List all papers
CEOS SAR 200931 papers
List all papersCEOS SAR 200931 papers |
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| # | Title | Authors | Abstract | TPC group | Presenter |
|---|---|---|---|---|---|
| 1569250637 | The Source of SAR Calibration Requirements | Evert Attema; Paul Snoeij; Malcolm Davidson; Nicolas Floury; Bjorn Rommen | With the emergence of accurate well-calibrated Synthetic Aperture Radar (SAR) missions designed for operational and/or scientific purposes - rather than for technology demonstration - the development of calibration schemes aiming at the best possible accuracy may not be justified. Especially for operational long-term monitoring applications sustainability and cost need to be considered. Design-to-cost necessitates revisiting calibration requirements. The typical current performance levels, 0.5-1 dB amplitude uncertainty and 5-10 degrees phase uncertainty may not be satisfactory. In the paper it is argued that calibration requirements should be derived from the scientific or operational end-user requirements in terms of the information product (e.g. soil moisture, land motion velocity, sea surface wind speed) rather than in terms of technical parameters (e.g. intensity uncertainties, phase errors, noise, ambiguities, polarisation purity). It appears necessary to consider end-to-end calibration requirements linking information product requirements and technical requirements, but analyses of this type are not very common. Reasons for this are analysed including those associated with the disparity of the different communities involved: instruments designers, retrieval algorithm developers and market analysts. Based on a case study of soil moisture estimation using C-band SAR it is demonstrated that in principle the derivation of end-to-end calibration requirements is not very difficult as long as information on instrument, retrieval algorithm and user requirements are collected. Practical details and representative numbers in the paper are derived from analyses by the authors as part of their involvement in the development of Sentinel-1, the new operational C-band SAR mission contributing to the joint Global Monitoring for Environment and Security (GMES) initiative of the European Union and the European Space Agency. | Calibration Requirements | Attema |
| 1569250681 | GMES Sentinel-1 Transponder Development | Paul Snoeij; Evert Attema; Bjorn Rommen; Nicolas Floury; Malcolm Davidson | ESA is developing the Sentinel-1 European Radar Observatory, a constellation of two polar orbiting satellites for operational SAR applications. To ensure that the commissioning of a Sentinel-1 satellite can be performed within the allocated time and that the data from the Sentinel-1 constellation can be regularly assessed for quality and performance, it is necessary to have a set of precision transponders to act as point targets that can be automatically programmed and accessed during the mission life. The transponders shall be able to be operated in a rigorous climate, ranging from the tropical to the arctic regions with the required performance. This paper will discuss the requirements for the GMES Sentinel-1 transponders and will present a potential implementation. | Calibration Techniques | Snoeij |
| 1569254091 | Linking Sentinel-1 Level-1 data quality with Level-2 performance | Malcolm Davidson; Evert Attema; Paul Snoeij; Nicolas Floury; Bjorn Rommen | Data products involving information about geophysical variables (Level-2 products) such as ocean surface wind speed, ocean waves and currents, surface pollution, ice type, soil moisture and land cover can be derived from image data products (Level-1 products) using suitable retrieval models. Consequently the accuracy of Level-2 products are affected by measurement uncertainties associated with Level-1 products as well as by uncertainties associated with the retrieval models. Unlike soil moisture and wind speed estimation from the Sentinel-1 images whereby the absolute accuracy of the image intensity is essential many other Sentinel-1 data products rely on image intensity classification and detection of targets. For these types of products sufficient intensity contrast between different surfaces of between a target and its background is more important than the absolute accuracy. Products in this category include land cover classification, forest mapping, ice type classification, ship detection and oil spill detection at the ocean surface. In terms of the Level-1 data quality, Sentinel-1 radiometric and phase performance are defined by the magnitude of a number of error sources influencing the amplitude and the phase of its complex image products as well as the intensity of its detected image products. They include: - Instrument gain and phase characteristics - Thermal Noise - Effective number of looks - Non-linearity's including quantisation - Errors introduced in the processing and data distribution chain To assess the accuracy of the geophysical products of Sentinel-1, the Level-1 uncertainties above need to be translated into uncertainties in the final geophysical product through simulations based on actual or simplified retrieval algorithms. This presentation provides an overview of the methods and results achieved for the ESA Sentinel-1 mission | Future Missions | Snoeij |
| 1569255087 | Environmental Science Combining Data from a Small SAR on an Unmanned Aircraft with Satellite Observations: The microASAR on the NASA SIERRA UAS for the Characterization of Arctic Sea Ice Experiment (CASIE) | Evan C. Zaugg; David G. Long; Matthew Edwards; Matthew Fladeland; Richard Kolyer; Roger Crocker; James Maslanik; Ute Herzfeld | Combining a variety of remote sensing methods, including satellite observations and unmanned aircraft systems (UAS) offers additional capabilities for conducting scientific research. CASIE combines satellite observations and UAS measurements, to provide fundamental new insights into sea ice. This paper describes the microASAR, a small SAR system carried on board the NASA SIERRA UAS, and its role as part of CASIE-09. | Airborne Radars | Edwards |
| 1569256769 | Polarimetric calibration of the Ingara bistatic SAR | Alvin Goh; Mark Preiss; Nick Stacy; Doug Gray | The collection and analysis of bistatic polarimetric radar measurements is an area of potential research interest. Accordingly, a bistatic collection capability was recently added to the Australian Defence Science and Technology Organisation's Ingara X-band fully-polarimetric airborne SAR by supplementing it with a newly-developed fully-polarimetric stationary ground-based receiver, and high-resolution monostatic and bistatic SAR data sets have subsequently been collected with both airborne and ground-based receivers operating simultaneously. For the valid inference of target polarimetric scattering characteristics, system-introduced polarimetric distortions must first be corrected by polarimetric calibration, but established calibration procedures for bistatic polarimeters are best suited to stationary laboratory-type instrumentation radars rather than systems (like Ingara) with a moving airborne component. This paper discusses the calibration of the Ingara monostatic and bistatic data by a combination of alternative methods involving distributed-targets, calibration reflectors and the direct-path signal. | Airborne Radars | Stacy |
| 1569257053 | Comparison of Sentinel-1 and TerraSAR-X TOPS Processor Implementations based on Simulated Data | Josef Hermann Martin Mittermayer; Davide D'Aria; Evert Attema; Andrea Monti Guarnieri; Riccardo Piantanida; Pau Prats; Stefan Sauer; Paul Snoeij | The paper reports about the comparison of the “Experimental TerraSAR-X TOPS processor” with the “Sentinel-1 Prototype TOPS processor”. The comparison is based on the analysis of processing results from simulated data, i.e. simulated TerraSAR-X and Sentinel-1 TOPS raw data. The comparison program and the analysed performance parameters are presented. The task was rather challenging since two completely different processing approaches were compared to each other. | Ongoing Missions | D'Aria |
| 1569258303 | RADARSAT-2 Image Quality and Mode Maintenance and Enhancement | Anthony P. Luscombe | RADARSAT-2 started its Operational Phase in late April 2008, after a Commissioning Period of about 4 months. All of the original set of imaging modes were available and calibrated at that time, and all image quality specifications were met. However, since that time there has been ongoing work to enhance the imaging performance with the initial modes and to add additional capabilities to the system. This paper will report on that work, providing examples of some of the enhancements and additions. The presentation will illustrate some of the new capabilities that have been developed, and have either been added to the operational system or are currently being prepared as additions. | Ongoing Missions | Luscombe |
| 1569258305 | Local Incidence Angle Considered Harmful | David Small; Nuno Miranda; Erich H. Meier | We use ENVISAT ASAR Wide Swath imagery of Switzerland to demonstrate the differences between different normalisation methodogies to compensate for terrain variations during backscatter retrieval. Comparing conventional geocoded-terrain-corrected, commonly used local incidence angle normalisation, and image simulation based radiometric terrain correction, we conclude that the latter should be used when possible the improve the reliability of the retrieved backscatter values. | Calibration Techniques | Small |
| 1569258325 | Canadian Government Calibration Operations: The 13-year SAR Performance History of RADARSAT-1, and Independent RADARSAT-2 SAR Quality Measurements | Satish K Srivastava; Stephane Cote; Stephanie Muir; Bob Hawkins | Results from the calibration monitoring operations at the Canadian Space Agency are presented. The performance achieved by the RADARSAT-1 SAR since its initial calibration in 1997 is monitored by executing the mission's Calibration Plan. In addition, basic RADARSAT-2 SAR performance is monitored by the Canadian Government, to conduct an independent quality assurance mandate for this mission. | Ongoing Missions | Cote |
| 1569258339 | Canadian Government Calibration Operations: Exploitation of Distributed Target Sites within the RADARSAT Program | Stephane Cote; Stephanie Muir; Satish K Srivastava; Tom I Lukowski | The use of natural distributed targets is fundamental to maintaining SAR calibration. This report presents the distributed target areas that were exploited and experimented as part of the calibration activities of the Canadian Government within the RADARSAT Program, largely for elevation beam pattern determination. | Ongoing Missions | Cote |
| 1569258437 | TerraSAR-X Calibration Status - 2 Years in Flight | Dirk Schrank; Marco Schwerdt; Markus Bachmann; Björn J. Döring; Clemens Schulz | As TerraSAR-X, launched in June 2007, is an operational scientific mission with commercial potential, product quality is of paramount importance. The success or failure of the mission is essentially dependent on the calibration of the TerraSAR-X system ensuring the product quality and the correct in-orbit operation of the entire SAR system. Based on the excellent calibration results achieved during the commissioning phase after launch, continuing calibration guarantees a stable product quality and monitors the correct operation of the entire SAR system during whole life time of TerraSAR-X. Therefore, one essential task is long term system monitoring (LTSM) performed by periodic measurements over rainforest and permanently deployed reference targets, to ensure stable antenna patterns and constant radiometric accuracy of the instrument. In addition to regular LTSM measurements, an extended re calibration of the TerraSAR-X system was performed in July 2009. In contrast to the nominal LTSM task several beams for a wide range of incidence angles have been measured against a multitude of reference targets. Due to this great amount of different measurements precise results based on reliable statistics have been achieved. The paper describes the different activities performed for LTSM and re calibration of TerraSAR-X and discusses the results. | Ongoing Missions | Schrank |
| 1569258477 | Innovative and Efficient Strategy of Calibrating Sentinel-1 | Marco Schwerdt; Björn J. Döring; Manfred Zink; Dirk Schrank | The paper describes the strategy and the in-orbit calibration plan for efficiently conducting all required calibration procedures to externally calibrate Sentinel-1. The presented external calibration scenario demonstrates the capability to perform the different calibration procedures within the tight Sentinel-1 commissioning schedule. | Future Missions | Döring |
| 1569258519 | TanDEM-X: Mission Overview and Status | Manfred Zink; Gerhard Krieger; Hauke Fiedler; Alberto Moreira; Björn J. Döring | TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurement) opens a new era in space borne radar remote sensing. A single-pass SAR-interferometer with adjustable baselines in across- and in along-track directions is formed by adding a second (TDX), almost identical spacecraft, to TerraSAR-X (TSX) and flying the two satellites in a closely controlled formation. TDX has SAR system parameters which are fully compatible with TSX, allowing not only independent operation from TSX in a mono-static mode, but also synchronized operation (e.g. in a bi-static mode). With typical across-track baselines of 200-400m DEMs according to the High Resolution Terrain Information (HRTI)-3 standard will be generated. The HELIX concept provides a save solution for the close formation flight with vertical separation of the two satellites over the poles and adjustable horizontal baselines at the ascending/descending node crossings. | Ongoing Missions | Döring |
| 1569258621 | Investigating the Performance of the RADARSAT Precision Transponders | Bob Hawkins; Satish K Srivastava; Lana Ikkers; Peter Hoang; Kevin Murnaghan; Benjamin Nicholls | Since their development and deployment in 1995, the RADARSAT transponders have been used for many purposes and a wealth of experience has been acquired from their use. This paper talks about this experience and revisits the radiometric and geometric calibration of these instruments. In particular, the uncertainties associated with re-calibration, deployment, and polarization are highlighted in a more comprehensive error budget. | Ongoing Missions | Hawkins |
| 1569258625 | TSP-2 Solving the Radar Target Pointing Problem | Bob Hawkins; Jack Gibson; Luke Yaraskavitch; Kevin Marshall | Many SAR users are interested in the deployment and use of radar targets for a variety of reasons. Sometimes it relates to instrument calibration; sometimes, to geocoding; and, sometimes, to image marking. Whatever the reason, the target needs to be pointed toward the radar. The pointing depends on the target, the location on the earth, the spacecraft ephemeris, and the operating parameters of the sensor. With so many operating space-borne SARs in place, it is desirable to have a single piece of software which can accurately calculate the required pointing. This paper reviews the theoretical and practical implementation of a piece of SW developed at CCRS and known as TSP-2. | Calibration Techniques | Hawkins |
| 1569258659 | Calibration Requirements for Interferometric SAR by Comparison to Lidar in the Frequency Domain | Robert Neil Treuhaft; Fábio Guimarães Gonçalves; Jason Drake; Bruce Chapman; Joao Roberto Dos Santos; Luciano Dutra; Paulo Maurcio de Alencastro Graca | This paper focuses on the measurement accuracies of InSAR as suggested by biomass estimates from both lidar from LVIS [Blair et al. 2006] and interferometric SAR (InSAR) from AirSAR [Treuhaft et al. 2009] over tropical forests. Typically, forest biomass estimation with lidar is done with some form of forest height. We first demonstrate forest biomass regression results, using the height of median lidar energy (HOME). HOME was shown to perform at the 20% level by Drake et al. 2002 for biomasses up to about 250 Mg/ha. Only 14 of our 30 stands have biomass under 250 Mg/ha, and we also realize about a 20% result with HOME. However, when we increase the upper limit of the biomass to 500 Mg/ha, we now have 28 of our 30 stands and HOME performs at the 35-40% level, for biomasses from 20 to 500 Mg/ha. InSAR biomass estimates from mean height perform similarly. We show that HOME, mean height, and total height are related to the low Fourier vertical spatial frequency part of the lidar spectrum. By using higher frequency components of the lidar, we are able to improve lidar performance to 20-25% up to 500 Mg/ha. We make the correspondence between lidar vertical Fourier frequencies and InSAR baselines and compare the two. InSAR spatial frequencies derived from InSAR vertical profiles perform worse than the lidar, at about the 30% level for biomass estimation. Our analysis suggests that the InSAR biomass estimate performance could be potentially improved to that of the lidar with few-degree phase accuracy and few-percent coherence accuracy for baselines with vertical wavelengths of 20 m to 100 m (kappa_z of .06 to 0.3). J. B. Blair, M. A. Hofton, and D. L. Rabine, Processing of NASA LVIS elevation and canopy (LGE, LCE and LGW) data products, version 1.01, http://lvis.gsfc.nasa.gov, (2006). Treuhaft RN, Chapman BD, Santos JR, Gonçalves FG, Dutra LV, Graça PMA, Drake JB, Journal of Geophysical Research Atmospheres, doi:10.1029/2008JD011674, in press. | Calibration Requirements | Treuhaft |
| 1569258855 | Radiometric calibration aided by permanent scatterer: current status and future capabilities | Davide D'Aria; Andrea Monti Guarnieri; Paul Snoeij; Betlem Rosich; Davide Giudici; Paolo Biancardi | The PS calibration exploits both external devices, like corner reflectors, transponders etc and the stable target to provide continuous monitoring of the radiometric quality of a SAR instrument. It is therefore capable to provide, on the bases of image blocks (say 10 x 10 km), the precise geolocation and the full polarimetric calibration. This is achieved by identifying the stable targets, and using calibrated sites to provide the full characterization of the PS scattering matrix. In that way, it would be possible to calibrate even a dual polarimetric system, and estimate the space varying Faraday rotations in an L band sensor. In the paper, we discuss the problem of PS selection, the accuracy achievable by such approach and the current status obtained by processing data from ERS, Ground Based RADAR and full polarimetric data of the AgriSAR campaign. | Calibration Techniques | Giudici |
| 1569260399 | Requirement on Antenna Isolation for operational use of c-band Dual-Polarized SAR IN FUTURE constellation Mission | Ridha Touzi; Paris Vachon; John Wolfe; Bob Hawkins | Envisat ASAR (launched in 2002) was the first space-base SAR to use a dual-polarized antenna for measurement of target backscattering at single (HH, HV, or VV) and dual (HH-HV, VV-VH and HH-VV) polarization. ASAR is operating with a dual polarized antenna with an actual isolation of about -35 dB [1], and this permit the acquisition of pure HV measurement even at steep incidence angle (14° to 22° with the IS1 mode) . Since the launch of ASAR, several new satellite SARs with dual-polarized antennas have been launched, including ALOS L-band PALSAR with an actual antenna isolation of about -32 dB [2], RADARSAT-2 C-band SAR with an actual antenna isolation close to -35 dB [3], and TerraSAR X-band SAR with an antenna isolation of about -25dB [4]. In 2012, a new era in the operational use of dual-polarized SARs will start with the launch of two constellations of SAR satellites including the European Sentinel-1 (with a requirement of -30 dB isolation) [4] and the Canadian RADARSAT Constellation Mission. An issue that could influence dual-polarized SAR imaging is the antenna isolation. In the last CEOS-ASAR workshop (Vancouver, June 2007), a minimum antenna isolation requirement was endorsed by the calibration community as -25 dB for X-, C-, and L-band SAR. In this study, calibrated polarimetric RADARSAT-2 data were used to simulate the impact of low antenna isolation on key C-band SAR applications. Radar backscattering at HV from ocean and natural extended targets is generally much lower than the backscattering at HH or VV (e.g., 6 dB lower in dense forests). As a result, significant contamination of the HV channel (i.e., through HH and VV cross-talk) could occur under low antenna isolation conditions. In the following, key applications that rely on cross-polarization measurements are considered. In particular, we know that HV performs much better than HH or VV for ship detection at incidence angles in the 15° to 45° range [5]. Also, it has recently been shown using RADARSAT-2 data that HV can provide an accurate measurement of wind speed that is independent of wind direction and SAR illumination angle [7]. To demonstrate the impact of antenna isolation, simulated single polarization images have been generated at 20°, 30° and 40° incidence angles with various antenna isolations, and the impact on ship detection and wind speed measurement has been quantified. It is shown that a minimum requirement of -30 dB should be adopted for C-band SAR antennas in order to minimize the impact of like-polarization cross-talk on these applications. Furthermore, a -35 dB antenna isolation is desirable to almost completely cancel any residual like-polarization contamination at steep incidence angle (i.e., at 20° and steeper). [1] B. Rosich, M. Zink, R. Torres et al., “ASAR instrument performance and product quality status”, IGARSS’03, Toulouse, Framce, 2003. [2] R. Touzi and M. Shimada, “Calibration of polarimetric PALSAR”, IEEE TGRS, ALOS special issue, in press. [3] A.P. Luscombe, RADARSAT-2 Polarimetric Mode Calibration and Data Quality Assessment, Proceedings of CEOS SAR Workshop 2008, CEOS Working Group on Calibration and Validation, SAR Subgroup, 27-28 November 2008, DLR, Germany. [4] R. Werninghaus. W. Balzer, S. Buckreuss, P. Mühlbauer, and W. Pitz, “The TerrSAR-X Mission”, Proceedings of EUSAR 2004, vol. 1, pp. 21-22, May 2004. [5] E.Attema, P. Snoeij et al., “The European GMES Sentinel-1 Radar Mission”, IGARSS’08, Boston, USA, 2008. [6] R. Touzi, F. Charbonneau, R.K. Hawkins, and P.W. Vachon, “Ship detection and characterization using polarimetric SAR”. Canadian Journal of Remote Sensing, Special issue on RADARSAT-2, June 2004. [7] P.W. Vachon and J. Wolfe, “Cross-pol wind retrieval?”, to be presented at the First National Meeting on Operationalization of Synthetic Aperture Radar (SAR) Winds, 5-6 Nov. 2009, Ottawa, Canada | Future Missions | Hawkins |
| 1569260513 | SAR Image Quality Measures Relevant for Operational Ship and Oil Spill Detection | Michele Vespe; Harm Greidanus | This paper aims to give an overview discussion of which SAR image quality aspects are the most relevant for ship and oil spill detection products, and how measures of image quality can be defined that can be used in practical situations. This effort should eventually contribute to the consistency of the operational service products, designed to deliver consistent indications of critical importance. | Calibration Requirements | Vespe |
| 1569260763 | SAR Calibration Requirements for Interferometry Applications: inching towards sub millimeter measurements | Fabio Rocca; Alessandro Ferretti; Andrea Monti Guarnieri | In order to achieve a consistent design of a SAR mission, it is reasonable to start from a specific goal and then, if doable, to fit to that goal the entire measurement chain, in order to avoid overdesign or bottlenecks. We start from the requisite of 1mm dispersion of subsidence over 1 year of measurements, justified by results of similar order of magnitude that can be obtained using optical leveling or GPS. SAR data have the advantages of giving areal measurements, of being much cheaper and able to revisit the past, and the disadvantage of not being able to exactly evaluate the structure and nature of the scattering targets. We know that these results can be obtained using either Permanent Scatterers or, using the decorrelation statistics gathered in C band in the three days revisit cycle, also distributed and decorrelating scatterers, provided that at least say about 50 of them move at the same speed. After showing the feasibility of millimeter results in C band, to be exploited in the forthcoming Sentinel 1 mission, we discuss the possibility of improvement also using higher frequencies, like X or Ku band. The needs for this improvement come, for example, from the needs of geophysical inversion, to measure permeability of oil reservoirs or possibilities and risks in the sequestration of CO2. In these cases, more than the spatial resolution, the precision and the sub weekly frequency of the measurements are paramount, and indeed, with Sentinel 1 A/B the measurement chain from the quantization to the revisit time will be upgraded with respect to the present situation. Results from the CESI experiment in Milano and from ground based radar show that this improved precision is indeed achievable in C as well as in Ku band, provided that an accurate model of the delay due to atmospheric water vapor is available or that precise reference points are close by. Inroads in the improvements of the general weather forecast models, that are requested only to yield the water vapor delay averaged over all the interferometric takes, and the dream of a geosynchronous SAR satellite to measure that delay, will conclude the talk. | Calibration Requirements | Rocca |
| 1569260851 | Recent dramatic advances in developing fully polarimetric space SAR sensors: Why must reduced Compact SAR concepts not be accepted for satellite sensor implementation, and where do we go from here? | Wolfgang Boerner | Land cover monitoring is one of the most potential applications of Polarimetric Synthetic Aperture Radar (POLSAR) sensing and so is Repeat-Pass Polarimetric-Interferometric SAR (RP-DIFF-POL-IN-SAR) stress-change assessment by air/high-altitude/space-borne SAR sensor deployment. Provided fully polarimetric SAR information can be made available, a plethora of novel POLSAR matrix decomposition methods can be implemented for recovering rather precise scattering contributions from isolated and distributed scattering scenarios, and so can rather exact environmental changes from consecutive repeat-pass observations at 1 m resolution from air and from space. With the recent launches of the fully polarimetric satellites JAXA-ALOS (PAL-SAR-L-Band), the DLR TerraSAR-X (X-Band) and of RADASAT-2 (C-Band), a new era in space imaging of the terrestrial terrain and ocean surfaces has arrived providing unforeseen advantages. Here, it needs to be explicitly emphasized that the ill-received Compact-SAR concepts cannot provide the required image interpretation which can only be achieved by fully polarimet-ric POL-SAR sensors in air and in space. Whereas in the past, POLSAR applications were focused mainly on information product gathering for agriculture, forestry and the fisheries, little emphasis was placed on demonstrating its full capacity also for the assessment of natural habitats and especially wetlands and desert regions for which Compact and Dual-Pol SAR sensors were sufficient. However by implementing fully polarimetric Space-SAR sensors, we are now able to demonstrate how seasonal changes and features of vegetation in natural habitats, shallow vegetated lakes and wetlands & deserts can be recovered under worst weather conditions and at day and during night at most distant and often inaccessible hidden sites, where for example migrant birds rest. Land cover monitoring is one of the most potential applications of Polarimetric Synthetic Aper-ture Radar (POLSAR) sensing and so is Repeat-Pass Polarimetric-Interferometric SAR (RP-DIFF-POL-IN-SAR) stress-change assessment by air/high-altitude/space-borne SAR sensor deployment. Provided fully polarimetric SAR information can be made available, a plethora of novel POLSAR matrix decomposition methods can be implemented for recovering rather precise scattering contributions from isolated and distributed scattering scenarios, and so can rather exact environmental changes from consecutive repeat-pass observations at 1 m resolution from air and from space. It is essential to emphasize that fully polarimetric SAR image data sets are strictly required for optimal information extraction and compacted or hybrid quasi-polarimetric SAR imaging will fail to discover intricate detailed feature characteristics and parameters. | Future Missions | Boerner |
| 1569262107 | SMAP Calibration Requirements and Level 1 Processing | Richard West | This presentation will describe the soil moisture science requirements and their impact on the design parameters of the Soil Moisture Active Passive (SMAP) radar, and on the level 1 sigma0 processing. The current basic requirement is 1 dB accuracy (one-sigma) in the sigma0 measurements at a resolution of 3 km. This measurement accuracy provides for a soil moisture accuracy of 6% volumetric. The main error contributions come from speckle noise, calibration uncertainty, and residual RFI interference. Speckle noise is determined by system design parameters. The calibration of the L1 sigma0 data will be based on pre-launch characterization of the radar components and analysis of post-launch data. Both the radar and radiometer will take advantage of a cold-space viewing maneuver performed shortly after launch to measure the receive path gain and noise temperature. Then data collected over known distributed targets such as the Amazon and over the oceans will be evaluated to provide an absolute calibration. This absolute calibration will be verified against other L-band spaceborne instruments such as ALOS-PALSAR and Aquarius that observe the same distributed targets. Relative calibration performance will be verified by checking for systematic scan angle dependencies in the image data over uniform distributed targets. Radio Frequency Interference (RFI) survey measurements will be included to measure the extent of RFI around the world. The SMAP radar is designed to be able to hop the operating frequency within the 80 MHz allocated band to avoid the worst RFI emitters. Data processing will detect and discard further RFI contaminated measurements. Additional RFI mitigation will be incorporated as needed to meet requirements. This work is supported by the SMAP project at JPL – CalTech. | Future Missions | West |
| 1569262407 | Country-Wide 3D Mapping by Airborne InSAR | Bryan Mercer | Three-dimensional data-sets as manifested in Digital Surface Models (DSMs) and Digital Terrain Models (DTMs) have become an integral part of most geospatial applications, both traditional and emerging. However, one difficulty for the user is that there has existed a gap between the broad coverage, low cost DSM afforded by SRTM and the highly detailed but costly and sporadic coverage of lidar. Moreover, in the European context, the historical data sets are referenced to a variety of datums, ellipsoids and geoids. On the other hand, many applications do not stop at political boundaries. NEXTMap® Europe is Intermap’s solution to fill the gap with a 1 meter vertical (RMSE) , 5 meter gridded elevation data set that is trans-national across a broad portion of Western Europe. In May 2009, Intermap announced the completion of its current NEXTMap® Europe program. The resulting data set spans 15 countries and 2.2Million km². Meanwhile a similar program , NEXTMap® USA, covering more than 8 Million km2 has seen completion of the acquisition phase and is scheduled for total completion and data-base availability by early 2010. In this paper we provide the technical and operational background to this accomplishment, demonstrate the wide-area consistency of the vertical accuracy supported by the data and provide a few examples from a range of applications. While the former relates to an operationally established program, we also wish to provide a short update on an R&D activity relating to the use of a single-pass, fully polarimetric airborne L-Band InSAR system for DTM extraction and forest height recovery using Pol-InSAR methodology. The virtue of this single-pass system is to remove the issue of temporal de-correlation which impacts PolInSAR results from repeat-pass systems. In this discussion we will focus on tree height recovery results from two test sites in western Canada. | Airborne Radars | Mercer |
| 1569263927 | Performance of PALSAR sensor on-board ALOS: Towards the retrieval of bio- and geo-physical parameters | Nicolas Longépé; Masanobu Shimada; Osamu Isoguchi; Preesan Rakwatin; Takeo Tadono | In this study, the results obtained from the geometric and radiometric calibrations are summarized. The relevance of PALSAR for forest monitoring at regional scale is then detailed. Beyond forestry, the usefulness of PALSAR for the retrieval of bio- and geo-physical parameters is finally presented for other natural media (cryosphere, ocean...). | Ongoing Missions | Longépé |
| 1569265929 | Recent Calibration/Validation Activities at the Harvard Forest in Support of the DESDynI mission | Paul Siqueira; Razi Ahmed | During the summer of 2009, a concerted ground validation campaign was conducted in the Northeast Region, for the purpose of supporting the Ecosystem Science component of the DESDynI mission. In addition to the 15 hectare collection of vegetation structural parameters, the effort was complemented by observations made by UAVSAR, LVIS, ALOS/PALSAR, a 30 cm resolution imaging camera, as well and the Echidna terrestrial lidar. The large collection of ground validation and remotely sensed data represents a superset of information that can be used for testing DESDynI related algorithms for determining characteristics of forest structure and, more importantly, configurational variables that will effect retrieval accuracy for a mission like DESDynI. In this talk, we discuss the approach being taken for incorporating the variety of observational resources as well as for assessing time-dependent variables in the observations that will ultimately affect desired outcomes. | Future Missions | Siqueira |
| 1569266319 | The Aquarius Mission Calibration/Validation Overview | Adam Freedman; Dalia McWatters | The Aquarius/SAC-D Mission includes a combined radiometer and scatterometer to measure ocean salinity. The radiometer measures ocean brightness temperature (a function of sea-surface temperature, ocean roughness, and salinity), while the scatterometer measures ocean roughness in order to correct the ocean brightness. This talk will give an overview of the Aquarius instrument and its measurement requirements, highlighting the differences between its scatterometer radar requirements and those for SAR systems. The strategies for both internal and external calibration of the radar and radiometer will be discussed. Test data validating the internal stability of the scatterometer with both an internal loopback path and an external fiber-optic delay line will be shown. Plans for on-orbit calibration will also be presented. | Future Missions | Freedman |
| 1569267291 | UAVSAR Polarimetric Calibration | Alex Fore; Bruce Chapman; Scott Hensley; Thierry Michel; Ronald Muellerschoen | UAVSAR is a reconfigurable, polarimetric L-band synthetic aperture radar (SAR), is specifically designed to acquire airborne repeat track SAR data for differential interferometric measurements. Using a precision autopilot and differential GPS, the system is designed to fly within a 10m tube to enable airborne repeat track interferometry. In this talk, we discuss the radiometric and polarimetric calibration of the UAVSAR instrument. We use an array of trihedral corner reflectors as well as distributed targets for radiometric and phase calibration. We find that the radiometric calibration of UAVSAR is good to less than 1 dB and the phase calibration is good to about 5 degrees as measured at the corner reflectors. For cross-talk calibration we have explored the methods of Quegan and Ainsworth, both of which use the data itself for computing the calibration. We find that the method of Quegan gives cross-talk estimates that seem to depend on target type while the method of Ainsworth gives more stable cross-talk estimates. | Airborne Radars | Fore |
| 1569267641 | SAR Calibration Requirements for Soil Moisture Estimation | Zoltan Bartalis; Wolfgang Wagner; Vahid Naeimi; Daniel Sabel; Carsten Pathe | The importance of soil moisture in controlling the energy fluxes and water exchange between land and atmosphere is indisputable. Together with snow cover, it is also the most important component of meteorological memory for the climate system over land. Information about global soil moisture is also urgently required for assessing the impacts and feedback mechanisms of global warming on the Earth land surfaces. Recent advances in retrieval algorithms have offered the possibility to obtain soil moisture information from passive microwave instruments (SMMR, SSM/I, AMSR-E, etc.) as well as active sensors, both synthetic aperture ones (Envisat ASAR, etc) and real aperture scatterometers (the ERS scatterometers, ASCAT onboard Metop). One method based on the latter two instruments is the one developed at Vienna University of Technology. The algorithm makes strong use of change detection, and is, as such, highly dependent on the relative and absolute calibration of the scatterometers. In this paper we discuss our findings with respect to scatterometer calibration requirements for soil moisture retrieval, and relate these to deriving soil moisture using SAR instruments. | Calibration Requirements | Bartalis |
| Detection and Characterization of Ionospheric Effects in ALOS PALSAR Data | Franz Meyer; Jeremy Nicoll; Rayjan Wilson | Calibration Techniques | Wilson | ||
| Target Design and Deployment for In-Field GeoSAR Calibration | Mark Williams; Mark Sanford; Jim Reis; Bert Kampes; Boris Kofman; Alina Yohannan; Louis Dean | Airborne Radars | Williams | ||
| The Soil Moisture Active and Passive (SMAP) Observing System | Mike Spencer; Richard West | Future Missions | West |