative geo-information products and services. TerraSAR is a space and ground system conceived to consist of an initial deployment and operation of 2 Radar satellites (one in X- and one in L-band) flying in a tandem configuration in the same orbit. The design of TerraSAR is driven by the market and is user-oriented. TerraSAR is key to capturing a significant proportion of the existing market and to opening new market opportunities, when it becomes operational. The InfoTerra/TerraSAR Initiative has evolved gradually. It started in 1997 as a joint venture between German (DSS) and British (MMS-UK) space industry, strongly supported by both space agencies, DLR and BNSC. In early 2001, DLR and BNSC submitted to ESA the Formal Programme Proposal for InfoTerra/TerraSAR to become an essential element of ESA"s Earth Watch Programme. In summer 2001, when it became evident that there was not yet sufficient support from the ESA Member States to allow immediate start entering into TerraSAR Phase C/D, it has been decided to implement first a TerraSAR consolidation phase. In early 2002, in order to avoid further delays, a contract was signed between DLR and Astrium GmbH on the development of one component of TerraSAR, the TerraSAR-X, in the frame of a national programme, governed by a Public Private Partnership Agreement. Even if now the different launch dates for TerraSAR-X and TerraSAR-L are narrowing down the window of common data acquisition, it is a reasonable starting point, but it should always be kept in mind that the utmost goal for the longterm is to achieve self sustainability by supplying geo-information products and services

  7. Wavelet Analysis of SAR Images for Coastal Monitoring

    NASA Technical Reports Server (NTRS)

    Liu, Antony K.; Wu, Sunny Y.; Tseng, William Y.; Pichel, William G.

    1998-01-01

    The mapping of mesoscale ocean features in the coastal zone is a major potential application for satellite data. The evolution of mesoscale features such as oil slicks, fronts, eddies, and ice edge can be tracked by the wavelet analysis using satellite data from repeating paths. The wavelet transform has been applied to satellite images, such as those from Synthetic Aperture Radar (SAR), Advanced Very High-Resolution Radiometer (AVHRR), and ocean color sensor for feature extraction. In this paper, algorithms and techniques for automated detection and tracking of mesoscale features from satellite SAR imagery employing wavelet analysis have been developed. Case studies on two major coastal oil spills have been investigated using wavelet analysis for tracking along the coast of Uruguay (February 1997), and near Point Barrow, Alaska (November 1997). Comparison of SAR images with SeaWiFS (Sea-viewing Wide Field-of-view Sensor) data for coccolithophore bloom in the East Bering Sea during the fall of 1997 shows a good match on bloom boundary. This paper demonstrates that this technique is a useful and promising tool for monitoring of coastal waters.

  8. The application of satellite differential SAR interferometry-derived ground displacements in hydrogeology

    USGS Publications Warehouse

    Galloway, D.L.; Hoffmann, J.

    2007-01-01

    The application of satellite differential synthetic aperture radar (SAR) interferometry, principally coherent (InSAR) and to a lesser extent, persistent-scatterer (PSI) techniques to hydrogeologic studies has improved capabilities to map, monitor, analyze, and simulate groundwater flow, aquifer-system compaction and land subsidence. A number of investigations over the previous decade show how the spatially detailed images of ground displacements measured with InSAR have advanced hydrogeologic understanding, especially when a time series of images is used in conjunction with histories of changes in water levels and management practices. Important advances include: (1) identifying structural or lithostratigraphic boundaries (e.g. faults or transitional facies) of groundwater flow and deformation; (2) defining the material and hydraulic heterogeneity of deforming aquifer-systems; (3) estimating system properties (e.g. storage coefficients and hydraulic conductivities); and (4) constraining numerical models of groundwater flow, aquifer-system compaction, and land subsidence. As a component of an integrated approach to hydrogeologic monitoring and characterization of unconsolidated alluvial groundwater basins differential SAR interferometry contributes unique information that can facilitate improved management of groundwater resources. Future satellite SAR missions specifically designed for differential interferometry will enhance these contributions. ?? Springer-Verlag 2006.

  9. Special Issue on Results from Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (Sir-C/X-SAR): Foreword

    NASA Technical Reports Server (NTRS)

    Plaut, Jefferey J.

    1996-01-01

    The two flights of the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the Space Shuttle Endeavour represent a major advance in remote sensing technology for studies of planetary surfaces.

  10. Remote sensing-based Information for crop monitoring: contribution of SAR and Moderate resolution optical data on Asian rice production

    NASA Astrophysics Data System (ADS)

    Boschetti, Mirco; Holectz, Francesco; Manfron, Giacinto; Collivignarelli, Francesco; Nelson, Andrew

    2013-04-01

    Updated information on crop typology and status are strongly required to support suitable action to better manage agriculture production and reduce food insecurity. In this field, remote sensing has been demonstrated to be a suitable tool to monitor crop condition however rarely the tested system became really operative. The ones today available, such as the European Commission MARS, are mainly based on the analysis of NDVI time series and required ancillary external information like crop mask to interpret the seasonal signal. This condition is not always guarantied worldwide reducing the potentiality of the remote sensing monitoring. Moreover in tropical countries cloud contamination strongly reduce the possibility of using optical remote sensing data for crop monitoring. In this framework we focused our analysis on the rice production monitoring in Asian tropical area. Rice is in fact the staple food for half of the world population (FAO 2004), in Asia almost 90% of the world's rice is produced and consumed and Rice and poverty often coincide. In this contest the production of reliable rice production information is of extreme interest. We tried to address two important issue in terms of required geospatial information for crop monitoring: rice crop detection (rice map) and seasonal dynamics analysis (phenology). We use both SAR and Optical data in order to exploit the potential complementarity of this system. Multi-temporal ASAR Wide Swath data are in fact the best option to deal with cloud contamination. SAR can easily penetrate the clouds providing information on the surface target. Temporal analysis of archive ASAR data allowed to derived accurate map, at 100m spatial resolution, of permanent rice cultivated areas. On the other and high frequency revisiting optical data, in this case MODIS, have been used to extract seasonal information for the year under analysis. MOD09A1 Surface Reflectance 8-Day L3 Global 500m have been exploited to derive time series of

  11. Monitoring of Three Case Studies of Creeping Landslides in Ecuador using L-band SAR Interferometry (InSAR)

    NASA Astrophysics Data System (ADS)

    Mayorga Torres, T. M.; Mohseni Aref, M.

    2015-12-01

    Tannia Mayorga Torres1,21 Universidad Central del Ecuador. Faculty of Geology, Mining, Oil, and Environment 2 Hubert H. Humphrey Fellowship 2015-16 IntroductionLandslides lead to human and economic losses across the country, mainly in the winter season. On the other hand, satellite radar data has cost-effective benefits due to open-source software and free availability of data. With the purpose of establishing an early warning system of landslide-related surface deformation, three case studies were designed in the Coast, Sierra (Andean), and Oriente (jungle) regions. The objective of this work was to assess the capability of L-band InSAR to get phase information. For the calculation of the interferograms in Repeat Orbit Interferometry PACkage, the displacement was detected as the error and was corrected. The coherence images (Figure 1) determined that L-band is suitable for InSAR processing. Under this frame, as a first approach, the stacking DInSAR technique [1] was applied in the case studies [2]; however, due to lush vegetation and steep topography, it is necessary to apply advanced InSAR techniques [3]. The purpose of the research is to determine a pattern of data acquisition and successful results to understand the spatial and temporal ground movements associated with landslides. The further work consists of establishing landslide inventories to combine phases of SAR images to generate maps of surface deformation in Tumba-San Francisco and Guarumales to compare the results with ground-based measurements to determine the maps' accuracy. References[1] Sandwell D., Price E. (1998). Phase gradient approach to stacking interferograms. Journal of Geophysical Research, Vol. 103, N. B12, pp. 30,183-30,204. [2] Mayorga T., Platzeck G. (2014). Using DInSAR as a tool to detect unstable terrain areas in an Andes region in Ecuador. NH3.5-Blue Poster B298, Vol. 16, EGU2014-16203. Austria. [3] Wasowski J., Bovenga F. (2014). Investigating landslides and unstable slopes with

  12. Cross-calibration between airborne SAR sensors

    NASA Technical Reports Server (NTRS)

    Zink, Manfred; Olivier, Philippe; Freeman, Anthony

    1993-01-01

    As Synthetic Aperture Radar (SAR) system performance and experience in SAR signature evaluation increase, quantitative analysis becomes more and more important. Such analyses require an absolute radiometric calibration of the complete SAR system. To keep the expenditure on calibration of future multichannel and multisensor remote sensing systems (e.g., X-SAR/SIR-C) within a tolerable level, data from different tracks and different sensors (channels) must be cross calibrated. The 1989 joint E-SAR/DC-8 SAR calibration campaign gave a first opportunity for such an experiment, including cross sensor and cross track calibration. A basic requirement for successful cross calibration is the stability of the SAR systems. The calibration parameters derived from different tracks and the polarimetric properties of the uncalibrated data are used to describe this stability. Quality criteria for a successful cross calibration are the agreement of alpha degree values and the consistency of radar cross sections of equally sized corner reflectors. Channel imbalance and cross talk provide additional quality in case of the polarimetric DC-8 SAR.

  13. SAR Speckle Noise Reduction Using Wiener Filter

    NASA Technical Reports Server (NTRS)

    Joo, T. H.; Held, D. N.

    1983-01-01

    Synthetic aperture radar (SAR) images are degraded by speckle. A multiplicative speckle noise model for SAR images is presented. Using this model, a Wiener filter is derived by minimizing the mean-squared error using the known speckle statistics. Implementation of the Wiener filter is discussed and experimental results are presented. Finally, possible improvements to this method are explored.

  14. Coordinated Response to SARS, Vancouver, Canada

    PubMed Central

    Petric, Martin; Daly, Patricia; Parker, Robert A.; Bryce, Elizabeth; Doyle, Patrick W.; Noble, Michael A.; Roscoe, Diane L.; Tomblin, Joan; Yang, Tung C.; Krajden, Mel; Patrick, David M.; Pourbohloul, Babak; Goh, Swee Han; Bowie, William R.; Booth, Tim F.; Tweed, S. Aleina; Perry, Thomas L.; McGeer, Allison; Brunham, Robert C.

    2006-01-01

    Two Canadian urban areas received travelers with severe acute respiratory syndrome (SARS) before the World Health Organization issued its alert. By July 2003, Vancouver had identified 5 cases (4 imported); Toronto reported 247 cases (3 imported) and 43 deaths. Baseline preparedness for pandemic threats may account for the absence of sustained transmission and fewer cases of SARS in Vancouver. PMID:16494736

  15. Large Scale Assessment of Radio Frequency Interference Signatures in L-band SAR Data

    NASA Astrophysics Data System (ADS)

    Meyer, F. J.; Nicoll, J.

    2011-12-01

    Imagery of L-band Synthetic Aperture Radar (SAR) systems such as the PALSAR sensor on board the Advanced Land Observing Satellite (ALOS) has proven to be a valuable tool for observing environmental changes around the globe. Besides offering 24/7 operability, the L-band frequency provides improved interferometric coherence, and L-band polarimetric data has shown great potential for vegetation monitoring, sea ice classification, and the observation of glaciers and ice sheets. To maximize the benefit of missions such as ALOS PALSAR for environmental monitoring, data consistency and calibration are vital. Unfortunately, radio frequency interference (RFI) signatures from ground-based radar systems regularly impair L-band SAR data quality and consistency. With this study we present a large-scale analysis of typical RFI signatures that are regularly observed in L-band SAR data over the Americas. Through a study of the vast archive of L-band SAR data in the US Government Research Consortium (USGRC) data pool at the Alaska Satellite Facility (ASF) we were able to address the following research goals: 1. Assessment of RFI Signatures in L-band SAR data and their Effects on SAR Data Quality: An analysis of time-frequency properties of RFI signatures in L-band SAR data of the USGRC data pool is presented. It is shown that RFI-filtering algorithms implemented in the operational ALOS PALSAR processor are not sufficient to remove all RFI-related artifacts. In examples, the deleterious effects of RFI on SAR image quality, polarimetric signature, SAR phase, and interferometric coherence are presented. 2. Large-Scale Assessment of Severity, Spatial Distribution, and Temporal Variation of RFI Signatures in L-band SAR data: L-band SAR data in the USGRC data pool were screened for RFI using a custom algorithm. Per SAR frame, the algorithm creates geocoded frame bounding boxes that are color-coded according to RFI intensity and converted to KML files for analysis in Google Earth. From

  16. Regularization Analysis of SAR Superresolution

    SciTech Connect

    DELAURENTIS,JOHN M.; DICKEY,FRED M.

    2002-04-01

    Superresolution concepts offer the potential of resolution beyond the classical limit. This great promise has not generally been realized. In this study we investigate the potential application of superresolution concepts to synthetic aperture radar. The analytical basis for superresolution theory is discussed. In a previous report the application of the concept to synthetic aperture radar was investigated as an operator inversion problem. Generally, the operator inversion problem is ill posed. This work treats the problem from the standpoint of regularization. Both the operator inversion approach and the regularization approach show that the ability to superresolve SAR imagery is severely limited by system noise.

  17. Multi-temporal intensity and coherence analysis of SAR images for land cover change detection on the Island of Crete

    NASA Astrophysics Data System (ADS)

    Nikolaeva, E.; Sykioti, O.; Elias, P.; Kontoes, C.

    2015-10-01

    This study presents the use of multi-temporal Synthetic Aperture Radar (SAR) images for detection of land cover changes in the eastern part of the Island of Crete (Greece). For this purpose, fourteen Envisat ASAR acquisitions from July 2004 to December 2006 were calibrated and registered. We applied a temporal filter and spatial averaging to the backscatter intensity to reduce the noise. Furthermore, we used the concept that the changes between different backscatter intensity observations can show changes on the target dielectric properties. In order to detect changes due to geometrical characteristics of land cover types, we created coherence maps using twenty-seven interferometric pairs with proper spatial and temporal baselines. In all calculations, layover and shadow effects, as well as the sea, were masked by using information from the digital elevation model of the area. The observed changes in the coherence values were analyzed with respect to different decorrelation factors that can contribute to the loss of coherence. Our results present the different backscatter values for several land cover types (farmland, olive groves, forests, etc.). In addition, some land cover types such as olive groves show variations of backscatter signal due to the density and height of trees. Furthermore, olive groves show good coherence in interferograms with short time intervals. All interferometric pairs have low coherence in farmland because of the rapid growth of plants. Finally, the maps of backscatter temporal changes and coherence changes were superimposed and compared to auxiliary data such as multi-temporal optical satellite imagery (i.e. Landsat/ETM, Terra/Aqua MODIS) and thematic land cover maps (Corinne 2000). We found that changes are mostly due to plant growth and man-made activity. This ongoing study shows the potential of SAR in providing complementary information such as changes in dielectric and geometric properties to optical data in land cover dynamics

  18. Affordable miniaturized SAR for tactical UAV applications

    NASA Astrophysics Data System (ADS)

    Sloan, George R.; Dubbert, Dale F.

    2004-08-01

    Sandia"s fielded and experimental SAR systems are well known for their real time, high resolution imagery. Previous designs, such as the Lynx radar, have been successfully demonstrated on medium-payload UAVs, including Predator and Fire Scout. However, fielding a high performance SAR sensor on even smaller (sub-50 pound payload) UAVs will require at least a 5x reduction in size, weight, and cost. This paper gives an overview of Sandia"s system concept and roadmap for near-term SAR miniaturization. Specifically, the "miniSAR" program, which plans to demonstrate a 25 pound system with 4 inch resolution in early 2005, is detailed. Accordingly, the conceptual approach, current status, design tradeoffs, and key facilitating technologies are reviewed. Lastly, future enhancements and directions are described, such as the follow-on demonstration of a sub-20 pound version with multi-mode (SAR/GMTI) capability.

  19. Programmable Real-Time Acousto-Optic/CCD SAR processor

    NASA Technical Reports Server (NTRS)

    Haney, M.; Wagner, K.; Psaltis, D.

    1984-01-01

    The theory of operation of the Real-Time Acousto-Optic SAR Processor is reviewed and recent experimental results are presented. The results include a demonstration of the real-time imaging capability of the processor with simulated radar signals. An advanced version of this processor is then described in which a programmable reference function is entered via a second acousto-optic device to eliminate the need for a 2-D SLM. In this implementation the reference function is updated by electronic means to give the processor the flexibility to adapt rapidly to changes in the parameters of the radar/target geometry.

  20. SARS and population health technology.

    PubMed

    Eysenbach, Gunther

    2003-01-01

    The recent global outbreak of SARS (severe acute respiratory syndrome) provides an opportunity to study the use and impact of public health informatics and population health technology to detect and fight a global epidemic. Population health technology is the umbrella term for technology applications that have a population focus and the potential to improve public health. This includes the Internet, but also other technologies such as wireless devices, mobile phones, smart appliances, or smart homes. In the context of an outbreak or bioterrorism attack, such technologies may help to gather intelligence and detect diseases early, and communicate and exchange information electronically worldwide. Some of the technologies brought forward during the SARS epidemic may have been primarily motivated by marketing efforts, or were more directed towards reassuring people that "something is being done," ie, fighting an "epidemic of fear." To understand "fear epidemiology" is important because early warning systems monitoring data from a large number of people may not be able to discriminate between a biological epidemic and an epidemic of fear. The need for critical evaluation of all of these technologies is stressed. PMID:12857670

  1. History of SAR at Lockheed Martin (previously Goodyear Aerospace)

    NASA Astrophysics Data System (ADS)

    Lasswell, Stephen W.

    2005-05-01

    Synthetic Aperture Radar (SAR) was invented by Carl Wiley at Goodyear Aircraft Company in Goodyear, Arizona, in 1951. From that time forward, as the company became Goodyear Aerospace Corporation, Loral Corporation, and finally Lockheed Martin Corporation, the Arizona employees past and present played a long and storied role in numerous SAR firsts. These include the original SAR patent (known as Simultaneous Doppler Buildup), the first demonstration SAR and flight test, the first operational SAR system, the first operational SAR data link, the first 5-foot resolution operational SAR system, the first 1-foot resolution SAR system, and the first large scale SAR digital processor. The company has installed and flown over five hundred SAR systems on more than thirty different types of aircraft for numerous countries throughout the world. The company designed and produced all of the evolving high performance SAR systems for the U. S. Air Force SR-71 "Blackbird" spy plane throughout its entire operational history, spanning some twenty-nine years. Recent SAR accomplishments include long-range standoff high performance SAR systems, smaller high resolution podded SAR systems for fighter aircraft, and foliage penetration (FOPEN) SAR. The company is currently developing the high performance SAR/MTI (Moving Target Indication) radar for the Army Aerial Common Sensor (ACS) system.

  2. InSAR Scientific Computing Environment

    NASA Technical Reports Server (NTRS)

    Rosen, Paul A.; Sacco, Gian Franco; Gurrola, Eric M.; Zabker, Howard A.

    2011-01-01

    This computing environment is the next generation of geodetic image processing technology for repeat-pass Interferometric Synthetic Aperture (InSAR) sensors, identified by the community as a needed capability to provide flexibility and extensibility in reducing measurements from radar satellites and aircraft to new geophysical products. This software allows users of interferometric radar data the flexibility to process from Level 0 to Level 4 products using a variety of algorithms and for a range of available sensors. There are many radar satellites in orbit today delivering to the science community data of unprecedented quantity and quality, making possible large-scale studies in climate research, natural hazards, and the Earth's ecosystem. The proposed DESDynI mission, now under consideration by NASA for launch later in this decade, would provide time series and multiimage measurements that permit 4D models of Earth surface processes so that, for example, climate-induced changes over time would become apparent and quantifiable. This advanced data processing technology, applied to a global data set such as from the proposed DESDynI mission, enables a new class of analyses at time and spatial scales unavailable using current approaches. This software implements an accurate, extensible, and modular processing system designed to realize the full potential of InSAR data from future missions such as the proposed DESDynI, existing radar satellite data, as well as data from the NASA UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar), and other airborne platforms. The processing approach has been re-thought in order to enable multi-scene analysis by adding new algorithms and data interfaces, to permit user-reconfigurable operation and extensibility, and to capitalize on codes already developed by NASA and the science community. The framework incorporates modern programming methods based on recent research, including object-oriented scripts controlling legacy and

  3. SAR image formation toolbox for MATLAB

    NASA Astrophysics Data System (ADS)

    Gorham, LeRoy A.; Moore, Linda J.

    2010-04-01

    While many synthetic aperture radar (SAR) image formation techniques exist, two of the most intuitive methods for implementation by SAR novices are the matched filter and backprojection algorithms. The matched filter and (non-optimized) backprojection algorithms are undeniably computationally complex. However, the backprojection algorithm may be successfully employed for many SAR research endeavors not involving considerably large data sets and not requiring time-critical image formation. Execution of both image reconstruction algorithms in MATLAB is explicitly addressed. In particular, a manipulation of the backprojection imaging equations is supplied to show how common MATLAB functions, ifft and interp1, may be used for straight-forward SAR image formation. In addition, limits for scene size and pixel spacing are derived to aid in the selection of an appropriate imaging grid to avoid aliasing. Example SAR images generated though use of the backprojection algorithm are provided given four publicly available SAR datasets. Finally, MATLAB code for SAR image reconstruction using the matched filter and backprojection algorithms is provided.

  4. Application of Polarimetric-Interferometric Phase Coherence Optimization (PIPCO) Procedure to SIR-C/X-SAR Tien-Shan Tracks 122.20(94 Oct. 08)/154.20(94 Oct. 09) Repeat-Orbit C/L-Band Pol-D-InSAR Imag

    NASA Technical Reports Server (NTRS)

    Boerner, W. M.; Mott, H.; Verdi, J.; Darizhapov, D.; Dorjiev, B.; Tsybjito, T.; Korsunov, V.; Tatchkov, G.; Bashkuyev, Y.; Cloude, S.; Papathanassiou, K.; Pottier, E.; Lee, J.; Ainsworth, T.; Schuler, D.; Grandi, G.; Rosen, P.; Peltzer, G.

    1998-01-01

    During the past decade, Radar Polarimetry has established itself as a mature science and advanced technology in high resolution POL-SAR imaging, image target characterization and selective image feature extraction.

  5. First Results from an Airborne Ka-band SAR Using SweepSAR and Digital Beamforming

    NASA Technical Reports Server (NTRS)

    Sadowy, Gregory; Ghaemi, Hirad; Hensley, Scott

    2012-01-01

    NASA/JPL has developed SweepSAR technique that breaks typical Synthetic Aperture Radar (SAR) trade space using time-dependent multi-beam DBF on receive. Developing SweepSAR implementation using array-fed reflector for proposed DESDynI Earth Radar Mission concept. Performed first-of-a-kind airborne demonstration of the SweepSAR concept at Ka-band (35.6 GHz). Validated calibration and antenna pattern data sufficient for beam forming in elevation. (1) Provides validation evidence that the proposed Deformation Ecosystem Structure Dynamics of Ice (DESDynI) SAR architecture is sound. (2) Functions well even with large variations in receiver gain / phase. Future plans include using prototype DESDynI SAR digital flight hardware to do the beam forming in real-time onboard the aircraft.

  6. Mars Mission Concepts: SAR and Solar Electric Propulsion

    NASA Astrophysics Data System (ADS)

    Elsperman, Michael; Clifford, S.; Lawrence, S.; Klaus, K.; Smith, D.

    2013-10-01

    Introduction: The time has come to leverage technology advances to reduce the cost and increase the flight rate of planetary missions, while actively developing a scientific and engineering workforce to achieve national space objectives. Mission Science at Mars: A SAR imaging radar offers an ability to conduct high resolution investigations of the shallow subsurface of Mars, enabling identification of fine-scale layering within the Martian polar layered deposits (PLD), as well as the identification of pingos, investigations of polygonal terrain, and measurements of the thickness of mantling layers at non-polar latitudes. It would allow systematic near-surface prospecting, which is tremendously useful for human exploration purposes. Limited color capabilities in a notional high-resolution stereo imaging system would enable the generation of false color images, resulting in useful science results, and the stereo data could be reduced into high-resolution Digital Elevation Models uniquely useful for exploration planning and science purposes. Mission Concept: Using a common spacecraft for multiple missions reduces costs. Solar electric propulsion (SEP) provides the flexibility required for multiple mission objectives. Our concept involves using a Boeing 702SP with a highly capable SAR imager that also conducts autonomous rendezvous and docking experiments accomplished from Mars orbit. Summary/Conclusions: A robust and compelling Mars mission can be designed to meet the 2018 Mars launch window opportunity. Using advanced in-space power and propulsion technologies like High Power Solar Electric Propulsion provides enormous mission flexibility to execute the baseline science mission and conduct necessary Mars Sample Return Technology Demonstrations in Mars orbit on the same mission. An observation spacecraft platform like the high power 5Kw) 702SP at Mars also enables the use of a SAR instrument to reveal new insights and understanding of the Mars regolith for both

  7. Operational SAR Data Processing in GIS Environments for Rapid Disaster Mapping

    NASA Astrophysics Data System (ADS)

    Meroni, A.; Bahr, T.

    2013-05-01

    Having access to SAR data can be highly important and critical especially for disaster mapping. Updating a GIS with contemporary information from SAR data allows to deliver a reliable set of geospatial information to advance civilian operations, e.g. search and rescue missions. Therefore, we present in this paper the operational processing of SAR data within a GIS environment for rapid disaster mapping. This is exemplified by the November 2010 flash flood in the Veneto region, Italy. A series of COSMO-SkyMed acquisitions was processed in ArcGIS® using a single-sensor, multi-mode, multi-temporal approach. The relevant processing steps were combined using the ArcGIS ModelBuilder to create a new model for rapid disaster mapping in ArcGIS, which can be accessed both via a desktop and a server environment.

  8. NASA/JPL Aircraft SAR Workshop Proceedings

    NASA Technical Reports Server (NTRS)

    Donovan, N. (Editor); Evans, D. L. (Editor); Held, D. N. (Editor)

    1985-01-01

    Speaker-supplied summaries of the talks given at the NASA/JPL Aircraft SAR Workshop on February 4 and 5, 1985, are provided. These talks dealt mostly with composite quadpolarization imagery from a geologic or ecologic prespective. An overview and summary of the system characteristics of the L-band synthetic aperture radar (SAR) flown on the NASA CV-990 aircraft are included as supplementary information. Other topics ranging from phase imagery and interferometric techniques classifications of specific areas, and the potentials and limitations of SAR imagery in various applications are discussed.

  9. Primary studies of Chinese spaceborne SAR

    NASA Technical Reports Server (NTRS)

    Wang, Zhen-Song; Wu, Guo-Xiang; Guo, Hua-Dong; Wei, Zhong-Quan; Zhu, Min-Hui

    1993-01-01

    The primary studies on spaceborne synthetic aperture radar (SAR) in China are discussed. The SAR will be launched aboard a Chinese satellite and operated at L-band with HH polarization. The purpose of the mission in consideration is dedicated to resources and environment uses, especially to natural disaster monitoring. The ground resolution is designed as 25 m x 25 m for detailed mode and 100 m x 100 m for wide scan-SAR mode. The off-nadir angle can be varied from 20 to 40 deg. The key system concepts are introduced.

  10. SAR observations of coastal zone conditions

    NASA Technical Reports Server (NTRS)

    Meadows, G. A.; Kasischke, E. S.; Shuchman, R. A.

    1980-01-01

    Applications of Synthetic Aperture Radar (SAR) technology to the observation of coastal zones phenomena are detailed. The conditions observed include gravity wave detection, surf zone location, surface currents, and long-period 'surf beats'. Algorithms have been developed and successfully tested that determine significant wave and current parameters from the sea surface backscatter of microwave energy. Doppler information from the SAR optical correlator allows a rough estimation of near shore surface flow velocities that has been found in agreement with both theory and in situ observations as well. Seasat SAR data of the Scotland and North Carolina coasts are considered, as well as the results of bathymetric updating of coastal area charts.

  11. Measurement of Sinkhole Formation and Progression with InSAR

    NASA Astrophysics Data System (ADS)

    Jones, C. E.; Blom, R. G.

    2013-12-01

    The Bayou Corne Sinkhole initially formed in August 2012 from sidewall collapse of a brine cavern within the Napoleonville Salt Dome in southeastern Louisiana. The sinkhole, initially ~1 hectare in size, has expanded to ~10 hectare surface coverage by July 2013, as material continued to fill the subterranean void. Here we show that synthetic aperture radar (SAR) interferometry (InSAR) could have reliably forecast the formation and location of the Bayou Corne Sinkhole at least a month in advance from the large precursory surface deformation that occurred in the area where the sinkhole later formed. The Mississippi delta region has been imaged since 2009 using the NASA Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR), and radar data over the Napoleonville Salt Dome had been acquired on 2 July 2012, only a month before the sinkhole developed. Using radar interferometry, we show significant surface deformation of up to 250 mm occurred between 23 June 2011, and 2 July 2012, in an extended area encompassing the sinkhole site. The InSAR results show no measurable deformation prior to 23 June 2011. The measured precursory deformation pattern is consistent with compressive loading at the surface due to removal of support caused by a vertically oriented subsurface fracture. The measured strains relate directly to subsurface geology, salt rock properties, and internal stresses caused by the salt dome sidewall collapse. Measurements made with UAVSAR since the sinkhole formation, between August 2012 and July 2013, show progression of the surface deformation well beyond the limited extent of the sinkhole itself, with growth of the sinkhole following the direction of maximum surface deformation. These results show that even in radar-challenging environments such as the swamplands of Bayou Corne, L-band InSAR can be used to study the underlying geophysics of sinkhole formation and, furthermore, that InSAR data collected operationally for hazard monitoring could

  12. Similarity measures of full polarimetric SAR images fusion for improved SAR image matching

    NASA Astrophysics Data System (ADS)

    Ding, H.

    2015-06-01

    China's first airborne SAR mapping system (CASMSAR) developed by Chinese Academy of Surveying and Mapping can acquire high-resolution and full polarimetric (HH, HV, VH and VV) Synthetic aperture radar (SAR) data. It has the ability to acquire X-band full polarimetric SAR data at a resolution of 0.5m. However, the existence of speckles which is inherent in SAR imagery affects visual interpretation and image processing badly, and challenges the assumption that conjugate points appear similar to each other in matching processing. In addition, researches show that speckles are multiplicative speckles, and most similarity measures of SAR image matching are sensitive to them. Thus, matching outcomes of SAR images acquired by most similarity measures are not reliable and with bad accuracy. Meanwhile, every polarimetric SAR image has different backscattering information of objects from each other and four polarimetric SAR data contain most basic and a large amount of redundancy information to improve matching. Therefore, we introduced logarithmically transformation and a stereo matching similarity measure into airborne full polarimetric SAR imagery. Firstly, in order to transform the multiplicative speckles into additivity ones and weaken speckles' influence on similarity measure, logarithmically transformation have to be taken to all images. Secondly, to prevent performance degradation of similarity measure caused by speckles, measure must be free or insensitive of additivity speckles. Thus, we introduced a stereo matching similarity measure, called Normalized Cross-Correlation (NCC), into full polarimetric SAR image matching. Thirdly, to take advantage of multi-polarimetric data and preserve the best similarity measure value, four measure values calculated between left and right single polarimetric SAR images are fused as final measure value for matching. The method was tested for matching under CASMSAR data. The results showed that the method delivered an effective

  13. Bridge Deformation Monitoring: Instight From InSAR Time-Series And Finite Element Modelling

    NASA Astrophysics Data System (ADS)

    Shamshiri, Roghayeh; Motagh, Mahdi; Baes, Marzieh; Sharifi, Mohammad-Ali

    2013-12-01

    This paper presents the capability of advanced InSAR time-series techniques such as Small BAseline Subset (SBAS) for monitoring of civil engineering structures like bridge. Deformation monitoring of bridges are essential to mitigate not only the financial and human losses, but also ecological and environmental-related problems. Assessment of deformation during bridge lifespan can provide invaluable insight for better planning and management. The study area, Lake Urmia Causeway (LUC) in northwest Iran, consists of one bridge and two embankments on both sides of it. The difference between the deformation rate of the embankments on both sides of the bridge may seriously damage the bridge itself, so it is very important to accurately monitor them in space and time in order to assess the state of the bridge concerning deformations. In this study we apply the InSAR time-series technique of SBAS for 58 SAR images including 10 ALOS, 30 Envisat and 18 TerraSAR-X (TSX) to assess deflation of embankments of Urmia bridge during 2003-2013. The InSAR results are used in a 2D Finite Element Model (FEM) to assess structural stability of the embankments.

  14. Accelerating Spaceborne SAR Imaging Using Multiple CPU/GPU Deep Collaborative Computing.

    PubMed

    Zhang, Fan; Li, Guojun; Li, Wei; Hu, Wei; Hu, Yuxin

    2016-04-07

    With the development of synthetic aperture radar (SAR) technologies in recent years, the huge amount of remote sensing data brings challenges for real-time imaging processing. Therefore, high performance computing (HPC) methods have been presented to accelerate SAR imaging, especially the GPU based methods. In the classical GPU based imaging algorithm, GPU is employed to accelerate image processing by massive parallel computing, and CPU is only used to perform the auxiliary work such as data input/output (IO). However, the computing capability of CPU is ignored and underestimated. In this work, a new deep collaborative SAR imaging method based on multiple CPU/GPU is proposed to achieve real-time SAR imaging. Through the proposed tasks partitioning and scheduling strategy, the whole image can be generated with deep collaborative multiple CPU/GPU computing. In the part of CPU parallel imaging, the advanced vector extension (AVX) method is firstly introduced into the multi-core CPU parallel method for higher efficiency. As for the GPU parallel imaging, not only the bottlenecks of memory limitation and frequent data transferring are broken, but also kinds of optimized strategies are applied, such as streaming, parallel pipeline and so on. Experimental results demonstrate that the deep CPU/GPU collaborative imaging method enhances the efficiency of SAR imaging on single-core CPU by 270 times and realizes the real-time imaging in that the imaging rate outperforms the raw data generation rate.

  15. Accelerating Spaceborne SAR Imaging Using Multiple CPU/GPU Deep Collaborative Computing

    PubMed Central

    Zhang, Fan; Li, Guojun; Li, Wei; Hu, Wei; Hu, Yuxin

    2016-01-01

    With the development of synthetic aperture radar (SAR) technologies in recent years, the huge amount of remote sensing data brings challenges for real-time imaging processing. Therefore, high performance computing (HPC) methods have been presented to accelerate SAR imaging, especially the GPU based methods. In the classical GPU based imaging algorithm, GPU is employed to accelerate image processing by massive parallel computing, and CPU is only used to perform the auxiliary work such as data input/output (IO). However, the computing capability of CPU is ignored and underestimated. In this work, a new deep collaborative SAR imaging method based on multiple CPU/GPU is proposed to achieve real-time SAR imaging. Through the proposed tasks partitioning and scheduling strategy, the whole image can be generated with deep collaborative multiple CPU/GPU computing. In the part of CPU parallel imaging, the advanced vector extension (AVX) method is firstly introduced into the multi-core CPU parallel method for higher efficiency. As for the GPU parallel imaging, not only the bottlenecks of memory limitation and frequent data transferring are broken, but also kinds of optimized strategies are applied, such as streaming, parallel pipeline and so on. Experimental results demonstrate that the deep CPU/GPU collaborative imaging method enhances the efficiency of SAR imaging on single-core CPU by 270 times and realizes the real-time imaging in that the imaging rate outperforms the raw data generation rate. PMID:27070606

  16. Accelerating Spaceborne SAR Imaging Using Multiple CPU/GPU Deep Collaborative Computing.

    PubMed

    Zhang, Fan; Li, Guojun; Li, Wei; Hu, Wei; Hu, Yuxin

    2016-01-01

    With the development of synthetic aperture radar (SAR) technologies in recent years, the huge amount of remote sensing data brings challenges for real-time imaging processing. Therefore, high performance computing (HPC) methods have been presented to accelerate SAR imaging, especially the GPU based methods. In the classical GPU based imaging algorithm, GPU is employed to accelerate image processing by massive parallel computing, and CPU is only used to perform the auxiliary work such as data input/output (IO). However, the computing capability of CPU is ignored and underestimated. In this work, a new deep collaborative SAR imaging method based on multiple CPU/GPU is proposed to achieve real-time SAR imaging. Through the proposed tasks partitioning and scheduling strategy, the whole image can be generated with deep collaborative multiple CPU/GPU computing. In the part of CPU parallel imaging, the advanced vector extension (AVX) method is firstly introduced into the multi-core CPU parallel method for higher efficiency. As for the GPU parallel imaging, not only the bottlenecks of memory limitation and frequent data transferring are broken, but also kinds of optimized strategies are applied, such as streaming, parallel pipeline and so on. Experimental results demonstrate that the deep CPU/GPU collaborative imaging method enhances the efficiency of SAR imaging on single-core CPU by 270 times and realizes the real-time imaging in that the imaging rate outperforms the raw data generation rate. PMID:27070606

  17. Canadian SAR remote sensing for the Terrestrial Wetland Global Change Research Network (TWGCRN)

    USGS Publications Warehouse

    Kaya, Shannon; Brisco, Brian; Cull, Andrew; Gallant, Alisa L.; Sadinski, Walter J.; Thompson, Dean

    2010-01-01

    The Canada Centre for Remote Sensing (CCRS) has more than 30 years of experience investigating the use of SAR remote sensing for many applications related to terrestrial water resources. Recently, CCRS scientists began contributing to the Terrestrial Wetland Global Change Research Network (TWGCRN), a bi-national research network dedicated to assessing impacts of global change on interconnected wetland-upland landscapes across a vital portion of North America. CCRS scientists are applying SAR remote sensing to characterize wetland components of these landscapes in three ways. First, they are using a comprehensive set of RADARSAT-2 SAR data collected during April to September 2009 to extract multi-temporal surface water information for key TWGCRN study landscapes in North America. Second, they are analyzing polarimetric RADARSAT-2 data to determine areas where double-bounce represents the primary scattering mechanism and is indicative of flooded vegetation in these landscapes. Third, they are testing advanced interferometric SAR techniques to estimate water levels with RADARSAT-2 Fine Quad polarimetric image pairs. The combined information from these three SAR analysis activities will provide TWGCRN scientists with an integrated view and monitoring capability for these dynamic wetland-upland landscapes. These data are being used in conjunction with other remote sensing and field data to study interactions between landscape and animal (birds and amphibians) responses to climate/global change.

  18. Atmosphere Observations by Geosynchronous SARs

    NASA Astrophysics Data System (ADS)

    Monti guarnieri, Andrea; Rocca, Fabio; Wadge, Geoff; Schulz, Detlef

    2014-05-01

    We analyze different geosynchronous Synthetic Aperture RADAR concepts aimed to get both tropospheric and ionospheric delay maps with a revisit time of minutes and sub-continental coverage. Such products could be used either to compensate the delay in LEO-SAR missions and GNSS, or to generate integrated water-vapor maps to be used for Numerical Weather Forecast. The system exploits the principle of RADAR location, by transmitting a pulse with a suitable bandwidth, and the residual non-zero eccentricity of COMmunication SATellites. Different concepts are proposed as payload in COMSAT, or constellations of small satellites, that is monostatic or bistatic/multistatic RADARS. The selection of the best frequency, from L to Ku, and the analysis of performances is presented.

  19. SEASAT SAR performance evaluation study

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The performance of the SEASAT synthetic aperture radar (SAR) sensor was evaluated using data processed by the MDA digital processor. Two particular aspects are considered the location accuracy of image data, and the calibration of the measured backscatter amplitude of a set of corner reflectors. The image location accuracy was assessed by selecting identifiable targets in several scenes, converting their image location to UTM coordinates, and comparing the results to map sheets. The error standard deviation is measured to be approximately 30 meters. The amplitude was calibrated by measuring the responses of the Goldstone corner reflector array and comparing the results to theoretical values. A linear regression of the measured against theoretical values results in a slope of 0.954 with a correlation coefficient of 0.970.

  20. Seismic hazard models for the central Apennines constrained by GPS and InSAR: mid-term review results of the ESA Pathfinder project CHARMING

    NASA Astrophysics Data System (ADS)

    Merryman Boncori, John Peter; Pezzo, Giuseppe; Visini, Francesco; Carafa, Michele; Devoti, Roberto; Atzori, Simone; Kastelic, Vanja; Berardino, Paolo; Fornaro, Gianfranco; Riguzzi, Federica; Pietrantonio, Grazia; d'Amico, Vera; Meletti, Carlo; Salvi, Stefano

    2015-04-01

    The contribution of space geodetic techniques to earthquake rate estimation, and thus seismic hazard modelling, has been recognized since two decades and made possible in more recent years by the increased availability and accuracy of geodetic measurements. We present the mid-term review results of a feasibility study named "Constraining Seismic Hazard Models with InSAR and GPS (CHARMING)", funded by the European Space Agency's (ESA) Support to Science Element (STSE) Pathfinders 2013 project. The area of interest considered at this stage of the project comprises a 200 km x 200 km area, covering the Abruzzi region (central Italy). In a later stage this area shall be extended to comprise a large portion of central and southern Italy, including most of the highest strain regions identified by recent studies. We present the interseismic velocities derived by ~60 permanent GPS stations and measurements derived from coast-to-coast strips of Synthetic Aperture Radar imagery from the ERS-1/2 AMI, ENVISAT ASAR and ALOS PALSAR sensors. The latter are processed with the Intermittent Small Baseline Subset (ISBAS) techniques, which greatly improves the measurement coverage compared to previous studies. Corrections are applied concerning tropospheric propagation errors, using ENVISAT MERIS precipitable water vapour maps and ERA-Interim numerical weather model parameters, as well as for the recently discovered oscillator drift of the ENVISAT ASAR sensor. Finally, measurements from individual SAR tracks are calibrated using GPS to ensure a common reference frame. For a set of composite seismogenic sources extracted from the DISS v.3.1.1 catalogue (Database of Italian Seismogenic Sources), we use the kinematic finite element NeoKinema model to derive long term average velocity fields and slip rates. We then derive earthquake rates, i.e. the number of earthquakes in a given time period above an established magnitude threshold, following the Seismic Hazard Inferred From Tectonics

  1. Satellite SAR imagery for site discovery, change detection and monitoring activities in cultural heritage sites: experiments on the Nasca region, Peru

    NASA Astrophysics Data System (ADS)

    Tapete, D.; Cigna, F.; Masini, N.; Lasaponara, R.

    2012-04-01

    data stacks were selected: ERS-2 ascending data acquired in 2001-2011, ENVISAT ASAR ascending and descending data acquired in 2003-2007, and ALOS PALSAR descending and ascending data acquired in 2007 and 2008. The feature extraction was specifically addressed to the recognition of buried structures, archaeological deposits and the study of the buried networks of aqueducts, as well as the morphological study of the Nasca geoglyphs. Change detection analysis also included the multi-temporal reconstruction of the evolution of the Rio Nasca catchment basin, while specific tests were performed to demonstrate the usefulness of SAR imagery for monitoring looting activities. The results of the radar-interpretation compared and integrated with the field investigations will support the archaeological activities and contribute to the monitoring and enhancement of archaeological heritage and cultural landscape of the Nasca region.

  2. Formation Flying for Distributed InSAR

    NASA Technical Reports Server (NTRS)

    Scharf, Daniel P.; Murray, Emmanuell A.; Ploen, Scott R.; Gromov, Konstantin G.; Chen, Curtis W.

    2006-01-01

    We consider two spacecraft flying in formation to create interferometric synthetic aperture radar (InSAR). Several candidate orbits for such in InSar formation have been previously determined based on radar performance and Keplerian orbital dynamics. However, with out active control, disturbance-induced drift can degrade radar performance and (in the worst case) cause a collision. This study evaluates the feasibility of operating the InSAR spacecraft as a formation, that is, with inner-spacecraft sensing and control. We describe the candidate InSAR orbits, design formation guidance and control architectures and algorithms, and report the (Delta)(nu) and control acceleration requirements for the candidate orbits for several tracking performance levels. As part of determining formation requirements, a formation guidance algorithm called Command Virtual Structure is introduced that can reduce the (Delta)(nu) requirements compared to standard Leader/Follower formation approaches.

  3. SAR/LANDSAT image registration study

    NASA Technical Reports Server (NTRS)

    Murphrey, S. W. (Principal Investigator)

    1978-01-01

    The author has identified the following significant results. Temporal registration of synthetic aperture radar data with LANDSAT-MSS data is both feasible (from a technical standpoint) and useful (from an information-content viewpoint). The greatest difficulty in registering aircraft SAR data to corrected LANDSAT-MSS data is control-point location. The differences in SAR and MSS data impact the selection of features that will serve as a good control points. The SAR and MSS data are unsuitable for automatic computer correlation of digital control-point data. The gray-level data can not be compared by the computer because of the different response characteristics of the MSS and SAR images.

  4. An algorithm for segmenting polarimetric SAR imagery

    NASA Astrophysics Data System (ADS)

    Geaga, Jorge V.

    2015-05-01

    We have developed an algorithm for segmenting fully polarimetric single look TerraSAR-X, multilook SIR-C and 7 band Landsat 5 imagery using neural nets. The algorithm uses a feedforward neural net with one hidden layer to segment different surface classes. The weights are refined through an iterative filtering process characteristic of a relaxation process. Features selected from studies of fully polarimetric complex single look TerraSAR-X data and multilook SIR-C data are used as input to the net. The seven bands from Landsat 5 data are used as input for the Landsat neural net. The Cloude-Pottier incoherent decomposition is used to investigate the physical basis of the polarimetric SAR data segmentation. The segmentation of a SIR-C ocean surface scene into four classes is presented. This segmentation algorithm could be a very useful tool for investigating complex polarimetric SAR phenomena.

  5. Polarimetric SAR Interferometry Evaluation in Mangroves

    NASA Technical Reports Server (NTRS)

    Lee, Seung-Kuk; Fatoyinbo,Temilola; Osmanoglu, Batuhan; Sun, Guoqing

    2014-01-01

    TanDEM-X (TDX) enables to generate an interferometric coherence without temporal decorrelation effect that is the most critical factor for a successful Pol-InSAR inversion, as have recently been used for forest parameter retrieval. This paper presents mangrove forest height estimation only using single-pass/single-baseline/dual-polarization TDX data by means of new dual-Pol-InSAR inversion technique. To overcome a lack of one polarization in a conventional Pol- InSAR inversion (i.e. an underdetermined problem), the ground phase in the Pol-InSAR model is directly estimated from TDX interferograms assuming flat underlying topography in mangrove forest. The inversion result is validated against lidar measurement data (NASA's G-LiHT data).

  6. SAR Polarimetry for Oil at Sea Observation

    NASA Astrophysics Data System (ADS)

    Migliaccio, M.; Nunziata, F.

    2013-03-01

    Synthetic aperture radar (SAR) oil slick observation is a topic of great applicative relevance which has been physically recast by a set of new polarimetric approaches that, exploiting the departure from Bragg scattering, allow observing oil at sea in a very robust and effective way. In this study, these polarimetric approaches are reviewed and their performances are discussed with respect to some thought experiments undertaken on quad-pol full-resolution L- and C-band SAR data.

  7. RADARSAT high throughput SAR processor development

    NASA Technical Reports Server (NTRS)

    George, P.

    1986-01-01

    MacDonald Dettwiler & Associates has been involved with the Canadian Radarsat (RSAT) project for a number of years. This included Phase A definition studies and for the past two years, Phase B ground station design and processor prototyping efforts. The current baseline design for the SAR processing facility (SARDPF) is described along with its requirements and functional decomposition. This forms the context for then discussing the prototype SAR processor and extensions necessary to meet current ground station processing requirements.

  8. SARS: Key factors in crisis management.

    PubMed

    Tseng, Hsin-Chao; Chen, Thai-Form; Chou, Shieu-Ming

    2005-03-01

    This study was conducted at a single hospital selected in Taipei during the SARS (Severe Acute Respiratory Syndrome) outbreak from March to July, 2003 in Taiwan. During this period of time, 104 SARS patients were admitted to the hospital. There were no negative reports related to the selected hospital despite its being located right in the center of an area struck by the epidemic. The purpose of this study was to identify the key factors enabling the hospital to survive SARS unscathed. Data were collected from in-depth interviews with the nursing directors and nursing managers of the SARS units, along with a review of relevant hospital documents. The five key elements identified as survival factors during this SARS crisis are as follows: 1. good control of timing for crisis management, 2. careful decision-making, 3. thorough implementation, 4. effective communication, and 5. trust between management and employees. The results of this study reconfirmed the selected hospital as a model for good crisis management during the SARS epidemic.

  9. Land subsidence in the Yangtze River Delta, China revealed from multi-frequency SAR Interferometry

    NASA Astrophysics Data System (ADS)

    Li, Zhenhong; Motagh, Mahdi; Yu, Jun; Gong, Xulong; Wu, Jianqiang; Zhu, Yefei; Chen, Huogen; Zhang, Dengming; Xu, Yulin

    2014-05-01

    Land subsidence is a major worldwide hazard, and its principal causes are subsurface fluid withdrawal, drainage of organic soils, sinkholes, underground mining, hydrocompaction, thawing permafrost, and natural consolidation. Land subsidence causes many problems including: damage to public facilities such as bridges, roads, railroads, electric power lines, underground pipes; damage to private and public buildings; and in some cases of low-lying land, can increase the risk of coastal flooding from storm surges and rising sea-levels. In China, approximately 48600 km2 of land, an area roughly 30 times of the size of the Greater London, has subsided (nearly 50 cities across 16 provinces), and the annual direct economic loss is estimated to be more than RMB 100 million (~12 million). It is believed that the Suzhou-Wuxi-Changzhou region within the Yangtze River Delta is the most severely affected area for subsidence hazards in China. With its global coverage and all-weather imaging capability, Interferometric SAR (InSAR) is revolutionizing our ability to image the Earth's surface and the evolution of its shape over time. In this paper, an advanced InSAR time series technique, InSAR TS + AEM, has been employed to analysed ERS (C-band), Envisat (C-band) and TerraSAR-X (X-band) data collected over the Suzhou-Wuxi-Changzhou region during the period from 1992 to 2013. Validation with precise levelling and GPS data suggest: (1) the accuracy of the InSAR-derived mean velocity measurements is 1-3 mm/yr; (2) InSAR-derived displacements agreed with precise levelling with root mean square errors around 5 mm. It is evident that InSAR TS + AEM can be used to image the evolution of deformation patterns in the Suzhou-Wuxi-Changzhou region over time: the maximum mean velocity decreased from ~12 cm/yr during the period of 1992-1993 to ~2 cm/yr in 2003-2013. This is believed to be a result of the prohibition of groundwater use carried out by Jiangsu provincial government. The combination

  10. Estimation and Analysis of Snow Water Equivalents Based on C-band SAR Data and Field Measurements

    NASA Astrophysics Data System (ADS)

    Che, T.

    2015-12-01

    The spatial distribution of the snow water equivalent (SWE) of ground snow cover is one of the most important variables for understanding and simulating cold-region hydrological processes in high mountain areas. In this paper, the characteristics of C-band synthetic aperture radar (SAR) data in an area of shallow dry snow cover were analyzed based on microwave backscattering models and field snow cover measurements. The analysis revealed that the backscattering of shallow dry snow cover was dominated by the scattering of the snow-ground interface, and the dielectric constant and roughness parameters of the underlying frozen soil were the primary factors that affected the total scattering. The dielectric constant of the soil depended on the amount of liquid water present in the soil, and the amount of liquid water was primarily determined by the soil temperature. Furthermore, the insulation properties (thermal resistance) of the snow cover affected the underlying soil temperature. Consequently, the snow cover characteristics affected the backscattering signal recorded by the SAR sensors. Based on an investigation involving ENVISAT-ASAR data and simultaneous ground-based snow observations conducted on March 14, 2008, we found that the snow temperature decreased with increasing snow depth when the snow depth was less than 20 cm, and the temperature increased with decreasing snow depth when the snow depth exceeded 20 cm. Additionally, the amount of liquid water in the underlying frozen soil rapidly increased with increasing temperature. To estimate the SWE, we used a small number of field measurements data and SAR ratio images to develop two equations. The first equation defined the relationship between the snow's thermal resistance and backscattering ratio, and the second equation yielded the SWE from the estimated thermal resistance of the snow-covered area. The root mean square and relative errors of the estimated SWE were approximately 7.41 mm and 6

  11. UAVSAR: InSAR and PolSAR Test Bed for the Proposed NI-SAR Mission

    NASA Astrophysics Data System (ADS)

    Jones, C. E.; Hensley, S.; Lou, Y.

    2014-12-01

    UAVSAR, which first became operational in 2009, has served as an operational testbed for the NI-SAR L-band radar concept and a unique instrument in its own right. UAVSAR supports a broad array of basic and applied geoscience, covering on smaller scale all the disciplines NI-SAR would be able to address on a global scale. Although designed specifically to provide high accuracy repeated flight tracks and precise imaging geometry for InSAR-based solid earth studies, its fully polarimetric operation, low noise, and consistent calibration accuracy has made it a premier instrument for PolSAR-based studies also. Since 2009 it has successfully imaged more than 16 million km2 and >4300 quad-polarimetric data products are now publicly available online. Upgrades made in the last year to automate the repeat track processing serve as a model for generating large volumes of InSAR products: Since January 2014 more than 700 interferometric products have been released, exceeding the output of all previous years combined. Standardly available products now include browse images of all InSAR acquisitions and coregistered single-look complex image stacks suitable for standard time series analysis. Here we present an overview of the wide range of studies utilizing UAVSAR data including those based on polarimetry and pair-wise and times series interferometry, highlighting both the unique capabilities of UAVSAR and the ways in which NI-SAR would be able to dramatically extend the capabilities. This research was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  12. Online Health Education on SARS to University Students during the SARS Outbreak

    ERIC Educational Resources Information Center

    Wong, Mee Lian; Koh, David; Iyer, Prasad; Seow, Adeline; Goh, Lee Gan; Chia, Sin Eng; Lim, Meng Kin; Ng, Daniel; Ong, Choon Nam; Phua, Kai Hong; Tambyah, Paul; Chow, Vincent T K; Chew, Suok Kai; Chandran, Ravi; Lee, Hin Peng

    2005-01-01

    Little is known about how online learning may be used to disseminate health information rapidly and widely to large university populations if there is an infectious disease outbreak. During the SARS outbreak in Singapore in 2003, a six-lesson elearning module on SARS was developed for a large university population of 32,000 students. The module…

  13. 20. OVERVIEW OF SAR3 COMPLEX, SHOWING FORMER RESIDENTIAL AREA, SAR3 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. OVERVIEW OF SAR-3 COMPLEX, SHOWING FORMER RESIDENTIAL AREA, SAR-3 SWITCH RACK, MAINTENANCE YARD, AND GREENSPOT BRIDGE. NOTE ALSO LARGE PIPE CONDUCTING TAILRACE WATER INTO IRRIGATION SYSTEM. VIEW TO SOUTHWEST. - Santa Ana River Hydroelectric System, Redlands, San Bernardino County, CA

  14. Ground deformation of the western rift of Corinth observed by means of PSI, SBAS and DInSAR methodologies

    NASA Astrophysics Data System (ADS)

    Elias, Panagiotis; Briole, Pierre

    2013-04-01

    The rift of Corinth has been long identified as a site of major importance in Europe due to its intense tectonic activity. It is one of the world's most rapidly extending continental regions and it has one of the highest seismicity rates in the Euro-Mediterranean region. It produces in average, an earthquake of magnitude 6 per century. The GPS studies conducted since 1990 indicate a north-south extension rate across the rift of ~1.5 cm year-1 around its western termination. Geological evidences show that the south coast of the rift is uplifting whereas the north part is subsiding. The western termination of the rift in the Patras broader area presents a major scientific and socio-economic importance, with the Psathopyrgos and the Rion-Patras faults being located very close to the city of Patras. The first DInSAR studies were carried out using SAR/ERS data after the Ms= 6.2 June 15, 1995 Aigion earthquake and contributed to its characterization. More recently the ground deformation of the area has been measured using a series of ASAR/ENVISAT, PALSAR/ALOS and RASARSAT-2 acquisitions. All datasets were processed by means of PSI (Persistent Scatterers Interferometry), SBAS (Small Baseline SubSet) and DInSAR (Differential Interferometry with SAR) methodologies. In addition to widely used tools (DIAPASON, ROI-PAC, STAMPS e.t.c.) in-house procedures and tools have been developed in order to exploit of the synergy of multiple characteristics/properties (frequency, viewing angles, sides, etc) of the SAR acquisitions aiming to the minimisation of the noise components. We verified the agreement between GPS and PSI/SBAS velocities at the location of the five permanent GPS stations operated in the rift since ten years. Ground deformations are visible at various scales and at various places in the produced PSI/SBAS maps and several known faults exhibit ground deformation around them with no earthquake occurred during the observations period: (a) On 18th and 22nd of January 2010

  15. Local ionospheric corrections derived from GNSS - A case study with TerraSAR-X

    NASA Astrophysics Data System (ADS)

    Gisinger, Christoph; Balss, Ulrich; Cong, Xiao Ying; Steigenberger, Peter; Eineder, Michael; Pail, Roland; Hugentobler, Urs

    2013-04-01

    Germany's synthetic aperture radar (SAR) satellites TerraSAR-X and TanDEM-X belong to the latest generation of radar satellites which have moved radar remote sensing to a new level. Besides being an all weather and all day imaging system, radar remote sensing offers various advanced methods like SAR interferometry or persistent scatterer interferometry that exploit magnitude and phase information of the radar signal. In order to achieve centimeter to millimeter accuracy with these advanced methods, all occurring error contributions (internal signal delay, orbit, troposphere, ionosphere, solid earth tides, loading effects, ...) have to be taken into account by applying appropriate corrections. Within the project DLR@Uni funded by the German Helmholtz Association HGF, an experimental framework at Wettzell station has been set up to perform a detailed analysis of all the corrections required for high resolution radar satellites and to achieve the goal of a 1cm precision level for absolute radar coordinates. This framework involves a 1.5 meter corner reflector (CR), a 1.5 year series of data takes from TerraSAR-X, and it makes use of the multi-sensor environment of Wettzell station. Besides Satellite Laser Ranging (SLR) for orbit assessment and the local geodetic network to control the CR reference coordinates, the Wettzell GNSS receivers are used for generating tropospheric and ionospheric corrections. By comparing the reference radar times (range and azimuth) available from geodetic survey with those from the TerraSAR-X data takes, the quality of the corrections can be investigated. Although often being considered negligible for X-band observations, the conducted experiment has clearly shown the necessity for ionospheric corrections, if the capabilities of current SAR satellites are to be fully exploited. For every TerraSAR-X data take, the ionospheric impact was derived from the geometry-free linear combination of the GNSS measurements and modeled in terms of

  16. Polarimetric target detection techniques and results from the Goddard Space Flight Center Search and Rescue Synthetic Aperature Radar (SAR2) program

    NASA Astrophysics Data System (ADS)

    Jackson, Christopher R.; Rais, Houra; Mansfield, Arthur W.

    1998-09-01

    Over the SAR2 programs seven year history, a great deal of original research has been done in the area of automatic target detection for identifying aircraft crash site locations in synthetic aperture radar (SAR) imagery. The efforts have focused on using the polarimetric properties of the radar signal to both improve image quality and distinguish the crash sits from the natural background. A crash sites polarimetric 'signature' is expected to be present even in the absence of a strong intensity return. Several of these advanced methods are summarized and a methodology for their application described. Several detection results are presented using data from the NASA/JPL AirSAR.

  17. Performance evaluation of SAR/GMTI algorithms

    NASA Astrophysics Data System (ADS)

    Garber, Wendy; Pierson, William; Mcginnis, Ryan; Majumder, Uttam; Minardi, Michael; Sobota, David

    2016-05-01

    There is a history and understanding of exploiting moving targets within ground moving target indicator (GMTI) data, including methods for modeling performance. However, many assumptions valid for GMTI processing are invalid for synthetic aperture radar (SAR) data. For example, traditional GMTI processing assumes targets are exo-clutter and a system that uses a GMTI waveform, i.e. low bandwidth (BW) and low pulse repetition frequency (PRF). Conversely, SAR imagery is typically formed to focus data at zero Doppler and requires high BW and high PRF. Therefore, many of the techniques used in performance estimation of GMTI systems are not valid for SAR data. However, as demonstrated by papers in the recent literature,1-11 there is interest in exploiting moving targets within SAR data. The techniques employed vary widely, including filter banks to form images at multiple Dopplers, performing smear detection, and attempting to address the issue through waveform design. The above work validates the need for moving target exploitation in SAR data, but it does not represent a theory allowing for the prediction or bounding of performance. This work develops an approach to estimate and/or bound performance for moving target exploitation specific to SAR data. Synthetic SAR data is generated across a range of sensor, environment, and target parameters to test the exploitation algorithms under specific conditions. This provides a design tool allowing radar systems to be tuned for specific moving target exploitation applications. In summary, we derive a set of rules that bound the performance of specific moving target exploitation algorithms under variable operating conditions.

  18. Random Forest and Rotation Forest for fully polarized SAR image classification using polarimetric and spatial features

    NASA Astrophysics Data System (ADS)

    Du, Peijun; Samat, Alim; Waske, Björn; Liu, Sicong; Li, Zhenhong

    2015-07-01

    Fully Polarimetric Synthetic Aperture Radar (PolSAR) has the advantages of all-weather, day and night observation and high resolution capabilities. The collected data are usually sorted in Sinclair matrix, coherence or covariance matrices which are directly related to physical properties of natural media and backscattering mechanism. Additional information related to the nature of scattering medium can be exploited through polarimetric decomposition theorems. Accordingly, PolSAR image classification gains increasing attentions from remote sensing communities in recent years. However, the above polarimetric measurements or parameters cannot provide sufficient information for accurate PolSAR image classification in some scenarios, e.g. in complex urban areas where different scattering mediums may exhibit similar PolSAR response due to couples of unavoidable reasons. Inspired by the complementarity between spectral and spatial features bringing remarkable improvements in optical image classification, the complementary information between polarimetric and spatial features may also contribute to PolSAR image classification. Therefore, the roles of textural features such as contrast, dissimilarity, homogeneity and local range, morphological profiles (MPs) in PolSAR image classification are investigated using two advanced ensemble learning (EL) classifiers: Random Forest and Rotation Forest. Supervised Wishart classifier and support vector machines (SVMs) are used as benchmark classifiers for the evaluation and comparison purposes. Experimental results with three Radarsat-2 images in quad polarization mode indicate that classification accuracies could be significantly increased by integrating spatial and polarimetric features using ensemble learning strategies. Rotation Forest can get better accuracy than SVM and Random Forest, in the meantime, Random Forest is much faster than Rotation Forest.

  19. Mars Mission Concepts: SAR and Solar Electric Propulsion

    NASA Astrophysics Data System (ADS)

    Elsperman, M.; Klaus, K.; Smith, D. B.; Clifford, S. M.; Lawrence, S. J.

    2012-12-01

    Introduction: The time has come to leverage technology advances (including advances in autonomous operation and propulsion technology) to reduce the cost and increase the flight rate of planetary missions, while actively developing a scientific and engineering workforce to achieve national space objectives. Mission Science at Mars: A SAR imaging radar offers an ability to conduct high resolution investigations of the shallow (<10 m depth) subsurface of Mars, enabling identification of fine-scale layering within the Martian polar layered deposits (PLD), as well as the identification of pingos, investigations of polygonal terrain, and measurements of the thickness of mantling layers at non-polar latitudes. It would allow systematic near-surface prospecting, which is tremendously useful for human exploration purposes (in particular, the identification of accessible ice deposits and quantification of Martian regolith properties). Limited color capabilities in a notional high-resolution stereo imaging system would enable the generation of false color images, resulting in useful science results, and the stereo data could be reduced into high-resolution Digital Elevation Models uniquely useful for exploration planning and science purposes. Since the SAR and the notional high-resolution stereo imaging system would be huge data volume producers - to maximize the science return we are currently considering the usage of laser communications systems; this notional spacecraft represents one pathway to evaluate the utility of laser communications in planetary exploration while providing useful science return.. Mission Concept: Using a common space craft for multiple missions reduces costs. Solar electric propulsion (SEP) provides the flexibility required for multiple mission objectives. SEP provides the greatest payload advantage albeit at the sacrifice of mission time. Our concept involves using a SEP enabled space craft (Boeing 702SP) with a highly capable SAR imager that also

  20. Development of a video SAR for FMV through clouds

    NASA Astrophysics Data System (ADS)

    Wallace, H. B.

    2015-05-01

    The Defense Advanced Research Projects Agency (DARPA) is developing a Video Synthetic Aperture Radar (ViSAR) system designed to provide a targeting capability for the AC-130 gunship in conditions where the current electro-optic systems will not perform. By using radar, the gunship's availability rises from 35% to 72%, as clouds currently obscure the EO/IR camera's view of the ground. Several technical issues must be addressed in the program in order to be successful. In order to achieve frame rates fast to track maneuvering targets, the radar must operate at frequencies over 170 which requires the development of new electronics. Secondly, as targets move in the FOV of a Synthetic Aperture Radar (SAR) their apparent position is translated in the generated imagery. Thirdly, as the imagery generated is range versus azimuth rather than elevation versus azimuth, tall objects appear to be "laid over" unless corrections are made for the true height of the object imaged. This paper will describe the DARPA program striving to overcome these issues and review the approaches be taken to achieve the imagery required for the close air support mission.

  1. Severe acute respiratory syndrome (SARS): a year in review.

    PubMed

    Skowronski, Danuta M; Astell, Caroline; Brunham, Robert C; Low, Donald E; Petric, Martin; Roper, Rachel L; Talbot, Pierre J; Tam, Theresa; Babiuk, Lorne

    2005-01-01

    Severe acute respiratory syndrome (SARS) emerged from China as an untreatable and rapidly spreading respiratory illness of unknown etiology. Following point source exposure in February 2003, more than a dozen guests infected at a Hong Kong hotel seeded multi-country outbreaks that persisted through the spring of 2003. The World Health Organization responded by invoking traditional public health measures and advanced technologies to control the illness and contain the cause. A novel coronavirus was implicated and its entire genome was sequenced by mid-April 2003. The urgency of responding to this threat focused scientific endeavor and stimulated global collaboration. Through real-time application of accumulating knowledge, the world proved capable of arresting the first pandemic threat of the twenty-first century, despite early respiratory-borne spread and global susceptibility. This review synthesizes lessons learned from this remarkable achievement. These lessons can be applied to re-emergence of SARS or to the next pandemic threat to arise. PMID:15660517

  2. Probability of detection of downed aircraft using SAR polarimetry

    NASA Astrophysics Data System (ADS)

    Chotoo, Kancham; Huxtable, Barton D.; Mansfield, Arthur W.; Rais, Houra

    2000-08-01

    In developing a beaconless search and rescue capability to quickly locate small aircraft that have crashed in remote areas, NASA's Search and Rescue Synthetic Aperture Radar (SAR2) program brings together advanced polarimetric synthetic aperture radar processing, field and laboratory tests, and state-of-the-art automated target detection algorithms. The fundamental idea underlying the search and rescue (S&R) approach is use of an airborne polarimetric radar. The downed aircraft is partly composed of metal, and consists of regular geometric shapes such as flat plates, dihedrals, trihedrals, etc., which produce a polarization signature expected to be distinct from that of surrounding terrain and foliage. Onboard polarimetric SAR image formation combined with automatic image exploitation will ultimately cue the S&R team to candidate crash sites in near real-time. We empirically examine the probability of detection (PD) and false alarm rate (FAR) for crash site detection using polarimetry to discriminate between aircraft target signatures within natural clutter. This briefing will present the latest results from the S&R Program activities, providing an update to the last program presentation to the SPIE Meeting in 1999.

  3. Automated rectification and geocoding of SAR imagery

    NASA Technical Reports Server (NTRS)

    Kwok, R.; Curlander, J. C.

    1987-01-01

    An automated post-processing system has been developed for rectification and geocoding of SAR (Synthetic Aperture Radar) imagery. The system uses as input a raw uncorrected image from the operational SAR correlator, and produces as a standard output a rectified and geocoded product. The accurate geolocation of SAR image pixels is provided by a spatial transformation model which maps the slant range-azimuth SAR image pixels into their location on a prespecified map grid. This model predicts the geodetic location of each pixel by utilizing: the sensor platform position; a geoid model; the parameters of the data collection system and the processing parameters used in the SAR correlator. Based on their geodetic locations, the pixels are mapped by using the desired cartographic projection equations. This rectification and geocoding technique has been tested with Seasat and SIR-B images. The test results demonstrate absolute location uncertainty of less than 50 m and relative distortion (scale factor and skew) of less than 0.1 percent relative to local variations from the assumed geoid.

  4. ICAO's anti-SARS airport activities.

    PubMed

    Finkelstein, Silvio; Curdt-Christiansen, Claus M

    2003-11-01

    To prevent SARS from spreading through air travel and in order to rebuild the confidence of the traveling public in the safety of air travel, ICAO has set up an "Anti-SARS Airport Evaluation Project." The first phase of this project was to develop a set of protective measures for international airports in affected areas to adopt and implement and then to send out, on the request of Contracting States, a team of inspectors to evaluate and assess airports and issue a "statement of evaluation" that the airport inspected complies with the ICAO anti-SARS protective measures. In cooperation with the World Health Organization (WHO), the first part of phase 1 was completed in early June this year, and the second part of phase 1 followed soon after. By mid-July, five international airports in Southeast Asia had been inspected and found to be in full compliance with the ICAO anti-SARS protective measures. The success of this ICAO project is believed to have contributed significantly to the recovery of international air travel and related industries now taking place. Phase 2 of the project is now being developed. It is aimed at preventing a resurgence of SARS, but it also contains elements to make the methodology developed applicable to future outbreaks of any other communicable disease in which the mode of transmission could involve aviation and/or the need to prevent the spread of the disease by air travel.

  5. A comparative evaluation of SAR and SLAR

    SciTech Connect

    Mastin, G.A.; Manson, J.J.; Bradley, J.D.; Axline, R.M.; Hover, G.L.

    1993-11-01

    Synthetic aperture radar (SAR) was evaluated as a potential technological improvement over the Coast Guard`s existing side-looking airborne radar (SLAR) for oil-spill surveillance applications. The US Coast Guard Research and Development Center (R&D Center), Environmental Branch, sponsored a joint experiment including the US Coast Guard, Sandia National Laboratories, and the Naval Oceanographic and Atmospheric Administration (NOAA), Hazardous Materials Division. Radar imaging missions were flown on six days over the coastal waters off Santa Barbara, CA, where there are constant natural seeps of oil. Both the Coast Guard SLAR and the Sandia National Laboratories SAR were employed to acquire simultaneous images of oil slicks and other natural sea surface features that impact oil-spill interpretation. Surface truth and other environmental data were also recorded during the experiment. The experiment data were processed at Sandia National Laboratories and delivered to the R&D Center on a computer workstation for analysis by experiment participants. Issues such as optimal spatial resolution, single-look vs. multi-look SAR imaging, and the utility of SAR for oil-spill analysis were addressed. Finally, conceptual design requirements for a possible future Coast Guard SAR were outlined and evaluated.

  6. SARS revisited: managing "outbreaks" with "communications".

    PubMed

    Menon, K U

    2006-05-01

    "Risk communications" has acquired some importance in the wake of our experience of SARS. Handled well, it helps to build mutual respect between a government or an organisation and the target groups with which it is communicating. It helps nurture public trust and confidence in getting over the crisis. The World Health Organization (WHO) has also come to recognise its importance after SARS and organised the first Expert Consultation on Outbreak Communications conference in Singapore in September 2004. This article assesses the context and the key features which worked to Singapore's advantage. Looking at the data now widely available on the Internet of the experience of SARS-infected countries like China, Taiwan, Canada, the article identifies the key areas of strategic communications in which Singapore fared particularly well. Another issue discussed is whether Singapore's experience has universal applicability or whether it is limited because of Singapore's unique cultural, historical and geographical circumstances. Finally, the article also looks at some of the post-SARS enhancements that have been put in place following the lessons learnt from SARS and the need to confront new infectious outbreaks like avian flu. PMID:16830005

  7. Calibration of the Geosar Dual Frequency Interferometric SAR

    NASA Technical Reports Server (NTRS)

    Chapine, Elaine

    1999-01-01

    GeoSAR is an airborne, interferometric Synthetic Aperture Radar (INSAR) system for terrain mapping, currently under development by a consortium including NASA's Jet Propulsion Laboratory (JPL), Calgis, Inc., and the California Department of Conservation (CalDOC) with funding provided by the Topographic Engineering Center (TEC) of the U.S. Army Corps of Engineers and the Defense Advanced Research Projects Agency (DARPA). The radar simultaneously maps swaths on both sides of the aircraft at two frequencies, X-Band and P-Band. For the P-Band system, data is collected for two across track interferometric baselines and at the crossed polarization. The aircraft position and attitude are measured using two Honeywell Embedded GPS Inertial Navigation Units (EGI) and an Ashtech Z12 GPS receiver. The mechanical orientation and position of the antennas are actively measured using a Laser Baseline Metrology System (LBMS). In the GeoSAR motion measurement software, these data are optimally combined with data from a nearby ground station using Ashtech PNAV software to produce the position, orientation, and baseline information are used to process the dual frequency radar data. Proper calibration of the GeoSAR system is essential to obtaining digital elevation models (DEMS) with the required sub-meter level planimetric and vertical accuracies. Calibration begins with the determination of the yaw and pitch biases for the two EGI units. Common range delays are determined for each mode, along with differential time and phase delays between channels. Because the antennas are measured by the LBMS, baseline calibration consists primarily of measuring a constant offset between mechanical center and the electrical phase center of the antennas. A phase screen, an offset to the interferometric phase difference which is a function of absolute phase, is applied to the interferometric data to compensate for multipath and leakage. Calibration parameters are calculated for each of the ten

  8. An improved MIMO-SAR simulator strategy with ray tracing

    NASA Astrophysics Data System (ADS)

    Xiang, Xingyu; Mo, Zijian; Wang, Zhonghai; Chen, Genshe; Pham, Khanh; Blasch, Erik

    2016-05-01

    High resolution and wide-swath imaging can be obtained by Multiple-Input Multiple-Output (MIMO) synthetic aperture radar (SAR) with the state of the art technologies. The time division multiple access (TDMA) MIMO SAR mimics the motion of the antenna of SAR systems by switching the array channels to transmit the radar signals at different time slots. In this paper, we develop a simulation tool with ray tracing techniques to retrieve high resolution and accurate SAR images for development of MIMO SAR imaging methods. Without loss of generality, in the proposed simulator, we apply a TDMA MIMO SAR system with 13 transmitting antennas and 8 receiving antennas, where all transmitting antennas share a single transmitter and the receiving antennas share a single receiver. By comparing with the normal simulation MIMO SAR strategies, the simulation image using ray tracing results validate that the proposed method provides more accurate and higher resolution SAR images.

  9. Statistical Approach To Determination Of Texture In SAR

    NASA Technical Reports Server (NTRS)

    Rignot, Eric J.; Kwok, Ronald

    1993-01-01

    Paper presents statistical approach to analysis of texture in synthetic-aperture-radar (SAR) images. Objective: to extract intrinsic spatial variability of distributed target from overall spatial variability of SAR image.

  10. Characterizing hydrologic changes of Great Dismal Swamp using SAR/InSAR technology

    NASA Astrophysics Data System (ADS)

    Kim, J. W.; Lu, Z.; Zhu, Z.

    2015-12-01

    Great Dismal Swamp is one of the largest, northernmost peatlands on the Atlantic Coastal Plain, and the swamp is underlain by a thick water-logged organic soil layer (peat) made up of dead and decaying plant material. The peatlands play a role as the sink of large amount of soil organic carbon and methane. However, the disturbance of the peatland negatively impacted the ecosystem and contributed to the climate change caused by the released greenhouse gas. Our SAR/InSAR methods observed the hydrologic changes in the peatlands, which is a key factor to conserve the wetland, through several methods. First, we compared averaged SAR intensity from C- and L-band SAR sensors with groundwater level changes, and deduced a linear relationship between the SAR backscattering intensity and the groundwater level change. Second, we extracted the inundated area during wet season from InSAR coherence. Third, we measured the relative water level changes in the inundated area using the interferometric phases. Finally, we estimated the groundwater level changes corresponding to the soil moisture changes from time-series InSAR method. Our results can provide the unique opportunity to understand the occurring hydrologic and vegetation changes in the Great Dismal Swamp.

  11. Completing the gaps in Kilauea's Father's Day InSAR displacement signature with ScanSAR

    NASA Astrophysics Data System (ADS)

    Bertran Ortiz, A.; Pepe, A.; Lanari, R.; Lundgren, P.; Rosen, P. A.

    2009-12-01

    Currently there are gaps in the known displacement signature obtained with InSAR at Kilauea between 2002 and 2009. InSAR data can be richer than GPS because of denser spatial cover. However, to better model rapidly varying and non-steady geophysical events InSAR is limited because of its less dense time observations of the area under study. The ScanSAR mode currently available in several satellites mitigates this effect because the satellite may illuminate a given area more than once within an orbit cycle. The Kilauea displacement graph below from Instituto per Il Rilevamento Electromagnetico dell'Ambiente (IREA) is a cut in space of the displacement signature obtained from a time series of several stripmap-to-stripmap interferograms. It shows that critical information is missing, especially between 2006 and 2007. The displacement is expected to be non-linear judging from the 2007-2008 displacement signature, thus simple interpolation would not suffice. The gap can be filled by incorporating Envisat stripmap-to-ScanSAR interferograms available during that time period. We propose leveraging JPL's new ROI-PAC ScanSAR module to create stripmap-to-ScanSAR interferograms. The new interferograms will be added to the stripmap ones in order to extend the existing stripmap time series generated by using the Small BAseline Subset (SBAS) technique. At AGU we will present denser graphs that better capture Kilauea's displacement between 2003 and 2009.

  12. An innovative methodological approach in the frame of Marine Strategy Framework Directive: a statistical model based on ship detection SAR data for monitoring programmes.

    PubMed

    Pieralice, Francesca; Proietti, Raffaele; La Valle, Paola; Giorgi, Giordano; Mazzolena, Marco; Taramelli, Andrea; Nicoletti, Luisa

    2014-12-01

    The Marine Strategy Framework Directive (MSFD, 2008/56/EC) is focused on protection, preservation and restoration of the marine environment by achieving and maintaining Good Environmental Status (GES) by 2020. Within this context, this paper presents a methodological approach for a fast and repeatable monitoring that allows quantitative assessment of seabed abrasion pressure due to recreational boat anchoring. The methodology consists of two steps: a semi-automatic procedure based on an algorithm for the ship detection in SAR imagery and a statistical model to obtain maps of spatial and temporal distribution density of anchored boats. Ship detection processing has been performed on 36 ASAR VV-pol images of Liguria test site, for the three years 2008, 2009 and 2010. Starting from the pointwise distribution layer produced by ship detection in imagery, boats points have been subdivided into 4 areas where a constant distribution density has been assumed for the entire period 2008-2010. In the future, this methodology will be applied also to higher resolution data of Sentinel-1 mission, specifically designed for the operational needs of the European Programme Copernicus. PMID:25096752

  13. Quantifying the dynamics of water bodies, wetlands and biomass in the Poyang Lake region: A multi-polarization SAR remote sensing approach

    NASA Astrophysics Data System (ADS)

    Sang, Huiyong

    sacchariflorus during its growth period result in over 10 dB spatial and temporal variation in ASAR backscatter in HH- and HV-polarization. The relationship of canopy height with ASAR backscattering coefficient is the most significant among the influencing factors (plant height, fresh biomass, dry biomass, vegetation water content) on radar backscattering mechanism (R2=0.9 for HH-polarization and R2=0.59 for HV-polarization) from Phragmites cummunis Trin. HH- and HV-backscatters are more sensitive to the variation of dry biomass (R2=0.76 for HH and R2=0.56 for HV) than to that of fresh biomass (R 2=0.07 for HV and R2=0.42 for HH). Plant water content plays a negative role and attenuates the backscattering signals in both polarizations. For Phragmites communis Trin. with tall stalks (over 2m) and long, blade-like leaves, HH-polarization is more sensitive to vegetation parameters than HV-polarization for C-band SAR signals. Similar to Phragmites communis Trin., ASAR backscattering coefficient in both polarizations is more sensitive to plant height and dry biomass of non-flooded Miscanthus sacchariflorus, and their regression coefficients (R2) are over 0.5 for HH-polarization and over 0.4 for HV-polarization. Plant water content has no evident effect on the variation of ASAR backscatter. HV-polarization is more sensitive to the variation of above-water canopy parameters than HH-polarization for flooded Miscanthus saccharifiorus. HH- and HV-polarized radar backscatters from Carex spp. wetlands increased significantly with the variation of plant height, fresh biomass and dry biomass, but they reach saturated when vegetation grows up to 30cm. Compared with those tall grass with stalks and long blade-like leaves, the correlation of fresh biomass with HV-polarization is more pronounced (R 2=0.78) than that with HH-polarization (R2=0.41) for Carex spp. Vegetation structure play a more important role in radar backscattering mechanism than plant water content for these three wetland

  14. An innovative methodological approach in the frame of Marine Strategy Framework Directive: a statistical model based on ship detection SAR data for monitoring programmes.

    PubMed

    Pieralice, Francesca; Proietti, Raffaele; La Valle, Paola; Giorgi, Giordano; Mazzolena, Marco; Taramelli, Andrea; Nicoletti, Luisa

    2014-12-01

    The Marine Strategy Framework Directive (MSFD, 2008/56/EC) is focused on protection, preservation and restoration of the marine environment by achieving and maintaining Good Environmental Status (GES) by 2020. Within this context, this paper presents a methodological approach for a fast and repeatable monitoring that allows quantitative assessment of seabed abrasion pressure due to recreational boat anchoring. The methodology consists of two steps: a semi-automatic procedure based on an algorithm for the ship detection in SAR imagery and a statistical model to obtain maps of spatial and temporal distribution density of anchored boats. Ship detection processing has been performed on 36 ASAR VV-pol images of Liguria test site, for the three years 2008, 2009 and 2010. Starting from the pointwise distribution layer produced by ship detection in imagery, boats points have been subdivided into 4 areas where a constant distribution density has been assumed for the entire period 2008-2010. In the future, this methodology will be applied also to higher resolution data of Sentinel-1 mission, specifically designed for the operational needs of the European Programme Copernicus.

  15. Absolute radiometric calibration of the CCRS SAR

    NASA Astrophysics Data System (ADS)

    Ulander, Lars M. H.; Hawkins, Robert K.; Livingstone, Charles E.; Lukowski, Tom I.

    1991-11-01

    Determining the radar scattering coefficients from SAR (synthetic aperture radar) image data requires absolute radiometric calibration of the SAR system. The authors describe an internal calibration methodology for the airborne Canada Centre for Remote Sensing (CCRS) SAR system, based on radar theory, a detailed model of the radar system, and measurements of system parameters. The methodology is verified by analyzing external calibration data acquired over a 6-month period in 1988 by the C-band radar using HH polarization. The results indicate that the overall error is +/- 0.8 dB (1-sigma) for incidence angles +/- 20 deg from antenna boresight. The dominant error contributions are due to the antenna radome and uncertainties in the elevation angle relative to the antenna boresight.

  16. Calibration of a polarimetric imaging SAR

    NASA Technical Reports Server (NTRS)

    Sarabandi, K.; Pierce, L. E.; Ulaby, F. T.

    1991-01-01

    Calibration of polarimetric imaging Synthetic Aperture Radars (SAR's) using point calibration targets is discussed. The four-port network calibration technique is used to describe the radar error model. The polarimetric ambiguity function of the SAR is then found using a single point target, namely a trihedral corner reflector. Based on this, an estimate for the backscattering coefficient of the terrain is found by a deconvolution process. A radar image taken by the JPL Airborne SAR (AIRSAR) is used for verification of the deconvolution calibration method. The calibrated responses of point targets in the image are compared both with theory and the POLCAL technique. Also, response of a distributed target are compared using the deconvolution and POLCAL techniques.

  17. Block adaptive quantization of Magellan SAR data

    NASA Technical Reports Server (NTRS)

    Kwok, Ronald; Johnson, William T. K.

    1989-01-01

    A report is presented on a data compression scheme that will be used to reduce the SAR data rate on the NASA Magellan mission to Venus. The spacecraft has only one scientific instrument, a radar system for imaging the surface, for altimetric profiling of the planet topography, and for measuring radiation from the planet surface. A straightforward implementation of the scientific requirements of the mission results in a data rate higher than can be accommodated by the available system bandwidth. A data-rate-reduction scheme which includes operation of the radar in burst mode and block-adaptive quantization of the SAR data is selected to satisfy the scientific requirements. Descriptions of the quantization scheme and its hardware implementation are given. Burst-mode SAR operation is also briefly discussed.

  18. The Radarsat SAR multi-beam antenna

    NASA Astrophysics Data System (ADS)

    Martins-Camelo, L.; Cooper, R. T.; Zimcik, D. G.

    1984-10-01

    Radarsat, the Canadian radar imaging satellite, will have a Synthetic Aperture Radar (SAR) antenna as one of its sensors. The requirements on the performance of the SAR antenna are such as to make it a complex system. Radarsat is required to have some unique characteristics which present some new challenges to the antenna designers. The requirements for switchability among 4 shaped beams and high power of transmit operation are major design constraints which strongly impact on the antenna complexity, weight, and cost. A trade-off study was carried out to select the preferred antenna type for the Radarsat SAR function. The antenna types analyzed were planar-array and array-fed reflector. A set of comparison criteria was developed. The antenna concepts studied were then compared against these criteria, and a final decision was reached.

  19. New approaches in interferometric SAR data processing

    NASA Technical Reports Server (NTRS)

    Lin, Qian; Vesecky, John F.; Zebker, Howard A.

    1992-01-01

    It is well established that interferometric synthetic aperture radar (SAR) images can be inverted to perform surface elevation mapping. Among the factors critical to the mapping accuracy are registration of the interfering SAR images and phase unwrapping. A novel registration algorithm is presented that determines the registration parameters through optimization. A new figure of merit is proposed that evaluates the registration result during the optimization. The phase unwrapping problem is approached through a new method involving fringe line detection. The algorithms are tested with two SEASAT SAR images of terrain near Yellowstone National Park. These images were collected on Seasat orbits 1334 and 1420, which were very close together in space, i.e., less than 100 m. The resultant elevation map is compared with the USGS digital terrain elevation model.

  20. Linear Approximation SAR Azimuth Processing Study

    NASA Technical Reports Server (NTRS)

    Lindquist, R. B.; Masnaghetti, R. K.; Belland, E.; Hance, H. V.; Weis, W. G.

    1979-01-01

    A segmented linear approximation of the quadratic phase function that is used to focus the synthetic antenna of a SAR was studied. Ideal focusing, using a quadratic varying phase focusing function during the time radar target histories are gathered, requires a large number of complex multiplications. These can be largely eliminated by using linear approximation techniques. The result is a reduced processor size and chip count relative to ideally focussed processing and a correspondingly increased feasibility for spaceworthy implementation. A preliminary design and sizing for a spaceworthy linear approximation SAR azimuth processor meeting requirements similar to those of the SEASAT-A SAR was developed. The study resulted in a design with approximately 1500 IC's, 1.2 cubic feet of volume, and 350 watts of power for a single look, 4000 range cell azimuth processor with 25 meters resolution.

  1. Stop outbreak of SARS with infrared cameras

    NASA Astrophysics Data System (ADS)

    Wu, Yigang M.

    2004-04-01

    SARS (Severe Acute Respiratory Syndrome, commonly known as Atypical Pneumonia in mainland China) caused 8422 people affected and resulting in 918 deaths worldwide in half year. This disease can be transmitted by respiratory droplets or by contact with a patient's respiratory secretions. This means it can be spread out very rapidly through the public transportations by the travelers with the syndrome. The challenge was to stop the SARS carriers traveling around by trains, airplanes, coaches and etc. It is impractical with traditional oral thermometers or spot infrared thermometers to screen the tens of travelers with elevated body temperature from thousands of normal travelers in hours. The thermal imager with temperature measurement function is a logical choice for this special application although there are some limitations and drawbacks. This paper discusses the real SARS applications of industrial infrared cameras in China from April to July 2003.

  2. SAR-EDU - An education initiative for applied Synthetic Aperture Radar remote sensing

    NASA Astrophysics Data System (ADS)

    Eckardt, Robert; Richter, Nicole; Auer, Stefan; Eineder, Michael; Roth, Achim; Hajnsek, Irena; Walter, Diana; Braun, Matthias; Motagh, Mahdi; Pathe, Carsten; Pleskachevsky, Andrey; Thiel, Christian; Schmullius, Christiane

    2013-04-01

    Since the 1970s, radar remote sensing techniques have evolved rapidly and are increasingly employed in all fields of earth sciences. Applications are manifold and still expanding due to the continuous development of new instruments and missions as well as the availability of very high-quality data. The trend worldwide is towards operational employment of the various algorithms and methods that have been developed. However, the utilization of operational services does not keep up yet with the rate of technical developments and the improvements in sensor technology. With the enhancing availability and variety of space borne Synthetic Aperture Radar (SAR) data and a growing number of analysis algorithms the need for a vital user community is increasing. Therefore the German Aerospace Center (DLR) together with the Friedrich-Schiller-University Jena (FSU) and the Technical University Munich (TUM) launched the education initiative SAR-EDU. The aim of the project is to facilitate access to expert knowledge in the scientific field of radar remote sensing. Within this effort a web portal will be created to provide seminar material on SAR basics, methods and applications to support both, lecturers and students. The overall intension of the project SAR-EDU is to provide seminar material for higher education in radar remote sensing covering the topic holistically from the very basics to the most advanced methods and applications that are available. The principles of processing and interpreting SAR data are going to be taught using test data sets and open-source as well as commercial software packages. The material that is provided by SAR-EDU will be accessible at no charge from a DLR web portal. The educational tool will have a modular structure, consisting of separate modules that broach the issue of a particular topic. The aim of the implementation of SAR-EDU as application-oriented radar remote sensing educational tool is to advocate the development and wider use of

  3. Adaptive InSAR combined with surveying techniques for an improved characterisation of active landslides (El Portalet)

    NASA Astrophysics Data System (ADS)

    Duro, Javier; Albiol, David; Sánchez, Francisco; Herrera, Gerardo; García Davalillo, Juan Carlos; Fernandez Merodo, Jose Antonio; Allasia, Paolo; Lollino, Piernicola; Manconi, Andrea

    2014-05-01

    InSAR and the Persistent Scatterer Interferometry (PSI) are well established techniques for monitoring urban and rural areas. Besides the large number of available SAR data in the past, the current and forthcoming space-borne SAR sensors offer the possibility of selecting the optimal acquisition configuration (wavelength, resolution, incidence angle, etc.) for each application. However, optimal data takes are not always possible and/or the processing area is difficult to analyse under an InSAR point of view. In such situations, additional and adaptive InSAR developments combined with other surveying techniques provide consistent solutions that meet the requirements of different application cases This work presents an advanced InSAR processing adapted for an active slow deformation landslide in a mountainous area. The presentation will show the benefits of applying advanced and adaptive filtering strategies for improving the InSAR quality in highly decorrelated environments. The availability of Artificial Corner Reflectors over the area of interest enables to tune the filtering procedure and thus maximize the detection and exploitation of natural targets (bare soil, roads, rocks) as measurement points while preserving the phase characteristics over individual and punctual targets (building corners, poles). The new results will be evaluated in terms of final density and quality of measurement points that can be retrieved. The results will show that a very high density of measurements improves the detection of the deformation gradients and its perimeters resulting in a more accurate characterization of the landslide area. The area of study is El Portalet, an active slow deformation landslide area in Central Spanish Pyrenees. During many years the slope of interest has been monitored with several surveying techniques like DGPS, extensometers, inclinometers, GB-SAR and InSAR jointly with an extensive geological interpretation. Currently, in the frame of the FP7 Project

  4. SAR imagery using chaotic carrier frequency agility pulses

    NASA Astrophysics Data System (ADS)

    Xu, Xiaojian; Feng, Xiangzhi

    2011-06-01

    Synthetic aperture radar (SAR) systems are getting more and more applications in both civilian and military remote sensing missions. With the increasing deployment of electronic countermeasures (ECM) on modern battlefields, SAR encounters more and more interference jamming signals. The ECM jamming signals cause the SAR system to receive and process erroneous information which results in severe degradations in the output SAR images and/or formation of phony images of nonexistent targets. As a consequence, development of the electronic counter-countermeasures (ECCM) capability becomes one of the key problems in SAR system design. This paper develops radar signaling strategies and algorithms that enhance the ability of synthetic aperture radar to image targets under conditions of electronic jamming. The concept of SAR using chaotic carrier frequency agility pulses (CCFAP-SAR) is first proposed. Then the imaging procedure for CCFAP-SAR is discussed in detail. The ECCM performance of CCFAP-SAR for both depressive noise jamming and deceptive repeat jamming is analyzed. The impact of the carrier frequency agility range on the image quality of CCFAP-SAR is also studied. Simulation results demonstrate that, with adequate agility range of the carrier frequency, the proposed CCFAP-SAR performs as well as conventional radar with linear frequency modulation (LFM) waveform in image quality and slightly better in anti-noise depressive jamming; while performs very well in anti-deception jamming which cannot be rejected by LFM-SAR.

  5. Severe Acute Respiratory Syndrome (SARS) Prevention in Taiwan

    ERIC Educational Resources Information Center

    Liu, Hsueh-Erh

    2004-01-01

    Severe Acute Respiratory Syndrome (SARS) is a newly identified respiratory disease that threatened Taiwan between April 14 and July 5, 2003. Chang Gung University experienced various SARS-related episodes, such as the postponement of classes for 7 days, the reporting of probable SARS cases, and the isolation of students under Level A and B…

  6. Investigation of the Creep Along the Hazar - Palu Section of the East Anatolian Fault (Turkey) Using InSAR and GPS Observations

    NASA Astrophysics Data System (ADS)

    Cetin, Seda; Ergintav, Semih; Dogan, Ugur; Cakir, Ziyadin; Senturk, Selver; Karabulut, Hayrullah; Saroglu, Fuat; Julaiti, Wumiti; Ozener, Haluk

    2016-04-01

    Investigation of surface creep along the East Anatolian Fault (EAF) is important to improve the existing earthquake hazard models in the region, which are related to the long-term behavior of EAF. To investigate the surface creep, interseismic velocity field along the Hazar - Palu section has been calculated using the permanent scatters approach of the InSAR method (PsInSAR) with the ENVISAT ASAR data between 2003 and 2010. The mean velocity fields obtained on three descending and neighboring tracks provide clear evidence for surface fault creep. The results indicate that a 100-km-long section of the Palu segment in the Elazıǧ - Bingöl seismic gap is exhibiting aseismic creep at rates reaching up to long term GPS velocity of the EAF (i.e., ~10 mm/yr). Preliminary analysis and modeling the velocity field and seismicity suggests that the fault may be creeping from surface all the way down to the bottom of the seismogenic crust. Thus, some section of the fault may be accumulated no strain at all and, therefore may not be capable of producing major earthquakes. In order to monitor and control the creep rate, a new GPS network was established in 2015 with 6 fault perpendicular profiles along the fault. GPS sites were selected in the area less than 2 km away from the EAF. Far field continuous GPS sites will also be used in determining the long-term slip rate and locking and creping depth along the EAF by combining the results of the near field data during the modeling studies. The first GPS measurements were carried out at 27 GPS sites in 8 - 13 September 2015. Together with the GPS the present day surface creep will be investigated with Sentinel 1 SAR data. For the first time, the earthquake hazard models will be improved with the multidisciplinary investigation of creeping characteristics along the EAF with this study (supported by TUBITAK no: 114Y250 project). KEYWORDS : East Anatolian Fault, creep, InSAR, GPS

  7. First Results from an Airborne Ka-Band SAR Using SweepSAR and Digital Beamforming

    NASA Technical Reports Server (NTRS)

    Sadowy, Gregory A.; Ghaemi, Hirad; Hensley, Scott C.

    2012-01-01

    SweepSAR is a wide-swath synthetic aperture radar technique that is being studied for application on the future Earth science radar missions. This paper describes the design of an airborne radar demonstration that simulates an 11-m L-band (1.2-1.3 GHz) reflector geometry at Ka-band (35.6 GHz) using a 40-cm reflector. The Ka-band SweepSAR Demonstration system was flown on the NASA DC-8 airborne laboratory and used to study engineering performance trades and array calibration for SweepSAR configurations. We present an instrument and experiment overview, instrument calibration and first results.

  8. Efficacy of various disinfectants against SARS coronavirus.

    PubMed

    Rabenau, H F; Kampf, G; Cinatl, J; Doerr, H W

    2005-10-01

    The recent severe acute respiratory syndrome (SARS) epidemic in Asia and Northern America led to broad use of various types of disinfectant in order to control the public spread of the highly contagious virus. However, only limited data were available to demonstrate their efficacy against SARS coronavirus (SARS-CoV). We therefore investigated eight disinfectants for their activity against SARS-CoV according to prEN 14476. Four hand rubs were tested at 30s (Sterillium, based on 45% iso-propanol, 30% n-propanol and 0.2% mecetronium etilsulphate; Sterillium Rub, based on 80% ethanol; Sterillium Gel, based on 85% ethanol; Sterillium Virugard, based on 95% ethanol). Three surface disinfectants were investigated at 0.5% for 30 min and 60 min (Mikrobac forte, based on benzalkonium chloride and laurylamine; Kohrsolin FF, based on benzalkonium chloride, glutaraldehyde and didecyldimonium chloride; Dismozon pur, based on magnesium monoperphthalate), and one instrument disinfectant was investigated at 4% for 15 min, 3% for 30 min and 2% for 60 min [Korsolex basic, based on glutaraldehyde and (ethylenedioxy)dimethanol]. Three types of organic load were used: 0.3% albumin, 10% fetal calf serum, and 0.3% albumin with 0.3% sheep erythrocytes. Virus titres were determined by a quantitative test (endpoint titration) in 96-well microtitre plates. With all tested preparations, SARS-CoV was inactivated to below the limit of detection (reduction factor mostly > or =4), regardless of the type of organic load. In summary, SARS-CoV can be inactivated quite easily with many commonly used disinfectants.

  9. SAR measurement in MRI: an improved method

    NASA Astrophysics Data System (ADS)

    Romano, Rocco; Acernese, Fausto; Indovina, Pietro Luigi; Barone, Fabrizio

    2009-03-01

    During an MR procedure, the patient absorbs a portion of the transmitted RF energy, which may result in tissue heating and other adverse effects, such as alterations in visual, auditory and neural functions. The Specific Absorption Rate (SAR), in W/kg, is the RF power absorbed per unit mass of tissue and is one of the most important parameters related with thermal effects and acts as a guideline for MRI safety. Strict limits to the SAR levels are imposed by patient safety international regulations (CEI - EN 60601 - 2 - 33) and SAR measurements are required in order to verify its respect. The recommended methods for mean SAR measurement are quite problematic and often require a maintenance man intervention and long stop machine. For example, in the CEI recommended pulse energy method, the presence of a maintenance man is required in order to correctly connect the required instrumentation; furthermore, the procedure is complex and requires remarkable processing and calculus. Simpler are the calorimetric methods, also if in this case long acquisition times are required in order to have significant temperature variations and accurate heat capacity knowledge (CEI - EN 60601 - 2- 33). The phase transition method is a new method to measure SAR in MRI which has the advantages to be very simple and to overcome all the typical calorimetric method problems. It does not require in gantry temperature measurements, any specific heat or heat capacity knowledge, but only mass and time measurement. Furthermore, in this method, it is possible to show that all deposited SAR power can be considered acquired and measured.

  10. CCD architecture for spacecraft SAR image processing

    NASA Technical Reports Server (NTRS)

    Arens, W. E.

    1977-01-01

    A real-time synthetic aperture radar (SAR) image processing architecture amenable to future on-board spacecraft applications is currently under development. Using state-of-the-art charge-coupled device (CCD) technology, low cost and power are inherent features. Other characteristics include the ability to reprogram correlation reference functions, correct for range migration, and compensate for antenna beam pointing errors on the spacecraft in real time. The first spaceborne demonstration is scheduled to be flown as an experiment on a 1982 Shuttle imaging radar mission (SIR-B). This paper describes the architecture and implementation characteristics of this initial spaceborne CCD SAR image processor.

  11. Estimating IMU heading error from SAR images.

    SciTech Connect

    Doerry, Armin Walter

    2009-03-01

    Angular orientation errors of the real antenna for Synthetic Aperture Radar (SAR) will manifest as undesired illumination gradients in SAR images. These gradients can be measured, and the pointing error can be calculated. This can be done for single images, but done more robustly using multi-image methods. Several methods are provided in this report. The pointing error can then be fed back to the navigation Kalman filter to correct for problematic heading (yaw) error drift. This can mitigate the need for uncomfortable and undesired IMU alignment maneuvers such as S-turns.

  12. Unsupervised Segmentation Of Polarimetric SAR Data

    NASA Technical Reports Server (NTRS)

    Rignot, Eric J.; Dubois, Pascale; Van Zyl, Jakob; Kwok, Ronald; Chellappa, Rama

    1994-01-01

    Method of unsupervised segmentation of polarimetric synthetic-aperture-radar (SAR) image data into classes involves selection of classes on basis of multidimensional fuzzy clustering of logarithms of parameters of polarimetric covariance matrix. Data in each class represent parts of image wherein polarimetric SAR backscattering characteristics of terrain regarded as homogeneous. Desirable to have each class represent type of terrain, sea ice, or ocean surface distinguishable from other types via backscattering characteristics. Unsupervised classification does not require training areas, is nearly automated computerized process, and provides nonsubjective selection of image classes naturally well separated by radar.

  13. InSAR Time Series Analysis of Interseismic Deformation in Eastern Iran

    NASA Astrophysics Data System (ADS)

    Mousavi, Z.; Pathier, E.; Walpersdorf, A.; Lassere, C.; Tavakli, F.; Nankali, H.

    2012-04-01

    The high seismicity of Iran, with large and shallow destructive earthquakes, reflects its intense tectonic activity that takes place in the Alpine-Himalayan belt context. Active tectonics in the Iranian plateau is dominated by the convergence between the Arabian and Eurasian plates, taking place inside the political borders of the country. The part of the convergence that is not absorbed in Zagros at its SW border must be accommodated by shear deformation between Central Iran and the Helmand sub-plate to the east of Iran. Consequently, Eastern Iran has a crucial role in accommodating N-S right-lateral shear between Central Iran and Afghanistan. The tectonic deformation in eastern Iran is localized mainly on NS oriented right-lateral faults surrounding the aseismic Lut block, and EW left-lateral faults at the northern boundary of the Lut block. Previous studies on these major left-lateral faults in Eastern Iran show discrepancies especially between the GPS interseismic slip rate (less than 1 mm/yr on the Doruneh fault and geological slip rates (2.4±0.3 mm/yr). The spatial coverage, acceptable resolution and precision of space-borne radar interferometry (InSAR) make it a powerful technique to resolve some open questions of fault mechanisms and their role in the regional tectonics. Several InSAR studies have been already successful in measuring long-wavelength ground displacements related to interseismic fault deformation on similar continental strike-slip faults (like the North Anatolian fault or the Haiyuan fault). The most important difficulty of the present study is the slow slip rate of the targeted faults (1 to 3 mm/yr). Even if the East-West orientation of the Doruneh or Dasht-e-Bayaz strike-slip faults is favourable to the measurement from descending or ascending ENVISAT orbits, such low slip rate faults still require some methodological improvement with respect to conventional InSAR. In this study, we use ENVISAT ASAR images from 2003 to 2010, in descending

  14. Engaging students in geodesy: A quantitative InSAR module for undergraduate tectonics and geophysics classes

    NASA Astrophysics Data System (ADS)

    Taylor, H.; Charlevoix, D. J.; Pritchard, M. E.; Lohman, R. B.

    2013-12-01

    In the last several decades, advances in geodetic technology have allowed us to significantly expand our knowledge of processes acting on and beneath the Earth's surface. Many of these advances have come as a result of EarthScope, a community of scientists conducting multidisciplinary Earth science research utilizing freely accessible data from a variety of instruments. The geodetic component of EarthScope includes the acquisition of synthetic aperture radar (SAR) images, which are archived at the UNAVCO facility. Interferometric SAR complements the spatial and temporal coverage of GPS and allows monitoring of ground deformation in remote areas worldwide. However, because of the complex software required for processing, InSAR data are not readily accessible to most students. Even with these challenges, exposure at the undergraduate level is important for showing how geodesy can be applied in various areas of the geosciences and for promoting geodesy as a future career path. Here we present a module focused on exploring the tectonics of the western United States using InSAR data for use in undergraduate tectonics and geophysics classes. The module has two major objectives: address topics concerning tectonics in the western U.S. including Basin and Range extension, Yellowstone hotspot activity, and creep in southern California, and familiarize students with how imperfect real-world data can be manipulated and interpreted. Module questions promote critical thinking skills and data literacy by prompting students to use the information given to confront and question assumptions (e.g. 'Is there a consistency between seismic rates and permanent earthquake deformation? What other factors might need to be considered besides seismicity?'). The module consists of an introduction to the basics of InSAR and three student exercises, each focused on one of the topics listed above. Students analyze pre-processed InSAR data using MATLAB, or an Excel equivalent, and draw on GPS and

  15. First In-Orbit Experience of TerraSAR-X Flight Dynamics Operations

    NASA Technical Reports Server (NTRS)

    Kahle, R.; Kazeminejad, B.; Kirschner, M.; Yoon, Y.; Kiehling, R.; D'Amico, S.

    2007-01-01

    TerraSAR-X is an advanced synthetic aperture radar satellite system for scientific and commercial applications that is realized in a public-private partnership between the German Aerospace Center (DLR) and the Astrium GmbH. TerraSAR-X was launched at June 15, 2007 on top of a Russian DNEPR-1 rocket into a 514 km sun-synchronous dusk-dawn orbit with an 11-day repeat cycle and will be operated for a period of at least 5 years during which it will provide high resolution SAR-data in the X-band. Due to the objectives of the interferometric campaigns the satellite has to comply to tight orbit control requirements, which are formulated in the form of a 250 m toroidal tube around a pre-flight determined reference trajectory (see [1] for details). The acquisition of the reference orbit was one of the main and key activities during the Launch and Early Orbit Phase (LEOP) and had to compensate for both injection errors and spacecraft safe mode attitude control thruster activities. The paper summarizes the activities of GSOC flight dynamics team during both LEOP and early Commissioning Phase, where the main tasks have been 1) the first-acquisition support via angle-tracking and GPS-based orbit determination, 2) maneuver planning for target orbit acquisition and maintenance, and 3) precise orbit and attitude determination for SAR processing support. Furthermore, a presentation on the achieved results and encountered problems will be addressed.

  16. Monitoring dam structural health from space: Insights from novel InSAR techniques and multi-parametric modeling applied to the Pertusillo dam Basilicata, Italy

    NASA Astrophysics Data System (ADS)

    Milillo, Pietro; Perissin, Daniele; Salzer, Jacqueline T.; Lundgren, Paul; Lacava, Giusy; Milillo, Giovanni; Serio, Carmine

    2016-10-01

    The availability of new constellations of synthetic aperture radar (SAR) sensors is leading to important advances in infrastructure monitoring. These constellations offer the advantage of reduced revisit times, providing low-latency data that enable analysis that can identify infrastructure instability and dynamic deformation processes. In this paper we use COSMO-SkyMed (CSK) and TerraSAR-X (TSX) data to monitor seasonal induced deformation at the Pertusillo dam (Basilicata, Italy) using multi-temporal SAR data analysis. We analyzed 198 images spanning 2010-2015 using a coherent and incoherent PS approach to merge COSMO-SkyMed adjacent tracks and TerraSAR-X acquisitions, respectively. We used hydrostatic-seasonal-temporal (HST) and hydrostatic-temperature-temporal (HTT) models to interpret the non-linear deformation at the dam wall using ground measurements together with SAR time-series analysis. Different look geometries allowed us to characterize the horizontal deformation field typically observed at dams. Within the limits of our models and the SAR acquisition sampling we found that most of the deformation at the Pertusillo dam can be explained by taking into account only thermal seasonal dilation and hydrostatic pressure. The different models show slightly different results when interpreting the aging term at the dam wall. The results highlight how short-revisit SAR satellites in combination with models widely used in the literature for interpreting pendulum and GPS data can be used for supporting structural health monitoring and provide valuable information to ground users directly involved in field measurements.

  17. Investigating the backscatter contrast anomaly in synthetic aperture radar (SAR) imagery of the dunes along the Israel-Egypt border

    NASA Astrophysics Data System (ADS)

    Rozenstein, Offer; Siegal, Zehava; Blumberg, Dan G.; Adamowski, Jan

    2016-04-01

    The dune field intersected by the Israel-Egypt borderline has attracted many remote sensing studies over the years because it exhibits unique optical phenomena in several domains, from the visual to the thermal infrared. These phenomena are the result of land-use policies implemented by the two countries, which have differing effects on the two ecosystems. This study explores the surface properties that affect radar backscatter, namely the surface roughness and dielectric properties, in order to determine the cause for the variation across the border. The backscatter contrast was demonstrated for SIR-C, the first synthetic aperture radar (SAR) sensor to capture this phenomenon, as well as ASAR imagery that coincides with complementary ground observations. These field observations along the border, together with an aerial image from the same year as the SIR-C acquisition were used to analyze differences in vegetation patterns that can affect the surface roughness. The dielectric permittivity of two kinds of topsoil (sand, biocrust) was measured in the field and in the laboratory. The results suggest that the vegetation structure and spatial distribution differ between the two sides of the border in a manner that is consistent with the radar observations. The dielectric permittivity of sand and biocrust was found to be similar, although they are not constant across the radar spectral region (50 MHz-20 GHz). These findings support the hypothesis that changes to the vegetation, as a consequence of the different land-use practices in Israel and Egypt, are the cause for the radar backscatter contrast across the border.

  18. In-pixel conversion with a 10 bit SAR ADC for next generation X-ray FELs

    NASA Astrophysics Data System (ADS)

    Lodola, L.; Batignani, G.; Benkechkache, M. A.; Bettarini, S.; Casarosa, G.; Comotti, D.; Dalla Betta, G. F.; Fabris, L.; Forti, F.; Grassi, M.; Latreche, S.; Malcovati, P.; Manghisoni, M.; Mendicino, R.; Morsani, F.; Paladino, A.; Pancheri, L.; Paoloni, E.; Ratti, L.; Re, V.; Rizzo, G.; Traversi, G.; Vacchi, C.; Verzellesi, G.; Xu, H.

    2016-07-01

    This work presents the design of an interleaved Successive Approximation Register (SAR) ADC, part of the readout channel for the PixFEL detector. The PixFEL project aims at substantially advancing the state-of-the-art in the field of 2D X-ray imaging for applications at the next generation Free Electron Laser (FEL) facilities. For this purpose, the collaboration is developing the fundamental microelectronic building blocks for the readout channel. This work focuses on the design of the ADC carried out in a 65 nm CMOS technology. To obtain a good tradeoff between power consumption, conversion speed and area occupation, an interleaved SAR ADC architecture was adopted.

  19. The "Myth" of the Minimum SAR Antenna Area Constraint

    NASA Technical Reports Server (NTRS)

    Freeman, A.; Johnson, W. T. K.; Huneycutt, B.; Jordan, R.; Hensley, S.; Siqueira, P.; Curlander, J.

    1998-01-01

    A design constraint traceable ot the early days of spaceborne Synthetic Aperture Radar (SAR) is known as the minimum antenna area constraint for SAR. In this paper, it is confirmed that this constraint strictly applies only to the case where both the best possible resolution and the widest possible swath are the design goals. SAR antennas with area smaller than the constraint allows are shown to be possible, have been used on spaceborne SAR missions in the past, and should permit further, lower-cost SAR mission in the future.

  20. A New Design of Metamaterials for SAR Reduction

    NASA Astrophysics Data System (ADS)

    Faruque, M. R. I.; Islam, M. T.; Ali, M. A. M.

    2013-04-01

    The purpose of this paper is to calculate the reduction of specific absorption rate (SAR) with a new design of square metamaterials (SMMs). The finite-difference time-domain (FDTD) method with lossy-Drude model is adopted in this analysis. The method of SAR reduction is discussed and the effects of location, distance, and size of metamaterials are analyzed. SMMs have achieved a 53.06% reduction of the initial SAR value for the case of 10 gm SAR. These results put forward a guideline to select various types of metamaterials with the maximum SAR reducing effect for a cellular phone.

  1. Ambiguity noise analysis of a SAR system

    NASA Astrophysics Data System (ADS)

    Tian, Haishan; Chang, Wenge; Li, Xiangyang

    2015-12-01

    The presence of range and azimuth (or Doppler) ambiguities in synthetic aperture radars (SARs) is well known. The ambiguity noise is related to the antenna pattern and the value of pulse repetition frequency (PRF). Because a new frequency modulated continuous wave (FMCW) SAR has the characters of low cost and small size, and the capacity of real-time signal processing, the antenna will likely vibrate or deform due to a lack of the stabilized platform. And the value of PRF cannot be much high because of the high computation burden for the real-time processing. The aim of this study is to access and improve the performance of a new FMCW SAR system based on the ambiguity noise. First, the quantitative analysis of the system's ambiguity noise level is performed; an antenna with low sidelobes is designed. The conclusion is that the range ambiguity noise is small; the azimuth ambiguity noise is somewhat increased, however, it is sufficiently small to have marginal influence on the image quality. Finally, the ambiguity noise level is measured using the imaging data from a Ku-band FMCW SAR. The results of this study show that the measured noise level coincides with the theoretical noise level.

  2. Epidemic Models for SARS and Measles

    ERIC Educational Resources Information Center

    Rozema, Edward

    2007-01-01

    Recent events have led to an increased interest in emerging infectious diseases. This article applies various deterministic models to the SARS epidemic of 2003 and a measles outbreak in the Netherlands in 1999-2000. We take a historical approach beginning with the well-known logistic curve and a lesser-known extension popularized by Pearl and Reed…

  3. Acousto-Optical/Electronic Processor For SAR

    NASA Technical Reports Server (NTRS)

    Bicknell, T. J.; Farr, W. H.

    1992-01-01

    Lightweight, compact, low-power apparatus processes synthetic-aperture-radar (SAR) returns in real time, providing imagery aboard moving aircraft or spacecraft platform. Processor includes optical and electronic subsystems that, together, resolve range and azimuth coordinates of radar targets by combination of spatial and temporal integrations.

  4. SAR Image Despeckling Via Structural Sparse Representation

    NASA Astrophysics Data System (ADS)

    Lu, Ting; Li, Shutao; Fang, Leyuan; Benediktsson, Jón Atli

    2016-12-01

    A novel synthetic aperture radar (SAR) image despeckling method based on structural sparse representation is introduced. The proposed method utilizes the fact that different regions in SAR images correspond to varying terrain reflectivity. Therefore, SAR images can be split into a heterogeneous class (with a varied terrain reflectivity) and a homogeneous class (with a constant terrain reflectivity). In the proposed method, different sparse representation based despeckling schemes are designed by combining the different region characteristics in SAR images. For heterogeneous regions with rich structure and texture information, structural dictionaries are learned to appropriately represent varied structural characteristics. Specifically, each patch in these regions is sparsely coded with the best fitted structural dictionary, thus good structure preservation can be obtained. For homogenous regions without rich structure and texture information, the highly redundant photometric self-similarity is exploited to suppress speckle noise without introducing artifacts. That is achieved by firstly learning the sub-dictionary, then simultaneously sparsely coding for each group of photometrically similar image patches. Visual and objective experimental results demonstrate the superiority of the proposed method over the-state-of-the-art methods.

  5. The Seamless SAR Archive (SSARA) Project and Other SAR Activities at UNAVCO

    NASA Astrophysics Data System (ADS)

    Baker, S.; Crosby, C. J.; Meertens, C. M.; Fielding, E. J.; Bryson, G.; Buechler, B.; Nicoll, J.; Baru, C.

    2014-12-01

    The seamless synthetic aperture radar archive (SSARA) implements a seamless distributed access system for SAR data and derived data products (i.e. interferograms). SSARA provides a unified application programming interface (API) for SAR data search and results at the Alaska Satellite Facility and UNAVCO (WInSAR and EarthScope data archives) through the use of simple web services. A federated query service was developed using the unified APIs, providing users a single search interface for both archives. Interest from the international community has prompted an effort to incorporate ESA's Virtual Archive 4 Geohazard Supersites and Natural Laboratories (GSNL) collections and other archives into the federated query service. SSARA also provides Digital Elevation Model access for topographic correction via a simple web service through OpenTopography and tropospheric correction products through JPL's OSCAR service. Additionally, UNAVCO provides data storage capabilities for WInSAR PIs with approved TerraSAR-X and ALOS-2 proposals which allows easier distribution to US collaborators on associated proposals and facilitates data access through the SSARA web services. Further work is underway to incorporate federated data discovery for GSNL across SAR, GPS, and seismic datasets provided by web services from SSARA, GSAC, and COOPEUS.

  6. Modeling and a correlation algorithm for spaceborne SAR signals

    NASA Technical Reports Server (NTRS)

    Wu, C.; Liu, K. Y.; Jin, M.

    1982-01-01

    A mathematical model of a spaceborne synthetic aperture radar (SAR) response is presented. Thhe associated SAR system performance, in terms of the resolution capability, is also discussed. The analysis of spaceborne SAR target response indicates that the SAR correlation problem is a two-dimensional one with a linear shift-variant response function. A new digital processing algorithm is proposed here in order to realize an economical digital SAR correlation system. The proposed algorithm treats the two-dimensional correlation by a combination of frequency domain fast correlation in the azimuth dimension and a time-domain convolver type of operation in the range dimension. Finally, digitally correlated SEASAT satellite SAR imagery is used in an exemplary sense to validate the SAR response model and the new digital processing technique developed.

  7. Science Results from the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR): Progress Report

    NASA Technical Reports Server (NTRS)

    Evans, Diane L. (Editor); Plaut, Jeffrey (Editor)

    1996-01-01

    The Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) is the most advanced imaging radar system to fly in Earth orbit. Carried in the cargo bay of the Space Shuttle Endeavour in April and October of 1994, SIR-C/X-SAR simultaneously recorded SAR data at three wavelengths (L-, C-, and X-bands; 23.5, 5.8, and 3.1 cm, respectively). The SIR-C/X-SAR Science Team consists of 53 investigator teams from more than a dozen countries. Science investigations were undertaken in the fields of ecology, hydrology, ecology, and oceanography. This report contains 44 investigator team reports and several additional reports from coinvestigators and other researchers.

  8. Cassini RADAR's first SAR observations of Enceladus

    NASA Astrophysics Data System (ADS)

    Mitchell, K. L.; West, R. D.; Anderson, Y.; Team, T.

    2011-12-01

    On November 6th, 2011, Cassini RADAR will have its first opportunity to image a non-Titan icy world at close-range, including a 240 m resolution, 16 km wide Synthetic Aperture RADAR (SAR) swath of southern latitudes down to ~66° S. In addition, the spacecraft will obtain moderate resolution (~1-2 km) HiSAR and scatterometric scans for 2 northern hemisphere regions, and low resolution HiSAR & scatterometric scans (>2 km) of both inbound and outbound hemispheres in their entirety. Passive radiometry will also be obtained, co-spatial to the SAR swath at ~12 km resolution, as well as distant full disk observations. The fly-by in its entirely will provide near-global multi-layered products, massively enriching our remotely-sensed dataset for Enceladus. The goals are to: (1) Enrich our remotely-sensed coverage of Enceladus, providing a complementary imaging dataset that's sensitive to ~2.2-cm texture and dielectric properties, revealing previously undiscovered trends and anomalies; (2) Look for textural and compositional trends radial to the south polar sulci indicative of eruption processes; (3) Give moderate resolution radiometry at a wavelength complementary to CIRS to better characterize the thermal environment; (4) Provide a basis for comparison (limited "ground truth") with Titan imagery in an area covered by high resolution optical and thermal imagery; (5) Show how geology differs between Titan and Enceladus, giving insight into how Titan's geological and environmental peculiarities modulate surface landforms; and (6) Reveal surfaces with unusually high RADAR backscatter at similar resolutions to Titan SAR, to inform models of anomalously high backscatter surfaces on Titan (esp. Xanadu). We will present these observations and preliminary interpretations at the meeting, and discuss how they compare and contrast with previous optical and thermal data.

  9. BioSAR Airborne Biomass Sensing System

    SciTech Connect

    Graham, R.L.; Johnson, P.

    2007-05-24

    This CRADA was developed to enable ORNL to assist American Electronics, Inc. test a new technology--BioSAR. BioSAR is a an airborne, low frequency (80-120 MHz {approx} FM radio frequencies) synthetic aperture radar (SAR) technology which was designed and built for NASA by ZAI-Amelex under Patrick Johnson's direction. At these frequencies, leaves and small branches are nearly transparent and the majority of the energy reflected from the forest and returned to the radar is from the tree trunks. By measuring the magnitude of the back scatter, the volume of the tree trunk and therefore the biomass of the trunks can be inferred. The instrument was successfully tested on tropical rain forests in Panama. Patrick Johnson, with American Electronics, Inc received a Phase II SBIR grant from DOE Office of Climate Change to further test and refine the instrument. Mr Johnson sought ORNL expertise in measuring forest biomass in order for him to further validate his instrument. ORNL provided ground truth measurements of forest biomass at three locations--the Oak Ridge Reservation, Weyerhaeuser Co. commercial pine plantations in North Carolina, and American Energy and Power (AEP) Co. hardwood forests in southern Ohio, and facilitated flights over these forests. After Mr. Johnson processed the signal data from BioSAR instrument, the processed data were given to ORNL and we attempted to derive empirical relationships between the radar signals and the ground truth forest biomass measurements using standard statistical techniques. We were unsuccessful in deriving such relationships. Shortly before the CRADA ended, Mr Johnson discovered that FM signal from local radio station broadcasts had interfered with the back scatter measurements such that the bulk of the signal received by the BioSAR instrument was not backscatter from the radar but rather was local radio station signals.

  10. Analysis of Multipath Pixels in SAR Images

    NASA Astrophysics Data System (ADS)

    Zhao, J. W.; Wu, J. C.; Ding, X. L.; Zhang, L.; Hu, F. M.

    2016-06-01

    As the received radar signal is the sum of signal contributions overlaid in one single pixel regardless of the travel path, the multipath effect should be seriously tackled as the multiple bounce returns are added to direct scatter echoes which leads to ghost scatters. Most of the existing solution towards the multipath is to recover the signal propagation path. To facilitate the signal propagation simulation process, plenty of aspects such as sensor parameters, the geometry of the objects (shape, location, orientation, mutual position between adjacent buildings) and the physical parameters of the surface (roughness, correlation length, permittivity)which determine the strength of radar signal backscattered to the SAR sensor should be given in previous. However, it's not practical to obtain the highly detailed object model in unfamiliar area by field survey as it's a laborious work and time-consuming. In this paper, SAR imaging simulation based on RaySAR is conducted at first aiming at basic understanding of multipath effects and for further comparison. Besides of the pre-imaging simulation, the product of the after-imaging, which refers to radar images is also taken into consideration. Both Cosmo-SkyMed ascending and descending SAR images of Lupu Bridge in Shanghai are used for the experiment. As a result, the reflectivity map and signal distribution map of different bounce level are simulated and validated by 3D real model. The statistic indexes such as the phase stability, mean amplitude, amplitude dispersion, coherence and mean-sigma ratio in case of layover are analyzed with combination of the RaySAR output.

  11. Detecting slow moving targets in SAR images

    NASA Astrophysics Data System (ADS)

    Linnehan, Robert; Perlovsky, Leonid; Mutz, Chris W.; Schindler, John

    2004-08-01

    Ground moving target indication (GMTI) radars can detect slow-moving targets if their velocities are high enough to produce distinguishable Doppler frequencies. However, no reliable technique is currently available to detect targets that fall below the minimum detectable velocity (MDV) of GMTI radars. In synthetic aperture radar (SAR) images, detection of moving targets is difficult because of target smear due to motion, which could make low-RCS targets fall below stationary ground clutter. Several techniques for SAR imaging of moving targets have been discussed in the literature. These techniques require sufficient signal-to-clutter ratio (SCR) and adequate MDV for pre-detection. Other techniques require complex changes in hardware. Extracting the maximum information from SAR image data is possible using adaptive, model-based approaches. However, these approaches lead to computational complexity, which exceeds current processing power for more than a single object in an image. This combinatorial complexity is due to the need for having to consider a large number of combinations between multiple target models and the data, while estimating unknown parameters of the target models. We are developing a technique for detecting slow-moving targets in SAR images with low signal-to-clutter ratio, without minimal velocity requirements, and without combinatorial complexity. This paper briefly summarizes the difficulties related to current model-based detection algorithms. A new concept, dynamic logic, is introduced along with an algorithm suitable for the detection of very slow-moving targets in SAR images. This new mathematical technique is inspired by the analysis of biological systems, like the human brain, which combines conceptual understanding with emotional evaluation and overcomes the combinatorial complexity of model-based techniques.

  12. InSAR imagery pattern matching validation for landslide assessment

    NASA Astrophysics Data System (ADS)

    Serbulea, Manole-Stelian; Gogu, Radu; Teleaga, Delia; Marcel Manoli, Daniel; Priceputu, Adrian; Gaitanaru, Dragos Stefan; Ungureanu, Constantin; Anghel, Alexandra; Andronic, Adrian; Niculescu, Alexandru; Liviu Bugea, Adrian

    2013-04-01

    The need for identifying over large areas ongoing instability phenomena and spotting the old ones pushed the boundaries of geotechnical engineering from numerical modeling and point-wise in-situ measurements towards geodesic and geographic sciences. Regardless of the ground-based monitoring techniques' precision and reliability, a larger scale monitoring is often useful to either better correlate the scattered results or to identify additional monitoring points. Using aerial ortho-photogrammetry and site visit recognition represent a good, yet costly method to obtain qualitative information about old inactive landslides. A more suitable approach is using ground-based or satellite radar interferometry (InSAR). The obvious disadvantage of the ground-based system is that the monitoring has to be carried out on a predetermined site while the space-borne system may be set to collect information from various sites in range by each successive passing. The quantitative results acquired through the means of InSAR provide a precise set of information regarding the soil surface displacement, with high accuracy and reliability. They provide a great means of identifying danger zones as well as a way of calibrating and augmenting the classical monitoring techniques. This work describes the possibility of integrating the InSAR measurements with the ground monitoring techniques to identify landslide occurrence hazard and reveal the whole of affected areas even when minute symptoms develop. One of the objectives is to propose InSAR monitoring as a fast and efficient mapping tool to help authorities minimize the damage produced by landslides. It can also provide engineers and scientists additional information to further study landslides dynamics phenomena (such as propagation). Interferometry on SAR data uses phase values from two radar images. When a point changes position, the distance between it and the sensor alters, modifying the phase of the signal. This change is used to

  13. Answering the right question - integration of InSAR with other datasets

    NASA Astrophysics Data System (ADS)

    Holley, Rachel; McCormack, Harry; Burren, Richard

    2014-05-01

    The capabilities of satellite Interferometric Synthetic Aperture Radar (InSAR) are well known, and utilized across a wide range of academic and commercial applications. However there is a tendency, particularly in commercial applications, for users to ask 'What can we study with InSAR?'. When establishing a new technique this approach is important, but InSAR has been possible for 20 years now and, even accounting for new and innovative algorithms, this ground has been thoroughly explored. Too many studies conclude 'We show the ground is moving here, by this much', and mention the wider context as an afterthought. The focus needs to shift towards first asking the right questions - in fields as diverse as hazard awareness, resource optimization, financial considerations and pure scientific enquiry - and then working out how to achieve the best possible answers. Depending on the question, InSAR (and ground deformation more generally) may provide a large or small contribution to the overall solution, and there are usually benefits to integrating a number of techniques to capitalize on the complementary capabilities and provide the most useful measurements. However, there is still a gap between measurements and answers, and unlocking the value of the data relies heavily on appropriate visualization, integrated analysis, communication between technique and application experts, and appropriate use of modelling. We present a number of application examples, and demonstrate how their usefulness can be transformed by moving from a focus on data to answers - integrating complementary geodetic, geophysical and geological datasets and geophysical modeling with appropriate visualization, to enable comprehensive solution-focused interpretation. It will also discuss how forthcoming developments are likely to further advance realisation of the full potential satellite InSAR holds.

  14. Surface deformation analysis of the Istanbul (Turkey) city retrieved via the SBAS-DInSAR technique

    NASA Astrophysics Data System (ADS)

    Manzo, Mariarosaria; Lanari, Riccardo; Manconi, Andrea; Solaro, Giuseppe; Walter, Thomas R.; Zschau, Jochen

    2010-05-01

    Remote sensing techniques make possible to collect information on dangerous or inaccessible areas. In this context, space-based geodetic techniques as Differential SAR Interferometry (DInSAR) have been used in several areas in order to obtain co-seismic surface deformation maps in a few days or even hours following large earthquakes. The retrieved surface deformation can be used to constrain analytical and/or numerical models to derive parameters such as depth, dimension, orientation, and slip occurred on the fault plane. Moreover, advanced DInSAR techniques allow observing the temporal evolution of the surface displacements, and are thus able to furnish a picture of the pre-seismic state as well as of the post-seismic effects. In this work, we present DInSAR analyses of the deformation patterns in areas that are affected by seismic hazard. In particular, we focus on ground displacements occurred in the greater city area of Istanbul (Turkey) in the last 17 years. To this aim, we exploited the advanced DInSAR algorithm, referred to as Small BAseline Subset (SBAS) technique (Berardino et al., 2002). Displacement time series are retrieved from data acquired by the ERS-1/2 and ENVISAT (Pepe et al., 2005) satellites of the European Space Agency (ESA) between 1992 and 2009. First, we show the results of an analysis carried out at a spatial resolution of about 100 x 100 m. This shows, in addition to the co-seismic displacement caused by the Izmit earthquake (17 August 1999) and associated events, several areas that are subject to subsidence (often in excess of 10 cm per decade) within the city of Istanbul. Moreover, in selected case studies, we further exploited localized phenomena by "zooming" in the areas of interest and carrying out analyses at full spatial resolution scale (10 x 10 m) (Lanari et al., 2004). This additional effort allowed us to discriminate among deformation phenomena occurring at regional and at the building scale. This study provides an updated

  15. Sinking Chao Phraya delta plain, Thailand, derived from SAR interferometry time series analysis

    NASA Astrophysics Data System (ADS)

    Tanaka, A.; Mio, A.; Saito, Y.

    2013-12-01

    The Bangkok Metropolitan region and its surrounding provinces are located in a low-lying delta plain of the Chao Phraya River. Extensive groundwater use from the late 1950s has caused the decline of groundwater levels in the aquifers and Holocene clay compaction beneath the Bangkok Region, resulting in significant subsidence of the ground. This ground deformation has been monitored using leveling surveys since 1978, and differential InSAR (Interferometric Synthetic Aperture Radar) analysis. It shows that the Bangkok Metropolitan region is subsiding at a rate of about 20 mm/year during the recent years due to law-limited groundwater pumping, although the highest subsidence rate as high as 120 mm/year was recorded in 1981. The subsidence rate in the Bangkok area has significantly decreased since the late 1980s; however, the affected area has spread out to the surrounding areas. The maximum subsidence rate up to 30 mm/year occurred in the outlying southeast and southwest coastal zones in 2002. In this study, we apply a SAR interferometry time series analysis to monitor ground deformations in the lower Chao Phraya delta plain (Lower Central Plain), Thailand, using ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array type L-band SAR) data acquired between July 2007 and September 2010. We derive a single reference time series interferogram from the stacking of unwrapped phases under the assumptions that those phases are smoothly and continuously connected, and apply a smoothness-constrained inversion algorithm that optimizes the displacement from the phase unwrapping of multitemporal differential SAR interferograms. The SAR interferometry time series analysis succeeds to monitor the incremental line-of-sight (LOS)-change between SAR scene acquisitions. LOS displacements are converted to vertical displacements, based on the assumption that the ground displacement in this area occurs only in the vertical directions. This reveals an overall pattern of subsidence

  16. Characterizing and estimating noise in InSAR and InSAR time series with MODIS

    USGS Publications Warehouse

    Barnhart, William D.; Lohman, Rowena B.

    2013-01-01

    InSAR time series analysis is increasingly used to image subcentimeter displacement rates of the ground surface. The precision of InSAR observations is often affected by several noise sources, including spatially correlated noise from the turbulent atmosphere. Under ideal scenarios, InSAR time series techniques can substantially mitigate these effects; however, in practice the temporal distribution of InSAR acquisitions over much of the world exhibit seasonal biases, long temporal gaps, and insufficient acquisitions to confidently obtain the precisions desired for tectonic research. Here, we introduce a technique for constraining the magnitude of errors expected from atmospheric phase delays on the ground displacement rates inferred from an InSAR time series using independent observations of precipitable water vapor from MODIS. We implement a Monte Carlo error estimation technique based on multiple (100+) MODIS-based time series that sample date ranges close to the acquisitions times of the available SAR imagery. This stochastic approach allows evaluation of the significance of signals present in the final time series product, in particular their correlation with topography and seasonality. We find that topographically correlated noise in individual interferograms is not spatially stationary, even over short-spatial scales (<10 km). Overall, MODIS-inferred displacements and velocities exhibit errors of similar magnitude to the variability within an InSAR time series. We examine the MODIS-based confidence bounds in regions with a range of inferred displacement rates, and find we are capable of resolving velocities as low as 1.5 mm/yr with uncertainties increasing to ∼6 mm/yr in regions with higher topographic relief.

  17. Antiviral drug discovery against SARS-CoV.

    PubMed

    Wu, Yu-Shan; Lin, Wen-Hsing; Hsu, John T-A; Hsieh, Hsing-Pang

    2006-01-01

    Severe Acute Respiratory Syndrome (SARS) is a life-threatening infectious disease caused by SARS-CoV. In the 2003 outbreak, it infected more than 8,000 people worldwide and claimed the lives of more than 900 victims. The high mortality rate resulted, at least in part, from the absence of definitive treatment protocols or therapeutic agents. Although the virus spreading has been contained, due preparedness and planning, including the successful development of antiviral drugs against SARS-CoV, is necessary for possible reappearance of SARS. In this review, we have discussed currently available strategies for antiviral drug discovery and how these technologies have been utilized to identify potential antiviral agents for the inhibition of SARS-CoV replication. Moreover, progress in the drug development based on different molecular targets is also summarized, including 1) Compounds that block the S protein-ACE2-mediated viral entry; 2) Compounds targeting SARS-CoV M(pro); 3) Compounds targeting papain-like protease 2 (PLP2); 4) Compounds targeting SARS-CoV RdRp; 5) Compounds targeting SARS-CoV helicase; 6) Active compounds with unspecified targets; and 7) Research on siRNA. This review aims to provide a comprehensive account of drug discovery on SARS. The experiences with the SARS outbreak and drug discovery would certainly be an important lesson for the drug development for any new viral outbreaks that may emerge in the future.

  18. Synergistic measurements of ocean winds and waves from SAR

    NASA Astrophysics Data System (ADS)

    Zhang, Biao; Li, Xiaofeng; Perrie, William; He, Yijun

    2015-09-01

    In this study we present a synergistic method to retrieve both ocean surface wave and wind fields from spaceborne quad-polarization (QP) synthetic aperture radar (SAR) imaging mode data. This algorithm integrates QP-SAR wind vector retrieval model and the wave retrieval model, with consideration to the nonlinear mapping relationship between ocean wave spectra and SAR image spectra, in order to synergistically retrieve wind fields and wave directional spectra. The method does not require a priori information on the sea state. It combines the observed VV-polarized SAR image spectra with the retrieved wind vectors from the VH-polarized SAR image, to estimate the wind-generated wave directional spectra. The differences between the observed SAR spectra and optimal SAR image spectra associated with the wind waves are interpreted as the contributions from the swell waves. The retrieved ocean wave spectra are used to estimate the integrated spectral wave parameters such as significant wave heights, wavelengths, wave directions and wave periods. The wind and wave parameters retrieved by QP-SAR are validated against those measured by the National Data Buoy Center (NDBC) directional wave buoys under different sea states. The validation results show that the QP-SAR SAR has potential to simultaneously measure the ocean surface waves and wind fields from space.

  19. Simulation of SAR backscatter for forest vegetation

    NASA Astrophysics Data System (ADS)

    Prajapati, Richa; Kumar, Shashi; Agrawal, Shefali

    2016-05-01

    Synthetic Aperture Radar (SAR) is one of the most recent imaging technology to study the forest parameters. The invincible characteristics of microwave acquisition in cloudy regions and night imaging makes it a powerful tool to study dense forest regions. A coherent combination of radar polarimetry and interferometry (PolInSAR) enhances the accuracy of retrieved biophysical parameters. This paper attempts to address the issue of estimation of forest structural information caused due to instability of radar platforms through simulation of SAR image. The Terai Central Forest region situated at Haldwani area in Uttarakhand state of India was chosen as the study area. The system characteristics of PolInSAR dataset of Radarsat-2 SAR sensor was used for simulation process. Geometric and system specifications like platform altitude, center frequency, mean incidence angle, azimuth and range resolution were taken from metadata. From the field data it was observed that average tree height and forest stand density were 25 m and 300 stems/ha respectively. The obtained simulated results were compared with the sensor acquired master and slave intensity images. It was analyzed that for co-polarized horizontal component (HH), the mean values of simulated and real master image had a difference of 0.3645 with standard deviation of 0.63. Cross-polarized (HV) channel showed better results with mean difference of 0.06 and standard deviation of 0.1 while co-polarized vertical component (VV) did not show similar values. In case of HV polarization, mean variation between simulated and real slave images was found to be the least. Since cross-polarized channel is more sensitive to vegetation feature therefore better simulated results were obtained for this channel. Further the simulated images were processed using PolInSAR inversion modelling approach using three different techniques DEM differencing, Coherence Amplitude Inversion and Random Volume over Ground Inversion. DEM differencing

  20. Development of an array-antenna GPR system (SAR-GPR)

    NASA Astrophysics Data System (ADS)

    Sato, Motoyuki; Feng, Xuan; Kobayashi, Takao; Zhou, Zheng-Shu; Savelyev, Timofei G.; Fujiwara, Jun

    2005-06-01

    SAR-GPR is a sensor system composed of a GPR and a metal detector for landmine detection. The GPR employs an array antenna for advanced signal processing for better subsurface imaging. This system combined with synthetic aperture radar algorithm, can suppress clutter and can image buried objects in strongly inhomogeneous material. SAR-GPR is a stepped frequency radar system, whose RF component is a newly developed compact vector network analyzers. The size of the system is 30cm x 30cm x 30cm, composed from 6 Vivaldi antennas and 3 vector network analyzers. The weight of the system is less than 30kg, and it can be mounted on a robotic arm on a small unmanned vehicle. The field test of this system was carried out in March 2005 in Japan, and some results on this test are reported.

  1. Calibration of 2D Hydraulic Inundation Models with SAR Imagery in the Floodplain Region of the Lower Tagus River

    NASA Astrophysics Data System (ADS)

    Pestana, Rita; Matias, Magda; Canelas, Ricardo; Roque, Dora; Araujo, Amelia; Van Zeller, Emilia; Trigo-Teixeira, Antonio; Ferreira, Rui; Oliveira, Rodrigo; Heleno, Sandra; Falcão, Ana Paula; Gonçalves, Alexandre B.

    2014-05-01

    for the different land cover classes. Flood extent maps, derived from satellite-born Synthetic Aperture Radar (SAR), namely ERS SAR and ENVISAT ASAR imagery, provided the spatially distributed data needed for the calibration of the hydraulic models for the several floods. The flood extent maps obtained for each simulation were then compared with the flood extent maps derived from SAR imagery for each flood and the roughness coefficients changed accordingly. The models were also calibrated in terms of the stage at the gauging station Almourol, located 12km downriver from Tramagal. The combination of the calibration results for the several past floods provided 100 meters resolution Manning coefficient maps of the study area. An application of the obtained calibrated Manning coefficient maps was made for the largest flood of the 20th century (February 1979), for which no SAR imagery was available. In this case validation of the model was made in terms of the stage at the gauging station Almourol and at flood stage marks distributed throughout the floodplain.

  2. Operational SAR Data Processing in GIS Environments for Rapid Disaster Mapping

    NASA Astrophysics Data System (ADS)

    Bahr, Thomas

    2014-05-01

    The use of SAR data has become increasingly popular in recent years and in a wide array of industries. Having access to SAR can be highly important and critical especially for public safety. Updating a GIS with contemporary information from SAR data allows to deliver a reliable set of geospatial information to advance civilian operations, e.g. search and rescue missions. SAR imaging offers the great advantage, over its optical counterparts, of not being affected by darkness, meteorological conditions such as clouds, fog, etc., or smoke and dust, frequently associated with disaster zones. In this paper we present the operational processing of SAR data within a GIS environment for rapid disaster mapping. For this technique we integrated the SARscape modules for ENVI with ArcGIS®, eliminating the need to switch between software packages. Thereby the premier algorithms for SAR image analysis can be directly accessed from ArcGIS desktop and server environments. They allow processing and analyzing SAR data in almost real time and with minimum user interaction. This is exemplified by the November 2010 flash flood in the Veneto region, Italy. The Bacchiglione River burst its banks on Nov. 2nd after two days of heavy rainfall throughout the northern Italian region. The community of Bovolenta, 22 km SSE of Padova, was covered by several meters of water. People were requested to stay in their homes; several roads, highways sections and railroads had to be closed. The extent of this flooding is documented by a series of Cosmo-SkyMed acquisitions with a GSD of 2.5 m (StripMap mode). Cosmo-SkyMed is a constellation of four Earth observation satellites, allowing a very frequent coverage, which enables monitoring using a very high temporal resolution. This data is processed in ArcGIS using a single-sensor, multi-mode, multi-temporal approach consisting of 3 steps: (1) The single images are filtered with a Gamma DE-MAP filter. (2) The filtered images are geocoded using a reference

  3. Using APES for interferometric SAR imaging.

    PubMed

    Palsetia, M R; Li, J

    1998-01-01

    We present an adaptive finite impulse response (FIR) filtering approach, which is referred to as the Amplitude and Phase EStimation (APES) algorithm, for interferometric synthetic aperture radar (SAR) imaging. We compare the APES algorithm with other FIR filtering approaches including the Capon and fast Fourier transform (FFT) methods. We show via both numerical and experimental examples that the adaptive FIR filtering approaches such as Capon and APES can yield more accurate spectral estimates with much lower sidelobes and narrower spectral peaks than the FFT method. We show that although the APES algorithm yields somewhat wider spectral peaks than the Capon method, the former gives more accurate overall spectral estimates and SAR images than the latter and the FFT method.

  4. Non-parametric partitioning of SAR images

    NASA Astrophysics Data System (ADS)

    Delyon, G.; Galland, F.; Réfrégier, Ph.

    2006-09-01

    We describe and analyse a generalization of a parametric segmentation technique adapted to Gamma distributed SAR images to a simple non parametric noise model. The partition is obtained by minimizing the stochastic complexity of a quantized version on Q levels of the SAR image and lead to a criterion without parameters to be tuned by the user. We analyse the reliability of the proposed approach on synthetic images. The quality of the obtained partition will be studied for different possible strategies. In particular, one will discuss the reliability of the proposed optimization procedure. Finally, we will precisely study the performance of the proposed approach in comparison with the statistical parametric technique adapted to Gamma noise. These studies will be led by analyzing the number of misclassified pixels, the standard Hausdorff distance and the number of estimated regions.

  5. SAR observations in the Gulf of Mexico

    NASA Technical Reports Server (NTRS)

    Sheres, David

    1992-01-01

    The Gulf of Mexico (GOM) exhibits a wealth of energetic ocean features; they include the Loop Current with velocities of about 2 m/s and strong shear fronts, mesoscale eddies, double vortices, internal waves, and the outflow of the 'Mighty Mississippi' river. These energetic features can have a strong impact on the economies of the states surrounding the Gulf. Large fisheries, oil and gas production as well as pollution transport are relevant issues. These circulation features in the Gulf are invisible to conventional IR and visible satellite imagery during the Summer months due to cloud cover and uniform surface temperatures. Synthetic Aperture Radar (SAR) imagery of the Gulf does penetrate the cloud cover and shows a rich assembly of features there year-round. Below are preliminary results from GOM SAR imagery taken by SEASAT in 1978 and by the AIRSAR program in 1991.

  6. Joint enhancement of multichannel SAR data

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, Naveen; Ertin, Emre; Moses, Randolph L.

    2007-04-01

    In this paper we consider the problem of joint enhancement of multichannel Synthetic Aperture Radar (SAR) data. Previous work by Cetin and Karl introduced nonquadratic regularization methods for image enhancement using sparsity enforcing penalty terms. For multichannel data, independent enhancement of each channel is shown to degrade the relative phase information across channels that is useful for 3D reconstruction. We thus propose a method for joint enhancement of multichannel SAR data with joint sparsity constraints. We develop both a gradient-based and a Lagrange-Newton-based method for solving the joint reconstruction problem, and demonstrate the performance of the proposed methods on IFSAR height extraction problem from multi-elevation data.

  7. SAR impulse response with residual chirps.

    SciTech Connect

    Doerry, Armin Walter

    2009-06-01

    A Linear Frequency-Modulated (LFM) chirp is a function with unit amplitude and quadratic phase characteristic. In a focused Synthetic Aperture Radar (SAR) image, a residual chirp is undesired for targets of interest, as it coarsens the manifested resolution. However, for undesired spurious signals, a residual chirp is often advantageous because it spreads the energy and thereby diminishes its peak value. In either case, a good understanding of the effects of a residual LFM chirp on a SAR Impulse Response (IPR) is required to facilitate system analysis and design. This report presents an analysis of the effects of a residual chirp on the IPR. As reference, there is a rich body of publications on various aspects of LFM chirps. A quick search reveals a plethora of articles, going back to the early 1950s. We mention here purely as trivia one of the earlier analysis papers on this waveform by Klauder, et al.

  8. Utilization of spaceborne SAR data for mapping

    NASA Technical Reports Server (NTRS)

    Curlander, J. C.

    1984-01-01

    Recent developments in automated processing of digital SEASAT SAR imagery have made feasible the generation of large-scale high-resolution maps. Standard preprocessing of raw data into digital images results in geometrically distorted imagery. Computer algorithms have been developed for unsupervised pixel location, geometric rectification, and mosaicking of multiple-image frames without ground control points. These algorithms utilize knowledge of the spacecraft trajectory data, the imaging geometry, and the coherent properties of the sensor to generate the required processing parameters. This paper discusses the advantages as well as the inherent limitations of this technique, analyzes the associated errors, and presents results using SEASAT SAR imagery. Also discussed are the results of the recent shuttle imaging radar (SIR-A) experiment as well as a follow-on experiment (SIR-B) planned for 1984.

  9. Automated preprocessing of spaceborne SAR data

    NASA Technical Reports Server (NTRS)

    Curlander, J. C.; Wu, C.; Pang, A.

    1982-01-01

    An efficient algorithm has been developed for estimation of the echo phase delay in spaceborne synthetic aperture radar (SAR) data. This algorithm utilizes the spacecraft ephemeris data and the radar echo data to produce estimates of two parameters: (1) the centroid of the Doppler frequency spectrum f(d) and (2) the Doppler frequency rate. Results are presented from tests conducted with Seasat SAR data. The test data indicates that estimation accuracies of 3 Hz for f(d) and 0.3 Hz/sec for the Doppler frequency rate are attainable. The clutterlock and autofocus techniques used for estimation of f(d) and the Doppler frequency rate, respectively are discussed and the algorithm developed for optimal implementation of these techniques is presented.

  10. Snow and glacier mapping with polarimetric SAR

    NASA Technical Reports Server (NTRS)

    Shi, Jiancheng; Dozier, Jeff; Rott, Helmut; Davis, Robert E.

    1991-01-01

    The objective of this study was to examine the capability of mapping snow and glaciers in alpine regions using synthetic aperture radar (SAR) imagery when topographic information is not available. The topographic effects on the received power for a resolution cell can be explained by the change in illumination area and incidence angle in a slant-rante representation of SAR imagery. The specific polarization signatures and phase difference between HH and VV components are relatively independent of the illuminated are, and the incidence angle has only a small effect on these parameters. They provide a suitable measurement data set for snow and glacier mapping in a high-relief area. The results show that the C-band images of the enhancement factor, the phase difference between HH and VV scattering components, and the normalized cross product of VV scattering elements provide the capability to discriminate among snow with different wetnesses, glaciers, and rocky regions.

  11. Animal models for SARS and MERS coronaviruses

    PubMed Central

    Gretebeck, Lisa M; Subbarao, Kanta

    2015-01-01

    The emergence of Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) and Middle East Respiratory Syndrome coronavirus (MERS-CoV), two strains of animal coronaviruses that crossed the species barrier to infect and cause severe respiratory infections in humans within the last 12 years, have taught us that coronaviruses represent a global threat that does not recognize international borders. We can expect to see other novel coronaviruses emerge in the future. An ideal animal model should reflect the clinical signs, viral replication and pathology seen in humans. In this review, we present factors to consider in establishing an animal model for the study of novel coronaviruses and compare the different animal models that have been employed to study SARS-CoV and MERS-CoV. PMID:26184451

  12. Sentinel-1 DInSAR processing chain within Geohazard Exploitation Platform

    NASA Astrophysics Data System (ADS)

    Zinno, Ivana; Bonano, Manuela; Buonanno, Sabatino; Casu, Francesco; De Luca, Claudio; Fusco, Adele; Lanari, Riccardo; Manunta, Michele; Manzo, Mariarosaria; Ojha, Chandrakanta; Pepe, Antonio

    2016-04-01

    The Sentinel-1A (S1A) satellite has been launched on April 2014 to acquire SAR data in continuity with the ERS-1/2 and ENVISAT missions. It presents advanced characteristics in terms of revisit time, spatial coverage and service reliability. Such a satellite will be paired during 2016 with the Sentinel-1B twin system that will reduce the constellation revisit time from 12 to 6 days. Accordingly, a huge and ever-increasing data flow relevant to extended areas on Earth will be delivered with a "free and open access" data policy. The S1-A sensor is equipped with a C-band SAR instrument that is conceived for interferometric applications, thus allowing us to analyze Earth's surface displacements through the Differential SAR Interferometry (DInSAR) technique. In particular, S1A SAR data are collected through the Terrain Observation by Progressive Scans (TOPS) mode, which generates Interferometric Wide Swath (IWS) acquisitions. To properly handle S1A TOPS data, the existing DInSAR processing chains have to be adapted with new procedures, which properly take into account the characteristics of this new acquisition mode. Furthermore, another critical point to be taken into account in designing a S1A DInSAR processing chain is the achievement of a good computational efficiency. Indeed, the capability to process in reduced time frames the huge data stream expected by S1A (and, very soon, also by S1B) is a key aspect to fully exploit S1 data archives. In this work we present an efficient interferometric processing chain, based on the advanced DInSAR algorithm referred to as Parallel Small BAseline Subset (P-SBAS), for the generation of S1A IWS surface deformation time-series. It ingests the Single Look Complex data and generates, in unsupervised way, interferograms and displacement time-series. This processing chain is able to exploit distributed computing architectures taking advantage of both multi-node and multi-threading programming techniques. The proposed S1A P

  13. Interferometric SAR coherence classification utility assessment

    SciTech Connect

    Yocky, D.A.

    1998-03-01

    The classification utility of a dual-antenna interferometric synthetic aperture radar (IFSAR) is explored by comparison of maximum likelihood classification results for synthetic aperture radar (SAR) intensity images and IPSAR intensity and coherence images. The addition of IFSAR coherence improves the overall classification accuracy for classes of trees, water, and fields. A threshold intensity-coherence classifier is also compared to the intensity-only classification results.

  14. Alaska SAR Facility mass storage, current system

    NASA Technical Reports Server (NTRS)

    Cuddy, David; Chu, Eugene; Bicknell, Tom

    1993-01-01

    This paper examines the mass storage systems that are currently in place at the Alaska SAR Facility (SAF). The architecture of the facility will be presented including specifications of the mass storage media that are currently used and the performances that we have realized from the various media. The distribution formats and media are also discussed. Because the facility is expected to service future sensors, the new requirements and possible solutions to these requirements are also discussed.

  15. Processing of polarametric SAR images. Final report

    SciTech Connect

    Warrick, A.L.; Delaney, P.A.

    1995-09-01

    The objective of this work was to develop a systematic method of combining multifrequency polarized SAR images. It is shown that the traditional methods of correlation, hard targets, and template matching fail to produce acceptable results. Hence, a new algorithm was developed and tested. The new approach combines the three traditional methods and an interpolation method. An example is shown that demonstrates the new algorithms performance. The results are summarized suggestions for future research are presented.

  16. A 3-D SAR approach to IFSAR processing

    SciTech Connect

    DOERRY,ARMIN W.; BICKEL,DOUGLAS L.

    2000-03-01

    Interferometric SAR (IFSAR) can be shown to be a special case of 3-D SAR image formation. In fact, traditional IFSAR processing results in the equivalent of merely a super-resolved, under-sampled, 3-D SAR image. However, when approached as a 3-D SAR problem, a number of IFSAR properties and anomalies are easily explained. For example, IFSAR decorrelation with height is merely ordinary migration in 3-D SAR. Consequently, treating IFSAR as a 3-D SAR problem allows insight and development of proper motion compensation techniques and image formation operations to facilitate optimal height estimation. Furthermore, multiple antenna phase centers and baselines are easily incorporated into this formulation, providing essentially a sparse array in the elevation dimension. This paper shows the Polar Format image formation algorithm extended to 3 dimensions, and then proceeds to apply it to the IFSAR collection geometry. This suggests a more optimal reordering of the traditional IFSAR processing steps.

  17. SAR11 bacteria linked to ocean anoxia and nitrogen loss.

    PubMed

    Tsementzi, Despina; Wu, Jieying; Deutsch, Samuel; Nath, Sangeeta; Rodriguez-R, Luis M; Burns, Andrew S; Ranjan, Piyush; Sarode, Neha; Malmstrom, Rex R; Padilla, Cory C; Stone, Benjamin K; Bristow, Laura A; Larsen, Morten; Glass, Jennifer B; Thamdrup, Bo; Woyke, Tanja; Konstantinidis, Konstantinos T; Stewart, Frank J

    2016-08-11

    Bacteria of the SAR11 clade constitute up to one half of all microbial cells in the oxygen-rich surface ocean. SAR11 bacteria are also abundant in oxygen minimum zones (OMZs), where oxygen falls below detection and anaerobic microbes have vital roles in converting bioavailable nitrogen to N2 gas. Anaerobic metabolism has not yet been observed in SAR11, and it remains unknown how these bacteria contribute to OMZ biogeochemical cycling. Here, genomic analysis of single cells from the world's largest OMZ revealed previously uncharacterized SAR11 lineages with adaptations for life without oxygen, including genes for respiratory nitrate reductases (Nar). SAR11 nar genes were experimentally verified to encode proteins catalysing the nitrite-producing first step of denitrification and constituted ~40% of OMZ nar transcripts, with transcription peaking in the anoxic zone of maximum nitrate reduction activity. These results link SAR11 to pathways of ocean nitrogen loss, redefining the ecological niche of Earth's most abundant organismal group.

  18. Formation geometries for multistatic SAR tomography

    NASA Astrophysics Data System (ADS)

    Fasano, Giancarmine; Renga, Alfredo; D'Errico, Marco

    2014-03-01

    This paper analyzes relative orbit design for multi-satellite radar missions aimed at multistatic SAR tomography. To this end, formation requirements and performance parameters are derived by adapting existing models for SAR tomography to single pass techniques. Then, relative trajectory design is carried out on the basis of an analytical relative motion model including secular J2 effects. By properly scaling the differences in orbital parameters, different formation geometries enable uniform sampling of the effective baseline along the whole orbit. The difference among the possible choices lies in latitude coverage, formation stability, and collision avoidance aspects. A numerical example of relative trajectory design is discussed considering L-band as operating frequency. In particular, achievable height resolution and unambiguous height along the orbit are pointed out for a multi-cartwheel, a multi-pendulum, and a multi-helix formation. In view of future implementation of a multi-satellite SAR tomography mission, new concepts aimed at the reduction of required satellites, and long term evolution of designed formations, are also discussed.

  19. The InSAR Scientific Computing Environment

    NASA Technical Reports Server (NTRS)

    Rosen, Paul A.; Gurrola, Eric; Sacco, Gian Franco; Zebker, Howard

    2012-01-01

    We have developed a flexible and extensible Interferometric SAR (InSAR) Scientific Computing Environment (ISCE) for geodetic image processing. ISCE was designed from the ground up as a geophysics community tool for generating stacks of interferograms that lend themselves to various forms of time-series analysis, with attention paid to accuracy, extensibility, and modularity. The framework is python-based, with code elements rigorously componentized by separating input/output operations from the processing engines. This allows greater flexibility and extensibility in the data models, and creates algorithmic code that is less susceptible to unnecessary modification when new data types and sensors are available. In addition, the components support provenance and checkpointing to facilitate reprocessing and algorithm exploration. The algorithms, based on legacy processing codes, have been adapted to assume a common reference track approach for all images acquired from nearby orbits, simplifying and systematizing the geometry for time-series analysis. The framework is designed to easily allow user contributions, and is distributed for free use by researchers. ISCE can process data from the ALOS, ERS, EnviSAT, Cosmo-SkyMed, RadarSAT-1, RadarSAT-2, and TerraSAR-X platforms, starting from Level-0 or Level 1 as provided from the data source, and going as far as Level 3 geocoded deformation products. With its flexible design, it can be extended with raw/meta data parsers to enable it to work with radar data from other platforms

  20. Using APES for interferometric SAR imaging

    NASA Astrophysics Data System (ADS)

    Li, Jian; Palsetia, Marzban

    1996-06-01

    In this paper, we present an adaptive FIR filtering approach, which is referred to as the APES (amplitude and phase estimation of a sinusoid) algorithm, for interferometric SAR imaging. We apply the APES algorithm on the data obtained from two vertically displaced apertures of a SAR system to obtain the complex amplitude and the phase difference estimates, which are proportional to the radar cross section and the height of the scatterer, respectively, at the frequencies of interest. We also demonstrate how the APES algorithm can be applied to data matrices with large dimensions without incurring high computational overheads. We compare the APES algorithm with other FIR filtering approaches including the Capon and FFT methods. We show via both numerical and experimental examples that the adaptive FIR filtering approaches such as Capon and APES can yield more accurate spectral estimates with much lower sidelobes and narrower spectral peaks than the FFT method. We show that although the APES algorithm yields somewhat wider spectral peaks than the Capon method, the former gives more accurate overall spectral estimates and SAR images than the latter and the FFT method.

  1. Forming rotated SAR images by real-time motion compensation.

    SciTech Connect

    Doerry, Armin Walter

    2012-12-01

    Proper waveform parameter selection allows collecting Synthetic Aperture Radar (SAR) phase history data on a rotated grid in the Fourier Space of the scene being imaged. Subsequent image formation preserves the rotated geometry to allow SAR images to be formed at arbitrary rotation angles without the use of computationally expensive interpolation or resampling operations. This should be useful where control of image orientation is desired such as generating squinted stripmaps and VideoSAR applications, among others.

  2. Control Measures for Severe Acute Respiratory Syndrome (SARS) in Taiwan

    PubMed Central

    Twu, Shiing-Jer; Chen, Tzay-Jinn; Chen, Chien-Jen; Olsen, Sonja J.; Lee, Long-Teng; Fisk, Tamara; Hsu, Kwo-Hsiung; Chang, Shan-Chwen; Chen, Kow-Tong; Chiang, I-Hsin; Wu, Yi-Chun; Wu, Jiunn-Shyan

    2003-01-01

    As of April 14, 2003, Taiwan had had 23 probable cases of severe acute respiratory syndrome (SARS), all imported. Taiwan isolated these first 23 patients with probable SARS in negative-pressure rooms; extensive personal protective equipment was used for healthcare workers and visitors. For the first 6 weeks of the SARS outbreak, recognized spread was limited to one healthcare worker and three household contacts. PMID:12781013

  3. Interseismic deformation of the Central Tibetan Plateau measured using InSAR

    NASA Astrophysics Data System (ADS)

    Garthwaite, M. C.; Wright, T. J.

    2009-12-01

    Contrasting models have been proposed to describe the ongoing deformation of the Tibetan plateau as a result of the shortening imposed by the India-Asia Collision. One extreme involves rigid rotations of coherent blocks bounded by major faults which penetrate the entire lithosphere. The rigidity of each block implies that there is minimal internal deformation. This description implies relatively high slip rates on block bounding faults separated by narrow shear zones. In the alternative extreme, the bulk continental lithosphere is considered to deform continuously as a viscous fluid. Deformation in the brittle upper crust is driven by tractions imparted on its base from the viscous layer beneath, and distributed on a large number of shallow faults throughout the deforming zone. As a result, slip rates on faults are lower, and the number of discrete crustal blocks is larger. Geodetic observations of interseismic deformation around locked faults often show concentrated strain. If crustal blocks are separated by distances less than or equal to the locking depth (i.e. many small blocks), their straining zones will merge together. If a few large blocks exist, their strain zones should be distinct. There are very few GPS measurements of surface velocity in the plateau interior, therefore it has been difficult to verify either of the proposed models. Interferometric synthetic aperture radar (InSAR) is a powerful technique which dramatically increases the spatial density of velocity measurements. By combining multiple interferograms, interseismic strain can be measured using InSAR with an accuracy of approximately 6 millimetres per year (Wang et. al. GRL, 2009). We use 32 Envisat ASAR images acquired between 2003 and 2009 on descending track 176 in the plateau centre. The swath length of ~1500 km spans the entire plateau including the four major east-west trending strike-slip faults of Tibet - the Altyn Tagh, Kunlun, Jiali, and Xianshuihe. Interferograms are processed

  4. Geometric registration and rectification of spaceborne SAR imagery

    NASA Technical Reports Server (NTRS)

    Curlander, J. C.; Pang, S. N.

    1982-01-01

    This paper describes the development of automated location and geometric rectification techniques for digitally processed synthetic aperture radar (SAR) imagery. A software package has been developed that is capable of determining the absolute location of an image pixel to within 60 m using only the spacecraft ephemeris data and the characteristics of the SAR data collection and processing system. Based on this location capability algorithms have been developed that geometrically rectify the imagery, register it to a common coordinate system and mosaic multiple frames to form extended digital SAR maps. These algorithms have been optimized using parallel processing techniques to minimize the operating time. Test results are given using Seasat SAR data.

  5. Applications of SAR Interferometry in Earth and Environmental Science Research.

    PubMed

    Zhou, Xiaobing; Chang, Ni-Bin; Li, Shusun

    2009-01-01

    This paper provides a review of the progress in regard to the InSAR remote sensing technique and its applications in earth and environmental sciences, especially in the past decade. Basic principles, factors, limits, InSAR sensors, available software packages for the generation of InSAR interferograms were summarized to support future applications. Emphasis was placed on the applications of InSAR in seismology, volcanology, land subsidence/uplift, landslide, glaciology, hydrology, and forestry sciences. It ends with a discussion of future research directions. PMID:22573992

  6. Applications of SAR Interferometry in Earth and Environmental Science Research.

    PubMed

    Zhou, Xiaobing; Chang, Ni-Bin; Li, Shusun

    2009-01-01

    This paper provides a review of the progress in regard to the InSAR remote sensing technique and its applications in earth and environmental sciences, especially in the past decade. Basic principles, factors, limits, InSAR sensors, available software packages for the generation of InSAR interferograms were summarized to support future applications. Emphasis was placed on the applications of InSAR in seismology, volcanology, land subsidence/uplift, landslide, glaciology, hydrology, and forestry sciences. It ends with a discussion of future research directions.

  7. Crop identification of SAR data using digital textural analysis

    NASA Technical Reports Server (NTRS)

    Nuesch, D. R.

    1983-01-01

    After preprocessing SEASAT SAR data which included slant to ground range transformation, registration to LANDSAT MSS data and appropriate filtering of the raw SAR data to minimize coherent speckle, textural features were developed based upon the spatial gray level dependence method (SGLDM) to compute entropy and inertia as textural measures. It is indicated that the consideration of texture features are very important in SAR data analysis. The SEASAT SAR data are useful for the improvement of field boundary definitions and for an earlier season estimate of corn and soybean area location than is supported by LANDSAT alone.

  8. Epipolar geometry comparison of SAR and optical camera

    NASA Astrophysics Data System (ADS)

    Li, Dong; Zhang, Yunhua

    2016-03-01

    In computer vision, optical camera is often used as the eyes of computer. If we replace camera with synthetic aperture radar (SAR), we will then enter a microwave vision of the world. This paper gives a comparison of SAR imaging and camera imaging from the viewpoint of epipolar geometry. The imaging model and epipolar geometry of the two sensors are analyzed in detail. Their difference is illustrated, and their unification is particularly demonstrated. We hope these may benefit researchers in field of computer vision or SAR image processing to construct a computer SAR vision, which is dedicated to compensate and improve human vision by electromagnetically perceiving and understanding the images.

  9. Applications of SAR Interferometry in Earth and Environmental Science Research

    PubMed Central

    Zhou, Xiaobing; Chang, Ni-Bin; Li, Shusun

    2009-01-01

    This paper provides a review of the progress in regard to the InSAR remote sensing technique and its applications in earth and environmental sciences, especially in the past decade. Basic principles, factors, limits, InSAR sensors, available software packages for the generation of InSAR interferograms were summarized to support future applications. Emphasis was placed on the applications of InSAR in seismology, volcanology, land subsidence/uplift, landslide, glaciology, hydrology, and forestry sciences. It ends with a discussion of future research directions. PMID:22573992

  10. Relationships between autofocus methods for SAR and self-survey techniques for SONAR. [Synthetic Aperture Radar (SAR)

    SciTech Connect

    Wahl, D.E.; Jakowatz, C.V. Jr.; Ghiglia, D.C.; Eichel, P.H.

    1991-01-01

    Autofocus methods in SAR and self-survey techniques in SONAR have a common mathematical basis in that they both involve estimation and correction of phase errors introduced by sensor position uncertainties. Time delay estimation and correlation methods have been shown to be effective in solving the self-survey problem for towed SONAR arrays. Since it can be shown that platform motion errors introduce similar time-delay estimation problems in SAR imaging, the question arises as to whether such techniques could be effectively employed for autofocus of SAR imagery. With a simple mathematical model for motion errors in SAR, we will show why such correlation/time-delay techniques are not nearly as effective as established SAR autofocus algorithms such as phase gradient autofocus or sub-aperture based methods. This analysis forms an important bridge between signal processing methodologies for SAR and SONAR. 5 refs., 4 figs.

  11. Polymorphism of SARS-CoV genomes.

    PubMed

    Shang, Lei; Qi, Yan; Bao, Qi-Yu; Tian, Wei; Xu, Jian-Cheng; Feng, Ming-Guang; Yang, Huan-Ming

    2006-04-01

    In this work, severe acute respiratory syndrome associated coronavirus (SARS-CoV) genome BJ202 (AY864806) was completely sequenced. The genome was directly accessed from the stool sample of a patient in Beijing. Comparative genomics methods were used to analyze the sequence variations of 116 SARS-CoV genomes (including BJ202) available in the NCBI GenBank. With the genome sequence of GZ02 as the reference, there were 41 polymorphic sites identified in BJ202 and a total of 278 polymorphic sites present in at least two of the 116 genomes. The distribution of the polymorphic sites was biased over the whole genome. Nearly half of the variations (50.4%, 140/278) clustered in the one third of the whole genome at the 3' end (19.0 kb-29.7 kb). Regions encoding Orf10-11, Orf3/4, E, M and S protein had the highest mutation rates. A total of 15 PCR products (about 6.0 kb of the genome) including 11 fragments containing 12 known polymorphic sites and 4 fragments without identified polymorphic sites were cloned and sequenced. Results showed that 3 unique polymorphic sites of BJ202 (positions 13 804, 15 031 and 20 792) along with 3 other polymorphic sites (26 428, 26 477 and 27 243) all contained 2 kinds of nucleotides. It is interesting to find that position 18379 which has not been identified to be polymorphic in any of the other 115 published SARS-CoV genomes is actually a polymorphic site. The nucleotide composition of this site is A (8) to G (6). Among 116 SARS-CoV genomes, 18 types of deletions and 2 insertions were identified. Most of them were related to a 300 bp region (27,700-28,000) which encodes parts of the putative ORF9 and ORF10-11. A phylogenetic tree illustrating the divergence of whole BJ202 genome from 115 other completely sequenced SARS-CoVs was also constructed. BJ202 was phylogeneticly closer to BJ01 and LLJ-2004. PMID:16625834

  12. Legendary lost city Ciudad Blanca found under tropical forest in Honduras, using ERS-2 and JERS-1 SAR imagery

    NASA Astrophysics Data System (ADS)

    Yakam-Simen, Francis; Nezry, Edmond; Ewing, James J.; Maschal, Ted

    1998-10-01

    The legendary 'Ciudad Blanca' of Honduras was first referred to under the name Xucutaco by the Spanish conquistador Hernan Cortes already in 1526. Located in the remote, impenetrable and incompletely mapped rainforest of the Mosquito Coast, it was never conquered by the Spanish. With the time, it was slowly abandoned and forgotten. Two JERS-1 and one ERS-2 SLC Synthetic Aperture Radar (SAR) images have been used to identify and to locate the lost city, a task made difficult due to the thick vegetation cover. To this end, advanced processing tools for the detection of artificial targets under forest cover, and for SAR data fusion have been used. Among the techniques used, a new Bayesian Distribution Entropy Maximum A Posteriori (DE-MAP) vector speckle filter, particularly suited for the restoration of a strongly textured scene, has been used to enhance the SAR images. This new speckle filter incorporates a statistical description of the effects of the SAR imaging system: in order to account for the effects due to the spatial correlation of the speckle in SAR images, an estimator originating from the local spatial autocorrelation function (ACF) of the SAR signal are incorporated to this filter, to refine the evaluation of the non-stationary first order local statistics, to improve the restoration of the scene textural properties, and to preserve the useful spatial resolution in the speckle filtered image. On the other hand, radargrammetric techniques have been used to: (1) produce a Digital Elevation Model (DEM) of the study area; (2) fuse ERS and JERS information in order to allow visual identification of the remnants of Ciudad Blanca by visual photo-interpretation. Using the processed images, geocoded UTM spatio-maps of the region have also been produced to locate accurately our findings, and guide a ground expedition in the future.

  13. Long-term monitoring of geodynamic surface deformation using SAR interferometry

    NASA Astrophysics Data System (ADS)

    Gong, Wenyu

    Synthetic Aperture Radar Interferometry (InSAR) is a powerful tool to measure surface deformation and is well suited for surveying active volcanoes using historical and existing satellites. However, the value and applicability of InSAR for geodynamic monitoring problems is limited by the influence of temporal decorrelation and electromagnetic path delay variations in the atmosphere, both of which reduce the sensitivity and accuracy of the technique. The aim of this PhD thesis research is: how to optimize the quantity and quality of deformation signals extracted from InSAR stacks that contain only a low number of images in order to facilitate volcano monitoring and the study of their geophysical signatures. In particular, the focus is on methods of mitigating atmospheric artifacts in interferograms by combining time-series InSAR techniques and external atmospheric delay maps derived by Numerical Weather Prediction (NWP) models. In the first chapter of the thesis, the potential of the NWP Weather Research & Forecasting (WRF) model for InSAR data correction has been studied extensively. Forecasted atmospheric delays derived from operational High Resolution Rapid Refresh for the Alaska region (HRRR-AK) products have been compared to radiosonding measurements in the first chapter. The result suggests that the HRRR-AK operational products are a good data source for correcting atmospheric delays in spaceborne geodetic radar observations, if the geophysical signal to be observed is larger than 20 mm. In the second chapter, an advanced method for integrating NWP products into the time series InSAR workflow is developed. The efficiency of the algorithm is tested via simulated data experiments, which demonstrate the method outperforms other more conventional methods. In Chapter 3, a geophysical case study is performed by applying the developed algorithm to the active volcanoes of Unimak Island Alaska (Westdahl, Fisher and Shishaldin) for long term volcano deformation

  14. Accurate numerical forward model for optimal retracking of SIRAL2 SAR echoes over open ocean

    NASA Astrophysics Data System (ADS)

    Phalippou, L.; Demeestere, F.

    2011-12-01

    , altimeter transfer function) can be accurately accounted for, in order to minimise the systematic errors in the retrieval. The paper presents the retrieval of range and SWH for several Cryosat 2 orbits arcs, spanning different sea state conditions. The retrieval results are found to be in excellent agreement with the noise expectations derived from the Cramer-Rao bounds (see PE 2007.). The improvement upon conventional Low Resolution mode is about a factor of two in range. Improvements in SWH accuracy is also discussed. Comparisons with the MSL and conventional LRM-like retracking is also shown. Finally, the paper will give some insights for future oceanic altimetry missions. References : Wingham et al., 2005 : CryoSat: A mission to determine the fluctuations in Earth's land and marine ice fields. Advances in Space Research 37 (2006) 841-871 Raney, R.K. 2005 : Resolution and precision ofa delayDoppler Radar Altimeter, Proc IEEE OCEANS 2005. Phalippou L, V. Enjolras 2007 : Re-tracking of SAR altimeter ocean power waveforms and related accuracies of Sea surface Height, significant wave height and wind speed. Proc IEEE IGARSS 2007. Eyre, J. 1989 : Inversion of cloudy satellite radiances by non linear estimation : Theory and simulation for TOVS. Quaterly Journal of the Royal Meteorological Society, 115, pp1001-1026.

  15. Impact of the Regulators SigB, Rot, SarA and sarS on the Toxic Shock Tst Promoter and TSST-1 Expression in Staphylococcus aureus.

    PubMed

    Andrey, Diego O; Jousselin, Ambre; Villanueva, Maite; Renzoni, Adriana; Monod, Antoinette; Barras, Christine; Rodriguez, Natalia; Kelley, William L

    2015-01-01

    Staphylococcus aureus is an important pathogen manifesting virulence through diverse disease forms, ranging from acute skin infections to life-threatening bacteremia or systemic toxic shock syndromes. In the latter case, the prototypical superantigen is TSST-1 (Toxic Shock Syndrome Toxin 1), encoded by tst(H), and carried on a mobile genetic element that is not present in all S. aureus strains. Transcriptional regulation of tst is only partially understood. In this study, we dissected the role of sarA, sarS (sarH1), RNAIII, rot, and the alternative stress sigma factor sigB (σB). By examining tst promoter regulation predominantly in the context of its native sequence within the SaPI1 pathogenicity island of strain RN4282, we discovered that σB emerged as a particularly important tst regulator. We did not detect a consensus σB site within the tst promoter, and thus the effect of σB is likely indirect. We found that σB strongly repressed the expression of the toxin via at least two distinct regulatory pathways dependent upon sarA and agr. Furthermore rot, a member of SarA family, was shown to repress tst expression when overexpressed, although its deletion had no consistent measurable effect. We could not find any detectable effect of sarS, either by deletion or overexpression, suggesting that this regulator plays a minimal role in TSST-1 expression except when combined with disruption of sarA. Collectively, our results extend our understanding of complex multifactorial regulation of tst, revealing several layers of negative regulation. In addition to environmental stimuli thought to impact TSST-1 production, these findings support a model whereby sporadic mutation in a few key negative regulators can profoundly affect and enhance TSST-1 expression. PMID:26275216

  16. Impact of the Regulators SigB, Rot, SarA and sarS on the Toxic Shock Tst Promoter and TSST-1 Expression in Staphylococcus aureus.

    PubMed

    Andrey, Diego O; Jousselin, Ambre; Villanueva, Maite; Renzoni, Adriana; Monod, Antoinette; Barras, Christine; Rodriguez, Natalia; Kelley, William L

    2015-01-01

    Staphylococcus aureus is an important pathogen manifesting virulence through diverse disease forms, ranging from acute skin infections to life-threatening bacteremia or systemic toxic shock syndromes. In the latter case, the prototypical superantigen is TSST-1 (Toxic Shock Syndrome Toxin 1), encoded by tst(H), and carried on a mobile genetic element that is not present in all S. aureus strains. Transcriptional regulation of tst is only partially understood. In this study, we dissected the role of sarA, sarS (sarH1), RNAIII, rot, and the alternative stress sigma factor sigB (σB). By examining tst promoter regulation predominantly in the context of its native sequence within the SaPI1 pathogenicity island of strain RN4282, we discovered that σB emerged as a particularly important tst regulator. We did not detect a consensus σB site within the tst promoter, and thus the effect of σB is likely indirect. We found that σB strongly repressed the expression of the toxin via at least two distinct regulatory pathways dependent upon sarA and agr. Furthermore rot, a member of SarA family, was shown to repress tst expression when overexpressed, although its deletion had no consistent measurable effect. We could not find any detectable effect of sarS, either by deletion or overexpression, suggesting that this regulator plays a minimal role in TSST-1 expression except when combined with disruption of sarA. Collectively, our results extend our understanding of complex multifactorial regulation of tst, revealing several layers of negative regulation. In addition to environmental stimuli thought to impact TSST-1 production, these findings support a model whereby sporadic mutation in a few key negative regulators can profoundly affect and enhance TSST-1 expression.

  17. Impact of the Regulators SigB, Rot, SarA and sarS on the Toxic Shock Tst Promoter and TSST-1 Expression in Staphylococcus aureus

    PubMed Central

    Villanueva, Maite; Renzoni, Adriana; Monod, Antoinette; Barras, Christine; Rodriguez, Natalia; Kelley, William L.

    2015-01-01

    Staphylococcus aureus is an important pathogen manifesting virulence through diverse disease forms, ranging from acute skin infections to life-threatening bacteremia or systemic toxic shock syndromes. In the latter case, the prototypical superantigen is TSST-1 (Toxic Shock Syndrome Toxin 1), encoded by tst(H), and carried on a mobile genetic element that is not present in all S. aureus strains. Transcriptional regulation of tst is only partially understood. In this study, we dissected the role of sarA, sarS (sarH1), RNAIII, rot, and the alternative stress sigma factor sigB (σB). By examining tst promoter regulation predominantly in the context of its native sequence within the SaPI1 pathogenicity island of strain RN4282, we discovered that σB emerged as a particularly important tst regulator. We did not detect a consensus σB site within the tst promoter, and thus the effect of σB is likely indirect. We found that σB strongly repressed the expression of the toxin via at least two distinct regulatory pathways dependent upon sarA and agr. Furthermore rot, a member of SarA family, was shown to repress tst expression when overexpressed, although its deletion had no consistent measurable effect. We could not find any detectable effect of sarS, either by deletion or overexpression, suggesting that this regulator plays a minimal role in TSST-1 expression except when combined with disruption of sarA. Collectively, our results extend our understanding of complex multifactorial regulation of tst, revealing several layers of negative regulation. In addition to environmental stimuli thought to impact TSST-1 production, these findings support a model whereby sporadic mutation in a few key negative regulators can profoundly affect and enhance TSST-1 expression. PMID:26275216

  18. A sea ice concentration estimation algorithm utilizing radiometer and SAR data

    NASA Astrophysics Data System (ADS)

    Karvonen, J.

    2014-09-01

    We have studied the possibility of combining the high-resolution synthetic aperture radar (SAR) segmentation and ice concentration estimated by radiometer brightness temperatures. Here we present an algorithm for mapping a radiometer-based concentration value for each SAR segment. The concentrations are estimated by a multi-layer perceptron (MLP) neural network which has the AMSR-2 (Advanced Microwave Scanning Radiometer 2) polarization ratios and gradient ratios of four radiometer channels as its inputs. The results have been compared numerically to the gridded Finnish Meteorological Institute (FMI) ice chart concentrations and high-resolution AMSR-2 ASI (ARTIST Sea Ice) algorithm concentrations provided by the University of Hamburg and also visually to the AMSR-2 bootstrap algorithm concentrations, which are given in much coarser resolution. The differences when compared to FMI daily ice charts were on average small. When compared to ASI ice concentrations, the differences were a bit larger, but still small on average. According to our comparisons, the largest differences typically occur near the ice edge and sea-land boundary. The main advantage of combining radiometer-based ice concentration estimation and SAR segmentation seems to be a more precise estimation of the boundaries of different ice concentration zones.

  19. Development of InSAR tropospheric correction maps using continuous GPS data and weather models

    NASA Astrophysics Data System (ADS)

    Moore, A. W.; Kedar, S.; Owen, S. E.; Webb, F.; Fielding, E. J.; Fishbein, E.; Means, J. D.; Bock, Y.; Fang, P.; Jamason, P.; Squibb, M. B.; Bjorndahl, F.; Lofgren, J.

    2009-12-01

    As part of a NASA Advanced Information Systems Technology effort, we are building upon NASA's investment in the measurement of crustal deformation from continuous GPS by developing and implementing a system that will provide tropospheric delay correction maps to the InSAR community. SIO and JPL routinely produce independent, continuous GPS station position solutions using the GAMIT and GIPSY software packages, respectively, for the western North American region, including the Plate Boundary Observatory GPS network. These solutions, as well as combined and validated products, are available via a powerful portal environment known as GPS Explorer. Tropospheric zenith delay at each station is estimated as part of the solution process, and we now aim to add tropospheric products and related portal capabilities to GPS Explorer. GPS troposphere estimates have a high temporal resolution (typically 5 minutes), which suggests application in correcting the temporally variable tropospheric artifacts that obscure detection of ground deformation in InSAR. The spacing of GPS stations, however, is generally not sufficient to resolve short-wavelength tropospheric features. To overcome this limitation, we have tested the combination of GPS zenith delay solutions with delay data derived from weather forecast products (precipitable water vapor, surface temperature, and surface pressure). InSAR solutions over a short time period (unlikely to have significant deformation), when corrected by these combined GPS and weather model maps, have a reduced RMS compared to an uncorrected interferogram.

  20. Large and small scale circulation signatures of the ERS-1 SAR over the Gulf Stream

    NASA Technical Reports Server (NTRS)

    Beal, R.; Kudryavtsev, V.; Thompson, D.; Grodsky, S.; Tilley, D.; Dulov, V.

    1994-01-01

    Since September 1991, the ERS-1 SAR (Synthetic Aperture Radar) has collected approximately 170 frames of ocean imagery on 28 passes over the western Gulf Stream in support of ESA experiment US8-2c. SAR signatures of the north wall are seen on nearly all passes, with modulation depth varying from 3% to 35% for 100 m samples. Many small and mesoscale circulation features associated with the Stream are evident. The detailed form of the signature varies considerably, however. Narrow bright or dark linear features appear to follow streamlines, and on one occasion a strong dark line was associated with an in situ measurement of a sharp current shear. Similarly, larger spatial scale changes in backscatter over the Stream were associated with in situ measurements of atmospheric stability transitions. Physical explanations for the narrow features are not so obvious. However, the accumulation of surfactants along converging current boundaries or local short wave straining and breaking appear plausible. These preliminary results strongly suggest that a wide swath (approximately 500 km) SAR with at least 100 m resolution would be a useful adjunct to existing satellite AVHRR (Advanced Very High Resolution Radiometer) imagery.

  1. A system-level simulator for indoor mmW SAR imaging and its applications.

    PubMed

    Qi, Feng; Ocket, Ilja; Schreurs, Dominique; Nauwelaers, Bart

    2012-10-01

    Recently, the research interest in indoor active millimeter wave (mmW) imaging by applying the synthetic aperture radar (SAR) technique is increasing. However, there is a lack of proper computer-aided design (CAD) tools at the system level, and almost all the R&D activities rely on experiments solely. The high cost of such a system stops many researchers from investigating such a fascinating research topic. Moreover, the experiment-oriented studies may blind the researchers to some details during the imaging process, since in most cases they are only interested in the readout from the receivers and do not know how the waves perform in reality. To bridge such a gap, we propose a modeling approach at mmW frequencies, which is able to simulate the physical process during SAR imaging. We are not going to discuss about advanced image reconstruction algorithms, since they have already been investigated intensively for decades. To distinguish from previous work, for the first time, we model the data acquisition process in a SAR imaging system successfully at mmW frequencies. We show how to perform some system-level studies based on such a simulator via a common PC, including the influence of reflectivity contrast between object and background, sampling step, and antenna's directivity on image quality. The simulator can serve system design purposes and it can be easily extended to THz frequencies.

  2. The Yellowstone Fires as Observed by SIR-C SAR

    NASA Technical Reports Server (NTRS)

    Rignot, Eric; Despain, Don; Holecz, Francesco

    1996-01-01

    Covers SIR-C (Spaceborne Imaging Radar C) SAR (Synthetic Aperture Radar) imaging of the 1988 Yellowstone National Forest fires. Discusses some of the images and data collected, and some conclusions drawn from them about both the fires, and SIR-C SAR imaging capabilities.

  3. (Q)SAR: A Tool for the Toxicologist.

    PubMed

    Steinbach, Thomas; Gad-McDonald, Samantha; Kruhlak, Naomi; Powley, Mark; Greene, Nigel

    2015-01-01

    A continuing education (CE) course at the 2014 American College of Toxicology annual meeting covered the topic of (Quantitative) Structure-Activity Relationships [(Q)SAR]. The (Q)SAR methodologies use predictive computer modeling based on predefined rules to describe the relationship between chemical structure and a chemical's associated biological activity or statistical tools to find correlations between biologic activity and the molecular structure or properties of a compound. The (Q)SAR has applications in risk assessment, drug discovery, and regulatory decision making. Pressure within industry to reduce the cost of drug development and societal pressure for government regulatory agencies to produce more accurate and timely risk assessment of drugs and chemicals have necessitated the use of (Q)SAR. Producing a high-quality (Q)SAR model depends on many factors including the choice of statistical methods and descriptors, but first and foremost the quality of the data input into the model. Understanding how a (Q)SAR model is developed and applied is critical to the successful use of such a tool. The CE session covered the basic principles of (Q)SAR, practical applications of these computational models in toxicology, how regulatory agencies use and interpret (Q)SAR models, and potential pitfalls of using them.

  4. An Adaptive Ship Detection Scheme for Spaceborne SAR Imagery.

    PubMed

    Leng, Xiangguang; Ji, Kefeng; Zhou, Shilin; Xing, Xiangwei; Zou, Huanxin

    2016-01-01

    With the rapid development of spaceborne synthetic aperture radar (SAR) and the increasing need of ship detection, research on adaptive ship detection in spaceborne SAR imagery is of great importance. Focusing on practical problems of ship detection, this paper presents a highly adaptive ship detection scheme for spaceborne SAR imagery. It is able to process a wide range of sensors, imaging modes and resolutions. Two main stages are identified in this paper, namely: ship candidate detection and ship discrimination. Firstly, this paper proposes an adaptive land masking method using ship size and pixel size. Secondly, taking into account the imaging mode, incidence angle, and polarization channel of SAR imagery, it implements adaptive ship candidate detection in spaceborne SAR imagery by applying different strategies to different resolution SAR images. Finally, aiming at different types of typical false alarms, this paper proposes a comprehensive ship discrimination method in spaceborne SAR imagery based on confidence level and complexity analysis. Experimental results based on RADARSAT-1, RADARSAT-2, TerraSAR-X, RS-1, and RS-3 images demonstrate that the adaptive scheme proposed in this paper is able to detect ship targets in a fast, efficient and robust way. PMID:27563902

  5. Web-GIS-based SARS epidemic situation visualization

    NASA Astrophysics Data System (ADS)

    Lu, Xiaolin

    2004-03-01

    In order to research, perform statistical analysis and broadcast the information of SARS epidemic situation according to the relevant spatial position, this paper proposed a unified global visualization information platform for SARS epidemic situation based on Web-GIS and scientific virtualization technology. To setup the unified global visual information platform, the architecture of Web-GIS based interoperable information system is adopted to enable public report SARS virus information to health cure center visually by using the web visualization technology. A GIS java applet is used to visualize the relationship between spatial graphical data and virus distribution, and other web based graphics figures such as curves, bars, maps and multi-dimensional figures are used to visualize the relationship between SARS virus tendency with time, patient number or locations. The platform is designed to display the SARS information in real time, simulate visually for real epidemic situation and offer an analyzing tools for health department and the policy-making government department to support the decision-making for preventing against the SARS epidemic virus. It could be used to analyze the virus condition through visualized graphics interface, isolate the areas of virus source, and control the virus condition within shortest time. It could be applied to the visualization field of SARS preventing systems for SARS information broadcasting, data management, statistical analysis, and decision supporting.

  6. Wave retrieval from SAR imagery in the East China Sea

    NASA Astrophysics Data System (ADS)

    Lou, Xiulin; Chang, Junfang; Liu, Xiaoyan

    2015-12-01

    Synthetic aperture radar (SAR) plays an important role in measuring directional ocean wave spectra with continuous and global coverage. In this article, satellite SAR images were used to estimate the wave parameters in the East China Sea. The Max-Planck Institut (MPI) method was applied to retrieve directional wave spectra from the SAR imagers with the Simulating WAves Nearshore (SWAN) model data as the first guess wave spectra. In order to validate the SAR retrieved wave spectra, a set of buoy measurements during the SAR imaging times was collected and used. The SAR retrieved significant wave heights (SWHs) were analyzed against the buoy measurements to assess the wave retrieval of this study. The root-mean-square error between the SAR SWHs and the buoy measurements is 0.25 m, which corresponds to a relative error of 12%. The case study here shows that the SWAN model data is a potential first guess wave spectra source to the MPI method to retrieve ocean wave spectra from SAR imagery.

  7. Fully polarimetric data from the ARL RailSAR

    NASA Astrophysics Data System (ADS)

    Ranney, Kenneth; Kirose, Getachew; Phelan, Brian; Sherbondy, Kelly

    2016-05-01

    The U.S. Army Research Laboratory (ARL) has recently upgraded the indoor, rail-mounted synthetic aperture radar (SAR) system, RailSAR, to enable collection of large amounts of low-frequency, ultrawideband (UWB) data. Our intent is to provide a research tool that is capable of emulating airborne SAR configuration and associated data collection geometries against surrogate explosive hazard threat deployments. By having such a capability, ARL's facility will afford a more rapid response to the ever changing improvised characteristics associated with explosive hazards today and in the future. Therefore, upgrades to this RailSAR tool to improve functionality and performance are needed to meet the potential rapid response assessments to be carried out. The new, lighter RailSAR cart puts less strain on the radar positioning hardware and allows the system to move smoothly along a specified portion of the rail. In previous papers, we have presented co-polarized SAR data collected using the ARL RailSAR. Recently, however, researchers at ARL have leveraged this asset to collect polarimetric data against multiple targets. This paper presents the SAR imagery resulting from these experiments and documents characteristics of certain target signatures that should be of interest to developers of automatic target detection (ATD) algorithms.

  8. An Adaptive Ship Detection Scheme for Spaceborne SAR Imagery

    PubMed Central

    Leng, Xiangguang; Ji, Kefeng; Zhou, Shilin; Xing, Xiangwei; Zou, Huanxin

    2016-01-01

    With the rapid development of spaceborne synthetic aperture radar (SAR) and the increasing need of ship detection, research on adaptive ship detection in spaceborne SAR imagery is of great importance. Focusing on practical problems of ship detection, this paper presents a highly adaptive ship detection scheme for spaceborne SAR imagery. It is able to process a wide range of sensors, imaging modes and resolutions. Two main stages are identified in this paper, namely: ship candidate detection and ship discrimination. Firstly, this paper proposes an adaptive land masking method using ship size and pixel size. Secondly, taking into account the imaging mode, incidence angle, and polarization channel of SAR imagery, it implements adaptive ship candidate detection in spaceborne SAR imagery by applying different strategies to different resolution SAR images. Finally, aiming at different types of typical false alarms, this paper proposes a comprehensive ship discrimination method in spaceborne SAR imagery based on confidence level and complexity analysis. Experimental results based on RADARSAT-1, RADARSAT-2, TerraSAR-X, RS-1, and RS-3 images demonstrate that the adaptive scheme proposed in this paper is able to detect ship targets in a fast, efficient and robust way. PMID:27563902

  9. A short note on calculating the adjusted SAR index

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple algebraic technique is presented for computing the adjusted SAR Index proposed by Suarez (1981). The statistical formula presented in this note facilitates the computation of the adjusted SAR without the use of either a look-up table, custom computer software or the need to compute exact a...

  10. Agricultural Performance Monitoring with Polarimetric SAR and Optical Imagery

    NASA Astrophysics Data System (ADS)

    Dhar, T.; Gray, D.; Menges, C.

    2009-04-01

    This paper presents the results from an experiment measuring yield using TerraSAR-X dual-polarimetric mode and precision agriculture machinery which records harvested amounts every few meters. The experimental field setup and data collection using TerraSAR-X are discussed and some preliminary results are shown.

  11. Synthetic aperture design for increased SAR image rate

    DOEpatents

    Bielek, Timothy P.; Thompson, Douglas G.; Walker, Bruce C.

    2009-03-03

    High resolution SAR images of a target scene at near video rates can be produced by using overlapped, but nevertheless, full-size synthetic apertures. The SAR images, which respectively correspond to the apertures, can be analyzed in sequence to permit detection of movement in the target scene.

  12. An Adaptive Ship Detection Scheme for Spaceborne SAR Imagery.

    PubMed

    Leng, Xiangguang; Ji, Kefeng; Zhou, Shilin; Xing, Xiangwei; Zou, Huanxin

    2016-08-23

    With the rapid development of spaceborne synthetic aperture radar (SAR) and the increasing need of ship detection, research on adaptive ship detection in spaceborne SAR imagery is of great importance. Focusing on practical problems of ship detection, this paper presents a highly adaptive ship detection scheme for spaceborne SAR imagery. It is able to process a wide range of sensors, imaging modes and resolutions. Two main stages are identified in this paper, namely: ship candidate detection and ship discrimination. Firstly, this paper proposes an adaptive land masking method using ship size and pixel size. Secondly, taking into account the imaging mode, incidence angle, and polarization channel of SAR imagery, it implements adaptive ship candidate detection in spaceborne SAR imagery by applying different strategies to different resolution SAR images. Finally, aiming at different types of typical false alarms, this paper proposes a comprehensive ship discrimination method in spaceborne SAR imagery based on confidence level and complexity analysis. Experimental results based on RADARSAT-1, RADARSAT-2, TerraSAR-X, RS-1, and RS-3 images demonstrate that the adaptive scheme proposed in this paper is able to detect ship targets in a fast, efficient and robust way.

  13. Evaluation of DEM-assisted SAR coregistration

    NASA Astrophysics Data System (ADS)

    Nitti, D. O.; Hanssen, R. F.; Refice, A.; Bovenga, F.; Milillo, G.; Nutricato, R.

    2008-10-01

    Image alignment is without doubt the most crucial step in SAR Interferometry. Interferogram formation requires images to be coregistered with an accuracy of better than 1/8 pixel to avoid significant loss of phase coherence. Conventional interferometric precise coregistration methods for full-resolution SAR data (Single-Look Complex imagery, or SLC) are based on the cross-correlation of the SLC data, either in the original complex form or as squared amplitudes. Offset vectors in slant range and azimuth directions are computed on a large number of windows, according to the estimated correlation peaks. Then, a two-dimensional polynomial of a certain degree is usually chosen as warp function and the polynomial parameters are estimated through LMS fit from the shifts measured on the image windows. In case of rough topography and long baselines, the polynomial approximation for the warp function becomes inaccurate, leading to local misregistrations. Moreover, these effects increase with the spatial resolution and then with the sampling frequency of the sensor, as first results on TerraSAR-X interferometry confirm. An improved, DEM-assisted image coregistration procedure can be adopted for providing higher-order prediction of the offset vectors. Instead of estimating the shifts on a limited number of patches and using a polynomial approximation for the transformation, this approach computes pixel by pixel the correspondence between master and slave by using the orbital data and a reference DEM. This study assesses the performance of this approach with respect to the standard procedure. In particular, both analytical relationships and simulations will evaluate the impact of the finite vertical accuracy of the DEM on the final coregistration precision for different radar postings and relative positions of satellites. The two approaches are compared by processing real data at different carrier frequencies and using the interferometric coherence as quality figure.

  14. SAR digital spotlight implementation in MATLAB

    NASA Astrophysics Data System (ADS)

    Dungan, Kerry E.; Gorham, LeRoy A.; Moore, Linda J.

    2013-05-01

    Legacy synthetic aperture radar (SAR) exploitation algorithms were image-based algorithms, designed to exploit complex and/or detected SAR imagery. In order to improve the efficiency of the algorithms, image chips, or region of interest (ROI) chips, containing candidate targets were extracted. These image chips were then used directly by exploitation algorithms for the purposes of target discrimination or identification. Recent exploitation research has suggested that performance can be improved by processing the underlying phase history data instead of standard SAR imagery. Digital Spotlighting takes the phase history data of a large image and extracts the phase history data corresponding to a smaller spatial subset of the image. In a typical scenario, this spotlighted phase history data will contain much fewer samples than the original data but will still result in an alias-free image of the ROI. The Digital Spotlight algorithm can be considered the first stage in a "two-stage backprojection" image formation process. As the first stage in two-stage backprojection, Digital Spotlighting filters the original phase history data into a number of "pseudo"-phase histories that segment the scene into patches, each of which contain a reduced number of samples compared to the original data. The second stage of the imaging process consists of standard backprojection. The data rate reduction offered by Digital Spotlighting improves the computational efficiency of the overall imaging process by significantly reducing the total number of backprojection operations. This paper describes the Digital Spotlight algorithm in detail and provides an implementation in MATLAB.

  15. Towards monitoring of geohazards with ESA's Sentinel-1 C-band SAR data: nationwide feasibility mapping over Great Britain calibrated using ERS-1/2 and ENVISAT PSI data

    NASA Astrophysics Data System (ADS)

    Cigna, Francesca; Bateson, Luke; Dashwood, Claire; Jordan, Colm

    2013-04-01

    the major limitation over most of Britain, and areas of layover and shadow for each satellite mode do not exceed 1% of the entire landmass. Although the results from the landuse feasibility mapping confirm that landcover has stronger control on the potential of these technologies over Britain, the overall number of monitoring targets that might be identified over the entire landmass for each acquisition mode exceeds 12.8M. Based on the results of the feasibility mapping, we identified three categories of landsliding in Britain, over which we will carry out SAR-based ground motions studies with ERS-1/2 SAR and ENVISAT ASAR data covering the past 20 years, based on combination of change detection, SAR Interferometry (InSAR), PSI and Small Baseline (SBAS) approaches. Selected test sites include South Wales Coalfield, the Cotswold Escarpment, the Pennines, the North York Moors, as well as landsliding affecting transport/infrastructure and coastal sites in eastern and southern England. The results of our study act as milestones for future SAR applications and operational uses for a wide range of geohazards in Britain, including landslides, land subsidence/uplift due to groundwater abstraction/recharge, shrink-swell clays, as well as structural deformation of critical infrastructure, and show the potential of future nationwide monitoring of the entire landmass with the new Earth explorers of the Sentinel-1 constellation. Reference: Cigna F., Bateson L., Jordan C., Dashwood C. (2012), Feasibility of InSAR technologies for nationwide monitoring of geohazards in Great Britain. Remote Sensing and Photogrammetry Society Annual Conference, RSPSoc 2012, Greenwich (UK), 12-14 September 2012. Available at: http://nora.nerc.ac.uk/19876/

  16. Evaluating SAR polarization modes at L-band for forest classification purposes in Eastern Amazon, Brazil

    NASA Astrophysics Data System (ADS)

    Liesenberg, Veraldo; Gloaguen, Richard

    2013-04-01

    Single, interferometric dual, and quad-polarization mode data were evaluated for the characterization and classification of seven land use classes in an area with shifting cultivation practices located in the Eastern Amazon (Brazil). The Advanced Land-Observing Satellite (ALOS) Phased Array L-band Synthetic Aperture Radar (PALSAR) data were acquired during a six month interval. A clear-sky Landsat-5/TM image acquired at the same period was used as additional ground reference and as ancillary input data in the classification scheme. We evaluated backscattering intensity, polarimetric features, interferometric coherence and texture parameters for classification purposes using support vector machines (SVM) and feature selection. Results showed that the forest classes were characterized by low temporal backscattering intensity variability, low coherence and high entropy. Quad polarization mode performed better than dual and single polarizations but overall accuracies remain low and were affected by precipitation events on the date and prior SAR date acquisition. Misclassifications were reduced by integrating Landsat data and an overall accuracy of 85% was attained. The integration of Landsat to both quad and dual polarization modes showed similarity at the 5% significance level. SVM was not affected by SAR dimensionality and feature selection technique reveals that co-polarized channels as well as SAR derived parameters such as Alpha-Entropy decomposition were important ranked features after Landsat' near-infrared and green bands. We show that in absence of Landsat data, polarimetric features extracted from quad-polarization L-band increase classification accuracies when compared to single and dual polarization alone. We argue that the joint analysis of SAR and their derived parameters with optical data performs even better and thus encourage the further development of joint techniques under the Reducing Emissions from Deforestation and Degradation (REDD) mechanism.

  17. InSAR measurements of compaction and subsidence in the Ganges-Brahmaputra Delta, Bangladesh

    NASA Astrophysics Data System (ADS)

    Higgins, Stephanie A.; Overeem, Irina; Steckler, Michael S.; Syvitski, James P. M.; Seeber, Leonardo; Akhter, S. Humayun

    2014-08-01

    Many of the world's largest river deltas are sinking due to sediment loading, compaction, and tectonics but also recently because of groundwater extraction, hydrocarbon extraction, and reduced aggradation. Little is known, however, about the full spatial variability of subsidence rates in complex delta systems. This study reconstructs subsidence rates in the eastern portion of the Ganges-Brahmaputra Delta (GBD), Bangladesh, covering more than 10,000 km2 at a high spatial resolution of 100 m. The map was produced using Interferometric Synthetic Aperture Radar (InSAR) covering the period 2007 to 2011. Eighteen Advanced Land Observing Satellite Phased-Array L-band SAR scenes were used to generate 30 interferograms calibrated with GPS. Interferograms were stacked to yield average subsidence rates over the study period. Small Baseline Subset-InSAR was then applied to validate the results against an additional GPS record from Dhaka, Bangladesh. Land subsidence of 0 to > 10 mm/yr is seen in Dhaka, with variability likely related to local variations in shallow subsurface sediment properties. Outside of the city, rates vary from 0 to > 18 mm/yr, with the lowest rates appearing primarily in Pleistocene Madhupur Clay and the highest rates in Holocene organic-rich muds. Results demonstrate that subsidence in this delta is primarily controlled by local stratigraphy, with rates varying by more than an order of magnitude depending on lithology. The ability of L-band InSAR to differentiate between stratigraphic units in this humid, vegetated subtropical river delta demonstrates the power of interferometry as a tool for studying the subsurface in deltaic environments.

  18. Coastal Monitoring Using L-band Synthetic Aperture Radar (SAR) Image Data - Some Case Studies in Asian Delta Areas

    NASA Astrophysics Data System (ADS)

    Tanaka, A.

    2014-12-01

    Coastal geomorphology is highly variable as it is affected by sea-level changes and other naturally- and human-induced fluctuations. To effectively assess and monitor geomorphological changes in various time scales is thus critical for coastal management. Asian mega deltas are vulnerable to a sea-level rise due to its low-lying delta plain, and are dynamic region given a large amount of sediment supply. However, limited data availability and accessibility in the deltas have prevented establishment of systematic coastal monitoring. A variety of remote sensing systems can be used to monitor geomorphological changes in coastal areas as it has wide spatial coverage and high temporal repeatability. Especially, analysis using SAR (Synthetic Aperture Radar) data not affected by the cloud conditions offer potential for monitoring in the monsoon Asia region. We will present some case studies of Asian coastal regions using L-band SAR data, ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array type L-band SAR) and JERS-1 (Japanese Earth Resource Satellite-1) SAR data. One example is that time-series of radar amplitude images can be used to delineate changes quantitatively of the areal extent of river-mouth bars in distributaries of the Mekong River delta. It shows that the estimated areas of river mouthbars gradually increase on an annual time scale, and seasonal variations of areas were also recognized. Another example is that differential SAR interferometry is applied to the coast of the Yellow River delta in China. It shows very high subsidence rates, likely due to groundwater pumping. A further example is that we apply a SAR interferometry time series analysis to monitor ground deformations in the lower Chao Phraya delta plain, Thailand. A single reference time series interferogram from the stacking of unwrapped phases were applied. The subsidence and uplift pattern observed using the SAR interferometry time series analysis highlights the spatial complexity

  19. Monitoring of precursor landslide surface deformation using InSAR image in Kuchi-Sakamoto, Shizuoka Prefecture, Japan

    NASA Astrophysics Data System (ADS)

    Sato, H. P.; Nakajima, H.; Nakano, T.; Daimaru, H.

    2014-12-01

    Synthetic Aperture Radar (SAR) is the technique to obtain ground surface images using microwave that is emitted from and received on the antenna. The Kuchi-Sakamoto area, 2.2 km2 in precipitous mountains, central Japan, has suffered from frequent landslides, and slow landslide surface deformation has been monitored by on-site extensometer; however, such the monitoring method cannot detect the deformation in the whole area. Because satellite InSAR is effective tool to monitor slow landslide suface deformation, it is a promising tool for detecting precursor deformation and preparing effective measures against serious landslide disasters. In this study Advanced Land Observing Satellite (ALOS) / Phased Array type L-band SAR (PALSAR) data were used, and InSAR images were produced from the PALSAR data that were observed between 5 Sep 2008 and 21 Oct 2008 (from descending orbit) and between 20 Jul 2008 and 7 Sep 2009 (from ascending orbit). InSAR image from descending orbit was found to detect clear precursor landslide surface deformation on a slope; however, InSAR image on ascending orbit did not always detect clear precursor deformation. It is thought to be related with atmospheric moisture condition, length of observation baseline and so on. Furthermore, after phase unwrapping on InSAR images, 2.5-dimensional deformation was analized. This analysis needed both ascending and descending InSAR images and culculated quasi east-west deformation component (Figs. (a) and (b)) and quasi up-down deformation component (Figs. (c) and (d)). The resulting 2.5D calculation gave westward deformation and mixture of upward and downward deformations on the precursor landslide surface deformation slope (blue circles in Figs. (c) and (d)), where remarkable disrupted deep landslide occurred during Nov 2012 and 25 Jun 2013, judging from result of airborne LiDAR survey and field survey; the occurrence date is not precisely identified. The figure remains the issue that eliminating "real

  20. Fully exploitation of SBAS-DInSAR deformation time series for assessing structural damage: the case study of Rome, Italy

    NASA Astrophysics Data System (ADS)

    Bonano, Manuela; Arangio, Stefania; Calò, Fabiana; Di Mauro, Maria; Marsella, Maria; Manunta, Michele

    2014-05-01

    Remote sensing techniques have demonstrated to be effective tools to support natural and man-made risk mitigation activities. Among these, the Differential Synthetic Aperture Radar (SAR) Interferometry (DInSAR) technology is largely exploited in geoscience, oil and gas extraction, and landslide fields. Recently, thanks to the large availability of high resolution SAR systems (10 m or less), as well as to the development of advanced data processing techniques, DInSAR products have also started to be effectively used for applications in urban areas to detect localized displacements affecting single buildings and infrastructures. The advanced DInSAR technique referred to as Small Baseline Subset (SBAS) (Lanari et al., 2004) allows us to generate very long deformation time series, by exploiting large SAR datasets spanning up to 20 years (Bonano et al., 2012). Thanks to its capability to investigate wide areas, the SBAS-DInSAR technique is particularly suitable to remotely analyse the structural conditions of buildings located in densely urbanized zones. In this work, we fully exploit the results achieved over the city of Rome, Italy, through the well-established SBAS-DInSAR approach, aimed at performing a quantitative assessment of structural damage in urban areas affected by ground deformation (Arangio et al., 2013). More in details, we present an innovative methodology that integrates the SBAS-DInSAR measurements within an existing model, in order to assess the damage, and possibly estimate the future structural conditions, of single buildings affected by significant foundation settlements. In particular, a semi-empirical approach, based on a laminated beam model (Finno et al., 2005), is applied to investigate the damage of buildings located in the southern part of the city. The obtained results are in substantial agreement with in situ surveys, proving that the presented approach is an effective tool for the preliminary evaluation of the structural conditions in

  1. Salt Kinematics and InSAR

    NASA Technical Reports Server (NTRS)

    Aftabi, Pedarm; Talbot, hristopher; Fielding, Eric

    2005-01-01

    As part of a long-term attempt to learn how the climatic and tectonic signal interact to shape a steady state mountain monitored displacement of a markers in SE termination and also near the summit of a small viscous salt fountain extruding onto the Central plateau of Iran. The marker displacements relate to the first InSAR interferograms of salt extrusion (980913 to 990620) calculated Earth tides, winds, air pressures and temperatures. In the first documented staking exercise, hammered wooden stakes vertically through the surgical marl (c. 1 Ocm deep) onto the top of crystalline salt. These stakes installed in an irregular array elongate E-W along the c.50 m high cliff marking the effective SE terminus of the glacier at Qum Kuh(Centra1 Iran) ,just to the E of a NE trending river cliff about 40 m high. We merely measured the distances between pairs of stakes with known azimuth about 2 m apart to calculate sub horizontal strain in a small part of Qum Kuh. Stakes moved and micro strains for up to 46 pairs of stakes (p strain= ((lengthl-length2)/1engthl) x 10-1) was calculated for each seven stake epochs and plotted against their azimuth on simplified array maps. The data fit well the sine curves cxpected of the maximum and minimum strain ellipses. The first documented stakes located on the SE where the InSAR image show -1 1 to 0 mm pink to purple, 0 to lOmm purple to blue, and show high activity of salt in low activity area of the InSAR image (980913 to 990620).Short term micro strains of stake tie lines record anisotropic expansions due to heating and contraction due to cooling. All epochs changed between 7 to 1 17 days (990928 to000 1 16), showed 200 to 400 micro strain lengthening and shortening. The contraction and extension existed in each epoch, but the final strain was extension in E-W in Epoch land 6, contraction in E-W direction during epochs 2-3-4-5 and 7. The second pair of stakes hammered about 20 cm deep into the deep soils(more than 1 m) , near summit

  2. Detection of land degradation with polarimetric SAR

    NASA Technical Reports Server (NTRS)

    Ray, Terrill W.; Farr, Tom G.; Van Zyl, Jakob J.

    1992-01-01

    Multispectral radar polarimeter data were collected over the Manix Basin Area of the Mojave desert using an airborne SAR. An analysis of the data reveals unusual polarization responses which are attributed to the formation of wind ripples on the surfaces of fields that have been abandoned for more than 5 years. This hypothesis has been confirmed through field observations, and a second-order perturbation model is shown to effectively model the polarization responses. The results demonstrate the usefulness of remote sensing techniques for the study of land degradation at synoptic scales.

  3. Software For Calibration Of Polarimetric SAR Data

    NASA Technical Reports Server (NTRS)

    Van Zyl, Jakob; Zebker, Howard; Freeman, Anthony; Holt, John; Dubois, Pascale; Chapman, Bruce

    1994-01-01

    POLCAL (Polarimetric Radar Calibration) software tool intended to assist in calibration of synthetic-aperture radar (SAR) systems. In particular, calibrates Stokes-matrix-format data produced as standard product by NASA/Jet Propulsion Laboratory (JPL) airborne imaging synthetic aperture radar (AIRSAR). Version 4.0 of POLCAL is upgrade of version 2.0. New options include automatic absolute calibration of 89/90 data, distributed-target analysis, calibration of nearby scenes with corner reflectors, altitude or roll-angle corrections, and calibration of errors introduced by known topography. Reduces crosstalk and corrects phase calibration without use of ground calibration equipment. Written in FORTRAN 77.

  4. Single Baseline Tomography SAR for Forest Above Ground Biomass Estimation

    NASA Astrophysics Data System (ADS)

    Li, Wenmei; Chen, Erxue; Li, Zengyuan; Wang, Xinshuang; Feng, Qi

    2013-01-01

    Single baseline tomography SAR is used for forest height estimation as its little restriction on the number of baselines and configurations of tracks in recent years. There existed two kinds of single baseline tomography SAR techniques, the polarimetric coherence tomography (PCT) and the sum of Kronecker product (SKP), algebraic synthesis (AS) and Capon spectral estimator approach (SKP-AS-Capon). Few researches on forest above ground biomass (AGB) estimation are there using single baseline tomography SAR. In this paper, PCT and SKP-AS-Capon approaches are proposed for forest AGB estimation. L-band data set acquired by E-SAR airborne system in 2003 for the forest test site in Traunstein, is used for this experiment. The result shows that single baseline polarimetric tomography SAR can obtain forest AGB in forest stand scale, and SKP-AS-Capon method has better detailed vertical structure information, while the Freeman 3-component combined PCT approach gets a homogenous vertical structure in forest stand.

  5. The GeoSAR program: Development of a commercially viable 3-D radar terrain mapping system

    SciTech Connect

    Carlisle, R.G.; Davis, M.

    1996-11-01

    GeoSAR is joint development between the Defense Advanced Research Project Agency (DARPA) and the California Department of Conservation (CA DOC) to determine the technical and economic viability of an airborne interferometric and foliage penetration synthetic aperture radar for mapping terrain and man made objects in geographical areas obscured by foliage, urban buildings, and other concealments. The two core technology elements of this program are Interferometric Synthetic Aperture Radar (IFSAR) and Foliage Penetration Radar (FOPEN). These technologies have been developed by NASA and ARPA, principally for defense applications.

  6. New P2X3 receptor antagonists. Part 2: Identification and SAR of quinazolinones.

    PubMed

    Szántó, Gábor; Makó, Attila; Vágó, István; Hergert, Tamás; Bata, Imre; Farkas, Bence; Kolok, Sándor; Vastag, Mónika

    2016-08-15

    Numerous potent P2X3 antagonists have been discovered and the therapeutic potential of P2X3 antagonism already comprises proof-of-concept data obtained in clinical trials with the most advanced compound. We have lately reported the discovery and optimization of thia-triaza-tricycle compounds with potent P2X3 antagonistic properties. This Letter describes the SAR of a back-up series containing a 4-oxo-quinazoline central ring. The discovery of the highly potent compounds 51 is presented. PMID:27426300

  7. Internal wave parameters retrieval from space-borne SAR image

    NASA Astrophysics Data System (ADS)

    Fan, Kaiguo; Fu, Bin; Gu, Yanzhen; Yu, Xingxiu; Liu, Tingting; Shi, Aiqin; Xu, Ke; Gan, Xilin

    2015-12-01

    Based on oceanic internal wave SAR imaging mechanism and the microwave scattering imaging model for oceanic surface features, we developed a new method to extract internal wave parameters from SAR imagery. Firstly, the initial wind fields are derived from NCEP reanalysis data, the sea water density and oceanic internal wave pycnocline depth are estimated from the Levites data, the surface currents induced by the internal wave are calculated according to the KDV equation. The NRCS profile is then simulated by solving the action balance equation and using the sea surface radar backscatter model. Both the winds and internal wave pycnocline depth are adjusted by using the dichotomy method step by step to make the simulated data approach the SAR image. Then, the wind speed, pycnocline depth, the phase speed, the group velocity and the amplitude of internal wave can be retrieved from SAR imagery when a best fit between simulated signals and the SAR image appears. The method is tested on one scene SAR image near Dongsha Island, in the South China Sea, results show that the simulated oceanic internal wave NRCS profile is in good agreement with that on the SAR image with the correlation coefficient as high as 90%, and the amplitude of oceanic internal wave retrieved from the SAR imagery is comparable with the SODA data. Besides, the phase speeds retrieved from other 16 scene SAR images in the South China Sea are in good agreement with the empirical formula which describes the relations between internal wave phase speed and water depths, both the root mean square and relative error are less than 0.11 m•s-1 and 7%, respectively, indicating that SAR images are useful for internal wave parameters retrieval and the method developed in this paper is convergent and applicable.

  8. An introduction to the interim digital SAR processor and the characteristics of the associated Seasat SAR imagery

    NASA Technical Reports Server (NTRS)

    Wu, C.; Barkan, B.; Huneycutt, B.; Leang, C.; Pang, S.

    1981-01-01

    Basic engineering data regarding the Interim Digital SAR Processor (IDP) and the digitally correlated Seasat synthetic aperature radar (SAR) imagery are presented. The correlation function and IDP hardware/software configuration are described, and a preliminary performance assessment presented. The geometric and radiometric characteristics, with special emphasis on those peculiar to the IDP produced imagery, are described.

  9. Relations of SARS-Related Stressors and Coping to Chinese College Students' Psychological Adjustment during the 2003 Beijing SARS Epidemic

    ERIC Educational Resources Information Center

    Main, Alexandra; Zhou, Qing; Ma, Yue; Luecken, Linda J.; Liu, Xin

    2011-01-01

    This study examined the main and interactive relations of stressors and coping related to severe acute respiratory syndrome (SARS) with Chinese college students' psychological adjustment (psychological symptoms, perceived general health, and life satisfaction) during the 2003 Beijing SARS epidemic. All the constructs were assessed by self-report…

  10. A 100 MS/s 9 bit 0.43 mW SAR ADC with custom capacitor array

    NASA Astrophysics Data System (ADS)

    Jingjing, Wang; Zemin, Feng; Rongjin, Xu; Chixiao, Chen; Fan, Ye; Jun, Xu; Junyan, Ren

    2016-05-01

    A low power 9 bit 100 MS/s successive approximation register analog-to-digital converter (SAR ADC) with custom capacitor array is presented. A brand-new 3-D MOM unit capacitor is used as the basic capacitor cell of this capacitor array. The unit capacitor has a capacitance of 1 fF. Besides, the advanced capacitor array structure and switch mode decrease the power consumption a lot. To verify the effectiveness of this low power design, the 9 bit 100 MS/s SAR ADC is implemented in TSMC IP9M 65 nm LP CMOS technology. The measurement results demonstrate that this design achieves an effective number of bits (ENOB) of 7.4 bit, a signal-to-noise plus distortion ratio (SNDR) of 46.40 dB and a spurious-free dynamic range (SFDR) of 62.31 dB at 100 MS/s with 1 MHz input. The SAR ADC core occupies an area of 0.030 mm2 and consumes 0.43 mW under a supply voltage of 1.2 V. The figure of merit (FOM) of the SAR ADC achieves 23.75 fJ/conv. Project supported by the National High-Tech Research and Development Program of China (No. 2013AA014101).

  11. The Ecosystems SAR (EcoSAR) an Airborne P-band Polarimetric InSAR for the Measurement of Vegetation Structure, Biomass and Permafrost

    NASA Technical Reports Server (NTRS)

    Rincon, Rafael F.; Fatoyinbo, Temilola; Ranson, K. Jon; Osmanoglu, Batuhan; Sun, Guoqing; Deshpande, Manohar D.; Perrine, Martin L.; Du Toit, Cornelis F.; Bonds, Quenton; Beck, Jaclyn; Lu, Daniel

    2014-01-01

    EcoSAR is a new synthetic aperture radar (SAR) instrument being developed at the NASA/ Goddard Space Flight Center (GSFC) for the polarimetric and interferometric measurements of ecosystem structure and biomass. The instrument uses a phased-array beamforming architecture and supports full polarimetric measurements and single pass interferometry. This Instrument development is part of NASA's Earth Science Technology Office Instrument Incubator Program (ESTO IIP).

  12. Deformation along the western Indian plate boundary: new constraints from differential and multi-aperture InSAR data inversion for the 2008, Baluchistan (Western Pakistan) seismic sequence.

    NASA Astrophysics Data System (ADS)

    Pezzo, Giuseppe; Merryman Boncori, John Peter; Atzori, Simone; Antonioli, Andrea; Salvi, Stefano

    2014-05-01

    We use Synthetic Aperture Radar Differential Interferometry (DInSAR) and Multi-Aperture Interferometry (MAI) to constrain the sources of the three largest events of the 2008 Baluchistan (western Pakistan) seismic sequence, namely two Mw 6.4 events only 12 hours apart and an Mw 5.7event occurred 40 days later. The sequence took place in the Quetta Syntaxis, the most seismically active region of Baluchistan, tectonically located between the colliding Indian Plate and the Afghan block of the Eurasian Plate. Elastic dislocation modelling of the surface displacements, derived from ascending and descending ENVISAT ASAR acquisitions, yields slip distributions with peak values of 80 cm and 70 cm for the two main events on a pair of strike-slip near-vertical faults, and values up to 50 cm for the largest aftershock on a NE-SW strike-slip fault. The MAI measurements, with their high sensitivity to the north-south motion component, are crucial in this area to resolve the fault plane ambiguity of moment tensors. We also studied the relationships between the largest earthquakes of the sequence by means of the Coulomb Failure Function to verify the agreement of our source modelling with the stress variations induced by the October 28 earthquake on the October 29 fault plane, and the stress variations induced by the two mainshocks on the December 09 fault plane. Our results provide insight into the deformation style of the Quetta Syntaxis, suggesting that right-lateral slip released at intermediate depths on large NW fault planes is compatible with contemporaneous left-lateral activation on NE-SW minor faults at shallower depths, in agreement with a bookshelf deformation mechanism.

  13. Surface Creep Along the East Anatolian Fault (Turkey) Revealed by InSAR Time Series: Implications for Seismic Hazard and Mechanism of Creep

    NASA Astrophysics Data System (ADS)

    Senturk, S.; Cakir, Z.; Ergintav, S.; Dogan, U.; Cetin, S.; Akoglu, A. M.; Meghraoui, M.; Karabulut, H.

    2015-12-01

    Forming the boundary between the Anatolian and Arabian plates in Turkey, the East Anatolian Fault (EAF) is a major tectonic structure in the Eastern Mediterranean region. Together with its conjugate, the North Anatolian Fault (NAF), it accommodates the westward motion of the Anatolian plate with respect to Eurasia. Although it has been associated only with small-to-moderate sized earthquakes in the instrumental period and relatively quiet compared to the North Anatolian Fault, the EAF produced devastating large (M > 7) earthquakes in the historical time (Ambraseys et al., 1998). Analysis of historical seismicity (Nalbant et al., 2001) suggests that a seismic gap exists between the Lake of Hazar and Bingöl, referred here as to Palu seismic gap (PSG) We estimate the interseismic velocity field along the BSG using the Persistent Scatterer InSAR technique (Hooper, 2008). ENVISAT ASAR data acquired between 2003 and 2010 on three adjacent descending and overlapping tracks (T035, T264 and T493) are use to map the interseismic strain accumulation. The results reveal that the 100-km-long section of the Palu segment is exhibiting aseismic creep at the surface. The creep rate varies along the fault reaching, at some places, to the far field GPS-based plate velocity (i.e., 10 ± 0.3 mm/y; Reilinger et al., 2006), implying that significant portion of the elastic strain has been released aseismically. Preliminary modelling with elastic dislocations suggests that some sections of the fault may be creeping from surface down to the entire seismogenic crust. Geology of the fault zone is dominated by ophiolitic and volcanic rocks characterized by weak phyllosilicate minerals, suggesting that aseismic slip is promoted by minerals with low frictional properties. Furthermore, to monitor the surface creep, a GPS network has been established along the Palu segment. One survey has so far been realized and we expect the reliable results in 2 years (supported by TUBITAK no: 114Y250 project).

  14. Rapid inactivation of SARS-like coronaviruses.

    SciTech Connect

    Kapil, Sanjay; Oberst, R. D.; Bieker, Jill Marie; Tucker, Mark David; Souza, Caroline Ann; Williams, Cecelia Victoria

    2004-03-01

    Chemical disinfection and inactivation of viruses is largely understudied, but is very important especially in the case of highly infectious viruses. The purpose of this LDRD was to determine the efficacy of the Sandia National Laboratories developed decontamination formulations against Bovine Coronavirus (BCV) as a surrogate for the coronavirus that causes Severe Acute Respiratory Syndrome (SARS) in humans. The outbreak of SARS in late 2002 resulted from a highly infectious virus that was able to survive and remain infectious for extended periods. For this study, preliminary testing with Escherichia coli MS-2 (MS-2) and Escherichia coli T4 (T4) bacteriophages was conducted to develop virucidal methodology for verifying the inactivation after treatment with the test formulations following AOAC germicidal methodologies. After the determination of various experimental parameters (i.e. exposure, concentration) of the formulations, final testing was conducted on BCV. All experiments were conducted with various organic challenges (horse serum, bovine feces, compost) for results that more accurately represent field use condition. The MS-2 and T4 were slightly more resistant than BCV and required a 2 minute exposure while BCV was completely inactivated after a 1 minute exposure. These results were also consistent for the testing conducted in the presence of the various organic challenges indicating that the test formulations are highly effective for real world application.

  15. Ultrawideband VHF SAR design and measurements

    NASA Astrophysics Data System (ADS)

    Hellsten, Hans; Froelind, Per-Olov; Gustafsson, Anders; Jonsson, T.; Larsson, Bjoern; Stenstroem, Gunnar; Binder, Bradley T.; Mirkin, Mitchell I.; Ayasli, Serpil

    1994-07-01

    CARABAS, an acronym for `coherent all radio band sensing,' is an airborne, horizontal-polarization SAR operating across the frequency band 20 to 90 MHz, conceived, designed and built by FOA in Sweden. The original motivation for designing such a low frequency system was that a large relative or fractional bandwidth could be achieved at low frequencies. For reasons to be explained, a large fractional bandwidth was considered to be of potential benefit for radar detection in severe clutter environments. A feasibility study of a short wave ultra-wideband radar started at FOA in 1985. Actual construction of the CARABAS system commenced 1987, aircraft integration took place during 1991 and the first radar tests were conducted in early 1992. From the fall of 1992 onwards, field campaigns and evaluation studies have been conducted as a joint effort between FOA and MIT Lincoln Laboratory in the US. This article will focus on experiences concerning foliage penetration with the system. First we touch upon the CARABAS system characteristics, outline the arguments behind a large fractional bandwidth VHF-band SAR approach to foliage penetration, and finally present some early experimental results. We refer to other papers for a fuller explanation of the system, for more details of image calibration, and for results concerning underground imaging.

  16. SAR Image despeckling via sparse representation

    NASA Astrophysics Data System (ADS)

    Wang, Zhongmei; Yang, Xiaomei; Zheng, Liang

    2014-11-01

    SAR image despeckling is an active research area in image processing due to its importance in improving the quality of image for object detection and classification.In this paper, a new approach is proposed for multiplicative noise in SAR image removal based on nonlocal sparse representation by dictionary learning and collaborative filtering. First, a image is divided into many patches, and then a cluster is formed by clustering log-similar image patches using Fuzzy C-means (FCM). For each cluster, an over-complete dictionary is computed using the K-SVD method that iteratively updates the dictionary and the sparse coefficients. The patches belonging to the same cluster are then reconstructed by a sparse combination of the corresponding dictionary atoms. The reconstructed patches are finally collaboratively aggregated to build the denoised image. The experimental results show that the proposed method achieves much better results than many state-of-the-art algorithms in terms of both objective evaluation index (PSNR and ENL) and subjective visual perception.

  17. Classification SAR targets with support vector machine

    NASA Astrophysics Data System (ADS)

    Cao, Lanying

    2007-02-01

    With the development of Synthetic Aperture Radar (SAR) technology, automatic target recognition (ATR) is becoming increasingly important. In this paper, we proposed a 3-class target classification system in SAR images. The system is based on invariant wavelet moments and support vector machine (SVM) algorithm. It is a two-stage approach. The first stage is to extract and select a small set of wavelet invariant moment features to indicate target images. The wavelet invariant moments take both advantages of the wavelet inherent property of multi-resolution analysis and moment invariants quality of invariant to translation, scaling changes and rotation. The second stage is classification of targets with SVM algorithm. SVM is based on the principle of structural risk minimization (SRM), which has been shown better than the principle of empirical risk minimization (ERM) which is used by many conventional networks. To test the performance and efficiency of the proposed method, we performed experiments on invariant wavelet moments, different kernel functions, 2-class identification, and 3-class identification. Test results show that wavelet invariant moments indicate the target effectively; linear kernel function achieves better results than other kernel functions, and SVM classification approach performs better than conventional nearest distance approach.

  18. Pandemic Diseases and the Aviation Network SARS, a case study

    NASA Astrophysics Data System (ADS)

    Hufnagel, Lars; Brockmann, Dirk; Geisel, Theo

    2005-03-01

    We investigate the mechanisms of the worldwide spread of infectious diseases in a modern world in which humans travel on all scales. We introduce a probabilistic model which accounts for the worldwide spread of infectious diseases on the global aviation network. The analysis indicates that a forecast of the geographical spread of an epidemic is indeed possible, provided that local dynamical parameters of the disease such as the basic reproduction number are known. The model consists of local stochastic infection dynamics and stochastic transport of individuals on the worldwide aviation network which takes into account over 95% of the entire the national and international civil aviation traffic. Our simulations of the SARS outbreak are in surprisingly good agreement with published case reports. Despite the fact that the system is stochastic with a high number of degrees of freedom the outcome of a single simulation exhibits only a small magnitude of variability. We show that this is due to the strong heterogeneity of the network ranging from a few two over 25,000 passengers between nodes of the network. Thus, we propose that our model can be employed to predict the worldwide spread of future pandemic diseases and to identify endangered regions in advance. Based on the connectivity of the aviation network we evaluate the performance of different control strategies and show that a quick and focused reaction is essential to inhibit the global spread of infectious diseases.

  19. Fundamental SAR ATR performance predictions for design trade-offs: 1D HRR versus 2D SAR versus 3D SAR

    NASA Astrophysics Data System (ADS)

    Horowitz, Larry L.; Brendel, Gary F.

    1999-08-01

    This paper continues the development of a fundamental, algorithm-independent view of the ATR performance that can be achieved using SAR data. Such ATR performance predictions are intended to enable evaluation of performance tradeoffs for SAR designs, including both parameter selections (e.g., bandwidth and transmit power) and added domains of SAR observation, such as 3-D, full polarimetry, aspect diversity, and/or frequency diversity. Using a Bayesian framework, we show target classification performance predictions for two tactical targets (either stationary with radar netting assumed deployed, or moving) using three different domains of observation: 1-D HRR (high-range-resolution radar), 2-D SAR, and 3-D SAR. Comparisons of the three domains are made at 3m, 1m, 0.5m and 0.3m range and cross-range resolutions. The discussion of 3-D SAR includes parameter tradeoffs of various height resolutions at the target, and various numbers of sensors. For each measurement modality, we list some of the unique sensitivities which could cause performance degradations.

  20. Environmental Change Detection Using Multi-Temporal SAR Imagery

    NASA Astrophysics Data System (ADS)

    Fazel, Mohammad A.; Homayouni, Saeid; Aghakarimi, Armin

    2013-04-01

    several dual-pol L-band SAR image datasets acquired by the Advanced Land Observing Satellite (ALOS). The obtained time series change maps is used to evaluate and assess the environmental behavior of the lake area which is facing a very difficult period.

  1. SAR imaging via modern 2-D spectral estimation methods.

    PubMed

    DeGraaf, S R

    1998-01-01

    This paper discusses the use of modern 2D spectral estimation algorithms for synthetic aperture radar (SAR) imaging. The motivation for applying power spectrum estimation methods to SAR imaging is to improve resolution, remove sidelobe artifacts, and reduce speckle compared to what is possible with conventional Fourier transform SAR imaging techniques. This paper makes two principal contributions to the field of adaptive SAR imaging. First, it is a comprehensive comparison of 2D spectral estimation methods for SAR imaging. It provides a synopsis of the algorithms available, discusses their relative merits for SAR imaging, and illustrates their performance on simulated and collected SAR imagery. Some of the algorithms presented or their derivations are new, as are some of the insights into or analyses of the algorithms. Second, this work develops multichannel variants of four related algorithms, minimum variance method (MVM), reduced-rank MVM (RRMVM), adaptive sidelobe reduction (ASR) and space variant apodization (SVA) to estimate both reflectivity intensity and interferometric height from polarimetric displaced-aperture interferometric data. All of these interferometric variants are new. In the interferometric contest, adaptive spectral estimation can improve the height estimates through a combination of adaptive nulling and averaging. Examples illustrate that MVM, ASR, and SVA offer significant advantages over Fourier methods for estimating both scattering intensity and interferometric height, and allow empirical comparison of the accuracies of Fourier, MVM, ASR, and SVA interferometric height estimates.

  2. Synthetic aperture radar speckle reduction for circle mode SAR images

    NASA Astrophysics Data System (ADS)

    Musgrove, Cameron

    2016-05-01

    Synthetic aperture radar (SAR) images contain a grainy pattern, called speckle, that is a consequence of a coherent imaging system. For fine resolution SAR images speckle can obscure subtle features and reduce visual appeal. Many speckle reduction methods result in a loss of image resolution and reduce visual appeal which can obscure subtle features. Another approach to maintain resolution while reducing speckle is to register and combine multiple images. For persistent surveillance applications it is more efficient for an airborne platform to fly circles around the particular area of interest. In these cases, it would be beneficial to combine multiple circle mode SAR images, however the image registration process is not so straightforward because the layover angle changes in each image. This paper develops a SAR image registration process for combining multiple circle mode SAR images to reduce speckle while preserving resolution. The registration first uses a feature matching algorithm for a coarse rotation and alignment, and then uses a fine registration and warp. Ku band SAR data from a circle mode SAR collection is used to show the effectiveness of the registration and enhanced visual appeal from multi-looking.

  3. SARS Grid--an AG-based disease management and collaborative platform.

    PubMed

    Hung, Shu-Hui; Hung, Tsung-Chieh; Juang, Jer-Nan

    2006-01-01

    This paper describes the development of the NCHC's Severe Acute Respiratory Syndrome (SARS) Grid project-An Access Grid (AG)-based disease management and collaborative platform that allowed for SARS patient's medical data to be dynamically shared and discussed between hospitals and doctors using AG's video teleconferencing (VTC) capabilities. During the height of the SARS epidemic in Asia, SARS Grid and the SARShope website significantly curved the spread of SARS by helping doctors manage the in-hospital and in-home care of quarantined SARS patients through medical data exchange and the monitoring of the patient's symptoms. Now that the SARS epidemic has ended, the primary function of the SARS Grid project is that of a web-based informatics tool to increase pubic awareness of SARS and other epidemic diseases. Additionally, the SARS Grid project can be viewed and further studied as an outstanding model of epidemic disease prevention and/or containment.

  4. Ground Displacement Measurement of the 2013 Balochistan Earthquake with interferometric TerraSAR-X ScanSAR data

    NASA Astrophysics Data System (ADS)

    Yague-Martinez, N.; Fielding, E. J.; Haghshenas-Haghighi, M.; Cong, X.; Motagh, M.

    2014-12-01

    This presentation will address the 24 September 2013 Mw 7.7 Balochistan Earthquake in western Pakistan from the point of view of interferometric processing algorithms of wide-swath TerraSAR-X ScanSAR images. The algorithms are also valid for TOPS acquisition mode, the operational mode of the Sentinel-1A ESA satellite that was successfully launched in April 2014. Spectral properties of burst-mode data and an overview of the interferometric processing steps of burst-mode acquisitions, emphasizing the importance of the co-registration stage, will be provided. A co-registration approach based on incoherent cross-correlation will be presented and applied to seismic scenarios. Moreover geodynamic corrections due to differential atmospheric path delay and differential solid Earth tides are considered to achieve accuracy in the order of several centimeters. We previously derived a 3D displacement map using cross-correlation techniques applied to optical images from Landsat-8 satellite and TerraSAR-X ScanSAR amplitude images. The Landsat-8 cross-correlation measurements cover two horizontal directions, and the TerraSAR-X displacements include both horizontal along-track and slant-range (radar line-of-sight) measurements that are sensitive to vertical and horizontal deformation. It will be justified that the co-seismic displacement map from TerraSAR-X ScanSAR data may be contaminated by postseismic deformation due to the fact that the post-seismic acquisition took place one month after the main shock, confirmed in part by a TerraSAR-X stripmap interferogram (processed with conventional InSAR) covering part of the area starting on 27 September 2013. We have arranged the acquisition of a burst-synchronized stack of TerraSAR-X ScanSAR images over the affected area after the earthquake. It will be possible to apply interferometry to these data to measure the lower magnitude of the expected postseismic displacements. The processing of single interferograms will be discussed. A

  5. A Time Domain Along-Track SAR Interferometry Method

    NASA Astrophysics Data System (ADS)

    Cao, N.; Lee, H.; Jung, H. C.

    2015-12-01

    Differential interferometric synthetic aperture radar (DInSAR) has already been proven to be a useful technique for measuring ground displacement at millimeter level. One major drawback of traditional DInSAR technique is that only 1-D deformation in slant range direction can be detected. In order to obtain along-track displacement using a single InSAR pair, two major attempts have been made. The first one is based on cross-correlation between two SAR amplitude images. The second attempt is based on split-beam processing to generate two SAR images from forward- and backward-looking beams. Comparing with the former method, this multiple-aperture SAR interferometry (MAI) can achieve much better measurement accuracy. The major drawback of the MAI method is degraded signal to noise ratio (SNR) and along-track resolution since total along-track integration time decreases in the split-beam procedure. In order to improve the SNR and along-track resolution as well as to extract the terrain displacement in the along-track direction, a time domain along-track SAR interferometry method is proposed in this study. Using traditional time domain backprojection method, the phase component corresponding to slant range direction offset can be estimated and removed from the range compressed SAR signal. Then a phase estimation procedure is implemented to obtain the phase component in the along-track direction. Using ALOS PALSAR data over Kilauea Volcano area in Hawai'i, our experimental results demonstrate the improved performance of the proposed method in extracting 2-D terrain deformation map from one pair of SAR images.

  6. The experience of SARS-related stigma at Amoy Gardens.

    PubMed

    Lee, Sing; Chan, Lydia Y Y; Chau, Annie M Y; Kwok, Kathleen P S; Kleinman, Arthur

    2005-11-01

    Severe Acute Respiratory Syndrome (SARS) possesses characteristics that render it particularly prone to stigmatization. SARS-related stigma, despite its salience for public health and stigma research, has had little examination. This study combines survey and case study methods to examine subjective stigma among residents of Amoy Gardens (AG), the first officially recognized site of community outbreak of SARS in Hong Kong. A total of 903 residents of AG completed a self-report questionnaire derived from two focus groups conducted toward the end of the 3-month outbreak. Case studies of two residents who lived in Block E, the heart of the SARS epidemic at AG, complement the survey data. Findings show that stigma affected most residents and took various forms of being shunned, insulted, marginalized, and rejected in the domains of work, interpersonal relationships, use of services and schooling. Stigma was also associated with psychosomatic distress. Residents' strategies for diminishing stigma varied with gender, age, education, occupation, and proximity to perceived risk factors for SARS such as residential location, previous SARS infection and the presence of ex-SARS household members. Residents attributed stigma to government mismanagement, contagiousness of the mysterious SARS virus, and alarmist media reporting. Stigma clearly decreased, but never completely disappeared, after the outbreak. The findings confirm and add to existing knowledge on the varied origins, correlates, and impacts of stigma. They also highlight the synergistic roles of inconsistent health policy responses and risk miscommunication by the media in rapidly amplifying stigma toward an unfamiliar illness. While recognizing the intrinsically stigmatizing nature of public health measures to control SARS, we recommend that a consistent inter-sectoral approach is needed to minimize stigma and to make an effective health response to future outbreaks.

  7. Indoor experimental facility for airborne synthetic aperture radar (SAR) configurations - rail-SAR

    NASA Astrophysics Data System (ADS)

    Kirose, Getachew; Phelan, Brian R.; Sherbondy, Kelly D.; Ranney, Kenneth I.; Koenig, Francois; Narayanan, Ram M.

    2014-05-01

    The Army Research Laboratory (ARL) is developing an indoor experimental facility to evaluate and assess airborne synthetic-aperture-radar-(SAR)-based detection capabilities. The rail-SAR is located in a multi-use facility that also provides a base for research and development in the area of autonomous robotic navigation. Radar explosive hazard detection is one key sensordevelopment area to be investigated at this indoor facility. In particular, the mostly wooden, multi-story building houses a two (2) story housing structure and an open area built over a large sandbox. The housing structure includes reconfigurable indoor walls which enable the realization of multiple See-Through-The-Wall (STTW) scenarios. The open sandbox, on the other hand, allows for surface and buried explosive hazard scenarios. The indoor facility is not rated for true explosive hazard materials so all targets will need to be inert and contain surrogate explosive fills. In this paper we discuss the current system status and describe data collection exercises conducted using canonical targets and frequencies that may be of interest to designers of ultra-wideband (UWB) airborne, ground penetrating SAR systems. A bi-static antenna configuration will be used to investigate the effects of varying airborne SAR parameters such as depression angle, bandwidth, and integration angle, for various target types and deployment scenarios. Canonical targets data were used to evaluate overall facility capabilities and limitations. These data is analyzed and summarized for future evaluations. Finally, processing techniques for dealing with RF multi-path and RFI due to operating inside the indoor facility are described in detail. Discussion of this facility and its capabilities and limitations will provide the explosive hazard community with a great airborne platform asset for sensor to target assessment.

  8. Program Merges SAR Data on Terrain and Vegetation Heights

    NASA Technical Reports Server (NTRS)

    Siqueira, Paul; Hensley, Scott; Rodriguez, Ernesto; Simard, Marc

    2007-01-01

    X/P Merge is a computer program that estimates ground-surface elevations and vegetation heights from multiple sets of data acquired by the GeoSAR instrument [a terrain-mapping synthetic-aperture radar (SAR) system that operates in the X and bands]. X/P Merge software combines data from X- and P-band digital elevation models, SAR backscatter magnitudes, and interferometric correlation magnitudes into a simplified set of output topographical maps of ground-surface elevation and tree height.

  9. Mapping and monitoring renewable resources with space SAR

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.; Brisco, B.; Dobson, M. C.; Moezzi, S.

    1983-01-01

    The SEASAT-A SAR and SIR-A imagery was examined to evaluate the quality and type of information that can be extracted and used to monitor renewable resources on Earth. Two tasks were carried out: (1) a land cover classification study which utilized two sets of imagery acquired by the SEASAT-A SAR, one set by SIR-A, and one LANDSAT set (4 bands); and (2) a change detection to examine differences between pairs of SEASAT-A SAR images and relates them to hydrologic and/or agronomic variations in the scene.

  10. Process for combining multiple passes of interferometric SAR data

    DOEpatents

    Bickel, Douglas L.; Yocky, David A.; Hensley, Jr., William H.

    2000-11-21

    Interferometric synthetic aperture radar (IFSAR) is a promising technology for a wide variety of military and civilian elevation modeling requirements. IFSAR extends traditional two dimensional SAR processing to three dimensions by utilizing the phase difference between two SAR images taken from different elevation positions to determine an angle of arrival for each pixel in the scene. This angle, together with the two-dimensional location information in the traditional SAR image, can be transformed into geographic coordinates if the position and motion parameters of the antennas are known accurately.

  11. Use of SAR in Regional Methane Exchange Studies

    NASA Technical Reports Server (NTRS)

    Morrissey, L. A.; Livingston, G. P.; Durden, S. L.

    1994-01-01

    Significant sources of uncertainty in global trace gas budgets are due to lack of knowledge concerning the areal and temporal extent of source and sink areas. Synthetic aperture radar (SAR) is particularly suited to studies of northern ecosystems because of its all-weather operating capability which enables the acquisition of seasonal data. As key controls on methane exchange, the ability to differentiate major vegetation communities, inundation, and leaf area index (LAI) with satellite and airborne SAR data would increase the accuracy and precision of regional and seasonal estimates of methane exchange. The utility of SAR data for monitoring key controls on methane emissions from Arctic and boreal ecosystems is examined.

  12. The physics of vibrating scatterers in SAR imagery

    NASA Astrophysics Data System (ADS)

    André, D. B.; Blacknell, D.; Muff, D. G.; Nottingham, M. R.

    2011-06-01

    Measurement times for synthetic aperture radar (SAR) image collection can take from the order of seconds to minutes and consequently the technique is subject to imaging artefacts due to target motion. For example, imaged moving targets can be displaced and unfocussed and similarly for vibrating targets. Current understanding of this phenomenon is somewhat esoteric however this paper puts forward and demonstrates a visual explanation via the physics of modulated scatterer SAR images in the Fourier domain. This novel approach has led to an imagery analyst aid which associates a distinctive signature to modulated scatterer artefacts in SAR imagery and to an associated filter.

  13. Real-time SAR processing for search and rescue

    NASA Astrophysics Data System (ADS)

    Mansfield, Arthur W.; Rogers, George W.; Rais, Houra

    1998-09-01

    The most important parameter in Search and Rescue is the time it takes to locate the downed aircraft and rescue the survivors. The resulting requirement for wide-area coverage, fine resolution, and day-night all-weather operation dictates the use of a SAR sensor. The time urgency dictates a real-time or near real-time SAR processor. This paper presents alternative real-time architectures and gives the results of feasibility studies of the enabling technologies, including new work by the authors in the area of SAR data compression.

  14. Applications of the EOS SAR to monitoring global change

    NASA Technical Reports Server (NTRS)

    Schier, Marguerite; Way, Jobea; Holt, Benjamin

    1991-01-01

    The SAR employed by NASA's Earth Observing System (EOS) is a multifrequency multipolarization radar which can conduct global monitoring of geophysical and biophysical parameters. The present discussion of the EOS SAR's role in global monitoring emphasizes geophysical product variables applicable to global hydrologic, biogeochemical, and energy cycle models. EOS SAR products encompass biomass, wetland areas, and phenologic and environmental states, in the field of ecosystem dynamics; soil moisture, snow moisture and extent, and glacier and ice sheet extent and velocity, in hydrologic cycle studies; surface-wave fields and sea ice properties, in ocean/atmosphere circulation; and the topography, erosion, and land forms of the solid earth.

  15. SAR Reduction of PIFA with EBG Structures for Mobile Applications

    NASA Astrophysics Data System (ADS)

    Kwak, Sangil; Sim, Dong-Uk; Kwon, Jong Hwa; Yun, Je Hoon

    This paper proposes two types of electromagnetic bandgap (EBG) structures aimed for SAR reduction on a mobile phone antenna. The EBG structures, one which uses vias while the other does not can reduce the surface wave and prevent the undesired radiation from the antenna. Thus, these structures can reduce the electromagnetic fields toward the human head direction and reduction the SAR value. Tests demonstrate the reduction of SAR values and therefore, the human body can be protected from hazard electromagnetic fields by using the proposed EBG structures, regardless of whether vias are used or not.

  16. Geologic process studies using Synthetic Aperture Radar (SAR) data

    NASA Technical Reports Server (NTRS)

    Evans, Diane L.

    1992-01-01

    The use of SAR data to study geologic processes for better understanding of recent tectonic activity and climate change as well as the mitigation of geologic hazards and exploration for nonrenewable resources is discussed. The geologic processes that are particularly amenable to SAR-based data include volcanism; soil erosion, degradation, and redistribution; coastal erosion and inundation; glacier fluctuations; permafrost; and crustal motions. When SAR data are combined with data from other planned spaceborne sensors including ESA ERS, the Japanese Earth Resources Satellite, and the Canadian Radarsat, it will be possible to build a time-series view of temporal changes over many regions of earth.

  17. Alaska Synthetic Aperture Radar (SAR) Facility science data processing architecture

    NASA Technical Reports Server (NTRS)

    Hilland, Jeffrey E.; Bicknell, Thomas; Miller, Carol L.

    1991-01-01

    The paper describes the architecture of the Alaska SAR Facility (ASF) at Fairbanks, being developed to generate science data products for supporting research in sea ice motion, ice classification, sea-ice-ocean interaction, glacier behavior, ocean waves, and hydrological and geological study areas. Special attention is given to the individual substructures of the ASF: the Receiving Ground Station (RGS), the SAR Processor System, and the Interactive Image Analysis System. The SAR data will be linked to the RGS by the ESA ERS-1 and ERS-2, the Japanese ERS-1, and the Canadian Radarsat.

  18. SAR image effects on coherence and coherence estimation.

    SciTech Connect

    Bickel, Douglas Lloyd

    2014-01-01

    Radar coherence is an important concept for imaging radar systems such as synthetic aperture radar (SAR). This document quantifies some of the effects in SAR which modify the coherence. Although these effects can disrupt the coherence within a single SAR image, this report will focus on the coherence between separate images, such as for coherent change detection (CCD) processing. There have been other presentations on aspects of this material in the past. The intent of this report is to bring various issues that affect the coherence together in a single report to support radar engineers in making decisions about these matters.

  19. Evaluation of ERIM optically processed SEASAT SAR data

    NASA Technical Reports Server (NTRS)

    Shuchman, R. A.; Lyzenga, D. R. (Principal Investigator); Klooster, A., Jr.; Marks, J.

    1982-01-01

    The results of three studies on the radiometric and geometric properties of optically processed SEASAT SAR imagery are summarized. The accuracy with which the image scale can be predicted based upon a knowledge of the SAR platform and recording system parameters and the processor characteristics was evaluated. The considerations involved in making radiometric measurements from image films, the use of point targets for calibrating the effects of Doppler spectrum shifts on the radiometric calibration of the SAR image data over extended swath lengths was evaluated

  20. A fundamental model and efficient inference for SAR ocean imagery

    NASA Technical Reports Server (NTRS)

    Harger, R. O.

    1984-01-01

    Employing a synthetic aperture radar (SAR) imaging model based on fundamental models of nonlinear hydrodynamics, electromagnetic scattering from a two-scale surface, and SAR imaging of a time-variant scene, the optimal (minimum mean-square error) estimates of the parameters of a sinusoidal, long gravity wave, and the short gravity wave ensemble are found in an efficient recursive form and their performance evaluated, generally by numerical simulation, in a one-dimensional stationary version. An application is made to Seasat-SAR complex imagery.

  1. FlexSAR, a high-quality, flexible, cost-effective, prototype SAR system

    NASA Astrophysics Data System (ADS)

    Jensen, Mark; Knight, Chad; Haslem, Brent

    2015-05-01

    The FlexSAR radar system was designed to be a high quality, low-cost, flexible prototype instrument. Many radar researchers and practitioners desire the ability to efficiently prototype novel configurations. However, the cost and time required to modify existing radar systems is a challenging hurdle that can be prohibitive. The FlexSAR system couples an RF design that leverages connectorized components with digital commercial-off-the-shelf (COTS) cards. This design allows for a scalable system that supports software defined radio (SDR) capabilities. This paper focuses on the RF and digital system design, discussing the advantages and disadvantages. The FlexSAR system design objective was to support diverse configurations with minimal non-recurring engineering (NRE) costs. Multiple diverse applications are examined, demonstrating the flexible system nature. The configurations discussed utilize different system parameters (e.g., number of phase-centers, transmit configurations, etc.). The resultant products are examined, illustrating that high-quality data products are still attained.

  2. Measurement of long-term land subsidence by combination of InSAR and time series analysis - Application study to Kanto Plains of Japan -

    NASA Astrophysics Data System (ADS)

    Deguchi, T.; Rokugawa, S.; Matsushima, J.

    2009-04-01

    InSAR is an application technique of synthetic aperture radars and is now drawing attention as a methodology capable of measuring subtle surface deformation over a wide area with a high spatial resolution. In this study, the authors applied the method of measuring long-term land subsidence by combining InSAR and time series analysis to Kanto Plains of Japan using 28 images of ENVISAT/ASAR data. In this measuring method, the value of land deformation is set as an unknown parameter and the optimal solution to the land deformation amount is derived by applying a smoothness-constrained inversion algorithm. The vicinity of the Kanto Plain started to subside in the 1910s, and became exposed to extreme land subsidence supposedly in accordance with the reconstruction efforts after the Second World War and the economic development activities. The main causes of the land subsidence include the intake of underground water for the use in industries, agriculture, waterworks, and other fields. In the Kujukuri area, the exploitation of soluble natural gas also counts. The Ministry of Environment reported in its documents created in fiscal 2006 that a total of 214 km2 in Tokyo and the six prefectures around the Plain had undergone a subsidence of 1 cm or more per a year. As a result of long-term land subsidence over approximately five and a half years from 13th January, 2003, to 30th June, 2008, unambiguous land deformation was detected in six areas: (i) Haneda Airport, (ii) Urayasu City, (iii) Kasukabe-Koshigaya, (iv) Southern Kanagawa, (v) Toride-Ryugasaki, and (vi) Kujukuri in Chiba Prefecture. In particular, the results for the Kujukuri area were compared with the leveling data taken around the same area to verify the measuring accuracy. The comparative study revealed that the regression formula between the results obtained by time series analysis and those by the leveling can be expressed as a straight line with a gradient of approximately 1, though including a bias of about

  3. Measuring Water Level Fluctuations of two Connected Wetlands in the Dominican Republic Using InSAR

    NASA Astrophysics Data System (ADS)

    Pichardo Marcano, M. D.; Liu, L.; Zebker, H. A.

    2012-12-01

    Wetlands are ecosystems of high endemism and great biodiversity. Using the double-reflected radar waves off the water surface and trunks of inundated vegetation, Interferometric Synthetic Aperture Radar (InSAR) is capable of measuring water level fluctuations from space at a cm-level accuracy in these ecosystems with emergent vegetation. InSAR can provide a high spatial resolution over a large area that the more traditional terrestrial-based methods lack. In this study, we applied InSAR to study the seasonal variations in water level of the wetlands near two lakes in the southwest of the Dominican Republic: Lake Enriquillo, a highly saline lake designated as a Wetland of International Importance under the Ramsar Convention in 2002, and Laguna del Limon. Both lake-wetland systems are located in the Jaragua-Bahoruco-Enriquillo Biosphere Reserve. Since 2003 the water level of Lake Enriquillo has increased drastically and caused the evacuation of many farmers from nearby villages. Lake level changes also affected the habitats of several native and migratory species. We used the data acquired by the Phased Array type L-band Synthetic Aperture Radar (PALSAR) sensor on board of the Japanese Advanced Land Observation Satellite (ALOS) from October 2008 to January 2011. For the smaller lake, Laguna del Limon, we found a seasonal variation of 10-15 centimeters. This result was confirmed using two different satellite paths. For Lake Enriquillo we found a net decrease of about 20 centimeters in the water level from September 2009 to January 2011. This result agrees with an independent estimation based on lake hydrodynamics model predictions. In addition, our InSAR-based time series of lake level fluctuations revealed distinct behaviors of the two wetlands. For the Lake Enriquillo we found a continuous decrease in the water level throughout 2010 with a brief increase of the water level during the summer months, while for Laguna del Limon during the summer months the water level

  4. SAR-based Estimation of Glacial Extent and Velocity Fields on Isanotski Volcano, Aleutian Islands, Alaska

    NASA Astrophysics Data System (ADS)

    Sousa, D.; Lee, A.; Parker, O. P.; Pressler, Y.; Guo, S.; Osmanoglu, B.; Schmidt, C.

    2012-12-01

    Global studies show that Earth's glaciers are losing mass at increasing rates, creating a challenge for communities that rely on them as natural resources. Field observation of glacial environments is limited by cost and inaccessibility. Optical remote sensing is often precluded by cloud cover and seasonal darkness. Synthetic aperture radar (SAR) overcomes these obstacles by using microwave-frequency electromagnetic radiation to provide high resolution information on large spatial scales and in remote, atmospherically obscured environments. SAR is capable of penetrating clouds, operating in darkness, and discriminating between targets with ambiguous spectral signatures. This study evaluated the efficacy of two SAR Earth observation methods on small (< 7 km2) glaciers in rugged topography. The glaciers chosen for this study lie on Isanotski Volcano in Unimak Island, Aleutian Archipelago, USA. The local community on the island, the City of False Pass, relies on glacial melt for drinking water and hydropower. Two methods were used: (1) velocity field estimation based on Repeat Image Feature Tracking (RIFT) and (2) glacial boundary delineation based on interferometric coherence mapping. NASA Uninhabited Aerial Vehicle SAR (UAVSAR) single-polarized power images and JAXA Advanced Land Observing Satellite Phased Array type L-band SAR (ALOS PALSAR) single-look complex images were analyzed over the period 2008-2011. UAVSAR image pairs were coregistered to sub-pixel accuracy and processed with the Coregistration of Optically Sensed Images and Correlation (COSI-Corr) feature tracking module to derive glacial velocity field estimates. Maximum glacier velocities ranged from 28.9 meters/year to 58.3 meters/year. Glacial boundaries were determined from interferometric coherence of ALOS PALSAR data and subsequently refined with masking operations based on terrain slope and segment size. Accuracy was assessed against hand-digitized outlines from high resolution UAVSAR power images

  5. Wetland Maps of Central Canada based on L-band SAR Imagery

    NASA Astrophysics Data System (ADS)

    Whitcomb, J.; Clewley, D.; Moghaddam, M.; McDonald, K. C.

    2014-12-01

    Northern wetlands have the potential to become major sources of greenhouse gases. Detailed and accurate maps of the locations, types, and extents of these wetlands are therefore essential to the development of accurate carbon budgets. However, due to their vast extent and inaccessibility, most northern wetlands remain unmapped. We have been constructing high-resolution (100 m) thematic maps of boreal wetlands, with current focus on Canadian wetlands. The maps are developed using spaceborne synthetic aperture radar (SAR), which efficiently collects high-resolution imagery over extensive regions and, unlike optical sensors, is unimpaired by clouds or lack of sunlight. Spaceborne L-band (~1.3 GHz) SAR, in particular, records scene characteristics imperceptible to optical sensors such as vegetation structure and moisture content, soil moisture and roughness, and canopy-obscured surface waters. These attributes make it the best single tool for mapping boreal wetlands. Two L-band SAR-based wetland maps are being assembled: one using HH-polarized imagery from the JERS-1 satellite collected in the winter and summer of 1997-1998, and a second using dual-polarized (HH and HV) imagery from the PALSAR sensor of the ALOS satellite collected in the summer of 2008. Ancillary data layers such as image texture, topographic slope, and proximity to water are also generated, and a training/testing data layer is formed by merging polygons from the Canadian Wetland Inventory (CWI) with other land cover databases. A Random Forests decision tree classifier takes as input the SAR, ancillary, and training/testing data layers and uses them to produce thematic wetland maps. The accuracy of each map is quantified via producer and user error statistics. Finally, the SAR-based wetland maps are compared to form a 1998-2008 wetlands change map. Recent advances include a powerful new software suite developed to handle huge volumes of data and much-improved JERS-1 registration. Challenges, including

  6. What have we learnt from SARS?

    PubMed Central

    Weiss, Robin A; McLean, Angela R

    2004-01-01

    With outbreaks of infectious disease emerging from animal sources, we have learnt to expect the unexpected. We were, and are, expecting a new influenza A pandemic, but no one predicted the emergence of an unknown coronavirus (CoV) as a deadly human pathogen. Thanks to the preparedness of the international network of influenza researchers and laboratories, the cause of severe acute respiratory syndrome (SARS) was rapidly identified, but there is no complacency over the global or local management of the epidemic in terms of public health logistics. The human population was lucky that only a small proportion of infected persons proved to be highly infectious to others, and that they did not become so before they felt ill. These were the features that helped to make the outbreak containable. The next outbreak of another kind of transmissible disease may well be quite different. PMID:15306402

  7. Multiscale MAP filtering of SAR images.

    PubMed

    Foucher, S; Bénié, G B; Boucher, J M

    2001-01-01

    Synthetic aperture radar (SAR) images are disturbed by a multiplicative noise depending on the signal (the ground reflectivity) due to the radar wave coherence. Images have a strong variability from one pixel to another reducing essentially the efficiency of the algorithms of detection and classification. We propose to filter this noise with a multiresolution analysis of the image. The wavelet coefficient of the reflectivity is estimated with a Bayesian model, maximizing the a posteriori probability density function. The different probability density function are modeled with the Pearson system of distributions. The resulting filter combines the classical adaptive approach with wavelet decomposition where the local variance of high-frequency images is used in order to segment and filter wavelet coefficients.

  8. A comparison of interferometric SAR antenna options

    NASA Astrophysics Data System (ADS)

    Doerry, A. W.; Bickel, D. L.

    2013-05-01

    Interferometric Synthetic Aperture Radar (IFSAR or InSAR) uses multiple antenna phase centers to ultimately measure target scene elevation. Its ability to do so depends on the antenna configuration, and how the multiple phase centers are employed. We examine several different dual-phase-center antenna configurations and modalities, including a conventional arrangement where a dedicated antenna is used to transmit and receive with another to receive only, a configuration where transmit and receive operations are ping-ponged between phase centers, a monopulse configuration, and an orthogonal waveform configuration. Our figure of merit is the RMS height noise in the elevation estimation. We show that a monopulse configuration is equivalent to the ping-pong scheme, and both offer an advantage over the conventional arrangement. The orthogonal waveform offers the best potential performance, if sufficient isolation can be achieved.

  9. SAR polar format implementation with MATLAB.

    SciTech Connect

    Martin, Grant D.; Doerry, Armin Walter

    2005-11-01

    Traditional polar format image formation for Synthetic Aperture Radar (SAR) requires a large amount of processing power and memory in order to accomplish in real-time. These require