Radar signatures of road vehicles: airborne SAR experiments

NASA Astrophysics Data System (ADS)

Palubinskas, G.; Runge, H.; Reinartz, P.

2005-10-01

The German radar satellite TerraSAR-X is a high resolution, dual receive antenna SAR satellite, which will be launched in spring 2006. Since it will have the capability to measure the velocity of moving targets, the acquired interferometric data can be useful for traffic monitoring applications on a global scale. DLR has started already the development of an automatic and operational processing system which will detect cars, measure their speed and assign them to a road. Statistical approaches are used to derive the vehicle detection algorithm, which require the knowledge of the radar signatures of vehicles, especially under consideration of the geometry of the radar look direction and the vehicle orientation. Simulation of radar signatures is a very difficult task due to the lack of realistic models of vehicles. In this paper the radar signatures of the parking cars are presented. They are estimated experimentally from airborne E-SAR X-band data, which have been collected during flight campaigns in 2003-2005. Several test cars of the same type placed in carefully selected orientation angles and several over-flights with different heading angles made it possible to cover the whole range of aspect angles from 0° to 180°. The large synthetic aperture length or beam width angle of 7° can be divided into several looks. Thus processing of each look separately allows to increase the angle resolution. Such a radar signature profile of one type of vehicle over the whole range of aspect angles in fine resolution can be used further for the verification of simulation studies and for the performance prediction for traffic monitoring with TerraSAR-X.

Onboard Interferometric SAR Processor for the Ka-Band Radar Interferometer (KaRIn)

NASA Technical Reports Server (NTRS)

Esteban-Fernandez, Daniel; Rodriquez, Ernesto; Peral, Eva; Clark, Duane I.; Wu, Xiaoqing

2011-01-01

An interferometric synthetic aperture radar (SAR) onboard processor concept and algorithm has been developed for the Ka-band radar interferometer (KaRIn) instrument on the Surface and Ocean Topography (SWOT) mission. This is a mission- critical subsystem that will perform interferometric SAR processing and multi-look averaging over the oceans to decrease the data rate by three orders of magnitude, and therefore enable the downlink of the radar data to the ground. The onboard processor performs demodulation, range compression, coregistration, and re-sampling, and forms nine azimuth squinted beams. For each of them, an interferogram is generated, including common-band spectral filtering to improve correlation, followed by averaging to the final 1 1-km ground resolution pixel. The onboard processor has been prototyped on a custom FPGA-based cPCI board, which will be part of the radar s digital subsystem. The level of complexity of this technology, dictated by the implementation of interferometric SAR processing at high resolution, the extremely tight level of accuracy required, and its implementation on FPGAs are unprecedented at the time of this reporting for an onboard processor for flight applications.

Forest Attributes from Radar Interferometric Structure and its Fusion with Optical Remote Sensing

NASA Technical Reports Server (NTRS)

Treuhaft, Robert N.; Law, Beverly E.; Asner, Gregory P.

2004-01-01

The possibility of global, three-dimensional remote sensing of forest structure with interferometric synthetic aperture radar (InSAR) bears on important forest ecological processes, particularly the carbon cycle. InSAR supplements two-dimensional remote sensing with information in the vertical dimension. Its strengths in potential for global coverage complement those of lidar (light detecting and ranging), which has the potential for high-accuracy vertical profiles over small areas. InSAR derives its sensitivity to forest vertical structure from the differences in signals received by two, spatially separate radar receivers. Estimation of parameters describing vertical structure requires multiple-polarization, multiple-frequency, or multiple-baseline InSAR. Combining InSAR with complementary remote sensing techniques, such as hyperspectral optical imaging and lidar, can enhance vertical-structure estimates and consequent biophysical quantities of importance to ecologists, such as biomass. Future InSAR experiments will supplement recent airborne and spaceborne demonstrations, and together with inputs from ecologists regarding structure, they will suggest designs for future spaceborne strategies for measuring global vegetation structure.

Simulation of a weather radar display for over-water airborne radar approaches

NASA Technical Reports Server (NTRS)

Clary, G. R.

1983-01-01

Airborne radar approach (ARA) concepts are being investigated as a part of NASA's Rotorcraft All-Weather Operations Research Program on advanced guidance and navigation methods. This research is being conducted using both piloted simulations and flight test evaluations. For the piloted simulations, a mathematical model of the airborne radar was developed for over-water ARAs to offshore platforms. This simulated flight scenario requires radar simulation of point targets, such as oil rigs and ships, distributed sea clutter, and transponder beacon replies. Radar theory, weather radar characteristics, and empirical data derived from in-flight radar photographs are combined to model a civil weather/mapping radar typical of those used in offshore rotorcraft operations. The resulting radar simulation is realistic and provides the needed simulation capability for ongoing ARA research.

14 CFR 135.175 - Airborne weather radar equipment requirements.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airborne weather radar equipment... Aircraft and Equipment § 135.175 Airborne weather radar equipment requirements. (a) No person may operate a large, transport category aircraft in passenger-carrying operations unless approved airborne weather...

14 CFR 135.175 - Airborne weather radar equipment requirements.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Airborne weather radar equipment... Aircraft and Equipment § 135.175 Airborne weather radar equipment requirements. (a) No person may operate a large, transport category aircraft in passenger-carrying operations unless approved airborne weather...

14 CFR 135.175 - Airborne weather radar equipment requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Airborne weather radar equipment... Aircraft and Equipment § 135.175 Airborne weather radar equipment requirements. (a) No person may operate a large, transport category aircraft in passenger-carrying operations unless approved airborne weather...

14 CFR 135.175 - Airborne weather radar equipment requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Airborne weather radar equipment... Aircraft and Equipment § 135.175 Airborne weather radar equipment requirements. (a) No person may operate a large, transport category aircraft in passenger-carrying operations unless approved airborne weather...

14 CFR 135.175 - Airborne weather radar equipment requirements.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Airborne weather radar equipment... Aircraft and Equipment § 135.175 Airborne weather radar equipment requirements. (a) No person may operate a large, transport category aircraft in passenger-carrying operations unless approved airborne weather...

77 FR 21834 - Airborne Radar Altimeter Equipment (For Air Carrier Aircraft)

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-11

... DEPARTMENT OF TRANSPORTATION Federal Aviation Administration Airborne Radar Altimeter Equipment... Technical Standard Order (TSO)-C67, Airborne Radar Altimeter Equipment (For Air Carrier Aircraft). SUMMARY: This is a confirmation notice of the cancellation of TSO-C67, Airborne Radar Altimeter Equipment (For...

Theory and design of interferometric synthetic aperture radars

NASA Technical Reports Server (NTRS)

Rodriguez, E.; Martin, J. M.

1992-01-01

A derivation of the signal statistics, an optimal estimator of the interferometric phase, and the expression necessary to calculate the height-error budget are presented. These expressions are used to derive methods of optimizing the parameters of the interferometric synthetic aperture radar system (InSAR), and are then employed in a specific design example for a system to perform high-resolution global topographic mapping with a one-year mission lifetime, subject to current technological constraints. A Monte Carlo simulation of this InSAR system is performed to evaluate its performance for realistic topography. The results indicate that this system has the potential to satisfy the stringent accuracy and resolution requirements for geophysical use of global topographic data.

GeoSAR: A Radar Terrain Mapping System for the New Millennium

NASA Technical Reports Server (NTRS)

Thompson, Thomas; vanZyl, Jakob; Hensley, Scott; Reis, James; Munjy, Riadh; Burton, John; Yoha, Robert

2000-01-01

GeoSAR Geographic Synthetic Aperture Radar) is a new 3 year effort to build a unique, dual-frequency, airborne Interferometric SAR for mapping of terrain. This is being pursued via a Consortium of the Jet Propulsion Laboratory (JPL), Calgis, Inc., and the California Department of Conservation. The airborne portion of this system will operate on a Calgis Gulfstream-II aircraft outfitted with P- and X-band Interferometric SARs. The ground portions of this system will be a suite of Flight Planning Software, an IFSAR Processor and a Radar-GIS Workstation. The airborne P-band and X-band radars will be constructed by JPL with the goal of obtaining foliage penetration at the longer P-band wavelengths. The P-band and X-band radar will operate at frequencies of 350 Mhz and 9.71 Ghz with bandwidths of either 80 or 160 Mhz. The airborne radars will be complemented with airborne laser system for measuring antenna positions. Aircraft flight lines and radar operating instructions will be computed with the Flight Planning Software The ground processing will be a two-step step process. First, the raw radar data will be processed into radar images and interferometer derived Digital Elevation Models (DEMs). Second, these radar images and DEMs will be processed with a Radar GIS Workstation which performs processes such as Projection Transformations, Registration, Geometric Adjustment, Mosaicking, Merging and Database Management. JPL will construct the IFSAR Processor and Calgis, Inc. will construct the Radar GIS Workstation. The GeoSAR Project was underway in November 1996 with a goal of having the radars and laser systems fully integrated onto the Calgis Gulfstream-II aircraft in early 1999. Then, Engineering Checkout and Calibration-Characterization Flights will be conducted through November 1999. The system will be completed at the end of 1999 and ready for routine operations in the year 2000.

(abstract) Studies of Interferometric Penetration into Vegetation Canopies using Multifrequency Interferometry Data at JPL

NASA Technical Reports Server (NTRS)

Hensley, Scott; Rodriguez, Ernesto; Truhafft, Bob; van Zyl, Jakob; Rosen, Paul; Werner, Charles; Madsen, Sren; Chapin, Elaine

1997-01-01

Radar interferometric observations both from spaceborne and airborne platforms have been used to generate accurate topographic maps, measure milimeter level displacements from earthquakes and volcanoes, and for making land cover classification and land cover change maps. Interferometric observations have two basic measurements, interferometric phase, which depends upon the path difference between the two antennas and the correlation. One of the key questions concerning interferometric observations of vegetated regions is where in the canopy does the interferometric phase measure the height. Results for two methods of extracting tree heights and other vegetation parameters based upon the amount of volumetric decorrelation will be presented.

UAVSAR: An Airborne Window on Earth Surface Deformation

NASA Technical Reports Server (NTRS)

Hensley, Scott

2011-01-01

This study demonstrates that UAVSAR's precision autopilot and electronic steering have allowed for the reliable collection of airborne repeat pass radar interferometric data for deformation mapping. Deformation maps from temporal scales ranging from hours to months over a variety of signals of geophysical interest illustrate the utility of UAVSAR airborne repeat pass interferometry to these studies.

Airborne microwave radar measurements of surface velocity in a tidally-driven inlet

NASA Astrophysics Data System (ADS)

Farquharson, G.; Thomson, J. M.

2012-12-01

A miniaturized dual-beam along-track interferometric (ATI) synthetic aperture radar (SAR), capable of measuring two components of surface velocity at high resolution, was operated during the 2012 Rivers and Inlets Experiment (RIVET) at the New River Inlet in North Carolina. The inlet is predominantly tidally-driven, with little upstream river discharge. Surface velocities in the inlet and nearshore region were measured during ebb and flood tides during a variety of wind and offshore wave conditions. The radar-derived surface velocities range from around ±2~m~s1 during times of maximum flow. We compare these radar-derived surface velocities with surface velocities measured with drifters. The accuracy of the radar-derived velocities is investigated, especially in areas of large velocity gradients where along-track interferometric SAR can show significant differences with surface velocity. The goal of this research is to characterize errors in along-track interferometric SAR velocity so that ATI SAR measurements can be coupled with data assimilative modeling with the goal of developing the capability to adequately constrain nearshore models using remote sensing measurements.

Removing interfering clutter associated with radar pulses that an airborne radar receives from a radar transponder

DOEpatents

Ormesher, Richard C.; Axline, Robert M.

2008-12-02

Interfering clutter in radar pulses received by an airborne radar system from a radar transponder can be suppressed by developing a representation of the incoming echo-voltage time-series that permits the clutter associated with predetermined parts of the time-series to be estimated. These estimates can be used to estimate and suppress the clutter associated with other parts of the time-series.

Airborne radar radiometer measurements of tropical storms

NASA Technical Reports Server (NTRS)

Kumagai, H.; Meneghini, R.; Kozu, T.; Okamoto, K.

1992-01-01

The results from an airborne radar radiometer experiment of rainfall measurement in tropical storms are presented. The experiment was conducted in the Western Pacific in September 1990 with the NASA/DC-8 aircraft which was equipped with a nadir-loking dual-frequency rain radar operating at X band and Ka band, and several channels of microwave radiometers. The X-band radar has a capability of dual-polarization reception which enables the measurements of Linear Depolarization Ratio (LDR). The data of the microwave radiometers are compared with the radar data.

Software development for airborne radar

NASA Astrophysics Data System (ADS)

Sundstrom, Ingvar G.

Some aspects for development of software in a modern multimode airborne nose radar are described. First, an overview of where software is used in the radar units is presented. The development phases-system design, functional design, detailed design, function verification, and system verification-are then used as the starting point for the discussion. Methods, tools, and the most important documents are described. The importance of video flight recording in the early stages and use of a digital signal generators for performance verification is emphasized. Some future trends are discussed.

Real-time simulation of an airborne radar for overwater approaches

NASA Technical Reports Server (NTRS)

Karmarkar, J.; Clark, D.

1982-01-01

Software developed to provide a real time simulation of an airborne radar for overwater approaches to oil rig platforms is documented. The simulation is used to study advanced concepts for enhancement of airborne radar approaches (ARA) in order to reduce crew workload, improve approach tracking precision, and reduce weather minimums. ARA's are currently used for offshore helicopter operations to and from oil rigs.

The Next Generation Airborne Polarimetric Doppler Radar

NASA Astrophysics Data System (ADS)

Vivekanandan, J.; Lee, Wen-Chau; Loew, Eric; Salazar, Jorge; Chandrasekar, V.

2013-04-01

NCAR's Electra Doppler radar (ELDORA) with a dual-beam slotted waveguide array using dual-transmitter, dual-beam, rapid scan and step-chirped waveform significantly improved the spatial scale to 300m (Hildebrand et al. 1996). However, ELDORA X-band radar's penetration into precipitation is limited by attenuation and is not designed to collect polarimetric measurements to remotely estimate microphysics. ELDORA has been placed on dormancy because its airborne platform (P3 587) was retired in January 2013. The US research community has strongly voiced the need to continue measurement capability similar to the ELDORA. A critical weather research area is quantitative precipitation estimation/forecasting (QPE/QPF). In recent years, hurricane intensity change involving eye-eyewall interactions has drawn research attention (Montgomery et al., 2006; Bell and Montgomery, 2006). In the case of convective precipitation, two issues, namely, (1) when and where convection will be initiated, and (2) determining the organization and structure of ensuing convection, are key for QPF. Therefore collocated measurements of 3-D winds and precipitation microphysics are required for achieving significant skills in QPF and QPE. Multiple radars in dual-Doppler configuration with polarization capability estimate dynamical and microphysical characteristics of clouds and precipitation are mostly available over land. However, storms over complex terrain, the ocean and in forest regions are not observable by ground-based radars (Bluestein and Wakimoto, 2003). NCAR/EOL is investigating potential configurations for the next generation airborne radar that is capable of retrieving dynamic and microphysical characteristics of clouds and precipitation. ELDORA's slotted waveguide array radar is not compatible for dual-polarization measurements. Therefore, the new design has to address both dual-polarization capability and platform requirements to replace the ELDORA system. NCAR maintains a C-130

Wideband radar for airborne minefield detection

NASA Astrophysics Data System (ADS)

Clark, William W.; Burns, Brian; Dorff, Gary; Plasky, Brian; Moussally, George; Soumekh, Mehrdad

2006-05-01

Ground Penetrating Radar (GPR) has been applied for several years to the problem of detecting both antipersonnel and anti-tank landmines. RDECOM CERDEC NVESD is developing an airborne wideband GPR sensor for the detection of minefields including surface and buried mines. In this paper, we describe the as-built system, data and image processing techniques to generate imagery, and current issues with this type of radar. Further, we will display images from a recent field test.

Generation and evaluation of Cryosat-2 SARIn L1b Interferometric elevation

NASA Astrophysics Data System (ADS)

DONG, Y.; Zhang, K.; Liu, Q.; MA, J.; WANG, J.

2016-12-01

CryoSat-2 radar altimeter data have successfully used in mapping surface elevations of ice caps and ice sheets, finding the change of surface height in polar area. The SARIn mode of Synthetic Aperture Interferometric Altimeter (SIRAL), which working similar with the traditional Interferometric Synthetic Aperture Radar (IFSAR) method, can improve the across- and along-track resolution by IFSAR processing algorithm. In this study, three L1b Baseline-C SARIn tracks over the Filchner ice shelf are used to generate the location and height of ground points in sloping glacial terrain. The elevation data is mapped and validated with IceBridge Airborne Topographic Mapper (ATM) data acquired at Nov. 2, 2012. The comparison with ATM data shows a mean difference of -1.91 m with a stand deviation of 4.04 m.

The Next Generation of Airborne Polarimetric Doppler Weather Radar: NCAR/EOL Airborne Phased Array Radar (APAR) Development

NASA Astrophysics Data System (ADS)

Moore, James; Lee, Wen-Chau; Loew, Eric; Vivekanandan, Jothiram; Grubišić, Vanda; Tsai, Peisang; Dixon, Mike; Emmett, Jonathan; Lord, Mark; Lussier, Louis; Hwang, Kyuil; Ranson, James

2017-04-01

The National Center for Atmospheric Research (NCAR) Earth observing Laboratory (EOL) is entering the third year of preliminary system design studies, engineering prototype testing and project management plan preparation for the development of a novel Airborne Phased Array Radar (APAR). This system being designed by NCAR/EOL will be installed and operated on the NSF/NCAR C-130 aircraft. The APAR system will consist of four removable C-band Active Electronically Scanned Arrays (AESA) strategically placed on the fuselage of the aircraft. Each AESA measures approximately 1.5 x 1.9 m and is composed of 3000 active radiating elements arranged in an array of line replaceable units (LRU) to simplify maintenance. APAR will provide unprecedented observations, and in conjunction with the advanced radar data assimilation schema, will be able to address the key science questions to improve understanding and predictability of significant and high-impact weather APAR, operating at C-band, allows the measurement of 3-D kinematics of the more intense portions of storms (e.g. thunderstorm dynamics and tornadic development, tropical cyclone rainband structure and evolution) with less attenuation compared with current airborne Doppler radar systems. Polarimetric measurements are not available from current airborne tail Doppler radars. However, APAR, with dual-Doppler and dual polarization diversity at a lesser attenuating C-band wavelength, will further advance the understanding of the microphysical processes within a variety of precipitation systems. The radar is sensitive enough to provide high resolution measurements of winter storm dynamics and microphysics. The planned APAR development that would bring the system to operational readiness for research community use aboard the C-130 is expected to take 8 years once major funding support is realized. The authors will review the overall APAR design and provide new details of the system based on our Technical Requirements Document

Calibration of a 35-GHz Airborne Cloud Radar: Lessons Learned and Intercomparison with a 94-GHz Airborne Cloud Radar

NASA Astrophysics Data System (ADS)

Ewald, Florian; Gross, Silke; Hagen, Martin; Hirsch, Lutz; Delanoë, Julien

2017-04-01

Clouds play an important role in the climate system since they have a profound influence on Earth's radiation budget and the water cycle. Uncertainties associated with their spatial characteristics as well as their microphysics still introduce large uncertainties in climate change predictions. In recent years, our understanding of the inner workings of clouds has been greatly advanced by the deployment of cloud profiling microwave radars from ground as well as from space like CloudSat or the upcoming EarthCARE satellite mission. In order to validate and assess the limitations of these spaceborne missions, a well-calibrated, airborne cloud radar with known sensitivity to clouds is indispensable. Within this context, the German research aircraft HALO was equipped with the high-power (30kW peak power) cloud radar operating at 35 GHz and a high spectral resolution lidar (HSRL) system at 532 nm. During a number of flight experiments over Europe and over the tropical and extra-tropical North-Atlantic, several radar calibration efforts have been made using the ocean surface backscatter. Moreover, CloudSat underflights have been conducted to compare the radar reflectivity and measurement sensitivity between the air- and spaceborne instruments. Additionally, the influence of different radar wavelengths was explored with joint flights of HALO and the French Falcon 20 aircraft, which was equipped with the RASTA cloud radar at 94 GHz and a HSRL at 355 nm. In this presentation, we will give an overview of lessons learned from different calibration strategies using the ocean surface backscatter. Additional measurements of signal linearity and signal saturation will complement this characterization. Furthermore, we will focus on the coordinated airborne measurements regarding the different sensitivity for clouds at 35 GHz and 94 GHz. By using the highly sensitive lidar signals, we show if the high-power cloud radar at 35 GHz can be used to validate spaceborne and airborne

Airborne Microwave Imaging of River Velocities

NASA Technical Reports Server (NTRS)

Plant, William J.

2002-01-01

The objective of this project was to determine whether airborne microwave remote sensing systems can measure river surface currents with sufficient accuracy to make them prospective instruments with which to monitor river flow from space. The approach was to fly a coherent airborne microwave Doppler radar, developed by APL/UW, on a light airplane along several rivers in western Washington state over an extended period of time. The fundamental quantity obtained by this system to measure river currents is the mean offset of the Doppler spectrum. Since this scatter can be obtained from interferometric synthetic aperture radars (INSARs), which can be flown in space, this project provided a cost effective means for determining the suitability of spaceborne INSAR for measuring river flow.

Greenland annual accumulation along the EGIG line, 1959-2004, from ASIRAS airborne radar and neutron-probe density measurements

NASA Astrophysics Data System (ADS)

Overly, Thomas B.; Hawley, Robert L.; Helm, Veit; Morris, Elizabeth M.; Chaudhary, Rohan N.

2016-08-01

We report annual snow accumulation rates from 1959 to 2004 along a 250 km segment of the Expéditions Glaciologiques Internationales au Groenland (EGIG) line across central Greenland using Airborne SAR/Interferometric Radar Altimeter System (ASIRAS) radar layers and high resolution neutron-probe (NP) density profiles. ASIRAS-NP-derived accumulation rates are not statistically different (95 % confidence interval) from in situ EGIG accumulation measurements from 1985 to 2004. ASIRAS-NP-derived accumulation increases by 20 % below 3000 m elevation, and increases by 13 % above 3000 m elevation for the period 1995 to 2004 compared to 1985 to 1994. Three Regional Climate Models (PolarMM5, RACMO2.3, MAR) underestimate snow accumulation below 3000 m by 16-20 % compared to ASIRAS-NP from 1985 to 2004. We test radar-derived accumulation rates sensitivity to density using modeled density profiles in place of NP densities. ASIRAS radar layers combined with Herron and Langway (1980) model density profiles (ASIRAS-HL) produce accumulation rates within 3.5 % of ASIRAS-NP estimates in the dry snow region. We suggest using Herron and Langway (1980) density profiles to calibrate radar layers detected in dry snow regions of ice sheets lacking detailed in situ density measurements, such as those observed by the Operation IceBridge campaign.

Airborne Radar Observations of Severe Hailstorms: Implications for Future Spaceborne Radar

NASA Technical Reports Server (NTRS)

Heymsfield, Gerald M.; Tian, Lin; Li, Lihua; McLinden, Matthew; Cervantes, Jaime I.

2013-01-01

A new dual-frequency (Ku and Ka band) nadir-pointing Doppler radar on the high-altitude NASA ER-2 aircraft, called the High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP), has collected data over severe thunderstorms in Oklahoma and Kansas during the Midlatitude Continental Convective Clouds Experiment (MC3E). The overarching motivation for this study is to understand the behavior of the dualwavelength airborne radar measurements in a global variety of thunderstorms and how these may relate to future spaceborne-radar measurements. HIWRAP is operated at frequencies that are similar to those of the precipitation radar on the Tropical Rainfall Measuring Mission (Ku band) and the upcoming Global Precipitation Measurement mission satellite's dual-frequency (Ku and Ka bands) precipitation radar. The aircraft measurements of strong hailstorms have been combined with ground-based polarimetric measurements to obtain a better understanding of the response of the Ku- and Ka-band radar to the vertical distribution of the hydrometeors, including hail. Data from two flight lines on 24 May 2011 are presented. Doppler velocities were approx. 39m/s2at 10.7-km altitude from the first flight line early on 24 May, and the lower value of approx. 25m/s on a second flight line later in the day. Vertical motions estimated using a fall speed estimate for large graupel and hail suggested that the first storm had an updraft that possibly exceeded 60m/s for the more intense part of the storm. This large updraft speed along with reports of 5-cm hail at the surface, reflectivities reaching 70 dBZ at S band in the storm cores, and hail signals from polarimetric data provide a highly challenging situation for spaceborne-radar measurements in intense convective systems. The Ku- and Ka-band reflectivities rarely exceed approx. 47 and approx. 37 dBZ, respectively, in these storms.

UAVSAR: Airborne L-band Radar for Repeat Pass Interferometry

NASA Technical Reports Server (NTRS)

Moes, Timothy R.

2009-01-01

The primary objectives of the UAVSAR Project were to: a) develop a miniaturized polarimetric L-band synthetic aperture radar (SAR) for use on an unmanned aerial vehicle (UAV) or piloted vehicle. b) develop the associated processing algorithms for repeat-pass differential interferometric measurements using a single antenna. c) conduct measurements of geophysical interest, particularly changes of rapidly deforming surfaces such as volcanoes or earthquakes. Two complete systems were developed. Operational Science Missions began on February 18, 2009 ... concurrent development and testing of the radar system continues.

Processing of High Resolution, Multiparametric Radar Data for the Airborne Dual-Frequency Precipitation Radar APR-2

NASA Technical Reports Server (NTRS)

Tanelli, Simone; Meagher, Jonathan P.; Durden, Stephen L.; Im, Eastwood

2004-01-01

Following the successful Precipitation Radar (PR) of the Tropical Rainfall Measuring Mission, a new airborne, 14/35 GHz rain profiling radar, known as Airborne Precipitation Radar - 2 (APR-2), has been developed as a prototype for an advanced, dual-frequency spaceborne radar for a future spaceborne precipitation measurement mission. . This airborne instrument is capable of making simultaneous measurements of rainfall parameters, including co-pol and cross-pol rain reflectivities and vertical Doppler velocities, at 14 and 35 GHz. furthermore, it also features several advanced technologies for performance improvement, including real-time data processing, low-sidelobe dual-frequency pulse compression, and dual-frequency scanning antenna. Since August 2001, APR-2 has been deployed on the NASA P3 and DC8 aircrafts in four experiments including CAMEX-4 and the Wakasa Bay Experiment. Raw radar data are first processed to obtain reflectivity, LDR (linear depolarization ratio), and Doppler velocity measurements. The dataset is then processed iteratively to accurately estimate the true aircraft navigation parameters and to classify the surface return. These intermediate products are then used to refine reflectivity and LDR calibrations (by analyzing clear air ocean surface returns), and to correct Doppler measurements for the aircraft motion. Finally, the the melting layer of precipitation is detected and its boundaries and characteristics are identifIed at the APR-2 range resolution of 30m. The resulting 3D dataset will be used for validation of other airborne and spaceborne instruments, development of multiparametric rain/snow retrieval algorithms and melting layer characterization and statistics.

Description and availability of airborne Doppler radar data

NASA Technical Reports Server (NTRS)

Harrah, S. D.; Bracalente, E. M.; Schaffner, P. R.; Baxa, E. G.

1993-01-01

An airborne, forward-looking, pulse, Doppler radar has been developed in conjunction with the joint FAA/NASA Wind Shear Program. This radar represents a first in an emerging technology. The radar was developed to assess the applicability of an airborne radar to detect low altitude hazardous wind shears for civil aviation applications. Such a radar must be capable of looking down into the ground clutter environment and extracting wind estimates from relatively low reflectivity weather targets. These weather targets often have reflectivities several orders of magnitude lower than the surrounding ground clutter. The NASA radar design incorporates numerous technological and engineering achievements in order to accomplish this task. The basic R/T unit evolved from a standard Collins 708 weather radar, which supports specific pulse widths of 1-7 microns and Pulse Repetition Frequencies (PRF) of less than 1-10 kHz. It was modified to allow for the output of the first IF signal, which fed a NASA developed receiver/detector subsystem. The NASA receiver incorporated a distributed, high-speed digital attenuator, producing a range bin to range bin automatic gain control system with 65 dB of dynamic range. Using group speed information supplied by the aircraft's navigation system, the radar signal is frequency demodulated back to base band (zero Doppler relative to stationary ground). The In-phase & Quadrature-phase (I/Q) components of the measured voltage signal are then digitized by a 12-bit A-D converter (producing an additional 36 dB of dynamic range). The raw I/Q signal for each range bin is then recorded (along with the current radar & aircraft state parameters) by a high-speed Kodak tape recorder.

Interferometric millimeter wave and THz wave doppler radar

DOEpatents

Liao, Shaolin; Gopalsami, Nachappa; Bakhtiari, Sasan; Raptis, Apostolos C.; Elmer, Thomas

2015-08-11

A mixerless high frequency interferometric Doppler radar system and methods has been invented, numerically validated and experimentally tested. A continuous wave source, phase modulator (e.g., a continuously oscillating reference mirror) and intensity detector are utilized. The intensity detector measures the intensity of the combined reflected Doppler signal and the modulated reference beam. Rigorous mathematics formulas have been developed to extract bot amplitude and phase from the measured intensity signal. Software in Matlab has been developed and used to extract such amplitude and phase information from the experimental data. Both amplitude and phase are calculated and the Doppler frequency signature of the object is determined.

Airborne Doppler radar detection of low altitude windshear

NASA Technical Reports Server (NTRS)

Bracalente, Emedio M.; Jones, William R.; Britt, Charles L.

1990-01-01

As part of an integrated windshear program, the Federal Aviation Administration, jointly with NASA, is sponsoring a research effort to develop airborne sensor technology for the detection of low altitude windshear during aircraft take-off and landing. One sensor being considered is microwave Doppler radar operating at X-band or above. Using a Microburst/Clutter/Radar simulation program, a preliminary feasibility study was conducted to assess the performance of Doppler radars for this application. Preliminary results from this study are presented. Analysis show, that using bin-to-bin Automatic Gain Control (AGC), clutter filtering, limited detection range, and suitable antenna tilt management, windshear from a wet microburst can be accurately detected 10 to 65 seconds (.75 to 5 km) in front of the aircraft. Although a performance improvement can be obtained at higher frequency, the baseline X-band system that was simulated detected the presence of a windshear hazard for the dry microburst. Although this study indicates the feasibility of using an airborne Doppler radar to detect low altitude microburst windshear, further detailed studies, including future flight experiments, will be required to completely characterize the capabilities and limitations.

Measurements of Ocean Surface Scattering Using an Airborne 94-GHz Cloud Radar: Implication for Calibration of Airborne and Spaceborne W-band Radars

NASA Technical Reports Server (NTRS)

Li, Li-Hua; Heymsfield, Gerald M.; Tian, Lin; Racette, Paul E.

2004-01-01

Scattering properties of the Ocean surface have been widely used as a calibration reference for airborne and spaceborne microwave sensors. However, at millimeter-wave frequencies, the ocean surface backscattering mechanism is still not well understood, in part, due to the lack of experimental measurements. During the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE), measurements of ocean surface backscattering were made using a 94-GHz (W-band) cloud radar onboard a NASA ER-2 high-altitude aircraft. The measurement set includes the normalized Ocean surface cross section over a range of the incidence angles under a variety of wind conditions. Analysis of the radar measurements shows good agreement with a quasi-specular scattering model. This unprecedented dataset enhances our knowledge about the Ocean surface scattering mechanism at 94 GHz. The results of this work support the proposition of using the Ocean surface as a calibration reference for airborne millimeter-wave cloud radars and for the ongoing NASA CloudSat mission, which will use a 94-GHz spaceborne cloud radar for global cloud measurements.

Determining Snow Depth Using Airborne Multi-Pass Interferometric Synthetic Aperture Radar

DTIC Science & Technology

2013-09-01

relatively low resolution 10m DEM of the survey area was obtained from the USDA NAIP and then geocorrected to match the SAR image area. Centered on...Propulsion Laboratory LiDAR Light Detection and Ranging METAR Meteorological reporting observations medivac Medical Evacuation NASA National...Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X- SAR) mission was a joint National Aeronautical and Space Administration ( NASA

Using dynamic interferometric synthetic aperature radar (InSAR) to image fast-moving surface waves

DOEpatents

Vincent, Paul

2005-06-28

A new differential technique and system for imaging dynamic (fast moving) surface waves using Dynamic Interferometric Synthetic Aperture Radar (InSAR) is introduced. This differential technique and system can sample the fast-moving surface displacement waves from a plurality of moving platform positions in either a repeat-pass single-antenna or a single-pass mode having a single-antenna dual-phase receiver or having dual physically separate antennas, and reconstruct a plurality of phase differentials from a plurality of platform positions to produce a series of desired interferometric images of the fast moving waves.

Interferometric Radar Observations of Glaciar San Rafael, Chile

NASA Technical Reports Server (NTRS)

Rignot, Eric; Forster, Richard; Isacks, Bryan

1996-01-01

Interferometric radar observations of Glaciar San Rafael, Chile, were collected in October 1994 by NASA's Spaceborne Imaging Radar C (SIR-C) at both L- (24cm) and C-band frequency (5.6cm), with vertical transmit and receive polarization. The C-band data did not yield good geophysical products, because the temporal coherence of the signal was significantly reduced after 24h. The L-band data were, however, successfully employed to map the surface topography of the icefield with a 10m uncertainty in height, and measure ice velocity with a precision of 4 mm/d or 1.4 m/a. The corresponding error in strain rates is 0.05/a at a 30 m horizontal spacing. The one-dimensional interferometric velocities were subsequently converted to horizontal displacements by assuming a flow direction and complemented by feature-tracking results near the calving front. The results provide a comprehensive view of the ice-flow dynamics of Glaciar San Rafael. The glacier has a core of rapid flow, 4.5 km in width and 3.5 degrees in average slope,surrounded by slower moving ice, not by rock. Ice velocity is 2.6 m/d or 0.95 km/a near the equilibrium line altitude (1200m), increasing rapidly before the glacier enters the narrower terminal valley, to reach 17.5 m/d or 6.4 km/a at the calving front. Strain rates are dominated by lateral shearing at the glacier margins (0.4-0.7/a), except for the terminal-valley section, where longitudinal strain rates average close to 1/a. This spectacular longitudinal increase in ice velocity in the last few kilometers may be a fundamental feature of tidewater glaciers.

UAVSAR - A New Airborne L-Band Radar for Repeat Pass Interferometry

NASA Technical Reports Server (NTRS)

Mace, Thomas H.; Lou, Yunling

2009-01-01

NASA/JPL has developed a new airborne Synthetic Aperture Radar (SAR) which has become available for use by the scientific community in January, 2009. Pod mounted, the UAVSAR was designed to be portable among a variety of aircraft, including unmanned aerial systems (UAS). The instrument operates in the L-Band, has a resolution under 2m from a GPS altitude of 12Km and a swath width of approximately 20Km. UAVSAR currently flies on a modified Gulfstream-III aircraft, operated by NASA s Dryden Flight Research Center at Edwards, California. The G-III platform enables repeat-pass interferometric measurements, by using a modified autopilot and precise kinematic differential GPS to repeatedly fly the aircraft within a specified 10m tube. The antenna is electronically steered along track to assure that the antenna beam can be directed independently, regardless of speed and wind direction. The instrument can be controlled remotely, AS AN OPTION, using the Research Environment for Vehicle Embedded Analysis on Linux (REVEAL). This allows simulation of the telepresence environment necessary for flight on UAS. Potential earth science research and applications include surface deformation, volcano studies, ice sheet dynamics, and vegetation structure.

MARA (Multimode Airborne Radar Altimeter) system documentation. Volume 1: MARA system requirements document

NASA Technical Reports Server (NTRS)

Parsons, C. L. (Editor)

1989-01-01

The Multimode Airborne Radar Altimeter (MARA), a flexible airborne radar remote sensing facility developed by NASA's Goddard Space Flight Center, is discussed. This volume describes the scientific justification for the development of the instrument and the translation of these scientific requirements into instrument design goals. Values for key instrument parameters are derived to accommodate these goals, and simulations and analytical models are used to estimate the developed system's performance.

Assessing the influence of flight parameters, interferometric processing, slope and canopy density on the accuracy of X-band IFSAR-derived forest canopy height models.

Treesearch

H.-E. Andersen; R.J. McGaughey; S.E. Reutebuch

2008-01-01

High resolution, active remote sensing technologies, such as interferometric synthetic aperture radar (IFSAR) and airborne laser scanning (LIDAR) have the capability to provide forest managers with direct measurements of 3-dimensional forest canopy surface structure. Although LIDAR systems can provide highly accurate measurements of canopy and terrain surfaces, high-...

Application of vector analysis on study of illuminated area and Doppler characteristics of airborne pulse radar

NASA Astrophysics Data System (ADS)

Wang, Haijiang; Yang, Ling

2014-12-01

In this paper, the application of vector analysis tool in the illuminated area and the Doppler frequency distribution research for the airborne pulse radar is studied. An important feature of vector analysis is that it can closely combine the geometric ideas with algebraic calculations. Through coordinate transform, the relationship between the frame of radar antenna and the ground, under aircraft motion attitude, is derived. Under the time-space analysis, the overlap area between the footprint of radar beam and the pulse-illuminated zone is obtained. Furthermore, the Doppler frequency expression is successfully deduced. In addition, the Doppler frequency distribution is plotted finally. Using the time-space analysis results, some important parameters of a specified airborne radar system are obtained. Simultaneously, the results are applied to correct the phase error brought by attitude change in airborne synthetic aperture radar (SAR) imaging.

Bayes classification of interferometric TOPSAR data

NASA Technical Reports Server (NTRS)

Michel, T. R.; Rodriguez, E.; Houshmand, B.; Carande, R.

1995-01-01

We report the Bayes classification of terrain types at different sites using airborne interferometric synthetic aperture radar (INSAR) data. A Gaussian maximum likelihood classifier was applied on multidimensional observations derived from the SAR intensity, the terrain elevation model, and the magnitude of the interferometric correlation. Training sets for forested, urban, agricultural, or bare areas were obtained either by selecting samples with known ground truth, or by k-means clustering of random sets of samples uniformly distributed across all sites, and subsequent assignments of these clusters using ground truth. The accuracy of the classifier was used to optimize the discriminating efficiency of the set of features that was chosen. The most important features include the SAR intensity, a canopy penetration depth model, and the terrain slope. We demonstrate the classifier's performance across sites using a unique set of training classes for the four main terrain categories. The scenes examined include San Francisco (CA) (predominantly urban and water), Mount Adams (WA) (forested with clear cuts), Pasadena (CA) (urban with mountains), and Antioch Hills (CA) (water, swamps, fields). Issues related to the effects of image calibration and the robustness of the classification to calibration errors are explored. The relative performance of single polarization Interferometric data classification is contrasted against classification schemes based on polarimetric SAR data.

Interferometric synthetic aperture radar: Building tomorrow's tools today

USGS Publications Warehouse

Lu, Zhong

2006-01-01

A synthetic aperture radar (SAR) system transmits electromagnetic (EM) waves at a wavelength that can range from a few millimeters to tens of centimeters. The radar wave propagates through the atmosphere and interacts with the Earth’s surface. Part of the energy is reflected back to the SAR system and recorded. Using a sophisticated image processing technique, called SAR processing (Curlander and McDonough, 1991), both the intensity and phase of the reflected (or backscattered) signal of each ground resolution element (a few meters to tens of meters) can be calculated in the form of a complex-valued SAR image representing the reflectivity of the ground surface. The amplitude or intensity of the SAR image is determined primarily by terrain slope, surface roughness, and dielectric constants, whereas the phase of the SAR image is determined primarily by the distance between the satellite antenna and the ground targets, slowing of the signal by the atmosphere, and the interaction of EM waves with ground surface. Interferometric SAR (InSAR) imaging, a recently developed remote sensing technique, utilizes the interaction of EM waves, referred to as interference, to measure precise distances. Very simply, InSAR involves the use of two or more SAR images of the same area to extract landscape topography and its deformation patterns.

Multimission airborne radar for the 1990s

NASA Astrophysics Data System (ADS)

Robinson, Thomas H.

1986-07-01

The continuing trend towards the development and production of aircraft capable of multiple missions indicates that future airborne radars must provide a broad spectrum of air-to-air and air-to-ground modes. This paper investigates the modal and functional requirements of a multimode radar projected for the mid-1990s period. The paper is divided into two sections. In the first, the multimission capabilities of current radars are presented to establish trends and capabilities. In the second, the requirements of the next generation system are established. Current multimode radars lay the basis for future systems. The experience gained on the APG-65 and APG-63/70 radars is presented and conclusions are drawn regarding their impact on future system requirements. Not only are modes and performance reviewed for these radars but also their system architecture. The discussion starts with the APG-65 radar which is the first true multimission radar with programmable signal and data processing. Following this, the evolution of the APG-63 radar, culminating with the most recent upgrading resulting in redesignation of APG-70, is presented. The incorporation of air-to-ground capabilities in the APG-70, resulting from the Dual Role Fighter program, is reviewed. Results from the Advanced Fighter Capabilities Demonstration program are presented showing how high resolution SAR was incorporated into a full weapon delivery solution. The specific radar requirements for the next decade radar system are developed. This development is done in two parts. First, mode requirements are synthesized for air superiority, navigation and strike/interdiction operation. This includes low altitude penetration requirements and a review of radar timeline constraints which arise. Second, the fundamental functional requirements needed to implement the mode requirements are explored. Architectural issues and their impact on reliability and sustainability are also considered.

Effect of external digital elevation model on monitoring of mine subsidence by two-pass differential interferometric synthetic aperture radar

NASA Astrophysics Data System (ADS)

Tao, Qiuxiang; Gao, Tengfei; Liu, Guolin; Wang, Zhiwei

2017-04-01

The external digital elevation model (DEM) error is one of the main factors that affect the accuracy of mine subsidence monitored by two-pass differential interferometric synthetic aperture radar (DInSAR), which has been widely used in monitoring mining-induced subsidence. The theoretical relationship between external DEM error and monitored deformation error is derived based on the principles of interferometric synthetic aperture radar (DInSAR) and two-pass DInSAR. Taking the Dongtan and Yangcun mine areas of Jining as test areas, the difference and accuracy of 1:50000, ASTER GDEM V2, and SRTM DEMs are compared and analyzed. Two interferometric pairs of Advanced Land Observing Satellite Phased Array L-band SAR covering the test areas are processed using two-pass DInSAR with three external DEMs to compare and analyze the effect of three external DEMs on monitored mine subsidence in high- and low-coherence subsidence regions. Moreover, the reliability and accuracy of the three DInSAR-monitored results are compared and verified with leveling-measured subsidence values. Results show that the effect of external DEM on mine subsidence monitored by two-pass DInSAR is not only related to radar look angle, perpendicular baseline, slant range, and external DEM error, but also to the ground resolution of DEM, the magnitude of subsidence, and the coherence of test areas.

Estimation of penetration of forest canopies by Interferometric SAR measurements

NASA Technical Reports Server (NTRS)

Rodriguez, Ernesto; Michel, Thierry R.; Harding, David J.

1995-01-01

In contrast to traditional Synthetic Aperture Radar (SAR), an Interferometric SAR (INSAR) yields two additional measurements: the phase difference and the correlation between the two interferometric channels. The phase difference has been used to estimate topographic height. For homogeneous surfaces, the correlation depends on the system signal-to-noise (SNR) ratio, the interferometer parameters, and the local slope. In the presence of volume scattering, such as that encountered in vegetation canopies, the correlation between the two channels is also dependent on the degree of penetration of the radiation into the scattering medium. In this paper, we propose a method for removing system and slope effects in order to obtain the decorrelation due to penetration alone. The sensitivities and accuracy of the proposed method are determined by Monte Carlo experiments, and we show that the proposed technique has sufficient sensitivity to provide penetration measurements for airborne SAR systems. Next, we provide a theoretical model to estimate the degree of penetration in a way which is independent of the details of the scattering medium. We also present a model for the correlation from non-homogeneous layers. We assess the sensitivity of the proposed inversion technique to these inhomogeneous situations. Finally, we present a comparison of the interferometric results against in situ data obtained by an airborne laser profilometer which provides a direct measurement of tree height and an estimate of the vegetation density profile in the forested areas around Mt. Adams, WA.

Estimation of Snow Parameters from Dual-Wavelength Airborne Radar

NASA Technical Reports Server (NTRS)

Liao, Liang; Meneghini, Robert; Iguchi, Toshio; Detwiler, Andrew

1997-01-01

Estimation of snow characteristics from airborne radar measurements would complement In-situ measurements. While In-situ data provide more detailed information than radar, they are limited in their space-time sampling. In the absence of significant cloud water contents, dual-wavelength radar data can be used to estimate 2 parameters of a drop size distribution if the snow density is assumed. To estimate, rather than assume, a snow density is difficult, however, and represents a major limitation in the radar retrieval. There are a number of ways that this problem can be investigated: direct comparisons with in-situ measurements, examination of the large scale characteristics of the retrievals and their comparison to cloud model outputs, use of LDR measurements, and comparisons to the theoretical results of Passarelli(1978) and others. In this paper we address the first approach and, in part, the second.

An Airborne Radar Model For Non-Uniformly Spaced Antenna Arrays

DTIC Science & Technology

2006-03-01

Department of Defense, or the United States Government . AFIT-GE-ENG-06-58 An Airborne Radar Model For Non-Uniformly Spaced Antenna Arrays THESIS Presented...different circular arrays, one containing 24 elements and one containing 15 elements. The circular array per- formance is compared to that of a 6 × 6...model and compared to the radar model of [5, 6, 13]. The two models are mathematically equivalent when the uniformly spaced array is linear. The two

Estimating snow water equivalent (SWE) using interferometric synthetic aperture radar (InSAR)

NASA Astrophysics Data System (ADS)

Deeb, Elias J.

Since the early 1990s, radar interferometry and interferometric synthetic aperture radar (InSAR) have been used extensively to measure changes in the Earth's surface. Previous research has presented theory for estimating snow properties, including potential for snow water equivalent (SWE) retrieval, using InSAR. The motivation behind using remote sensing to estimate SWE is to provide a more complete, continuous set of "observations" to assist in water management operations, climate change studies, and flood hazard forecasting. The research presented here primarily investigates the feasibility of using the InSAR technique at two different wavelengths (C-Band and L-Band) for SWE retrieval of dry snow within the Kuparuk watershed, North Slope, Alaska. Estimating snow distribution around meteorological towers on the coastal plain using a three-day repeat orbit of C-Band InSAR data was successful (Chapter 2). A longer wavelength L-band SAR is evaluated for SWE retrievals (Chapter 3) showing the ability to resolve larger snow accumulation events over a longer period of time. Comparisons of InSAR estimates and late spring manual sampling of SWE show a R2 = 0.61 when a coherence threshold is used to eliminate noisy SAR data. Qualitative comparisons with a high resolution digital elevation model (DEM) highlight areas of scour on windward slopes and areas of deposition on leeward slopes. When compared to a mid-winter transect of manually sampled snow depths, the InSAR SWE estimates yield a RMSE of 2.21cm when a bulk snow density is used and corrections for bracketing the satellite acquisition timing is performed. In an effort to validate the interaction of radar waves with a snowpack, the importance of the "dry snow" assumption for the estimation of SWE using InSAR is tested with an experiment in Little Cottonwood Canyon, Alta, Utah (Chapter 5). Snow wetness is shown to have a significant effect on the velocity of propagation within the snowpack. Despite the radar

Validation of Airborne FMCW Radar Measurements of Snow Thickness Over Sea Ice in Antarctica

NASA Technical Reports Server (NTRS)

Galin, Natalia; Worby, Anthony; Markus, Thorsten; Leuschen, Carl; Gogineni, Prasad

2012-01-01

Antarctic sea ice and its snow cover are integral components of the global climate system, yet many aspects of their vertical dimensions are poorly understood, making their representation in global climate models poor. Remote sensing is the key to monitoring the dynamic nature of sea ice and its snow cover. Reliable and accurate snow thickness data are currently a highly sought after data product. Remotely sensed snow thickness measurements can provide an indication of precipitation levels, predicted to increase with effects of climate change in the polar regions. Airborne techniques provide a means for regional-scale estimation of snow depth and distribution. Accurate regional-scale snow thickness data will also facilitate an increase in the accuracy of sea ice thickness retrieval from satellite altimeter freeboard estimates. The airborne data sets are easier to validate with in situ measurements and are better suited to validating satellite algorithms when compared with in situ techniques. This is primarily due to two factors: better chance of getting coincident in situ and airborne data sets and the tractability of comparison between an in situ data set and the airborne data set averaged over the footprint of the antennas. A 28-GHz frequency modulated continuous wave (FMCW) radar loaned by the Center for Remote Sensing of Ice Sheets to the Australian Antarctic Division is used to measure snow thickness over sea ice in East Antarctica. Provided with the radar design parameters, the expected performance parameters of the radar are summarized. The necessary conditions for unambiguous identification of the airsnow and snowice layers for the radar are presented. Roughnesses of the snow and ice surfaces are found to be dominant determinants in the effectiveness of layer identification for this radar. Finally, this paper presents the first in situ validated snow thickness estimates over sea ice in Antarctica derived from an FMCW radar on a helicopterborne platform.

Interferometric synthetic aperture radar (InSAR)—its past, present and future

USGS Publications Warehouse

Lu, Zhong; Kwoun, Oh-Ig; Rykhus, R.P.

2007-01-01

Very simply, interferometric synthetic aperture radar (InSAR) involves the use of two or more synthetic aperture radar (SAR) images of the same area to extract landscape topography and its deformation patterns. A SAR system transmits electromagnetic waves at a wavelength that can range from a few millimeters to tens of centimeters and therefore can operate during day and night under all-weather conditions. Using SAR processing technique (Curlander and McDonough, 1991), both the intensity and phase of the reflected (or backscattered) radar signal of each ground resolution element (a few meters to tens of meters) can be calculated in the form of a complex-valued SAR image that represents the reflectivity of the ground surface. The amplitude or intensity of the SAR image is determined primarily by terrain slope, surface roughness, and dielectric constants, whereas the phase of the SAR image is determined primarily by the distance between the satellite antenna and the ground targets. InSAR imaging utilizes the interaction of electromagnetic waves, referred to as interference, to measure precise distances between the satellite antenna and ground resolution elements to derive landscape topography and its subtle change in elevation.

Development of the ECOSAR P-Band Synthetic Aperture Radar

NASA Technical Reports Server (NTRS)

Rincon, R. F.; Fatoyinbo, T.; Ranson, K. J.; Sun, G.; Deshpande, M.; Hale, R. D.; Bhat, A.; Perrine, M.; DuToit, C. F.; Bonds, Q.;

Proceedings of the Third Airborne Synthetic Aperture Radar (AIRSAR) Workshop

NASA Technical Reports Server (NTRS)

Vanzyl, Jakob J. (Editor)

1991-01-01

The Third Airborne Synthetic Aperture Radar (AIRSAR) Workshop was held on 23-24 May 1991 at JPL. Thirty oral presentations were made and 18 poster papers displayed during the workshop. Papers from these 25 presentations are presented which include analyses of AIRSAR operations and studies in SAR remote sensing, ecology, hydrology, soil science, geology, oceanography, volcanology, and SAR mapping and data handling. Results from these studies indicate the direction and emphasis of future orbital radar-sensor missions that will be launched during the 1990's.

Calibration and Validation of Airborne InSAR Geometric Model

NASA Astrophysics Data System (ADS)

Chunming, Han; huadong, Guo; Xijuan, Yue; Changyong, Dou; Mingming, Song; Yanbing, Zhang

2014-03-01

The image registration or geo-coding is a very important step for many applications of airborne interferometric Synthetic Aperture Radar (InSAR), especially for those involving Digital Surface Model (DSM) generation, which requires an accurate knowledge of the geometry of the InSAR system. While the trajectory and attitude instabilities of the aircraft introduce severe distortions in three dimensional (3-D) geometric model. The 3-D geometrical model of an airborne SAR image depends on the SAR processor itself. Working at squinted model, i.e., with an offset angle (squint angle) of the radar beam from broadside direction, the aircraft motion instabilities may produce distortions in airborne InSAR geometric relationship, which, if not properly being compensated for during SAR imaging, may damage the image registration. The determination of locations of the SAR image depends on the irradiated topography and the exact knowledge of all signal delays: range delay and chirp delay (being adjusted by the radar operator) and internal delays which are unknown a priori. Hence, in order to obtain reliable results, these parameters must be properly calibrated. An Airborne InSAR mapping system has been developed by the Institute of Remote Sensing and Digital Earth (RADI), Chinese Academy of Sciences (CAS) to acquire three-dimensional geo-spatial data with high resolution and accuracy. To test the performance of the InSAR system, the Validation/Calibration (Val/Cal) campaign has carried out in Sichun province, south-west China, whose results will be reported in this paper.

Interferometric inverse synthetic aperture radar imaging for space targets based on wideband direct sampling using two antennas

NASA Astrophysics Data System (ADS)

Tian, Biao; Liu, Yang; Xu, Shiyou; Chen, Zengping

2014-01-01

Interferometric inverse synthetic aperture radar (InISAR) imaging provides complementary information to monostatic inverse synthetic aperture radar (ISAR) imaging. This paper proposes a new InISAR imaging system for space targets based on wideband direct sampling using two antennas. The system is easy to realize in engineering since the motion trajectory of space targets can be known in advance, which is simpler than that of three receivers. In the preprocessing step, high speed movement compensation is carried out by designing an adaptive matched filter containing speed that is obtained from the narrow band information. Then, the coherent processing and keystone transform for ISAR imaging are adopted to reserve the phase history of each antenna. Through appropriate collocation of the system, image registration and phase unwrapping can be avoided. Considering the situation not to be satisfied, the influence of baseline variance is analyzed and compensation method is adopted. The corresponding size can be achieved by interferometric processing of the two complex ISAR images. Experimental results prove the validity of the analysis and the three-dimensional imaging algorithm.

Airborne polarimetric Doppler weather radar: trade-offs between various engineering specifications

NASA Astrophysics Data System (ADS)

Vivekanandan, Jothiram; Loew, Eric

2018-01-01

NCAR EOL is investigating potential configurations for the next-generation airborne phased array radar (APAR) that is capable of retrieving dynamic and microphysical characteristics of clouds and precipitation. The APAR will operate at C band. The APAR will use the electronic scanning (e-scan) feature to acquire the optimal number of independent samples for recording research-quality measurements. Since the airborne radar has only a limited time for collecting measurements over a specified region (moving aircraft platform ˜ 100 m s-1), beam multiplexing will significantly enhance its ability to collect high-resolution, research-quality measurements. Beam multiplexing reduces errors in radar measurements while providing rapid updates of scan volumes. Beamwidth depends on the size of the antenna aperture. Beamwidth and directivity of elliptical, circular, and rectangular antenna apertures are compared and radar sensitivity is evaluated for various polarimetric configurations and transmit-receive (T/R) elements. In the case of polarimetric measurements, alternate transmit with alternate receive (single-channel receiver) and simultaneous reception (dual-channel receiver) is compared. From an overall architecture perspective, element-level digitization of T/R module versus digital sub-array is considered with regard to flexibility in adaptive beamforming, polarimetric performance, calibration, and data quality. Methodologies for calibration of the radar and removing bias in polarimetric measurements are outlined. The above-mentioned engineering options are evaluated for realizing an optimal APAR system suitable for measuring the high temporal and spatial resolutions of Doppler and polarimetric measurements of precipitation and clouds.

Performance of the NASA Airborne Radar with the Windshear Database for Forward-Looking Systems

NASA Technical Reports Server (NTRS)

Switzer, George F.; Britt, Charles L.

1996-01-01

This document describes the simulation approach used to test the performance of the NASA airborne windshear radar. An explanation of the actual radar hardware and processing algorithms provides an understanding of the parameters used in the simulation program. This report also contains a brief overview of the NASA airborne windshear radar experimental flight test results. A description of the radar simulation program shows the capabilities of the program and the techniques used for certification evaluation. Simulation of the NASA radar is comprised of three steps. First, the choice of the ground clutter data must be made. The ground clutter is the return from objects in or nearby an airport facility. The choice of the ground clutter also dictates the aircraft flight path since ground clutter is gathered while in flight. The second step is the choice of the radar parameters and the running of the simulation program which properly combines the ground clutter data with simulated windshear weather data. The simulated windshear weather data is comprised of a number of Terminal Area Simulation System (TASS) model results. The final step is the comparison of the radar simulation results to the known windshear data base. The final evaluation of the radar simulation is based on the ability to detect hazardous windshear with the aircraft at a safe distance while at the same time not displaying false alerts.

A frequency domain radar interferometric imaging (FII) technique based on high-resolution methods

NASA Astrophysics Data System (ADS)

Luce, H.; Yamamoto, M.; Fukao, S.; Helal, D.; Crochet, M.

2001-01-01

In the present work, we propose a frequency-domain interferometric imaging (FII) technique for a better knowledge of the vertical distribution of the atmospheric scatterers detected by MST radars. This is an extension of the dual frequency-domain interferometry (FDI) technique to multiple frequencies. Its objective is to reduce the ambiguity (resulting from the use of only two adjacent frequencies), inherent with the FDI technique. Different methods, commonly used in antenna array processing, are first described within the context of application to the FII technique. These methods are the Fourier-based imaging, the Capon's and the singular value decomposition method used with the MUSIC algorithm. Some preliminary simulations and tests performed on data collected with the middle and upper atmosphere (MU) radar (Shigaraki, Japan) are also presented. This work is a first step in the developments of the FII technique which seems to be very promising.

A comparison of airborne and ground-based radar observations with rain gages during the CaPE experiment

NASA Technical Reports Server (NTRS)

Satake, Makoto; Short, David A.; Iguchi, Toshio

1992-01-01

The vicinity of KSC, where the primary ground truth site of the Tropical Rainfall Measuring Mission (TRMM) program is located, was the focal point of the Convection and Precipitation/Electrification (CaPE) experiment in Jul. and Aug. 1991. In addition to several specialized radars, local coverage was provided by the C-band (5 cm) radar at Patrick AFB. Point measurements of rain rate were provided by tipping bucket rain gage networks. Besides these ground-based activities, airborne radar measurements with X- and Ka-band nadir-looking radars on board an aircraft were also recorded. A unique combination data set of airborne radar observations with ground-based observations was obtained in the summer convective rain regime of central Florida. We present a comparison of these data intending a preliminary validation. A convective rain event was observed simultaneously by all three instrument types on the evening of 27 Jul. 1991. The high resolution aircraft radar was flown over convective cells with tops exceeding 10 km and observed reflectivities of 40 to 50 dBZ at 4 to 5 km altitude, while the low resolution surface radar observed 35 to 55 dBZ echoes and a rain gage indicated maximum surface rain rates exceeding 100 mm/hr. The height profile of reflectivity measured with the airborne radar show an attenuation of 6.5 dB/km (two way) for X-band, corresponding to a rainfall rate of 95 mm/hr.

Ice-type classifications from airborne pulse-limited radar altimeter return waveform characteristics

NASA Technical Reports Server (NTRS)

Fedor, L. S.; Hayne, G. S.; Walsh, E. J.

1989-01-01

During mid-March 1978, the NASA C-130 aircraft was deployed to Eielson Air Force Base in Fairbanks, Alaska, to make a series of flights over ice in the Beaufort Sea. The radar altimeter data analyzed were obtained northeast of Mackenzie Bay on March 14th in the vicinity of 69.9 deg N, 134.2 deg W. The data were obtained with a 13.9 GHz radar altimeter developed under the NASA Advanced Applications Flight Experiments (AAFE) Program. This airborne radar was built as a forerunner of the Seasat radar altimeter, and utilized the same pulse compression technique. Pulse-limited radar data taken with the altimeter from 1500-m altitude over sea ice are registered to high-quality photography. The backscattered power is statistically related the surface conductivity and to the number of facets whose surface normal is directed towards the radar. The variations of the radar return waveform shape and signal level are correlated with the variation of the ice type determined from photography. The AAFE altimeter has demonstrated that the return waveform shape and signal level of an airborne pulse-limited altimeter at 13.9 GHz respond to sea ice type. The signal level responded dramatically to even a very small fracture in the ice, as long as it occurred directly at the altimeter nadir point. Shear zones and regions of significant compression ridging consistently produced low signal levels. The return waveforms frequently evidenced the characteristics of both specular and diffuse scattering, and there was an indication that the power backscattered at 3 deg off-nadir in a shear zone was actually somewhat higher than that from nadir.

Hydrometeor discrimination in melting layer using multiparameter airborne radar measurement

NASA Technical Reports Server (NTRS)

Kumagai, H.; Meneghini, R.; Kozu, T.

1992-01-01

Results from a multiparameter airborne radar/radiometer experiment (the Typhoon experiment) are presented. The experiment was conducted in the western Pacific with the NASA DC-8 aircraft, in which a dual-wavelength at X-band and Ka-band and dual-polarization at X-band radar was installed. The signatures of dBZ(X), dBZ(Ka), LDR (linear depolarization ratio) at X-band and DZ=dBZ(X)-dBZ(Ka) are discussed for the data obtained in the penetration of the typhoon Flo. With emphasis on discrimination of hydrometeor particles, some statistical features of the brightband in stratiform rain are discussed.

The rapid terrain visualization interferometric synthetic aperture radar sensor

NASA Astrophysics Data System (ADS)

Graham, Robert H.; Bickel, Douglas L.; Hensley, William H.

2003-11-01

The Rapid Terrain Visualization interferometric synthetic aperture radar was designed and built at Sandia National Laboratories as part of an Advanced Concept Technology Demonstration (ACTD) to "demonstrate the technologies and infrastructure to meet the Army requirement for rapid generation of digital topographic data to support emerging crisis or contingencies." This sensor is currently being operated by Sandia National Laboratories for the Joint Precision Strike Demonstration (JPSD) Project Office to provide highly accurate digital elevation models (DEMs) for military and civilian customers, both inside and outside of the United States. The sensor achieves better than DTED Level IV position accuracy in near real-time. The system is being flown on a deHavilland DHC-7 Army aircraft. This paper outlines some of the technologies used in the design of the system, discusses the performance, and will discuss operational issues. In addition, we will show results from recent flight tests, including high accuracy maps taken of the San Diego area.

Application of Radar Data to Remote Sensing and Geographical Information Systems

NASA Technical Reports Server (NTRS)

vanZyl, Jakob J.

2000-01-01

The field of synthetic aperture radar changed dramatically over the past decade with the operational introduction of advance radar techniques such as polarimetry and interferometry. Radar polarimetry became an operational research tool with the introduction of the NASA/JPL AIRSAR system in the early 1980's, and reached a climax with the two SIR-C/X-SAR flights on board the space shuttle Endeavour in April and October 1994. Radar interferometry received a tremendous boost when the airborne TOPSAR system was introduced in 1991 by NASA/JPL, and further when data from the European Space Agency ERS-1 radar satellite became routinely available in 1991. Several airborne interferometric SAR systems are either currently operational, or are about to be introduced. Radar interferometry is a technique that allows one to map the topography of an area automatically under all weather conditions, day or night. The real power of radar interferometry is that the images and digital elevation models are automatically geometrically resampled, and could be imported into GIS systems directly after suitable reformatting. When combined with polarimetry, a technique that uses polarization diversity to gather more information about the geophysical properties of the terrain, a very rich multi-layer data set is available to the remote sensing scientist. This talk will discuss the principles of radar interferometry and polarimetry with specific application to the automatic categorization of land cover. Examples will include images acquired with the NASA/JPL AIRSAR/TOPSAR system in Australia and elsewhere.

Polarization differences in airborne ground penetrating radar performance for landmine detection

NASA Astrophysics Data System (ADS)

Dogaru, Traian; Le, Calvin

2016-05-01

The U.S. Army Research Laboratory (ARL) has investigated the ultra-wideband (UWB) radar technology for detection of landmines, improvised explosive devices and unexploded ordnance, for over two decades. This paper presents a phenomenological study of the radar signature of buried landmines in realistic environments and the performance of airborne synthetic aperture radar (SAR) in detecting these targets as a function of multiple parameters: polarization, depression angle, soil type and burial depth. The investigation is based on advanced computer models developed at ARL. The analysis includes both the signature of the targets of interest and the clutter produced by rough surface ground. Based on our numerical simulations, we conclude that low depression angles and H-H polarization offer the highest target-to-clutter ratio in the SAR images and therefore the best radar performance of all the scenarios investigated.

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

Applications of interferometrically derived terrain slopes: Normalization of SAR backscatter and the interferometric correlation coefficient

NASA Technical Reports Server (NTRS)

Werner, Charles L.; Wegmueller, Urs; Small, David L.; Rosen, Paul A.

1994-01-01

Terrain slopes, which can be measured with Synthetic Aperture Radar (SAR) interferometry either from a height map or from the interferometric phase gradient, were used to calculate the local incidence angle and the correct pixel area. Both are required for correct thematic interpretation of SAR data. The interferometric correlation depends on the pixel area projected on a plane perpendicular to the look vector and requires correction for slope effects. Methods for normalization of the backscatter and interferometric correlation for ERS-1 SAR are presented.

Ku band airborne radar altimeter observations of marginal sea ice during the 1984 Marginal Ice Zone Experiment

NASA Technical Reports Server (NTRS)

Drinkwater, Mark R.

1991-01-01

Pulse-limited, airborne radar data taken in June and July 1984 with a 13.8-GHz altimeter over the Fram Strait marginal ice zone are analyzed with the aid of large-format aerial photography, airborne synthetic aperture radar data, and surface observations. Variations in the radar return pulse waveforms are quantified and correlated with ice properties recorded during the Marginal Ice Zone Experiment. Results indicate that the wide-beam altimeter is a flexible instrument, capable of identifying the ice edge with a high degree of accuracy, calculating the ice concentration, and discriminating a number of different ice classes. This suggests that microwave radar altimeters have a sensitivity to sea ice which has not yet been fully exploited. When fused with SSM/I, AVHRR and ERS-1 synthetic aperture radar imagery, future ERS-1 altimeter data are expected to provide some missing pieces to the sea ice geophysics puzzle.

3D surface flow kinematics derived from airborne UAVSAR interferometric synthetic aperture radar to constrain the physical mechanisms controlling landslide motion

NASA Astrophysics Data System (ADS)

Delbridge, B. G.; Burgmann, R.; Fielding, E. J.; Hensley, S.; Schulz, W. H.

2013-12-01

This project focuses on improving our understanding of the physical mechanisms controlling landslide motion by studying the landslide-wide kinematics of the Slumgullion landslide in southwestern Colorado using interferometric synthetic aperture radar (InSAR) and GPS. The NASA/JPL UAVSAR airborne repeat-pass SAR interferometry system imaged the Slumgullion landslide from 4 look directions on eight flights in 2011 and 2012. Combining the four look directions allows us to extract the full 3-D velocity field of the surface. Observing the full 3-dimensional flow field allows us to extract the full strain tensor (assuming free surface boundary conditions and incompressible flow) since we have both the spatial resolution to take spatial derivates and full deformation information. COSMO-SkyMed(CSK) high-resolution Spotlight data was also acquired during time intervals overlapping with the UAVSAR one-week pairs, with intervals as short as one day. These observations allow for the quantitative testing of the deformation magnitude and estimated formal errors in the UAVSAR derived deformation field. We also test the agreement of the deformation at 20 GPS monitoring sites concurrently acquired by the USGS. We also utilize the temporal resolution of real-time GPS acquired by the UC Berkeley Active Tectonics Group during a temporary deployment from July 22nd - August 2nd. By combining this data with the kinematic data we hope to elucidate the response of the landslide to environmental changes such as rainfall, snowmelt, and atmospheric pressure, and consequently the mechanisms controlling the dynamics of the landslide system. To constrain the longer temporal dynamics, interferograms made from pairs of CSK images acquired in 2010, 2011, 2012 and 2013 reveal the slide deformation on a longer timescale by allowing us to measure meters of motion and see the average rates over year long intervals using pixel offset tracking of the high-resolution SAR amplitude images. The results of

New formulation for interferometric synthetic aperture radar for terrain mapping

NASA Astrophysics Data System (ADS)

Jakowatz, Charles V., Jr.; Wahl, Daniel E.; Eichel, Paul H.; Thompson, Paul A.

1994-06-01

The subject of interferometric synthetic aperture radar (IFSAR) for high-accuracy terrain elevation mapping continues to gain importance in the arena of radar signal processing. Applications to problems in precision terrain-aided guidance and automatic target recognition, as well as a variety of civil applications, are being studied by a number of researchers. Not unlike many other areas of SAR processing, the subject of IFSAR can, at first glance, appear to be somewhat mysterious. In this paper we show how the mathematics of IFSAR for terrain elevation mapping using a pair of spotlight mode SAR collections can be derived in a very straightforward manner. Here, we employ an approach that relies entirely on Fourier transforms, and utilizes no reference to range equations or Doppler concepts. The result is a simplified explanation of the fundamentals of interferometry, including an easily-seen link between image domain phase difference and terrain elevation height. The derivation builds upon previous work by the authors in which a framework for spotlight mode SAR image formation based on an analogy to 3D computerized axial tomography (CAT) was developed. After outlining the major steps in the mathematics, we show how a computer simulator which utilizes 3D Fourier transforms can be constructed that demonstrates all of the major aspects of IFSAR from spotlight mode collections.

Characterization of wetland, forest, and agricultural ecosystems in Belize with airborne radar (AIRSAR)

NASA Technical Reports Server (NTRS)

Pope, Kevin O.; Rey-Benayas, Jose Maria; Paris, Jack F.

1992-01-01

The Shuttle Imaging Radar-C/X-SAR (Synthetic Aperture Radar) Experiment includes the study of wetland dynamics in the seasonal tropics. In preparation for these wetland studies, airborne P, L, and C band radar (AIRSAR) data of Belize, Guatemala, and Mexico acquired by NASA and JPL in March 1990 were analyzed. The first phase of our study focuses on AIRSAR data from the Gallon Jug test site in northwestern Belize, for which ground data were also collected during the three days prior to the overflight. One of the main objectives of the Gallon Jug study is to develop a method for characterizing wetland vegetation types and their flooding status with multifrequency polarimetric radar data.

Fine resolution topographic mapping of the Jovian moons: a Ka-band high resolution topographic mapping interferometric synthetic aperture radar

NASA Technical Reports Server (NTRS)

Madsen, Soren N.; Carsey, Frank D.; Turtle, Elizabeth P.

2003-01-01

The topographic data set obtained by MOLA has provided an unprecedented level of information about Mars' geologic features. The proposed flight of JIMO provides an opportunity to accomplish a similar mapping of and comparable scientific discovery for the Jovian moons through us of an interferometric imaging radar analogous to the Shuttle radar that recently generated a new topographic map of Earth. A Ka-band single pass across-track synthetic aperture radar (SAR) interferometer can provide very high resolution surface elevation maps. The concept would use two antennas mounted at the ends of a deployable boom (similar to the Shuttle Radar Topographic Mapper) extended orthogonal to the direction of flight. Assuming an orbit altitude of approximately 100 km and a ground velocity of approximately 1.5 km/sec, horizontal resolutions at the 10 meter level and vertical resolutions at the sub-meter level are possible.

Fine Resolution Topographic Mapping of the Jovian Moons: A Ka-Band High Resolution Topographic Mapping Interferometric Synthetic Aperture Radar

NASA Technical Reports Server (NTRS)

Madsen, S. N.; Carsey, F. D.; Turtle, E. P.

2003-01-01

The topographic data set obtained by MOLA has provided an unprecedented level of information about Mars' geologic features. The proposed flight of JIMO provides an opportunity to accomplish a similar mapping of and comparable scientific discovery for the Jovian moons through use of an interferometric imaging radar analogous to the Shuttle radar that recently generated a new topographic map of Earth. A Ka-band single pass across-track synthetic aperture radar (SAR) interferometer can provide very high resolution surface elevation maps. The concept would use two antennas mounted at the ends of a deployable boom (similar to the Shuttle Radar Topographic Mapper) extended orthogonal to the direction of flight. Assuming an orbit altitude of approximately 100km and a ground velocity of approximately 1.5 km/sec, horizontal resolutions at the 10 meter level and vertical resolutions at the sub-meter level are possible.

Feasibility of inter-comparing airborne and spaceborne observations of radar backscattering coefficients

USDA-ARS?s Scientific Manuscript database

This paper investigates the feasibility of using an airborne synthetic aperture radar (SAR) to validate spaceborne SAR data. This is directed at soil moisture sensing and the recently launched Soil Moisture Active Passive (SMAP) satellite. The value of this approach is related to the fact that vicar...

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

Applications of Radar Interferometric Techniques to Assess Natural Hazards and their Controlling Factors

NASA Astrophysics Data System (ADS)

Sultan, M.; Becker, R.; Gebremichael, E.; Othman, A.; Emil, M.; Ahmed, M.; Elkadiri, R.; Pankratz, H. G.; Chouinard, K.

2015-12-01

Radar interferometric techniques including Persistent Scatterer (PS), Small BAseline Subset (SBAS), and two and three pass (differential interferometry) methods were applied to Synthetic Aperture Radar (SAR) datasets. These include the European Space Agency (ESA) ERS-1, ERS-2, Environmental satellite (Envisat), and Phased Array type L-band Synthetic Aperture Radar (PALSAR) to conduct the following: (1) map the spatial distribution of land deformation associated with a wide range of geologic settings, (2) quantify the rates of the observed land deformation, and (3) identify the factors controlling the observed deformation. The research topics/areas include: (1) subsidence associated with sediment compaction in a Delta setting (Nile Delta, Egypt), (2) deformation in a rifting setting (Red Sea rifting along the Red Sea coastal zone and proximal basement outcrops in Egypt and Saudi Arabia), (3) deformation associated with salt dome intrusion and the dissolution of sabkha deposits (Jazan area in Saudi Arabia), (4) mass transport associated with debris flows (Jazan area in Saudi Arabia), and (5) deformation preceding, contemporaneous with, or following large earthquakes (in Nepal; magnitude: 7.8; date: April, 25, 2015) and medium earthquakes (in Harrat Lunayyir volcanic field, central Saudi Arabia; magnitude: 5.7; date: May 19, 2009). The identification of the factor(s) controlling the observed deformation was attained through spatial correlation of extracted radar velocities with relevant temporal and static ground based and remotely sensed geological and cultural data sets (e.g., lithology, structure, precipitation, land use, and earthquake location, magnitude, and focal mechanism) in a Geographical Information System (GIS) environment.

Preliminary results from multiparameter airborne rain radar measurement in the western Pacific

NASA Technical Reports Server (NTRS)

Kumagai, Hiroshi; Meneghini, Robert; Kozu, Toshiaki

1993-01-01

Preliminary results are presented from multiparameter airborne radar measurements of tropical storms. The experiment was conducted in the western Pacific in September 1990 with the NASA DC-8 aircraft that was equipped with a dual-wavelength radar at X and Ka bands and several microwave radiometers. The modification to dual-polarization at X-band radar enabled measurements of the linear depolarization ratio (LDR). Vertical profiles of dual-polarization and dual-frequency observables for an example of stratiform rain and three examples of convective rain cells are examined. It is shown that at nadir incidence the LDR measurement often can be used to distinguish the phase states of the hydrometeors and to identify the melting layer. In addition to the information concerning particle shape and orientation from LDR, the ratio of the radar reflectivity factors in two frequency bands (X and Ka bands) provides insight into particle size. The capabilities of dual-wavelength and dual-polarization radar in the identification of particle size and phase will be important considerations in the design of future spaceborne weather radars.

Remote Sensing of Precipitation from Airborne and Spaceborne Radar. Chapter 13

NASA Technical Reports Server (NTRS)

Munchak, S. Joseph

2017-01-01

Weather radar measurements from airborne or satellite platforms can be an effective remote sensing tool for examining the three-dimensional structures of clouds and precipitation. This chapter describes some fundamental properties of radar measurements and their dependence on the particle size distribution (PSD) and radar frequency. The inverse problem of solving for the vertical profile of PSD from a profile of measured reflectivity is stated as an optimal estimation problem for single- and multi-frequency measurements. Phenomena that can change the measured reflectivity Z(sub m) from its intrinsic value Z(sub e), namely attenuation, non-uniform beam filling, and multiple scattering, are described and mitigation of these effects in the context of the optimal estimation framework is discussed. Finally, some techniques involving the use of passive microwave measurements to further constrain the retrieval of the PSD are presented.

Analysis of Airborne Radar Altimetry Measurements of the Greenland Ice Sheet

NASA Technical Reports Server (NTRS)

Ferraro, Ellen J.

1994-01-01

This dissertation presents an analysis of airborne altimetry measurements taken over the Greenland ice sheet with the 13.9 GHz Advanced Application Flight Experiment (AAFE) pulse compression radar altimeter. This Ku-band instrument was refurbished in 1990 by the Microwave Remote Sensing Laboratory at the University of Massachusetts to obtain high-resolution altitude measurements and to improve the tracking, speed, storage and display capabilities of the radar. In 1991 and 1993, the AAFE altimeter took part in the NASA Multisensor Airborne Altimetry Experiments over Greenland, along with two NASA laser altimeters. Altitude results from both experiments are presented along with comparisons to the laser altimeter and calibration passes over the Sondrestroem runway in Greenland. Although it is too early to make a conclusion about the growth or decay of the ice sheet, these results show that the instrument is capable of measuring small-scale surface changes to within 14 centimeters. In addition, results from these experiments reveal that the radar is sensitive to the different diagenetic regions of the ice sheet. Return waveforms from the wet- snow, percolation and dry-snow zones show varying effects of both surface scattering and sub-surface or volume scattering. Models of each of the diagenetic regions of Greenland are presented along with parameters such as rms surface roughness, rms surface slope and attenuation coefficient of the snow pack obtained by fitting the models to actual return waveforms.

An Accurate Co-registration Method for Airborne Repeat-pass InSAR

NASA Astrophysics Data System (ADS)

Dong, X. T.; Zhao, Y. H.; Yue, X. J.; Han, C. M.

2017-10-01

Interferometric Synthetic Aperture Radar (InSAR) technology plays a significant role in topographic mapping and surface deformation detection. Comparing with spaceborne repeat-pass InSAR, airborne repeat-pass InSAR solves the problems of long revisit time and low-resolution images. Due to the advantages of flexible, accurate, and fast obtaining abundant information, airborne repeat-pass InSAR is significant in deformation monitoring of shallow ground. In order to getting precise ground elevation information and interferometric coherence of deformation monitoring from master and slave images, accurate co-registration must be promised. Because of side looking, repeat observing path and long baseline, there are very different initial slant ranges and flight heights between repeat flight paths. The differences of initial slant ranges and flight height lead to the pixels, located identical coordinates on master and slave images, correspond to different size of ground resolution cells. The mismatching phenomenon performs very obvious on the long slant range parts of master image and slave image. In order to resolving the different sizes of pixels and getting accurate co-registration results, a new method is proposed based on Range-Doppler (RD) imaging model. VV-Polarization C-band airborne repeat-pass InSAR images were used in experiment. The experiment result shows that the proposed method leads to superior co-registration accuracy.

Annual Greenland Accumulation Rates (2009-2012) from Airborne Snow Radar

NASA Technical Reports Server (NTRS)

Koenig, Lora S.; Ivanoff, Alvaro; Alexander, Patrick M.; MacGregor, Joseph A.; Fettweis, Xavier; Panzer, Ben; Paden, John D.; Forster, Richard R.; Das, Indrani; McConnell, Joseph R.;

Multibeam monopulse radar for airborne sense and avoid system

NASA Astrophysics Data System (ADS)

Gorwara, Ashok; Molchanov, Pavlo

2016-10-01

The multibeam monopulse radar for Airborne Based Sense and Avoid (ABSAA) system concept is the next step in the development of passive monopulse direction finder proposed by Stephen E. Lipsky in the 80s. In the proposed system the multibeam monopulse radar with an array of directional antennas is positioned on a small aircaraft or Unmanned Aircraft System (UAS). Radar signals are simultaneously transmitted and received by multiple angle shifted directional antennas with overlapping antenna patterns and the entire sky, 360° for both horizontal and vertical coverage. Digitizing of amplitude and phase of signals in separate directional antennas relative to reference signals provides high-accuracy high-resolution range and azimuth measurement and allows to record real time amplitude and phase of reflected from non-cooperative aircraft signals. High resolution range and azimuth measurement provides minimal tracking errors in both position and velocity of non-cooperative aircraft and determined by sampling frequency of the digitizer. High speed sampling with high-accuracy processor clock provides high resolution phase/time domain measurement even for directional antennas with wide Field of View (FOV). Fourier transform (frequency domain processing) of received radar signals provides signatures and dramatically increases probability of detection for non-cooperative aircraft. Steering of transmitting power and integration, correlation period of received reflected signals for separate antennas (directions) allows dramatically decreased ground clutter for low altitude flights. An open architecture, modular construction allows the combination of a radar sensor with Automatic Dependent Surveillance - Broadcast (ADS-B), electro-optic, acoustic sensors.

Retrieving current and wind vectors from ATI SAR data: airborne evidence and inversion strategy

NASA Astrophysics Data System (ADS)

Martin, Adrien; Gommenginger, Christine; Chapron, Bertrand; Marquez, José; Doody, Sam

2017-04-01

Conventional and along-track interferometric (ATI) Synthetic Aperture Radar (SAR) sense the motion of the ocean surface by measuring the Doppler shift of reflected signals. Together with the water displacement associated with ocean currents, the SAR measurements are also affected by a Wind-wave induced Artefact Surface Velocity (WASV) caused by the velocity of Bragg scatterers and the orbital velocity of ocean surface gravity waves. The WASV has been modelled theoretically in past studies but has been estimated empirically only once using Envisat ASAR. Here we propose, firstly, to evaluate this WASV from airborne ATI SAR data, secondly, to validate the airborne retrieved surface current after correction of the WASV against HF radar measurements and thirdly to examine the best inversion strategy for a an Ocean Surface Current (OSC) satellite mission to retrieve accurately both the ocean surface current vector (OSCV) and the wind vector in the frame of an OSC satellite mission. The airborne ATI SAR data were acquired in the tidally dominated Irish Sea using a Wavemill-type dual-beam SAR interferometer. A comprehensive collection of airborne Wavemill data acquired in a star pattern over a well-instrumented site made it possible to estimate the magnitude and dependence on azimuth and incidence angle of the WASV. The airborne results compare favourably with those reported for Envisat ASAR, empirical model, which has been used to correct for it. Validation of the current retrieval capabilities of the proof-of-concept has been conducted against HF radar giving a precisions typically better than 0.1 m/s for surface current speed and 7° for direction. Comparisons with POLCOMS (1.8 km) indicate that the model reproduces well the overall temporal evolution but does not capture the high spatial variability of ocean surface currents at the maximum ebb flow. Airborne retrieved currents highlight a short-scale spatial variability up to 100m related to bathymetry channels, which

A portfolio of products from the rapid terrain visualization interferometric SAR

NASA Astrophysics Data System (ADS)

Bickel, Douglas L.; Doerry, Armin W.

2007-04-01

The Rapid Terrain Visualization interferometric synthetic aperture radar was designed and built at Sandia National Laboratories as part of an Advanced Concept Technology Demonstration (ACTD) to "demonstrate the technologies and infrastructure to meet the Army requirement for rapid generation of digital topographic data to support emerging crisis or contingencies." This sensor was built by Sandia National Laboratories for the Joint Programs Sustainment and Development (JPSD) Project Office to provide highly accurate digital elevation models (DEMs) for military and civilian customers, both inside and outside of the United States. The sensor achieved better than HRTe Level IV position accuracy in near real-time. The system was flown on a deHavilland DHC-7 Army aircraft. This paper presents a collection of images and data products from the Rapid Terrain Visualization interferometric synthetic aperture radar. The imagery includes orthorectified images and DEMs from the RTV interferometric SAR radar.

Extending interferometric synthetic aperture radar measurements from one to two dimensions

NASA Astrophysics Data System (ADS)

Bechor, Noah

Interferometric synthetic aperture radar (InSAR), a very effective technique for measuring crustal deformation, provides measurements in only one dimension, along the radar line of sight. Imaging radar measurements from satellite-based systems are sensitive to both vertical and across-track displacements, but insensitive to along-track displacement. Multiple observations can resolve the first two components, but the along-track component remains elusive. The best existing method to obtain the along-track displacement involves pixel-level azimuth cross-correlation. The measurements are quite coarse (typically 15 cm precision), and they require large computation times. In contrast, across-track and vertical InSAR measurements can reach centimeter-level precision and are readily derived. We present a new method to extract along-track displacements from InSAR data. The new method, multiple aperture InSAR (MAI), is based on split-beam processing of InSAR data to create forward- and backward-looking interferograms. The phase difference between the two modified interferograms provides the along-track displacement component. Thus, from each conventional InSAR pair we extract two components of the displacement vector: one along the line of sight, the other in the along-track direction. Multiple MAI observations, either at two look angles or from the ascending and descending radar passes, then yield the three-dimensional displacement field. We analyze precision of our method by comparing our solution to GPS and offset-derived along-track displacements from interferograms of the M7.1 1999, Hector Mine earthquake. The RMS error between GPS displacements and our results ranges from 5 to 8.8cm. Our method is consistent with along-track displacements derived by pixel-offsets, themselves limited to 12-15cm precision. The theoretical MAI precision depends on SNR and coherence. For SNR=100 the expected precision is 3, 11cm for coherence of 0.8, 0.4, respectively. Finally, we

On construction method of shipborne and airborne radar intelligence and related equipment knowledge graph

NASA Astrophysics Data System (ADS)

Hao, Ruizhe; Huang, Jian

2017-08-01

Knowledge graph construction in military intelligence domain is sprouting but technically immature. This paper presents a method to construct the heterogeneous knowledge graph in the field of shipborne and airborne radar and equipment. Based on the expert knowledge and the up-to-date Internet open source information, we construct the knowledge graph of radar characteristic information and the equipment respectively, and establish relationships between two graphs, providing the pipeline and method for the intelligence organization and management in the context of the crowding battlefields big data.

Gulf Coast Subsidence: Integration of Geodesy, Geophysical Modeling, and Interferometric Synthetic Aperture Radar Observations

NASA Astrophysics Data System (ADS)

Blom, R. G.; Chapman, B. D.; Deese, R.; Dokka, R. K.; Fielding, E. J.; Hawkins, B.; Hensley, S.; Ivins, E. R.; Jones, C. E.; Kent, J. D.; Liu, Z.; Lohman, R.; Zheng, Y.

2012-12-01

The vulnerability of the US Gulf Coast has received increased attention in the years since hurricanes Katrina and Rita. Agencies responsible for the long-term protection of lives and infrastructure require precise estimates of future subsidence and sea level rise. A quantitative, geophysically based methodology can provide such estimates by incorporating geological data, geodetic measurements, geophysical models of non-elastic mechanical behavior at depth, and geographically comprehensive deformation monitoring made possible with measurements from Interferometric Synthetic Aperture Radar (InSAR). To be effective, results must be available to user agencies in a format suitable for integration within existing decision-support processes. Work to date has included analysis of historical and continuing ground-based geodetic measurements. These reveal a surprising degree of complexity, including regions that are subsiding at rates faster than those considered for hurricane protection planning of New Orleans and other coastal communities (http://www.mvn.usace.army.mil/pdf/hps_verticalsettlement.pdf) as well as Louisiana's coastal restoration strategies (http://www.coast2050.gov/2050reports.htm) (Dokka, 2011, J. Geophys. Res., 116, B06403, doi:10.1029/2010JB008008). Traditional geodetic measurements provide precise information at single points, while InSAR observations provide geographically comprehensive measurements of surface deformation at lower vertical precision. Available InSAR data sources include X-, C- and L-band satellite, and NASA/JPL airborne UAVSAR L-band data. The Gulf Coast environment is very challenging for InSAR techniques, especially with systems not designed for interferometry. For example, the shorter wavelength C-band data decorrelates over short time periods requiring more elaborate time-series analysis techniques, with which we've had some success. Meanwhile, preliminary analysis of limited L-Band ALOS/PALSAR satellite data show promise

Analysis of airborne Doppler lidar, Doppler radar and tall tower measurements of atmospheric flows in quiescent and stormy weather

NASA Technical Reports Server (NTRS)

Bluestein, H. B.; Doviak, R. J.; Eilts, M. D.; Mccaul, E. W.; Rabin, R.; Sundara-Rajan, A.; Zrnic, D. S.

1986-01-01

The first experiment to combine airborne Doppler Lidar and ground-based dual Doppler Radar measurements of wind to detail the lower tropospheric flows in quiescent and stormy weather was conducted in central Oklahoma during four days in June-July 1981. Data from these unique remote sensing instruments, coupled with data from conventional in-situ facilities, i.e., 500-m meteorological tower, rawinsonde, and surface based sensors, were analyzed to enhance understanding of wind, waves and turbulence. The purposes of the study were to: (1) compare winds mapped by ground-based dual Doppler radars, airborne Doppler lidar, and anemometers on a tower; (2) compare measured atmospheric boundary layer flow with flows predicted by theoretical models; (3) investigate the kinematic structure of air mass boundaries that precede the development of severe storms; and (4) study the kinematic structure of thunderstorm phenomena (downdrafts, gust fronts, etc.) that produce wind shear and turbulence hazardous to aircraft operations. The report consists of three parts: Part 1, Intercomparison of Wind Data from Airborne Lidar, Ground-Based Radars and Instrumented 444 m Tower; Part 2, The Structure of the Convective Atmospheric Boundary Layer as Revealed by Lidar and Doppler Radars; and Part 3, Doppler Lidar Observations in Thunderstorm Environments.

Microphysical Retrievals Over Stratiform Rain Using Measurements from an Airborne Dual-Wavelength Radar-Radiometer

NASA Technical Reports Server (NTRS)

Meneghini, Robert; Kumagai, Hiroshi; Wang, James R.; Iguchi, Toshio; Kozu, Toshiaki

1997-01-01

The need to understand the complementarity of the radar and radiometer is important not only to the Tropical Rain Measuring Mission (TRMM) program but to a growing number of multi-instrumented airborne experiment that combine single or dual-frequency radars with multichannel radiometers. The method of analysis used in this study begins with the derivation of dual-wavelength radar equations for the estimation of a two-parameter drop size distribution (DSD). Defining a "storm model" as the set of parameters that characterize snow density, cloud water, water vapor, and features of the melting layer, then to each storm model there will usually correspond a set of range-profiled drop size distributions that are approximate solutions of the radar equations. To test these solutions, a radiative transfer model is used to compute the brightness temperatures for the radiometric frequencies of interest. A storm model or class of storm models is considered optimum if it provides the best reproduction of the radar and radiometer measurements. Tests of the method are made for stratiform rain using simulated storm models as well as measured airborne data. Preliminary results show that the best correspondence between the measured and estimated radar profiles usually can be obtained by using a moderate snow density (0.1-0.2 g/cu cm), the Maxwell-Garnett mixing formula for partially melted hydrometeors (water matrix with snow inclusions), and low to moderate values of the integrated cloud liquid water (less than 1 kg/sq m). The storm-model parameters that yield the best reproductions of the measured radar reflectivity factors also provide brightness temperatures at 10 GHz that agree well with the measurements. On the other hand, the correspondence between the measured and modeled values usually worsens in going to the higher frequency channels at 19 and 34 GHz. In searching for possible reasons for the discrepancies, It is found that changes in the DSD parameter Mu, the radar

The pulse-pair algorithm as a robust estimator of turbulent weather spectral parameters using airborne pulse Doppler radar

NASA Technical Reports Server (NTRS)

Baxa, Ernest G., Jr.; Lee, Jonggil

1991-01-01

The pulse pair method for spectrum parameter estimation is commonly used in pulse Doppler weather radar signal processing since it is economical to implement and can be shown to be a maximum likelihood estimator. With the use of airborne weather radar for windshear detection, the turbulent weather and strong ground clutter return spectrum differs from that assumed in its derivation, so the performance robustness of the pulse pair technique must be understood. Here, the effect of radar system pulse to pulse phase jitter and signal spectrum skew on the pulse pair algorithm performance is discussed. Phase jitter effect may be significant when the weather return signal to clutter ratio is very low and clutter rejection filtering is attempted. The analysis can be used to develop design specifications for airborne radar system phase stability. It is also shown that the weather return spectrum skew can cause a significant bias in the pulse pair mean windspeed estimates, and that the poly pulse pair algorithm can reduce this bias. It is suggested that use of a spectrum mode estimator may be more appropriate in characterizing the windspeed within a radar range resolution cell for detection of hazardous windspeed gradients.

Improved Absolute Radiometric Calibration of a UHF Airborne Radar

NASA Technical Reports Server (NTRS)

Chapin, Elaine; Hawkins, Brian P.; Harcke, Leif; Hensley, Scott; Lou, Yunling; Michel, Thierry R.; Moreira, Laila; Muellerschoen, Ronald J.; Shimada, Joanne G.; Tham, Kean W.;

Ground based interferometric radar initial look at Longview, Blue Springs, Tuttle Creek, and Milford Dams

NASA Astrophysics Data System (ADS)

Deng, Huazeng

Measuring millimeter and smaller deformation has been demonstrated in the literature using RADAR. To address in part the limitations in current commercial satellite-based SAR datasets, a University of Missouri (MU) team worked with GAMMA Remote Sensing to develop a specialized (dual-frequency, polarimetric, and interferometric) ground-based real-aperture RADAR (GBIR) instrument. The GBIR device is portable with its tripod system and control electronics. It can be deployed to obtain data with high spatial resolution (i.e. on the order of 1 meter) and high temporal resolution (i.e. on the order 1 minute). The high temporal resolution is well suited for measurements of rapid deformation. From the same geodetic position, the GBIR may collect dual frequency data set using C-band and Ku-band. The overall goal of this project is to measure the deformation from various scenarios by applying the GBIR system. Initial efforts have been focusing on testing the system performance on different types of targets. This thesis details a number of my efforts on experimental and processing activities at the start of the MU GBIR imaging project. For improved close range capability, a wideband dual polarized antenna option was produced and tested. For GBIR calibration, several trihedral corner reflectors were designed and fabricated. In addition to experimental activities and site selection, I participated in advanced data processing activities. I processed GBIR data in several ways including single-look-complex (SLC) image generation, imagery registration, and interferometric processing. A number of initial-processed GBIR image products are presented from four dams: Longview, Blue Springs, Tuttle Creek, and Milford. Excellent imaging performance of the MU GBIR has been observed for various target types such as riprap, concrete, soil, rock, metal, and vegetation. Strong coherence of the test scene has been observed in the initial interferograms.

Analysis and improved design considerations for airborne pulse Doppler radar signal processing in the detection of hazardous windshear

NASA Technical Reports Server (NTRS)

Lee, Jonggil

1990-01-01

High resolution windspeed profile measurements are needed to provide reliable detection of hazardous low altitude windshear with an airborne pulse Doppler radar. The system phase noise in a Doppler weather radar may degrade the spectrum moment estimation quality and the clutter cancellation capability which are important in windshear detection. Also the bias due to weather return Doppler spectrum skewness may cause large errors in pulse pair spectral parameter estimates. These effects are analyzed for the improvement of an airborne Doppler weather radar signal processing design. A method is presented for the direct measurement of windspeed gradient using low pulse repetition frequency (PRF) radar. This spatial gradient is essential in obtaining the windshear hazard index. As an alternative, the modified Prony method is suggested as a spectrum mode estimator for both the clutter and weather signal. Estimation of Doppler spectrum modes may provide the desired windshear hazard information without the need of any preliminary processing requirement such as clutter filtering. The results obtained by processing a NASA simulation model output support consideration of mode identification as one component of a windshear detection algorithm.

Techniques and Tools for Estimating Ionospheric Effects in Interferometric and Polarimetric SAR Data

NASA Technical Reports Server (NTRS)

Rosen, P.; Lavalle, M.; Pi, X.; Buckley, S.; Szeliga, W.; Zebker, H.; Gurrola, E.

2011-01-01

The InSAR Scientific Computing Environment (ISCE) is a flexible, extensible software tool designed for the end-to-end processing and analysis of synthetic aperture radar data. ISCE inherits the core of the ROI_PAC interferometric tool, but contains improvements at all levels of the radar processing chain, including a modular and extensible architecture, new focusing approach, better geocoding of the data, handling of multi-polarization data, radiometric calibration, and estimation and correction of ionospheric effects. In this paper we describe the characteristics of ISCE with emphasis on the ionospheric modules. To detect ionospheric anomalies, ISCE implements the Faraday rotation method using quadpolarimetric images, and the split-spectrum technique using interferometric single-, dual- and quad-polarimetric images. The ability to generate co-registered time series of quad-polarimetric images makes ISCE also an ideal tool to be used for polarimetric-interferometric radar applications.

Digital elevation model generation from satellite interferometric synthetic aperture radar: Chapter 5

USGS Publications Warehouse

Lu, Zhong; Dzurisin, Daniel; Jung, Hyung-Sup; Zhang, Lei; Lee, Wonjin; Lee, Chang-Wook

2012-01-01

An accurate digital elevation model (DEM) is a critical data set for characterizing the natural landscape, monitoring natural hazards, and georeferencing satellite imagery. The ideal interferometric synthetic aperture radar (InSAR) configuration for DEM production is a single-pass two-antenna system. Repeat-pass single-antenna satellite InSAR imagery, however, also can be used to produce useful DEMs. DEM generation from InSAR is advantageous in remote areas where the photogrammetric approach to DEM generation is hindered by inclement weather conditions. There are many sources of errors in DEM generation from repeat-pass InSAR imagery, for example, inaccurate determination of the InSAR baseline, atmospheric delay anomalies, and possible surface deformation because of tectonic, volcanic, or other sources during the time interval spanned by the images. This chapter presents practical solutions to identify and remove various artifacts in repeat-pass satellite InSAR images to generate a high-quality DEM.

A Methodology for Determining Statistical Performance Compliance for Airborne Doppler Radar with Forward-Looking Turbulence Detection Capability

NASA Technical Reports Server (NTRS)

Bowles, Roland L.; Buck, Bill K.

2009-01-01

The objective of the research developed and presented in this document was to statistically assess turbulence hazard detection performance employing airborne pulse Doppler radar systems. The FAA certification methodology for forward looking airborne turbulence radars will require estimating the probabilities of missed and false hazard indications under operational conditions. Analytical approaches must be used due to the near impossibility of obtaining sufficient statistics experimentally. This report describes an end-to-end analytical technique for estimating these probabilities for Enhanced Turbulence (E-Turb) Radar systems under noise-limited conditions, for a variety of aircraft types, as defined in FAA TSO-C134. This technique provides for one means, but not the only means, by which an applicant can demonstrate compliance to the FAA directed ATDS Working Group performance requirements. Turbulence hazard algorithms were developed that derived predictive estimates of aircraft hazards from basic radar observables. These algorithms were designed to prevent false turbulence indications while accurately predicting areas of elevated turbulence risks to aircraft, passengers, and crew; and were successfully flight tested on a NASA B757-200 and a Delta Air Lines B737-800. Application of this defined methodology for calculating the probability of missed and false hazard indications taking into account the effect of the various algorithms used, is demonstrated for representative transport aircraft and radar performance characteristics.

Estimation of snow in extratropical cyclones from multiple frequency airborne radar observations. An Expectation-Maximization approach

NASA Astrophysics Data System (ADS)

Grecu, M.; Tian, L.; Heymsfield, G. M.

2017-12-01

A major challenge in deriving accurate estimates of physical properties of falling snow particles from single frequency space- or airborne radar observations is that snow particles exhibit a large variety of shapes and their electromagnetic scattering characteristics are highly dependent on these shapes. Triple frequency (Ku-Ka-W) radar observations are expected to facilitate the derivation of more accurate snow estimates because specific snow particle shapes tend to have specific signatures in the associated two-dimensional dual-reflectivity-ratio (DFR) space. However, the derivation of accurate snow estimates from triple frequency radar observations is by no means a trivial task. This is because the radar observations can be subject to non-negligible attenuation (especially at W-band when super-cooled water is present), which may significantly impact the interpretation of the information in the DFR space. Moreover, the electromagnetic scattering properties of snow particles are computationally expensive to derive, which makes the derivation of reliable parameterizations usable in estimation methodologies challenging. In this study, we formulate an two-step Expectation Maximization (EM) methodology to derive accurate snow estimates in Extratropical Cyclones (ECTs) from triple frequency airborne radar observations. The Expectation (E) step consists of a least-squares triple frequency estimation procedure applied with given assumptions regarding the relationships between the density of snow particles and their sizes, while the Maximization (M) step consists of the optimization of the assumptions used in step E. The electromagnetic scattering properties of snow particles are derived using the Rayleigh-Gans approximation. The methodology is applied to triple frequency radar observations collected during the Olympic Mountains Experiment (OLYMPEX). Results show that snowfall estimates above the freezing level in ETCs consistent with the triple frequency radar

Rapid, Repeat-sample Monitoring of Crustal Deformations and Environmental Phenomena with the Uninhabited Aerial Vehicle Synthetic Aperture Radar

NASA Technical Reports Server (NTRS)

Smith, Robert C.

2006-01-01

The Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) is a precision repeat-pass Interferometric Synthetic Aperture Radar (InSAR) mission being developed by the Jet Propulsion Laboratory and the Dryden Flight Research Center in support of NASA s Science Mission Directorate. UAVSAR's unique ability to fly a repeatable flight path, along with an electronically steerable array, allows interferometric data to be obtained with accuracies measured in millimeters. Deploying the radar on an airborne platform will also allow for radar images to be collected and compared with images from the same area taken hours or even years later - providing for long-term trending and near real-time notification of changes and deformations. UAVSAR s data processing algorithms will provide for near-real time data reduction providing disaster planning and response teams with highly accurate data to aid in the prediction of, and response to, natural phenomena. UAVSAR data can be applied to increasing our understanding of the processes behind solid earth, cryosphere, carbon cycle and other areas of interest in earth science. Technologies developed for UAVSAR may also be applicable to a future earth-orbiting InSAR mission and possibly for missions to the Moon or Mars. The UAVSAR is expected to fly on a Gulfstream III aircraft this winter, followed by a flight test program lasting until the second half of 2007. Following radar calibration and data reduction activities, the platform will be ready for science users in the summer of 2008.

Extracting DEM from airborne X-band data based on PolInSAR

NASA Astrophysics Data System (ADS)

Hou, X. X.; Huang, G. M.; Zhao, Z.

2015-06-01

Polarimetric Interferometric Synthetic Aperture Radar (PolInSAR) is a new trend of SAR remote sensing technology which combined polarized multichannel information and Interferometric information. It is of great significance for extracting DEM in some regions with low precision of DEM such as vegetation coverage area and building concentrated area. In this paper we describe our experiments with high-resolution X-band full Polarimetric SAR data acquired by a dual-baseline interferometric airborne SAR system over an area of Danling in southern China. Pauli algorithm is used to generate the double polarimetric interferometry data, Singular Value Decomposition (SVD), Numerical Radius (NR) and Phase diversity (PD) methods are used to generate the full polarimetric interferometry data. Then we can make use of the polarimetric interferometric information to extract DEM with processing of pre filtering , image registration, image resampling, coherence optimization, multilook processing, flat-earth removal, interferogram filtering, phase unwrapping, parameter calibration, height derivation and geo-coding. The processing system named SARPlore has been exploited based on VC++ led by Chinese Academy of Surveying and Mapping. Finally compared optimization results with the single polarimetric interferometry, it has been observed that optimization ways can reduce the interferometric noise and the phase unwrapping residuals, and improve the precision of DEM. The result of full polarimetric interferometry is better than double polarimetric interferometry. Meanwhile, in different terrain, the result of full polarimetric interferometry will have a different degree of increase.

Segmentation of Oil Spills on Side-Looking Airborne Radar Imagery with Autoencoders.

PubMed

Gallego, Antonio-Javier; Gil, Pablo; Pertusa, Antonio; Fisher, Robert B

2018-03-06

In this work, we use deep neural autoencoders to segment oil spills from Side-Looking Airborne Radar (SLAR) imagery. Synthetic Aperture Radar (SAR) has been much exploited for ocean surface monitoring, especially for oil pollution detection, but few approaches in the literature use SLAR. Our sensor consists of two SAR antennas mounted on an aircraft, enabling a quicker response than satellite sensors for emergency services when an oil spill occurs. Experiments on TERMA radar were carried out to detect oil spills on Spanish coasts using deep selectional autoencoders and RED-nets (very deep Residual Encoder-Decoder Networks). Different configurations of these networks were evaluated and the best topology significantly outperformed previous approaches, correctly detecting 100% of the spills and obtaining an F 1 score of 93.01% at the pixel level. The proposed autoencoders perform accurately in SLAR imagery that has artifacts and noise caused by the aircraft maneuvers, in different weather conditions and with the presence of look-alikes due to natural phenomena such as shoals of fish and seaweed.

Segmentation of Oil Spills on Side-Looking Airborne Radar Imagery with Autoencoders

PubMed Central

2018-01-01

In this work, we use deep neural autoencoders to segment oil spills from Side-Looking Airborne Radar (SLAR) imagery. Synthetic Aperture Radar (SAR) has been much exploited for ocean surface monitoring, especially for oil pollution detection, but few approaches in the literature use SLAR. Our sensor consists of two SAR antennas mounted on an aircraft, enabling a quicker response than satellite sensors for emergency services when an oil spill occurs. Experiments on TERMA radar were carried out to detect oil spills on Spanish coasts using deep selectional autoencoders and RED-nets (very deep Residual Encoder-Decoder Networks). Different configurations of these networks were evaluated and the best topology significantly outperformed previous approaches, correctly detecting 100% of the spills and obtaining an F1 score of 93.01% at the pixel level. The proposed autoencoders perform accurately in SLAR imagery that has artifacts and noise caused by the aircraft maneuvers, in different weather conditions and with the presence of look-alikes due to natural phenomena such as shoals of fish and seaweed. PMID:29509720

Retrieval of Snow and Rain From Combined X- and W-B and Airborne Radar Measurements

NASA Technical Reports Server (NTRS)

Liao, Liang; Meneghini, Robert; Tian, Lin; Heymsfield, Gerald M.

2008-01-01

Two independent airborne dual-wavelength techniques, based on nadir measurements of radar reflectivity factors and Doppler velocities, respectively, are investigated with respect to their capability of estimating microphysical properties of hydrometeors. The data used to investigate the methods are taken from the ER-2 Doppler radar (X-band) and Cloud Radar System (W-band) airborne Doppler radars during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment campaign in 2002. Validity is assessed by the degree to which the methods produce consistent retrievals of the microphysics. For deriving snow parameters, the reflectivity-based technique has a clear advantage over the Doppler-velocity-based approach because of the large dynamic range in the dual-frequency ratio (DFR) with respect to the median diameter Do and the fact that the difference in mean Doppler velocity at the two frequencies, i.e., the differential Doppler velocity (DDV), in snow is small relative to the measurement errors and is often not uniquely related to Do. The DFR and DDV can also be used to independently derive Do in rain. At W-band, the DFR-based algorithms are highly sensitive to attenuation from rain, cloud water, and water vapor. Thus, the retrieval algorithms depend on various assumptions regarding these components, whereas the DDV-based approach is unaffected by attenuation. In view of the difficulties and ambiguities associated with the attenuation correction at W-band, the DDV approach in rain is more straightforward and potentially more accurate than the DFR method.

Semi-physical Simulation of the Airborne InSAR based on Rigorous Geometric Model and Real Navigation Data

NASA Astrophysics Data System (ADS)

Changyong, Dou; Huadong, Guo; Chunming, Han; yuquan, Liu; Xijuan, Yue; Yinghui, Zhao

2014-03-01

Raw signal simulation is a useful tool for the system design, mission planning, processing algorithm testing, and inversion algorithm design of Synthetic Aperture Radar (SAR). Due to the wide and high frequent variation of aircraft's trajectory and attitude, and the low accuracy of the Position and Orientation System (POS)'s recording data, it's difficult to quantitatively study the sensitivity of the key parameters, i.e., the baseline length and inclination, absolute phase and the orientation of the antennas etc., of the airborne Interferometric SAR (InSAR) system, resulting in challenges for its applications. Furthermore, the imprecise estimation of the installation offset between the Global Positioning System (GPS), Inertial Measurement Unit (IMU) and the InSAR antennas compounds the issue. An airborne interferometric SAR (InSAR) simulation based on the rigorous geometric model and real navigation data is proposed in this paper, providing a way for quantitatively studying the key parameters and for evaluating the effect from the parameters on the applications of airborne InSAR, as photogrammetric mapping, high-resolution Digital Elevation Model (DEM) generation, and surface deformation by Differential InSAR technology, etc. The simulation can also provide reference for the optimal design of the InSAR system and the improvement of InSAR data processing technologies such as motion compensation, imaging, image co-registration, and application parameter retrieval, etc.

The Information Content of Interferometric Synthetic Aperture Radar: Vegetation and Underlying Surface Topography

NASA Technical Reports Server (NTRS)

Treuhaft, Robert N.

1996-01-01

Drawing from recently submitted work, this paper first gives a heuristic description of the sensitivity of interferometric synthetic aperture radar (INSAR) to vertical vegetation distribution and under laying surface topography. A parameter estimation scenario is then described in which the INSAR cross correlation amplitude and phase are the observations from which vegetation and surface topographic parameters are estimated. It is shown that, even in the homogeneous layer model of the vegetation, the number of parameters needed to describe the vegetation and underlying topography exceeds the number of INSAR observations for single baseline, single frequency, single incidence-angle, single polarization INSAR. Using ancillary ground truth data to compensate for the under determination of the parameters, forest depths are estimated from the INSAR data. A recently analyzed multi-baseline data set is also discussed and the potential for stand alone INSAR parameter estimation is assessed. The potential of combining the information content of INSAR with that of infrared/optical remote sensing data is briefly discussed.

Hyperspectral and Radar Airborne Imagery over Controlled Release of Oil at Sea.

PubMed

Angelliaume, Sébastien; Ceamanos, Xavier; Viallefont-Robinet, Françoise; Baqué, Rémi; Déliot, Philippe; Miegebielle, Véronique

2017-08-02

Remote sensing techniques are commonly used by Oil and Gas companies to monitor hydrocarbon on the ocean surface. The interest lies not only in exploration but also in the monitoring of the maritime environment. Occurrence of natural seeps on the sea surface is a key indicator of the presence of mature source rock in the subsurface. These natural seeps, as well as the oil slicks, are commonly detected using radar sensors but the addition of optical imagery can deliver extra information such as thickness and composition of the detected oil, which is critical for both exploration purposes and efficient cleanup operations. Today, state-of-the-art approaches combine multiple data collected by optical and radar sensors embedded on-board different airborne and spaceborne platforms, to ensure wide spatial coverage and high frequency revisit time. Multi-wavelength imaging system may create a breakthrough in remote sensing applications, but it requires adapted processing techniques that need to be developed. To explore performances offered by multi-wavelength radar and optical sensors for oil slick monitoring, remote sensing data have been collected by SETHI (Système Expérimental de Télédection Hyperfréquence Imageur), the airborne system developed by ONERA (the French Aerospace Lab), during an oil spill cleanup exercise carried out in 2015 in the North Sea, Europe. The uniqueness of this dataset lies in its high spatial resolution, low noise level and quasi-simultaneous acquisitions of different part of the EM spectrum. Specific processing techniques have been developed to extract meaningful information associated with oil-covered sea surface. Analysis of this unique and rich dataset demonstrates that remote sensing imagery, collected in both optical and microwave domains, allows estimating slick surface properties such as the age of the emulsion released at sea, the spatial abundance of oil and the relative concentration of hydrocarbons remaining on the sea surface.

Levee Monitoring with Radar Remote Sensing

NASA Technical Reports Server (NTRS)

Jones, Cathleen E.

2012-01-01

Topics in this presentation are: 1. Overview of radar remote sensing 2. Surface change detection with Differential Interferometric Radar Processing 3. Study of the Sacramento - San Joaquin levees 4. Mississippi River Levees during the Spring 2011 floods.

Application of synthetic aperture radars for the ground displacement monitoring in mineral mining areas

NASA Astrophysics Data System (ADS)

Dobrynchenko, VV; Kokorinand, IS; Shebalkova, LV

2018-03-01

The authors discuss applicability of synthesized aperture radars to monitorthe ground surface displacement in mineral mining areas in terms of a synthesized-aperture interferometric radar. The operation principle of the interferometric method is demonstrated on studies of the ground surface displacements in areas of oil and gas reservoirs. The advantages of the synthetic aperture radar are substantiated.

Multifunctional millimeter-wave radar system for helicopter safety

NASA Astrophysics Data System (ADS)

Goshi, Darren S.; Case, Timothy J.; McKitterick, John B.; Bui, Long Q.

2012-06-01

A multi-featured sensor solution has been developed that enhances the operational safety and functionality of small airborne platforms, representing an invaluable stride toward enabling higher-risk, tactical missions. This paper demonstrates results from a recently developed multi-functional sensor system that integrates a high performance millimeter-wave radar front end, an evidence grid-based integration processing scheme, and the incorporation into a 3D Synthetic Vision System (SVS) display. The front end architecture consists of a w-band real-beam scanning radar that generates a high resolution real-time radar map and operates with an adaptable antenna architecture currently configured with an interferometric capability for target height estimation. The raw sensor data is further processed within an evidence grid-based integration functionality that results in high-resolution maps in the region surrounding the platform. Lastly, the accumulated radar results are displayed in a fully rendered 3D SVS environment integrated with local database information to provide the best representation of the surrounding environment. The integrated system concept will be discussed and initial results from an experimental flight test of this developmental system will be presented. Specifically, the forward-looking operation of the system demonstrates the system's ability to produce high precision terrain mapping with obstacle detection and avoidance capability, showcasing the system's versatility in a true operational environment.

Battlefield radar imaging through airborne millimetric wave SAR (Synthetic Aperture Radar)

NASA Astrophysics Data System (ADS)

Carletti, U.; Daddio, E.; Farina, A.; Morabito, C.; Pangrazi, R.; Studer, F. A.

Airborne synthetic aperture radar (SAR), operating in the millimetric-wave (mmw) region, is discussed with reference to a battlefield surveillance application. The SAR system provides high resolution real-time imaging of the battlefield and moving target detection, under adverse environmental conditions (e.g., weather, dust, smoke, obscurants). The most relevant and original aspects of the system are the band of operation (i.e., mmw in lieu of the more traditional microwave region) and the use of an unmanned platform. The former implies reduced weight and size requirements, thus allowing use of small unmanned platforms. The latter enchances the system operational effectiveness by permitting accomplishment of recognition missions in depth beyond the FEBA. An overall system architecture based on the onboard sensor, the platform, the communication equipment, and a mobile ground station is described. The main areas of ongoing investigation are presented: the simulation of the end-to-end system, and the critical technological issues such as mmw antenna, transmitter, signal processor for image formation and platform attitude errors compensation and detection and imaging of moving targets.

space Radar Image of Long Valley, California

NASA Image and Video Library

1999-05-01

An area near Long Valley, California, was mapped by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar aboard the space shuttle Endeavor on April 13, 1994, during the first flight of the radar instrument, and on October 4, 1994, during the second flight of the radar instrument. The orbital configurations of the two data sets were ideal for interferometric combination -- that is overlaying the data from one image onto a second image of the same area to create an elevation map and obtain estimates of topography. Once the topography is known, any radar-induced distortions can be removed and the radar data can be geometrically projected directly onto a standard map grid for use in a geographical information system. The 50 kilometer by 50 kilometer (31 miles by 31 miles) map shown here is entirely derived from SIR-C L-band radar (horizontally transmitted and received) results. The color shown in this image is produced from the interferometrically determined elevations, while the brightness is determined by the radar backscatter. The map is in Universal Transverse Mercator (UTM) coordinates. Elevation contour lines are shown every 50 meters (164 feet). Crowley Lake is the dark feature near the south edge of the map. The Adobe Valley in the north and the Long Valley in the south are separated by the Glass Mountain Ridge, which runs through the center of the image. The height accuracy of the interferometrically derived digital elevation model is estimated to be 20 meters (66 feet) in this image. http://photojournal.jpl.nasa.gov/catalog/PIA01749

Fourth Airborne Geoscience Workshop

NASA Technical Reports Server (NTRS)

1991-01-01

The focus of the workshop was on how the airborne community can assist in achieving the goals of the Global Change Research Program. The many activities that employ airborne platforms and sensors were discussed: platforms and instrument development; airborne oceanography; lidar research; SAR measurements; Doppler radar; laser measurements; cloud physics; airborne experiments; airborne microwave measurements; and airborne data collection.

A geologic analysis of the Side-Looking Airborne Radar imagery of southern New England

USGS Publications Warehouse

Banks, Paul T.

1975-01-01

Analysis of the side looking airborn radar imagery of Massachusetts, Connecticut and Rhode Island indicates that radar shows the topography in great detail. Since bedrock geologic features are frequently expressed in the topography the radar lends itself to geologic interpretation. The radar was studied by comparisons with field mapped geologic data first at a scale of approximately 1:125,000 and then at a scale of 1:500,000. The larger scale comparison revealed that faults, minor faults, joint sets, bedding and foliation attitudes, lithology and lithologic contacts all have a topographic expression interpretable on the imagery. Surficial geologic features were far less visible on the imagery over most of the area studied. The smaller scale comparisons revealed a pervasive, near orthogonal fracture set cutting all types and ages of rock and trending roughly N40?E and N30?W. In certain places the strike of bedding and foliation attitudes and some lithologic Contacts were visible in addition to the fractures. Fracturing in southern New England is apparently far more important than has been previously recognized. This new information, together with the visibility of many bedding and foliation attitudes and lithologic contacts, indicates the importance of radar imagery in improving the geologic interpretation of an area.

Comparison of Retracking Algorithms Using Airborne Radar and Laser Altimeter Measurements of the Greenland Ice Sheet

NASA Technical Reports Server (NTRS)

Ferraro, Ellen J.; Swift, Calvin T.

1995-01-01

This paper compares four continental ice sheet radar altimeter retracking algorithms using airborne radar and laser altimeter data taken over the Greenland ice sheet in 1991. The refurbished Advanced Application Flight Experiment (AAFE) airborne radar altimeter has a large range window and stores the entire return waveform during flight. Once the return waveforms are retracked, or post-processed to obtain the most accurate altitude measurement possible, they are compared with the high-precision Airborne Oceanographic Lidar (AOL) altimeter measurements. The AAFE waveforms show evidence of varying degrees of both surface and volume scattering from different regions of the Greenland ice sheet. The AOL laser altimeter, however, obtains a return only from the surface of the ice sheet. Retracking altimeter waveforms with a surface scattering model results in a good correlation with the laser measurements in the wet and dry-snow zones, but in the percolation region of the ice sheet, the deviation between the two data sets is large due to the effects of subsurface and volume scattering. The Martin et al model results in a lower bias than the surface scattering model, but still shows an increase in the noise level in the percolation zone. Using an Offset Center of Gravity algorithm to retrack altimeter waveforms results in measurements that are only slightly affected by subsurface and volume scattering and, despite a higher bias, this algorithm works well in all regions of the ice sheet. A cubic spline provides retracked altitudes that agree with AOL measurements over all regions of Greenland. This method is not sensitive to changes in the scattering mechanisms of the ice sheet and it has the lowest noise level and bias of all the retracking methods presented.

Detection of aquifer system compaction and land subsidence using interferometric synthetic aperture radar, Antelope Valley, Mojave Desert, California

USGS Publications Warehouse

Galloway, D.L.; Hudnut, K.W.; Ingebritsen, S.E.; Phillips, S.P.; Peltzer, G.; Rogez, F.; Rosen, P.A.

1998-01-01

Interferometric synthetic aperture radar (InSAR) has great potential to detect and quantify land subsidence caused by aquifer system compaction. InSAR maps with high spatial detail and resolution of range displacement (±10 mm in change of land surface elevation) were developed for a groundwater basin (∼103 km2) in Antelope Valley, California, using radar data collected from the ERS-1 satellite. These data allow comprehensive comparison between recent (1993–1995) subsidence patterns and those detected historically (1926–1992) by more traditional methods. The changed subsidence patterns are generally compatible with recent shifts in land and water use. The InSAR-detected patterns are generally consistent with predictions based on a coupled model of groundwater flow and aquifer system compaction. The minor inconsistencies may reflect our imperfect knowledge of the distribution and properties of compressible sediments. When used in conjunction with coincident measurements of groundwater levels and other geologic information, InSAR data may be useful for constraining parameter estimates in simulations of aquifer system compaction.

Validation of Forested Inundation Extent Revealed by L-Band Polarimetric and Interferometric SAR Data

NASA Technical Reports Server (NTRS)

Chapman, Bruce; Celi, Jorge; Hamilton, Steve; McDonald, Kyle

2013-01-01

UAVSAR, NASA's airborne Synthetic Aperture Radar (SAR), conducted an extended observational campaign in Central and South America in March 2013, primarily related to volcanic deformations along the Andean Mountain Range but also including a large number of flights studying other scientific phenomena. During this campaign, the L-Band SAR collected data over the Napo River in Ecuador. The objectives of this experiment were to acquire polarimetric and interferometric L-Band SAR data over an inundated tropical forest in Ecuador simultaneously with on-the-ground field work ascertaining the extent of inundation, and to then derive from this data a quantitative estimate for the error in the SAR-derived inundation extent. In this paper, we will first describe the processing and preliminary analysis of the SAR data. The polarimetric SAR data will be classified by land cover and inundation state. The interferometric SAR data will be used to identify those areas where change in inundation extent occurred, and to measure the change in water level between two observations separated by a week. Second, we will describe the collection of the field estimates of inundation, and have preliminary comparisons of inundation extent measured in the field field versus that estimated from the SAR data.

Full Chain Benchmarking for Open Architecture Airborne ISR Systems: A Case Study for GMTI Radar Applications

DTIC Science & Technology

2015-09-15

middleware implementations via a common object-oriented software hierarchy, with library -specific implementations of the five GMTI benchmark ...Full-Chain Benchmarking for Open Architecture Airborne ISR Systems A Case Study for GMTI Radar Applications Matthias Beebe, Matthew Alexander...time performance, effective benchmarks are necessary to ensure that an ARP system can meet the mission constraints and performance requirements of

Space Radar Image of Kilauea, Hawaii - Interferometry 1

NASA Image and Video Library

1999-05-01

This X-band image of the volcano Kilauea was taken on October 4, 1994, by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar. The area shown is about 9 kilometers by 13 kilometers (5.5 miles by 8 miles) and is centered at about 19.58 degrees north latitude and 155.55 degrees west longitude. This image and a similar image taken during the first flight of the radar instrument on April 13, 1994 were combined to produce the topographic information by means of an interferometric process. This is a process by which radar data acquired on different passes of the space shuttle is overlaid to obtain elevation information. Three additional images are provided showing an overlay of radar data with interferometric fringes; a three-dimensional image based on altitude lines; and, finally, a topographic view of the region. http://photojournal.jpl.nasa.gov/catalog/PIA01763

ScanSAR interferometric processing using existing standard InSAR software for measuring large scale land deformation

NASA Astrophysics Data System (ADS)

Liang, Cunren; Zeng, Qiming; Jia, Jianying; Jiao, Jian; Cui, Xi'ai

2013-02-01

Scanning synthetic aperture radar (ScanSAR) mode is an efficient way to map large scale geophysical phenomena at low cost. The work presented in this paper is dedicated to ScanSAR interferometric processing and its implementation by making full use of existing standard interferometric synthetic aperture radar (InSAR) software. We first discuss the properties of the ScanSAR signal and its phase-preserved focusing using the full aperture algorithm in terms of interferometry. Then a complete interferometric processing flow is proposed. The standard ScanSAR product is decoded subswath by subswath with burst gaps padded with zero-pulses, followed by a Doppler centroid frequency estimation for each subswath and a polynomial fit of all of the subswaths for the whole scene. The burst synchronization of the interferometric pair is then calculated, and only the synchronized pulses are kept for further interferometric processing. After the complex conjugate multiplication of the interferometric pair, the residual non-integer pulse repetition interval (PRI) part between adjacent bursts caused by zero padding is compensated by resampling using a sinc kernel. The subswath interferograms are then mosaicked, in which a method is proposed to remove the subswath discontinuities in the overlap area. Then the following interferometric processing goes back to the traditional stripmap processing flow. A processor written with C and Fortran languages and controlled by Perl scripts is developed to implement these algorithms and processing flow based on the JPL/Caltech Repeat Orbit Interferometry PACkage (ROI_PAC). Finally, we use the processor to process ScanSAR data from the Envisat and ALOS satellites and obtain large scale deformation maps in the radar line-of-sight (LOS) direction.

Surface Ruptures and Building Damage of the 2003 Bam, Iran, Earthquake Mapped by Satellite Synthetic Aperture Radar Interferometric Correlation

NASA Technical Reports Server (NTRS)

Fielding, Eric J.; Talebian, M.; Rosen, P. A.; Nazari, H.; Jackson, J. A.; Ghorashi, M.; Walker, R.

2005-01-01

We use the interferometric correlation from Envisat synthetic aperture radar (SAR) images to map the details of the surface ruptures related to the 26 December 2003 earthquake that devastated Bam, Iran. The main strike-slip fault rupture south of the city of Bam has a series of four segments with left steps shown by a narrow line of low correlation in the coseismic interferogram. This also has a clear expression in the field because of the net extension across the fault. Just south of the city limits, the surface strain becomes distributed over a width of about 500 m, probably because of a thicker layer of soft sedimentary material.

Detection of subglacial lakes in airborne radar sounding data from East Antarctica.

NASA Astrophysics Data System (ADS)

Carter, S. P.; Blankenship, D. D.; Peters, M. E.; Morse, D. L.

2004-12-01

Airborne ice penetrating radar is an essential tool for the identification of subglacial lakes. With it, we can measure the ice thickness, the amplitude of the reflected signal from the base of the ice, the depth to isochronous surfaces and, with high quality GPS, the elevation of the ice surface. These four measurements allow us to calculate the reflection coefficient from the base of the ice, the hydrostatic head, the surface slope and basal temperature. A subglacial lake will be characterized by: a consistently high reflection coefficient from the base of the ice, a nearly flat hydraulic gradient at a relative minimum in the hydraulic potential, an exceptionally smooth ice surface, and an estimated basal temperature that is at or near the pressure melting point of ice. We have developed a computerized algorithm to identify concurrences of the above-mentioned criteria in the radar data sets for East Antarctica collected by the University of Texas (UT). This algorithm is henceforth referred to as the "lake detector". Regions which meet three or more of the above mentioned criteria are identified as subglacial lakes, contingent upon a visual inspection by the human operator. This lake detector has added over 40 lakes to the most recent inventory of subglacial lakes for Antarctica. In locations where the UT flight lines approach or intersect flight lines from other airborne radar surveys, there is generally good agreement between the "lake detector" lakes and lakes identified in these data sets. In locations where the "lake detector" fails to identify a lake which is present in another survey, the most common failing is the estimated basal temperature. However, in some regions where a bright, smooth basal reflector is shown to exist, the lake detector may be failing due to a persistent slope in the hydraulic gradient. The nature of these "frozen" and "sloping" lakes is an additional focus of this presentation.

Hyperspectral and Radar Airborne Imagery over Controlled Release of Oil at Sea

PubMed Central

Angelliaume, Sébastien; Ceamanos, Xavier; Viallefont-Robinet, Françoise; Baqué, Rémi; Déliot, Philippe

2017-01-01

Remote sensing techniques are commonly used by Oil and Gas companies to monitor hydrocarbon on the ocean surface. The interest lies not only in exploration but also in the monitoring of the maritime environment. Occurrence of natural seeps on the sea surface is a key indicator of the presence of mature source rock in the subsurface. These natural seeps, as well as the oil slicks, are commonly detected using radar sensors but the addition of optical imagery can deliver extra information such as thickness and composition of the detected oil, which is critical for both exploration purposes and efficient cleanup operations. Today, state-of-the-art approaches combine multiple data collected by optical and radar sensors embedded on-board different airborne and spaceborne platforms, to ensure wide spatial coverage and high frequency revisit time. Multi-wavelength imaging system may create a breakthrough in remote sensing applications, but it requires adapted processing techniques that need to be developed. To explore performances offered by multi-wavelength radar and optical sensors for oil slick monitoring, remote sensing data have been collected by SETHI (Système Expérimental de Télédection Hyperfréquence Imageur), the airborne system developed by ONERA (the French Aerospace Lab), during an oil spill cleanup exercise carried out in 2015 in the North Sea, Europe. The uniqueness of this dataset lies in its high spatial resolution, low noise level and quasi-simultaneous acquisitions of different part of the EM spectrum. Specific processing techniques have been developed to extract meaningful information associated with oil-covered sea surface. Analysis of this unique and rich dataset demonstrates that remote sensing imagery, collected in both optical and microwave domains, allows estimating slick surface properties such as the age of the emulsion released at sea, the spatial abundance of oil and the relative concentration of hydrocarbons remaining on the sea surface

Quantifying monthly to decadal subsidence and assessing collapse potential near the Wink sinkholes, west Texas, using airborne lidar, radar interferometry, and microgravity

NASA Astrophysics Data System (ADS)

Paine, J. G.; Collins, E.; Yang, D.; Andrews, J. R.; Averett, A.; Caudle, T.; Saylam, K.

2014-12-01

We are using airborne lidar and satellite-based radar interferometry (InSAR) to quantify short-term (months to years) and longer-term (decades) subsidence in the area surrounding two large (100- to 200-m diameter) sinkholes that formed above Permian bedded salt in 1980 and 2002 in the Wink area, west Texas. Radar interferograms constructed from synthetic aperture radar data acquired between 2008 and 2011 with the ALOS PALSAR L-band satellite-borne instrument reveal local areas that are subsiding at rates that reach a few cm per month. Subsiding areas identified on radar interferograms enable labor-intensive ground investigations (such as microgravity surveys) to focus on areas where subsidence is occurring and shallow-source mass deficits might exist that could be sites of future subsidence or collapse. Longer-term elevation changes are being quantified by comparing digital elevation models (DEMs) constructed from high-resolution airborne lidar data acquired over a 32-km2 area in 2013 with older, lower-resolution DEMs constructed from data acquired during the NASA- and NGA-sponsored Shuttle Radar Topographic Mission in February 2000 and from USGS aerial photogrammetry-derived topographic data from the 1960s. Total subsidence reaches more than 10 m over 45 years in some areas. Maximum rates of subsidence measured on annual (from InSAR) and decadal (from lidar) time scales are about 0.25 m/yr. In addition to showing the extent and magnitude of subsidence at the 1980 and 2002 sinkholes, comparison of the 2013 lidar-derived DEM with the 1960s photogrammetry-derived DEM revealed other locations that have undergone significant (more than 1 m) elevation change since the 1960s, but show no evidence of recent (2008 to 2011) ground motion from satellite radar interferograms. Regional coverage obtained by radar interferometry and local coverage obtained with airborne lidar show that areas of measurable subsidence are all within a few km of the 1980 and 2002 sinkholes.

Two microstrip arrays for interferometric SAR applications

NASA Technical Reports Server (NTRS)

Huang, J.

1993-01-01

Two types of C-band aircraft interferometric Synthetic Aperture Radar (SAR) are being developed at JPL to measure the ocean wave characteristics. Each type requires two identical antennas with each having a long rectangular aperture to radiate fan-shaped beam(s). One type of these radars requires each of its antennas to radiate a broadside beam that will measure the target's cross-track velocity. The other type, having each of its antennas to radiate two off-broadside pointed beams, will allow the measurement of both the cross-track and the along-track velocities of the target. Because flush mounting of the antenna on the aircraft fuselage is desirable, microstrip patch array is selected for these interferometric SAR antennas. To meet the radar system requirement, each array needs a total of 76 microstrip patches which are arranged in a 38 x 2 rectangular aperture with a physical size of 1.6m x 16.5cm. To minimize the insertion loss and physical real estate of this relatively long array, a combined series/parallel feed technique is used. Techniques to suppress cross-pol radiation and to effectively utilize the RF power are also implemented. Cross-pol level of lower than -30 dB from the co-pol peak and low insertion loss of 0.36 dB have been achieved for both types of arrays. For the type of radar that requires two off-braodside pointed beams, a simple phasing technique is used to achieve this dual-beam capability with adequate antenna gain (20 dBi) and sidelobe level (-14 dB). Both radar arrays have been flight tested on aircraft with excellent antenna performance demonstrated.

An Efficient Adaptive Angle-Doppler Compensation Approach for Non-Sidelooking Airborne Radar STAP

PubMed Central

Shen, Mingwei; Yu, Jia; Wu, Di; Zhu, Daiyin

2015-01-01

In this study, the effects of non-sidelooking airborne radar clutter dispersion on space-time adaptive processing (STAP) is considered, and an efficient adaptive angle-Doppler compensation (EAADC) approach is proposed to improve the clutter suppression performance. In order to reduce the computational complexity, the reduced-dimension sparse reconstruction (RDSR) technique is introduced into the angle-Doppler spectrum estimation to extract the required parameters for compensating the clutter spectral center misalignment. Simulation results to demonstrate the effectiveness of the proposed algorithm are presented. PMID:26053755

Airborne Synthetic Aperature Radar (AIRSAR) on left rear fuselage of DC-8 Airborne Laboratory

NASA Technical Reports Server (NTRS)

1998-01-01

A view of the Airborne Synthetic Aperature Radar (AIRSAR) antenna on the left rear fuselage of the DC-8. The AIRSAR captures images of the ground from the side of the aircraft and can provide precision digital elevation mapping capabilities for a variety of studies. The AIRSAR is one of a number of research systems that have been added to the DC-8. NASA is using a DC-8 aircraft as a flying science laboratory. The platform aircraft, based at NASA's Dryden Flight Research Center, Edwards, Calif., collects data for many experiments in support of scientific projects serving the world scientific community. Included in this community are NASA, federal, state, academic and foreign investigators. Data gathered by the DC-8 at flight altitude and by remote sensing have been used for scientific studies in archeology, ecology, geography, hydrology, meteorology, oceanography, volcanology, atmospheric chemistry, soil science and biology.

Use of multi-frequency, multi-polarization, multi-angle airborne radars for class discrimination in a southern temperature forest

NASA Technical Reports Server (NTRS)

Mehta, N. C.

1984-01-01

The utility of radar scatterometers for discrimination and characterization of natural vegetation was investigated. Backscatter measurements were acquired with airborne multi-frequency, multi-polarization, multi-angle radar scatterometers over a test site in a southern temperate forest. Separability between ground cover classes was studied using a two-class separability measure. Very good separability is achieved between most classes. Longer wavelength is useful in separating trees from non-tree classes, while shorter wavelength and cross polarization are helpful for discrimination among tree classes. Using the maximum likelihood classifier, 50% overall classification accuracy is achieved using a single, short-wavelength scatterometer channel. Addition of multiple incidence angles and another radar band improves classification accuracy by 20% and 50%, respectively, over the single channel accuracy. Incorporation of a third radar band seems redundant for vegetation classification. Vertical transmit polarization is critically important for all classes.

UAVSAR Active Electronically Scanned Array

NASA Technical Reports Server (NTRS)

Sadowy, Gregory, A.; Chamberlain, Neil F.; Zawadzki, Mark S.; Brown, Kyle M.; Fisher, Charles D.; Figueroa, Harry S.; Hamilton, Gary A.; Jones, Cathleen E.; Vorperian, Vatche; Grando, Maurio B.

2011-01-01

The Uninhabited Airborne Vehicle Synthetic Aperture Radar (UAVSAR) is a pod-based, L-band (1.26 GHz), repeatpass, interferometric, synthetic aperture radar (InSAR) used for Earth science applications. Repeat-pass interferometric radar measurements from an airborne platform require an antenna that can be steered to maintain the same angle with respect to the flight track over a wide range of aircraft yaw angles. In order to be able to collect repeat-pass InSAR data over a wide range of wind conditions, UAVSAR employs an active electronically scanned array (AESA). During data collection, the UAVSAR flight software continuously reads the aircraft attitude state measured by the Embedded GPS/INS system (EGI) and electronically steers the beam so that it remains perpendicular to the flight track throughout the data collection

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.

Simulation of multistatic and backscattering cross sections for airborne radar

NASA Astrophysics Data System (ADS)

Biggs, Albert W.

1986-07-01

In order to determine susceptibilities of airborne radar to electronic countermeasures and electronic counter-countermeasures simulations of multistatic and backscattering cross sections were developed as digital modules in the form of algorithms. Cross section algorithms are described for prolate (cigar shape) and oblate (disk shape) spheroids. Backscattering cross section algorithms are also described for different categories of terrain. Backscattering cross section computer programs were written for terrain categorized as vegetation, sea ice, glacial ice, geological (rocks, sand, hills, etc.), oceans, man-made structures, and water bodies. PROGRAM SIGTERRA is a file for backscattering cross section modules of terrain (TERRA) such as vegetation (AGCROP), oceans (OCEAN), Arctic sea ice (SEAICE), glacial snow (GLASNO), geological structures (GEOL), man-made structures (MAMMAD), or water bodies (WATER). AGCROP describes agricultural crops, trees or forests, prairies or grassland, and shrubs or bush cover. OCEAN has the SLAR or SAR looking downwind, upwind, and crosswind at the ocean surface. SEAICE looks at winter ice and old or polar ice. GLASNO is divided into a glacial ice and snow or snowfields. MANMAD includes buildings, houses, roads, railroad tracks, airfields and hangars, telephone and power lines, barges, trucks, trains, and automobiles. WATER has lakes, rivers, canals, and swamps. PROGRAM SIGAIR is a similar file for airborne targets such as prolate and oblate spheroids.

Forest biomass change estimated from height change in interferometric SAR height models.

PubMed

Solberg, Svein; Næsset, Erik; Gobakken, Terje; Bollandsås, Ole-Martin

2014-12-01

There is a need for new satellite remote sensing methods for monitoring tropical forest carbon stocks. Advanced RADAR instruments on board satellites can contribute with novel methods. RADARs can see through clouds, and furthermore, by applying stereo RADAR imaging we can measure forest height and its changes. Such height changes are related to carbon stock changes in the biomass. We here apply data from the current Tandem-X satellite mission, where two RADAR equipped satellites go in close formation providing stereo imaging. We combine that with similar data acquired with one of the space shuttles in the year 2000, i.e. the so-called SRTM mission. We derive height information from a RADAR image pair using a method called interferometry. We demonstrate an approach for REDD based on interferometry data from a boreal forest in Norway. We fitted a model to the data where above-ground biomass in the forest increases with 15 t/ha for every m increase of the height of the RADAR echo. When the RADAR echo is at the ground the estimated biomass is zero, and when it is 20 m above the ground the estimated above-ground biomass is 300 t/ha. Using this model we obtained fairly accurate estimates of biomass changes from 2000 to 2011. For 200 m 2 plots we obtained an accuracy of 65 t/ha, which corresponds to 50% of the mean above-ground biomass value. We also demonstrate that this method can be applied without having accurate terrain heights and without having former in-situ biomass data, both of which are generally lacking in tropical countries. The gain in accuracy was marginal when we included such data in the estimation. Finally, we demonstrate that logging and other biomass changes can be accurately mapped. A biomass change map based on interferometry corresponded well to a very accurate map derived from repeated scanning with airborne laser. Satellite based, stereo imaging with advanced RADAR instruments appears to be a promising method for REDD. Interferometric

Airborne derivation of microburst alerts from ground-based Terminal Doppler Weather Radar information: A flight evaluation

NASA Technical Reports Server (NTRS)

Hinton, David A.

1993-01-01

An element of the NASA/FAA windshear program is the integration of ground-based microburst information on the flight deck, to support airborne windshear alerting and microburst avoidance. NASA conducted a windshear flight test program in the summer of 1991 during which airborne processing of Terminal Doppler Weather Radar (TDWR) data was used to derive microburst alerts. Microburst information was extracted from TDWR, transmitted to a NASA Boeing 737 in flight via data link, and processed to estimate the windshear hazard level (F-factor) that would be experienced by the aircraft in each microburst. The microburst location and F-factor were used to derive a situation display and alerts. The situation display was successfully used to maneuver the aircraft for microburst penetrations, during which atmospheric 'truth' measurements were made. A total of 19 penetrations were made of TDWR-reported microburst locations, resulting in 18 airborne microburst alerts from the TDWR data and two microburst alerts from the airborne reactive windshear detection system. The primary factors affecting alerting performance were spatial offset of the flight path from the region of strongest shear, differences in TDWR measurement altitude and airplane penetration altitude, and variations in microburst outflow profiles. Predicted and measured F-factors agreed well in penetrations near microburst cores. Although improvements in airborne and ground processing of the TDWR measurements would be required to support an airborne executive-level alerting protocol, the practicality of airborne utilization of TDWR data link data has been demonstrated.

Monitoring deformation at the Geysers Geothermal Field, California using C-band and X-band interferometric synthetic aperture radar

DOE PAGES

Vasco, D. W.; Rutqvist, Jonny; Ferretti, Alessandro; ...

2013-06-07

In this study, we resolve deformation at The Geysers Geothermal Field using two distinct sets of interferometric synthetic aperture radar (InSAR) data. The first set of observations utilize archived European Space Agency C-band synthetic aperture radar data from 1992 through 1999 to image the long-term and large-scale subsidence at The Geysers. The peak range velocity of approximately 50 mm/year agrees with previous estimates from leveling and global positioning system observations. Data from a second set of measurements, acquired by TerraSAR-X satellites, extend from May 2011 until April 2012 and overlap the C-band data spatially but not temporally. These X-band data,more » analyzed using a combined permanent and distributed scatterer algorithm, provide a higher density of scatterers (1122 per square kilometer) than do the C-band data (12 per square kilometer). The TerraSAR-X observations resolve 1 to 2 cm of deformation due to water injection into a Northwest Geysers enhanced geothermal system well, initiated on October 2011. Lastly, the temporal variation of the deformation is compatible with estimates from coupled numerical modeling.« less

The Utility and Validity of Kinematic GPS Positioning for the Geosar Airborne Terrain Mapping Radar System

NASA Technical Reports Server (NTRS)

Freedman, Adam; Hensley, Scott; Chapin, Elaine; Kroger, Peter; Hussain, Mushtaq; Allred, Bruce

1999-01-01

GeoSAR is an airborne, interferometric Synthetic Aperture Radar (IFSAR) system for terrain mapping, currently under development by a consortium including NASA's Jet Propulsion Laboratory (JPL), Calgis, Inc., a California mapping sciences company, and the California Department of Conservation (CaIDOC), with funding provided by the U.S. Army Corps of Engineers Topographic Engineering Center (TEC) and the U.S. Defense Advanced Research Projects Agency (DARPA). IFSAR data processing requires high-accuracy platform position and attitude knowledge. On 9 GeoSAR, these are provided by one or two Honeywell Embedded GPS Inertial Navigation Units (EGI) and an Ashtech Z12 GPS receiver. The EGIs provide real-time high-accuracy attitude and moderate-accuracy position data, while the Ashtech data, post-processed differentially with data from a nearby ground station using Ashtech PNAV software, provide high-accuracy differential GPS positions. These data are optimally combined using a Kalman filter within the GeoSAR motion measurement software, and the resultant position and orientation information are used to process the dual frequency (X-band and P-band) radar data to generate high-accuracy, high -resolution terrain imagery and digital elevation models (DEMs). GeoSAR requirements specify sub-meter level planimetric and vertical accuracies for the resultant DEMS. To achieve this, platform positioning errors well below one meter are needed. The goal of GeoSAR is to obtain 25 cm or better 3-D positions from the GPS systems on board the aircraft. By imaging a set of known point target corner-cube reflectors, the GeoSAR system can be calibrated. This calibration process yields the true position of the aircraft with an uncertainty of 20- 50 cm. This process thus allows an independent assessment of the accuracy of our GPS-based positioning systems. We will present an overview of the GeoSAR motion measurement system, focusing on the use of GPS and the blending of position data from the

A comparison of in situ and airborne radar observations of ocean wave directionality

NASA Technical Reports Server (NTRS)

Jackson, F. C.; Walton, W. T.; Peng, C. Y.

1985-01-01

The directional spectrum of a fully arisen, about 3 m sea as measured by an experimental airborne radar, the NASA K(u)-band radar ocean wave spectrometer (ROWS), is compared to reference pitch-roll buoy data and to the classical SWOP (stereo wave observations project) spectrum for fully developed conditions. The ROWS spectrum, inferred indirectly from backscattered power measurements at 5-km altitude, is shown to be in excellent agreement with the buoy spectrum. Specifically, excellent agreement is found between the two nondirectional height spectra, and mean wave directions and directional spreads as functions of frequency. A comparison of the ROWS and SWOP spectra shows the two spectra to be very similar, in detailed shape as well as in terms of the gross spreading characteristics. Both spectra are seen to exhibit bimodal structures which accord with the Phillips' (1958) resonance mechanism. This observation is thus seen to support Phillips' contention that the SWOP modes were indeed resonance modes, not statistical artifacts.

Measuring Geophysical Parameters of the Greenland Ice Sheet using Airborne Radar Altimetry

NASA Technical Reports Server (NTRS)

Ferraro, Ellen J.; Swift. Calvin T.

1995-01-01

This paper presents radar-altimeter scattering models for each of the diagenetic zones of the Greenland ice sheet. AAFE radar- altimeter waveforms obtained during the 1991 and 1993 NASA multi-sensor airborne altimetry experiments over Greenland reveal that the Ku-band return pulse changes significantly with the different diagenetic zones. These changes are due to varying amounts of surface and volume scattering in the return waveform. In the ablation and soaked zones, where surface scattering dominates the AAFE return, geophysical parameters such as rms surface height and rms surface slope are obtained by fitting the waveforms to a surface-scattering model. Waveforms from the percolation zone show that the sub-surface ice features have a much more significant effect on the return pulse than the surrounding snowpack. Model percolation waveforms, created using a combined surface- and volume-scattering model and an ice-feature distribution obtained during the 1993 field season, agree well with actual AAFE waveforms taken in the same time period. Using a combined surface- and volume-scattering model for the dry-snow-zone return waveforms, the rms surface height and slope and the attenuation coefficient of the snowpack are obtained. These scattering models not only allow geophysical parameters of the ice sheet to be measured but also help in the understanding of satellite radar-altimeter data.

Wind Retrieval Algorithms for the IWRAP and HIWRAP Airborne Doppler Radars with Applications to Hurricanes

NASA Technical Reports Server (NTRS)

Guimond, Stephen Richard; Tian, Lin; Heymsfield, Gerald M.; Frasier, Stephen J.

2013-01-01

Algorithms for the retrieval of atmospheric winds in precipitating systems from downward-pointing, conically-scanning airborne Doppler radars are presented. The focus in the paper is on two radars: the Imaging Wind and Rain Airborne Profiler(IWRAP) and the High-altitude IWRAP (HIWRAP). The IWRAP is a dual-frequency (Cand Ku band), multi-beam (incidence angles of 30 50) system that flies on the NOAAWP-3D aircraft at altitudes of 2-4 km. The HIWRAP is a dual-frequency (Ku and Kaband), dual-beam (incidence angles of 30 and 40) system that flies on the NASA Global Hawk aircraft at altitudes of 18-20 km. Retrievals of the three Cartesian wind components over the entire radar sampling volume are described, which can be determined using either a traditional least squares or variational solution procedure. The random errors in the retrievals are evaluated using both an error propagation analysis and a numerical simulation of a hurricane. These analyses show that the vertical and along-track wind errors have strong across-track dependence with values of 0.25 m s-1 at nadir to 2.0 m s-1 and 1.0 m s-1 at the swath edges, respectively. The across-track wind errors also have across-track structure and are on average, 3.0 3.5 m s-1 or 10 of the hurricane wind speed. For typical rotated figure four flight patterns through hurricanes, the zonal and meridional wind speed errors are 2 3 m s-1.Examples of measured data retrievals from IWRAP during an eyewall replacement cycle in Hurricane Isabel (2003) and from HIWRAP during the development of Tropical Storm Matthew (2010) are shown.

Weather Radars and Lidar for Observing the Atmosphere

NASA Astrophysics Data System (ADS)

(Vivek) Vivekanandan, J.

2010-05-01

The Earth Observing Laboratory (EOL) at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado develops and deploys state-of-the-art ground-based radar, airborne radar and lidar instruments to advance scientific understanding of the earth system. The ground-based radar (S-Pol) is equipped with dual-wavelength capability (S-band and Ka-band). S-Pol is the only transportable radar in the world. In order to capture faster moving weather events such as tornadoes and record observations of clouds over rugged mountainous terrain and ocean, an airborne radar (ELDORA) is used. It is the only airborne Doppler meteorological radar that is able to detect motions in the clear air. The EOL is in the process of building the first phase of a three phase dual wavelength W/Ka-band airborne cloud radar to be called the HIAPER Cloud Radar (HCR). This phase is a pod based W-band radar system with scanning capability. The second phase will add pulse compression and polarimetric capability to the W-band system, while the third phase will add complementary Ka-band radar. The pod-based radar is primarily designed to fly on the Gulfstream V (GV) and C-130 aircraft. The envisioned capability of a millimeter wave radar system on GV is enhanced by coordination with microwave radiometer, in situ probes, and especially by the NCAR GV High-Spectral Resolution Lidar (HSRL) which is also under construction. The presentation will describe the capabilities of current instruments and also planned instrumentation development.

The design and development of signal-processing algorithms for an airborne x-band Doppler weather radar

NASA Technical Reports Server (NTRS)

Nicholson, Shaun R.

1994-01-01

Improved measurements of precipitation will aid our understanding of the role of latent heating on global circulations. Spaceborne meteorological sensors such as the planned precipitation radar and microwave radiometers on the Tropical Rainfall Measurement Mission (TRMM) provide for the first time a comprehensive means of making these global measurements. Pre-TRMM activities include development of precipitation algorithms using existing satellite data, computer simulations, and measurements from limited aircraft campaigns. Since the TRMM radar will be the first spaceborne precipitation radar, there is limited experience with such measurements, and only recently have airborne radars become available that can attempt to address the issue of the limitations of a spaceborne radar. There are many questions regarding how much attenuation occurs in various cloud types and the effect of cloud vertical motions on the estimation of precipitation rates. The EDOP program being developed by NASA GSFC will provide data useful for testing both rain-retrieval algorithms and the importance of vertical motions on the rain measurements. The purpose of this report is to describe the design and development of real-time embedded parallel algorithms used by EDOP to extract reflectivity and Doppler products (velocity, spectrum width, and signal-to-noise ratio) as the first step in the aforementioned goals.

Multi-Antenna Radar Systems for Doppler Rain Measurements

NASA Technical Reports Server (NTRS)

Durden, Stephen; Tanelli, Simone; Siqueira, Paul

2007-01-01

Use of multiple-antenna radar systems aboard moving high-altitude platforms has been proposed for measuring rainfall. The basic principle of the proposed systems is a variant of that of along-track interferometric synthetic-aperture radar systems used previously to measure ocean waves and currents.

Estimating Forest Vertical Structure from Multialtitude, Fixed-Baseline Radar Interferometric and Polarimetric Data

NASA Technical Reports Server (NTRS)

Treuhaft, Robert N.; Law, Beverly E.; Siqueira, Paul R.

2000-01-01

Parameters describing the vertical structure of forests, for example tree height, height-to-base-of-live-crown, underlying topography, and leaf area density, bear on land-surface, biogeochemical, and climate modeling efforts. Single, fixed-baseline interferometric synthetic aperture radar (INSAR) normalized cross-correlations constitute two observations from which to estimate forest vertical structure parameters: Cross-correlation amplitude and phase. Multialtitude INSAR observations increase the effective number of baselines potentially enabling the estimation of a larger set of vertical-structure parameters. Polarimetry and polarimetric interferometry can further extend the observation set. This paper describes the first acquisition of multialtitude INSAR for the purpose of estimating the parameters describing a vegetated land surface. These data were collected over ponderosa pine in central Oregon near longitude and latitude -121 37 25 and 44 29 56. The JPL interferometric TOPSAR system was flown at the standard 8-km altitude, and also at 4-km and 2-km altitudes, in a race track. A reference line including the above coordinates was maintained at 35 deg for both the north-east heading and the return southwest heading, at all altitudes. In addition to the three altitudes for interferometry, one line was flown with full zero-baseline polarimetry at the 8-km altitude. A preliminary analysis of part of the data collected suggests that they are consistent with one of two physical models describing the vegetation: 1) a single-layer, randomly oriented forest volume with a very strong ground return or 2) a multilayered randomly oriented volume; a homogeneous, single-layer model with no ground return cannot account for the multialtitude correlation amplitudes. Below the inconsistency of the data with a single-layer model is followed by analysis scenarios which include either the ground or a layered structure. The ground returns suggested by this preliminary analysis seem

The application of airborne imaging radars (L and X-band) to earth resources problems

NASA Technical Reports Server (NTRS)

Drake, B.; Shuchman, R. A.; Bryan, M. L.; Larson, R. W.; Liskow, C. L.; Rendleman, R. A.

1974-01-01

A multiplexed synthetic aperture Side-Looking Airborne Radar (SLAR) that simultaneously images the terrain with X-band (3.2 cm) and L-band (23.0 cm) radar wavelengths was developed. The Feasibility of using multiplexed SLAR to obtain useful information for earth resources purposes. The SLAR imagery, aerial photographs, and infrared imagery are examined to determine the qualitative tone and texture of many rural land-use features imaged. The results show that: (1) Neither X- nor L-band SLAR at moderate and low depression angles can directly or indirectly detect pools of water under standing vegetation. (2) Many of the urban and rural land-use categories present in the test areas can be identified and mapped on the multiplexed SLAR imagery. (3) Water resources management can be done using multiplexed SLAR. (4) Drainage patterns can be determined on both the X- and L-band imagery.

The Coplane Analysis Technique for Three-Dimensional Wind Retrieval Using the HIWRAP Airborne Doppler Radar

NASA Technical Reports Server (NTRS)

Didlake, Anthony C., Jr.; Heymsfield, Gerald M.; Tian, Lin; Guimond, Stephen R.

2015-01-01

The coplane analysis technique for mapping the three-dimensional wind field of precipitating systems is applied to the NASA High Altitude Wind and Rain Airborne Profiler (HIWRAP). HIWRAP is a dual-frequency Doppler radar system with two downward pointing and conically scanning beams. The coplane technique interpolates radar measurements to a natural coordinate frame, directly solves for two wind components, and integrates the mass continuity equation to retrieve the unobserved third wind component. This technique is tested using a model simulation of a hurricane and compared to a global optimization retrieval. The coplane method produced lower errors for the cross-track and vertical wind components, while the global optimization method produced lower errors for the along-track wind component. Cross-track and vertical wind errors were dependent upon the accuracy of the estimated boundary condition winds near the surface and at nadir, which were derived by making certain assumptions about the vertical velocity field. The coplane technique was then applied successfully to HIWRAP observations of Hurricane Ingrid (2013). Unlike the global optimization method, the coplane analysis allows for a transparent connection between the radar observations and specific analysis results. With this ability, small-scale features can be analyzed more adequately and erroneous radar measurements can be identified more easily.

Reservoir monitoring and characterization using satellite geodetic data: Interferometric Synthetic Aperture Radar observations from the Krechba field, Algeria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vasco, D.W.; Ferretti, Alessandro; Novali, Fabrizio

2008-05-01

Deformation in the material overlying an active reservoir is used to monitor pressure change at depth. A sequence of pressure field estimates, eleven in all, allow us to construct a measure of diffusive travel time throughout the reservoir. The dense distribution of travel time values means that we can construct an exactly linear inverse problem for reservoir flow properties. Application to Interferometric Synthetic Aperture Radar (InSAR) data gathered over a CO{sub 2} injection in Algeria reveals pressure propagation along two northwest trending corridors. An inversion of the travel times indicates the existence of two northwest-trending high permeability zones. The highmore » permeability features trend in the same direction as the regional fault and fracture zones. Model parameter resolution estimates indicate that the features are well resolved.« less

Airborne and spaceborne radar images for geologic and environmental mapping in the Amazon rain forest, Brazil

NASA Technical Reports Server (NTRS)

Hurtak, James J.; Ford, John P.

1986-01-01

Spaceborne and airborne radar image of portions of the Middle and Upper Amazon basin in the state of Amazonas and the Territory of Roraima are compared for purposes of geological and environmental mapping. The contrasted illumination geometries and imaging parameters are related to terrain slope and surface roughness characteristics for corresponding areas that were covered by each of the radar imaging systems. Landforms range from deeply dissected mountain and plateau with relief up to 500 m in Roraima, revealing ancient layered rocks through folded residual mountains to deeply beveled pediplain in Amazonas. Geomorphic features provide distinct textural signatures that are characteristic of different rock associations. The principle drainages in the areas covered are the Rio Negro, Rio Branco, and the Rio Japura. Shadowing effects and low radar sensitivity to subtle linear fractures that are aligned parallel or nearly parallel to the direction of radar illumination illustrate the need to obtain multiple coverage with viewing directions about 90 degrees. Perception of standing water and alluvial forest in floodplains varies with incident angle and with season. Multitemporal data sets acquired over periods of years provide an ideal method of monitoring environmental changes.

An analysis of the economic impact of the AN/APS-134 FLAR (Forward Looking Airborne Radar) retrofit on Coast Guard HC-130 aircraft

NASA Astrophysics Data System (ADS)

Dunn, R. E.

1984-12-01

Concern over the growing drug smuggling problem and improved national defense capability are manifest in the need for a new forward looking airborne radar (FLAR) for Coast Guard HC-130 aircraft, with a capability of detecting a target of 1 square meter radar cross section. This thesis reexamines the analysis that selected the AN/APS-134 FLAR over other contenders based on mission need, radar performance and life cycle cost criteria. This thesis presents a better understanding of the resulting HC-130 force structure based on the impact of FLAR technology.

Preeruptive inflation and surface interferometric coherence characteristics revealed by satellite radar interferometry at Makushin Volcano, Alaska: 1993-2000

USGS Publications Warehouse

Lu, Z.; Power, J.A.; McConnell, V.S.; Wicks, C.; Dzurisin, D.

2002-01-01

Pilot reports in January 1995 and geologic field observations from the summer of 1996 indicate that a relatively small explosive eruption of Makushin, one of the more frequently active volcanoes in the Aleutian arc of Alaska, occured on 30 January 1995. Several independent radar interferograms that each span the time period from October 1993 to September 1995 show evidence of ???7 cm of uplift centered on the volcano's east flank, which we interpret as preeruptive inflation of a ???7-km-deep magma source (??V = 0.022 km3). Subsequent interferograms for 1995-2000, a period that included no reported eruptive activity, show no evidence of additional ground deformation. Interferometric coherence at C band is found to persist for 3 years or more on lava flow and other rocky surfaces covered with short grass and sparsely distributed tall grass and for at least 1 year on most pyroclastic deposits. On lava flow and rocky surfaces with dense tall grass and on alluvium, coherence lasts for a few months. Snow and ice surfaces lose coherence within a few days. This extended timeframe of coherence over a variety of surface materials makes C band radar interferometry an effective tool for studying volcano deformation in Alaska and other similar high-latitude regions.

Phased-array radar for airborne systems

NASA Astrophysics Data System (ADS)

Tahim, Raghbir S.; Foshee, James J.; Chang, Kai

2003-09-01

Phased array antenna systems, which support high pulse rates and high transmit power, are well suited for radar and large-scale surveillance. Sensors and communication systems can function as the eyes and ears for ballistic missile defense applications, providing early warning of attack, target detection and identification, target tracking, and countermeasure decision. In such applications, active array radar systems that contain solid-state transmitter sources and low-noise preamplifiers for transmission and reception are preferred over the conventional radar antennas, because the phased array radar offers the advantages of power management and efficiency, reliability, signal reception, beam steering target detection. The current phased array radar designs are very large, complex and expensive and less efficient because of high RF losses in the phase control circuits used for beam scan. Several thousands of phase shifters and drivers may be required for a single system thus making the system very complex and expensive. This paper describes the phased array radar system based on high power T/R modules, wide-band radiating planar antenna elements and very low loss wide-band phase control circuits (requiring reduced power levels) for beam scan. The phase shifter design is based on micro-strip feed lines perturbed by the proximity of voltage controlled piezoelectric transducer (PET). Measured results have shown an added insertion loss of less than 1 dB for a phase shift of 450 degrees from 2 to 20 GHz. The new wideband phased array radar design provides significant reduction in size cost and weight. Compared to the conventional phased array systems, the cost saving is more than 15 to 1.

Inner Core Structure of Hurricane Alicia from Airborne Doppler Radar Observations.

NASA Astrophysics Data System (ADS)

Marks, Frank D., Jr.; Houze, Robert A., Jr.

1987-05-01

Airborne Doppler radar measurements are used to determine the horizontal winds, vertical air motions, radar reflectivity and hydrometer fallspeeds over much of the inner-core region (within 40 km of the eye) of Hurricane Alicia (1983). The reconstructed flow field is more complete and detailed than any obtained previously. The data show both the primary (azimuthal) and secondary (radial-height) circulations. The primary circulation was characterized by an outward sloping maximum of tangential wind. The secondary circulation was characterized by a deep layer of radial inflow in the lower troposphere and a layer of intense outflow above 10 km altitude. The rising branch of the secondary circulation was located in the eyewall and sloped radially outward. Discrete convective-scale bubbles of more intense upward motion were superimposed on this mean rising current, and convective-scale downdrafts were located throughout and below the core of maximum precipitation in the eyewall.Precipitation particles in the eyewall rainshaft circulated 18-20 km downwind as they fell, consistent with the typical upwind slope with increasing altitude of eyewall precipitation cores Outside the eyewall, the precipitation was predominantly stratiform. A radar bright band was evident at the melting level. Above the melting level, ice particles were advected into the stratiform region from the upper levels of the eyewall and drifted downward through a mesoscale region of ascent. Hypothetical precipitation particle trajectories showed that as these particles fell slowly through the mesoscale updraft toward the melting level, they were carried azimuthally as many as 1 1/2 times around the storm. During this spiraling descent, the particles evidently grew vigorously. The amount of water condensed by the ambient mesoscale ascent exceeded that transported into the stratiform region by the eyewall outflow by a factor of 3. As the particles fell into the lower troposphere, they entered a mesoscale

Comparing helicopter-borne profiling radar with airborne laser scanner data for forest structure estimation.

NASA Astrophysics Data System (ADS)

Piermattei, Livia; Hollaus, Markus; Pfeifer, Norbert; Chen, Yuwei; Karjalainen, Mika; Hakala, Teemu; Hyyppä, Juha; Wagner, Wolfgang

2017-04-01

Forests are complex ecosystems that show substantial variation with respect to climate, management regime, stand history, disturbance, and needs of local communities. The dynamic processes of growth and disturbance are reflected in the structural components of forests that include the canopy vertical structure and geometry (e.g. size, height, and form), tree position and species diversity. Current remote-sensing systems to measure forest structural attributes include passive optical sensors and active sensors. The technological capabilities of active remote sensing like the ability to penetrate the vegetation and provide information about its vertical structure has promoted an extensive use of LiDAR (Light Detection And Ranging) and radar (RAdio Detection And Ranging) system over the last 20 years. LiDAR measurements from aircraft (airborne laser scanning, ALS) currently represents the primary data source for three-dimensional information on forest vertical structure. Contrary, despite the potential of radar remote sensing, their use is not yet established in forest monitoring. In order to better understand the interaction of pulsed radar with the forest canopy, and to increase the feasibility of this system, the Finnish Geospatial Research Institute has developed a helicopter-borne profiling radar system, called TomoRadar. TomoRadar is capable of recording a canopy-penetrating profile of forests. To georeference the radar measurements the system was equipped with a global navigation satellite system and an inertial measurement unit with a centimeter level accuracy of the flight trajectory. The TomoRadar operates at Ku-band, (wave lengths λ 1.5cm) with two separated parabolic antennas providing co- and cross-polarization modes. The purpose of this work is to investigate the capability of the TomoRadar system, for estimating the forest vertical profile, terrain topography and tree height. We analysed 600 m TomoRadar crosspolarized (i.e. horizontal - vertical

Time-series analysis of surface deformation at Brady Hot Springs geothermal field (Nevada) using interferometric synthetic aperture radar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ali, S. T.; Akerley, J.; Baluyut, E. C.

We analyze interferometric synthetic aperture radar (InSAR) data acquired between 2004 and 2014, by the ERS-2, Envisat, ALOS and TerraSAR-X/TanDEM-X satellite missions to measure and characterize time-dependent deformation at the Brady Hot Springs geothermal field in western Nevada due to extraction of fluids. The long axis of the ~4 km by ~1.5 km elliptical subsiding area coincides with the strike of the dominant normal fault system at Brady. Within this bowl of subsidence, the interference pattern shows several smaller features with length scales of the order of ~1 km. This signature occurs consistently in all of the well-correlated interferometric pairsmore » spanning several months. Results from inverse modeling suggest that the deformation is a result of volumetric contraction in shallow units, no deeper than 600 m, likely associated with damaged regions where fault segments mechanically interact. Such damaged zones are expected to extend downward along steeply dipping fault planes, providing a high permeability conduit to the production wells. Using time series analysis, we test the hypothesis that geothermal production drives the observed deformation. We find a good correlation between the observed deformation rate and the rate of production in the shallow wells. We also explore mechanisms that could potentially cause the observed deformation, including thermal contraction of rock, decline in pore pressure and dissolution of minerals over time.« less

Processor architecture for airborne SAR systems

NASA Technical Reports Server (NTRS)

Glass, C. M.

1983-01-01

Digital processors for spaceborne imaging radars and application of the technology developed for airborne SAR systems are considered. Transferring algorithms and implementation techniques from airborne to spaceborne SAR processors offers obvious advantages. The following topics are discussed: (1) a quantification of the differences in processing algorithms for airborne and spaceborne SARs; and (2) an overview of three processors for airborne SAR systems.

Advantages to Geoscience and Disaster Response from QuakeSim Implementation of Interferometric Radar Maps in a GIS Database System

NASA Astrophysics Data System (ADS)

Parker, Jay; Donnellan, Andrea; Glasscoe, Margaret; Fox, Geoffrey; Wang, Jun; Pierce, Marlon; Ma, Yu

2015-08-01

High-resolution maps of earth surface deformation are available in public archives for scientific interpretation, but are primarily available as bulky downloads on the internet. The NASA uninhabited aerial vehicle synthetic aperture radar (UAVSAR) archive of airborne radar interferograms delivers very high resolution images (approximately seven meter pixels) making remote handling of the files that much more pressing. Data exploration requiring data selection and exploratory analysis has been tedious. QuakeSim has implemented an archive of UAVSAR data in a web service and browser system based on GeoServer (http://geoserver.org). This supports a variety of services that supply consistent maps, raster image data and geographic information systems (GIS) objects including standard earthquake faults. Browsing the database is supported by initially displaying GIS-referenced thumbnail images of the radar displacement maps. Access is also provided to image metadata and links for full file downloads. One of the most widely used features is the QuakeSim line-of-sight profile tool, which calculates the radar-observed displacement (from an unwrapped interferogram product) along a line specified through a web browser. Displacement values along a profile are updated to a plot on the screen as the user interactively redefines the endpoints of the line and the sampling density. The profile and also a plot of the ground height are available as CSV (text) files for further examination, without any need to download the full radar file. Additional tools allow the user to select a polygon overlapping the radar displacement image, specify a downsampling rate and extract a modest sized grid of observations for display or for inversion, for example, the QuakeSim simplex inversion tool which estimates a consistent fault geometry and slip model.

Atmospheric parameters in the mesosphere and lower thermosphere estimated using the Platteville, CO (40°N, 105°W) interferometric meteor radars

NASA Astrophysics Data System (ADS)

de La Pena, Santiago

Two interferometric meteor radars operating at different frequencies have been collecting data for several years at the Platteville Atmospheric Observatory. Meteor decay rates measured by the two systems have been analyzed with the purpose of comparing estimates of the ambipolar diffusion in meteors made with the radars. Ambipolar diffusion is the main dispersion process for meteors. Due to its dependence on atmospheric conditions, it has been used in recent studies to estimate meteor height, and atmospheric temperature and pressure. The results of the comparison made shed light on the conditions under which meteor decay rates can be used to estimate ambipolar diffusion. The response of the two systems to sporadic and shower meteor activity was analyzed and discussed. The radars show similar temporal distributions of the echoes detected from meteor trails, but present some differences in the spatial distribution. The Statistics of the data collected by the radars present differences in the meteor echo spatial distribution between sporadic meteor activity and meteor shower events. Observations of a strong 2001 Leonid meteor storm were presented. A difference in the maximum altitude at which the radars detect meteors was seen. This limit in height is caused by a geophysical effect commonly known as meteor echo ceiling. Six years of horizontal wind estimates near the mesopause obtained from the meteor radars have been analyzed with the objective of studying the spatial and seasonal variability of the main tidal components identified in the wind structure. Interferometric capabilities allowed the estimation of the location of the detected meteor echoes, effectively providing vertical profiles of horizontal wind estimates. Spectral and harmonic analyses were made on the horizontal wind averages, and the main tidal components were identified. Diurnal and semidiurnal oscillations were found persistently, and six, 8, and 48 hour oscillations were more intermittent, but

Beyond Radar Backscatter: Estimating Forest Structure and Biomass with Radar Interferometry and Lidar Remote Sensing

NASA Astrophysics Data System (ADS)

Lavalle, M.; Ahmed, R.

2014-12-01

Mapping forest structure and aboveground biomass globally is a major challenge that the remote sensing community has been facing for decades. Radar backscatter is sensitive to biomass only up to a certain amount (about 150 tons/ha at L-band and 300 tons/ha at P-band), whereas lidar remote sensing is strongly limited by poor spatial coverage. In recent years radar interferometry, including its extension to polarimetric radar interferometry (PolInSAR), has emerged as a new technique to overcome the limitations of radar backscatter. The idea of PolInSAR is to use jointly interferometric and polarimetric radar techniques to separate different scattering mechanisms and retrieve the vertical structure of forests. The advantage is to map ecosystem structure continuously over large areas and independently of cloud coverage. Experiments have shown that forest height - an important proxy for biomass - can be estimated using PolInSAR with accuracy between 15% and 20% at plot level. At AGU we will review the state-of-art of repeat-pass PolInSAR for biomass mapping, including its potential and limitations, and discuss how merging lidar data with PolInSAR data can be beneficial not only for product cross-validation but also for achieving better estimation of ecosystem properties over large areas. In particular, lidar data are expected to aid the inversion of PolInSAR models by providing (1) better identification of ground under the canopy, (2) approximate information of canopy structure in limited areas, and (3) maximum tree height useful for mapping PolInSAR temporal decorrelation. We will show our tree height and biomass maps using PolInSAR L-band JPL/UAVSAR data collected in tropical and temperate forests, and P-band ONERA/TROPISAR data acquired in French Guiana. LVIS lidar data will be used, as well as SRTM data, field measurements and inventory data to support our study. The use of two different radar frequencies and repeat-pass JPL UAVSAR data will offer also the

Development and Evaluation of Science and Technology Education Program Using Interferometric SAR

NASA Astrophysics Data System (ADS)

Ito, Y.; Ikemitsu, H.; Nango, K.

2016-06-01

This paper proposes a science and technology education program to teach junior high school students to measure terrain changes by using interferometric synthetic aperture radar (SAR). The objectives of the proposed program are to evaluate and use information technology by performing SAR data processing in order to measure ground deformation, and to incorporate an understanding of Earth sciences by analyzing interferometric SAR processing results. To draft the teaching guidance plan for the developed education program, this study considers both science and technology education. The education program was used in a Japanese junior high school. An educational SAR processor developed by the authors and the customized Delft object-oriented radar interferometric software package were employed. Earthquakes as diastrophism events were chosen as practical teaching materials. The selected events indicate clear ground deformation in differential interferograms with high coherence levels. The learners were able to investigate the ground deformations and disasters caused by the events. They interactively used computers and became skilled at recognizing the knowledge and techniques of information technology, and then they evaluated the technology. Based on the results of pre- and post-questionnaire surveys and self-evaluation by the learners, it was clarified that the proposed program was applicable for junior high school education, and the learners recognized the usefulness of Earth observation technology by using interferometric SAR. The usefulness of the teaching materials in the learning activities was also shown through the practical teaching experience.

Bam, Iran, Radar Interferometry -- Earthquake

NASA Image and Video Library

2004-06-25

A magnitude 6.5 earthquake devastated the small city of Bam in southeast Iran on December 26, 2003. The two images from ESA Envisat show similar measures of the radar interferometric correlation in grayscale on the left and in false colors on the right.

Summaries of the Sixth Annual JPL Airborne Earth Science Workshop. Volume 2; AIRSAR Workshop

NASA Technical Reports Server (NTRS)

Kim, Yun-Jin (Editor)

1996-01-01

The Sixth Annual JPL Airborne Earth Science Workshop, held in Pasadena, California, on March 4-8, 1996, was divided into two smaller workshops:(1) The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) workshop, and The Airborne Synthetic Aperture Radar (AIRSAR) workshop. This current paper, Volume 2 of the Summaries of the Sixth Annual JPL Airborne Earth Science Workshop, presents the summaries for The Airborne Synthetic Aperture Radar (AIRSAR) workshop.

Interferometric synthetic aperture radar phase unwrapping based on sparse Markov random fields by graph cuts

NASA Astrophysics Data System (ADS)

Zhou, Lifan; Chai, Dengfeng; Xia, Yu; Ma, Peifeng; Lin, Hui

2018-01-01

Phase unwrapping (PU) is one of the key processes in reconstructing the digital elevation model of a scene from its interferometric synthetic aperture radar (InSAR) data. It is known that two-dimensional (2-D) PU problems can be formulated as maximum a posteriori estimation of Markov random fields (MRFs). However, considering that the traditional MRF algorithm is usually defined on a rectangular grid, it fails easily if large parts of the wrapped data are dominated by noise caused by large low-coherence area or rapid-topography variation. A PU solution based on sparse MRF is presented to extend the traditional MRF algorithm to deal with sparse data, which allows the unwrapping of InSAR data dominated by high phase noise. To speed up the graph cuts algorithm for sparse MRF, we designed dual elementary graphs and merged them to obtain the Delaunay triangle graph, which is used to minimize the energy function efficiently. The experiments on simulated and real data, compared with other existing algorithms, both confirm the effectiveness of the proposed MRF approach, which suffers less from decorrelation effects caused by large low-coherence area or rapid-topography variation.

Characteristics of Deep Tropical and Subtropical Convection from Nadir-Viewing High-Altitude Airborne Doppler Radar

NASA Technical Reports Server (NTRS)

Heymsfield, Gerald M.; Tian, Lin; Heymsfield, Andrew J.; Li, Lihua; Guimond, Stephen

2010-01-01

This paper presents observations of deep convection characteristics in the tropics and subtropics that have been classified into four categories: tropical cyclone, oceanic, land, and sea breeze. Vertical velocities in the convection were derived from Doppler radar measurements collected during several NASA field experiments from the nadir-viewing high-altitude ER-2 Doppler radar (EDOP). Emphasis is placed on the vertical structure of the convection from the surface to cloud top (sometimes reaching 18-km altitude). This unique look at convection is not possible from other approaches such as ground-based or lower-altitude airborne scanning radars. The vertical motions from the radar measurements are derived using new relationships between radar reflectivity and hydrometeor fall speed. Various convective properties, such as the peak updraft and downdraft velocities and their corresponding altitude, heights of reflectivity levels, and widths of reflectivity cores, are estimated. The most significant findings are the following: 1) strong updrafts that mostly exceed 15 m/s, with a few exceeding 30 m/s, are found in all the deep convection cases, whether over land or ocean; 2) peak updrafts were almost always above the 10-km level and, in the case of tropical cyclones, were closer to the 12-km level; and 3) land-based and sea-breeze convection had higher reflectivities and wider convective cores than oceanic and tropical cyclone convection. In addition, the high-resolution EDOP data were used to examine the connection between reflectivity and vertical velocity, for which only weak linear relationships were found. The results are discussed in terms of dynamical and microphysical implications for numerical models and future remote sensors.

Three-dimensional surface deformation derived from airborne interferometric UAVSAR: Application to the Slumgullion Landslide

USGS Publications Warehouse

Delbridge, Brent G.; Burgmann, Roland; Fielding, Eric; Hensley, Scott; Schulz, William

2016-01-01

In order to provide surface geodetic measurements with “landslide-wide” spatial coverage, we develop and validate a method for the characterization of 3-D surface deformation using the unique capabilities of the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) airborne repeat-pass radar interferometry system. We apply our method at the well-studied Slumgullion Landslide, which is 3.9 km long and moves persistently at rates up to ∼2 cm/day. A comparison with concurrent GPS measurements validates this method and shows that it provides reliable and accurate 3-D surface deformation measurements. The UAVSAR-derived vector velocity field measurements accurately capture the sharp boundaries defining previously identified kinematic units and geomorphic domains within the landslide. We acquired data across the landslide during spring and summer and identify that the landslide moves more slowly during summer except at its head, presumably in response to spatiotemporal variations in snowmelt infiltration. In order to constrain the mechanics controlling landslide motion from surface velocity measurements, we present an inversion framework for the extraction of slide thickness and basal geometry from dense 3-D surface velocity fields. We find that the average depth of the Slumgullion Landslide is 7.5 m, several meters less than previous depth estimates. We show that by considering a viscoplastic rheology, we can derive tighter theoretical bounds on the rheological parameter relating mean horizontal flow rate to surface velocity. Using inclinometer data for slow-moving, clay-rich landslides across the globe, we find a consistent value for the rheological parameter of 0.85 ± 0.08.

Airborne radar surveys of snow depth over Antarctic sea ice during Operation IceBridge

NASA Astrophysics Data System (ADS)

Panzer, B.; Gomez-Garcia, D.; Leuschen, C.; Paden, J. D.; Gogineni, P. S.

2012-12-01

Over the last decade, multiple satellite-based laser and radar altimeters, optimized for polar observations, have been launched with one of the major objectives being the determination of global sea ice thickness and distribution [5, 6]. Estimation of sea-ice thickness from these altimeters relies on freeboard measurements and the presence of snow cover on sea ice affects this estimate. Current means of estimating the snow depth rely on daily precipitation products and/or data from passive microwave sensors [2, 7]. Even a small uncertainty in the snow depth leads to a large uncertainty in the sea-ice thickness estimate. To improve the accuracy of the sea-ice thickness estimates and provide validation for measurements from satellite-based sensors, the Center for Remote Sensing of Ice Sheets deploys the Snow Radar as a part of NASA Operation IceBridge. The Snow Radar is an ultra-wideband, frequency-modulated, continuous-wave radar capable of resolving snow depth on sea ice from 5 cm to more than 2 meters from long-range, airborne platforms [4]. This paper will discuss the algorithm used to directly extract snow depth estimates exclusively using the Snow Radar data set by tracking both the air-snow and snow-ice interfaces. Prior work in this regard used data from a laser altimeter for tracking the air-snow interface or worked under the assumption that the return from the snow-ice interface was greater than that from the air-snow interface due to a larger dielectric contrast, which is not true for thick or higher loss snow cover [1, 3]. This paper will also present snow depth estimates from Snow Radar data during the NASA Operation IceBridge 2010-2011 Antarctic campaigns. In 2010, three sea ice flights were flown, two in the Weddell Sea and one in the Amundsen and Bellingshausen Seas. All three flight lines were repeated in 2011, allowing an annual comparison of snow depth. In 2011, a repeat pass of an earlier flight in the Weddell Sea was flown, allowing for a

Quantitative Estimation of Above Ground Crop Biomass using Ground-based, Airborne and Spaceborne Low Frequency Polarimetric Synthetic Aperture Radar

NASA Astrophysics Data System (ADS)

Koyama, C.; Watanabe, M.; Shimada, M.

2016-12-01

Estimation of crop biomass is one of the important challenges in environmental remote sensing related to agricultural as well as hydrological and meteorological applications. Usually passive optical data (photographs, spectral data) operating in the visible and near-infrared bands is used for such purposes. The virtue of optical remote sensing for yield estimation, however, is rather limited as the visible light can only provide information about the chemical characteristics of the canopy surface. Low frequency microwave signals with wavelength longer 20 cm have the potential to penetrate through the canopy and provide information about the whole vertical structure of vegetation from the top of the canopy down to the very soil surface. This phenomenon has been well known and exploited to detect targets under vegetation in the military radar application known as FOPEN (foliage penetration). With the availability of polarimetric interferometric SAR data the use PolInSAR techniques to retrieve vertical vegetation structures has become an attractive tool. However, PolInSAR is still highly experimental and suitable data is not yet widely available. In this study we focus on the use of operational dual-polarization L-band (1.27 GHz) SAR which is since the launch of Japan's Advanced Land Observing Satellite (ALOS, 2006-2011) available worldwide. Since 2014 ALOS-2 continues to deliver such kind of partial polarimetric data for the entire land surface. In addition to these spaceborne data sets we use airborne L-band SAR data acquired by the Japanese Pi-SAR-L2 as well as ultra-wideband (UWB) ground based SAR data operating in the frequency range from 1-4 GHz. By exploiting the complex dual-polarization [C2] Covariance matrix information, the scattering contributions from the canopy can be well separated from the ground reflections allowing for the establishment of semi-empirical relationships between measured radar reflectivity and the amount of fresh-weight above

Comments on airborne ISR radar utilization

NASA Astrophysics Data System (ADS)

Doerry, A. W.

2016-05-01

A sensor/payload operator for modern multi-sensor multi-mode Intelligence, Surveillance, and Reconnaissance (ISR) platforms is often confronted with a plethora of options in sensors and sensor modes. This often leads an over-worked operator to down-select to favorite sensors and modes; for example a justifiably favorite Full Motion Video (FMV) sensor at the expense of radar modes, even if radar modes can offer unique and advantageous information. At best, sensors might be used in a serial monogamous fashion with some cross-cueing. The challenge is then to increase the utilization of the radar modes in a manner attractive to the sensor/payload operator. We propose that this is best accomplished by combining sensor modes and displays into `super-modes'.

Airborne SAR systems for infrastructures monitoring

NASA Astrophysics Data System (ADS)

Perna, Stefano; Berardino, Paolo; Esposito, Carmen; Natale, Antonio

2017-04-01

The present contribution is aimed at showing the capabilities of Synthetic Aperture Radar (SAR) systems mounted onboard airborne platforms for the monitoring of infrastructures. As well known, airborne SAR systems guarantee narrower spatial coverage than satellite sensors [1]. On the other side, airborne SAR products are characterized by geometric resolution typically higher than that achievable in the satellite case, where larger antennas must be necessarily exploited. More important, airborne SAR platforms guarantee operational flexibility significantly higher than that achievable with satellite systems. Indeed, the revisit time between repeated SAR acquisitions in the satellite case cannot be freely decided, whereas in the airborne case it can be kept very short. This renders the airborne platforms of key interest for the monitoring of infrastructures, especially in case of emergencies. However, due to the platform deviations from a rectilinear, reference flight track, the generation of airborne SAR products is not a turn of the crank procedure as in the satellite case. Notwithstanding proper algorithms exist in order to circumvent this kind of limitations. In this work, we show how the exploitation of airborne SAR sensors, coupled to the use of such algorithms, allows obtaining high resolution monitoring of infrastructures in urban areas. [1] G. Franceschetti, and R.Lanari, Synthetic Aperture Radar Processing, CRC PRESS, New York, 1999.

Airborne Turbulence Detection System Certification Tool Set

NASA Technical Reports Server (NTRS)

Hamilton, David W.; Proctor, Fred H.

2006-01-01

A methodology and a corresponding set of simulation tools for testing and evaluating turbulence detection sensors has been presented. The tool set is available to industry and the FAA for certification of radar based airborne turbulence detection systems. The tool set consists of simulated data sets representing convectively induced turbulence, an airborne radar simulation system, hazard tables to convert the radar observable to an aircraft load, documentation, a hazard metric "truth" algorithm, and criteria for scoring the predictions. Analysis indicates that flight test data supports spatial buffers for scoring detections. Also, flight data and demonstrations with the tool set suggest the need for a magnitude buffer.

Detection and Identification of Archaeological Sites and Features Using Synthetic Aperture Radar (SAR) Data Collected from Airborne Platforms

DTIC Science & Technology

2006-04-26

sessions were used not only for signature development, but more 5 immediately to determine the spatial precision of images produced from...algorithms (e.g., NDVI and Tasseled Cap) available. The most instructive vectors were determined to be the SAR band polarizations vertically in the C...lands. Our principal, but not exclusive, focus has been on the use of high resolution airborne radar data in detection. in’<l’entoxy, and

Partly cloudy with a chance of migration: Weather, radars, and aeroecology

USGS Publications Warehouse

Chilson, Phillip B.; Frick, Winifred F.; Kelly, Jeffrey F.; Howard, Kenneth W.; Larkin, Ronald P.; Diehl, Robert H.; Westbrook, John K.; Kelly, T. Adam; Kunz, Thomas H.

2012-01-01

Aeroecology is an emerging scientific discipline that integrates atmospheric science, Earth science, geography, ecology, computer science, computational biology, and engineering to further the understanding of biological patterns and processes. The unifying concept underlying this new transdisciplinary field of study is a focus on the planetary boundary layer and lower free atmosphere (i.e., the aerosphere), and the diversity of airborne organisms that inhabit and depend on the aerosphere for their existence. Here, we focus on the role of radars and radar networks in aeroecological studies. Radar systems scanning the atmosphere are primarily used to monitor weather conditions and track the location and movements of aircraft. However, radar echoes regularly contain signals from other sources, such as airborne birds, bats, and arthropods. We briefly discuss how radar observations can be and have been used to study a variety of airborne organisms and examine some of the many potential benefits likely to arise from radar aeroecology for meteorological and biological research over a wide range of spatial and temporal scales. Radar systems are becoming increasingly sophisticated with the advent of innovative signal processing and dual-polarimetric capabilities. These capabilities should be better harnessed to promote both meteorological and aeroecological research and to explore the interface between these two broad disciplines. We strongly encourage close collaboration among meteorologists, radar scientists, biologists, and others toward developing radar products that will contribute to a better understanding of airborne fauna.

Imaging Radar in the Mojave Desert-Death Valley Region

NASA Technical Reports Server (NTRS)

Farr, Tom G.

2001-01-01

The Mojave Desert-Death Valley region has had a long history as a test bed for remote sensing techniques. Along with visible-near infrared and thermal IR sensors, imaging radars have flown and orbited over the area since the 1970's, yielding new insights into the geologic applications of these technologies. More recently, radar interferometry has been used to derive digital topographic maps of the area, supplementing the USGS 7.5' digital quadrangles currently available for nearly the entire area. As for their shorter-wavelength brethren, imaging radars were tested early in their civilian history in the Mojave Desert-Death Valley region because it contains a variety of surface types in a small area without the confounding effects of vegetation. The earliest imaging radars to be flown over the region included military tests of short-wavelength (3 cm) X-band sensors. Later, the Jet Propulsion Laboratory began its development of imaging radars with an airborne sensor, followed by the Seasat orbital radar in 1978. These systems were L-band (25 cm). Following Seasat, JPL embarked upon a series of Space Shuttle Imaging Radars: SIRA (1981), SIR-B (1984), and SIR-C (1994). The most recent in the series was the most capable radar sensor flown in space and acquired large numbers of data swaths in a variety of test areas around the world. The Mojave Desert-Death Valley region was one of those test areas, and was covered very well with 3 wavelengths, multiple polarizations, and at multiple angles. At the same time, the JPL aircraft radar program continued improving and collecting data over the Mojave Desert Death Valley region. Now called AIRSAR, the system includes 3 bands (P-band, 67 cm; L-band, 25 cm; C-band, 5 cm). Each band can collect all possible polarizations in a mode called polarimetry. In addition, AIRSAR can be operated in the TOPSAR mode wherein 2 antennas collect data interferometrically, yielding a digital elevation model (DEM). Both L-band and C-band can be

Multiple scattering effects on the Linear Depolarization Ratio (LDR) measured during CaPE by a Ka-band air-borne radar

NASA Technical Reports Server (NTRS)

Iguchi, Toshio; Meneghini, Robert

1993-01-01

Air-borne radar measurements of thunderstorms were made as part of the CaPE (Convection and Precipitation/Electrification) experiment in Florida in July 1991. The radar has two channels, X-band (10 GHz) and Ka-band (34.5 GHz), and is capable of measuring cross-polarized returns as well as co-polarized returns. In stratiform rain, the cross-polarized components can be observed only at the bright band region and from the surface reflection. The linear depolarization ratios (LDR's) measured at X-band and Ka-band at the bright band are nearly equal. In convective rain, however, the LDR in Ka-band often exceeds the X-band LDR by several dB, and sometimes by more than 10 dB, reaching LDR values of up to -5 dB over heavy convective rain. For randomly oriented hydrometeors, such high LDR values cannot be explained by single scattering from non-spherical scattering particles alone. Because the LDR by single backscatter depends weakly on the wavelength, the difference between the Ka-band and X-band LDR's suggests that multiple scattering effects prevail in the Ka-band LDR. In order to test this inference, the magnitude of the cross-polarized component created by double scattering was calculated using the parameters of the airborne radar, which for both frequencies has beamwidths of 5.1 degrees and pulse widths of 0.5 microsecond. Uniform rain beyond the range of 3 km is assumed.

Combined Use of Airborne Lidar and DBInSAR Data to Estimate LAI in Temperate Mixed Forests

NASA Technical Reports Server (NTRS)

Peduzzi, Alicia; Wynne, Randolph Hamilton; Thomas, Valerie A.; Nelson, Ross F.; Reis, James J.; Sanford, Mark

2012-01-01

The objective of this study was to determine whether leaf area index (LAI) in temperate mixed forests is best estimated using multiple-return airborne laser scanning (lidar) data or dual-band, single-pass interferometric synthetic aperture radar data (from GeoSAR) alone, or both in combination. In situ measurements of LAI were made using the LiCor LAI-2000 Plant Canopy Analyzer on 61 plots (21 hardwood, 36 pine, 4 mixed pine hardwood; stand age ranging from 12-164 years; mean height ranging from 0.4 to 41.2 m) in the Appomattox-Buckingham State Forest, Virginia, USA. Lidar distributional metrics were calculated for all returns and for ten one meter deep crown density slices (a new metric), five above and five below the mode of the vegetation returns for each plot. GeoSAR metrics were calculated from the X-band backscatter coefficients (four looks) as well as both X- and P-band interferometric heights and magnitudes for each plot. Lidar metrics alone explained 69% of the variability in LAI, while GeoSAR metrics alone explained 52%. However, combining the lidar and GeoSAR metrics increased the R2 to 0.77 with a CV-RMSE of 0.42. This study indicates the clear potential for X-band backscatter and interferometric height (both now available from spaceborne sensors), when combined with small-footprint lidar data, to improve LAI estimation in temperate mixed forests.

Use of Dual-wavelength Radar for Snow Parameter Estimates

NASA Technical Reports Server (NTRS)

Liao, Liang; Meneghini, Robert; Iguchi, Toshio; Detwiler, Andrew

2005-01-01

Use of dual-wavelength radar, with properly chosen wavelengths, will significantly lessen the ambiguities in the retrieval of microphysical properties of hydrometeors. In this paper, a dual-wavelength algorithm is described to estimate the characteristic parameters of the snow size distributions. An analysis of the computational results, made at X and Ka bands (T-39 airborne radar) and at S and X bands (CP-2 ground-based radar), indicates that valid estimates of the median volume diameter of snow particles, D(sub 0), should be possible if one of the two wavelengths of the radar operates in the non-Rayleigh scattering region. However, the accuracy may be affected to some extent if the shape factors of the Gamma function used for describing the particle distribution are chosen far from the true values or if cloud water attenuation is significant. To examine the validity and accuracy of the dual-wavelength radar algorithms, the algorithms are applied to the data taken from the Convective and Precipitation-Electrification Experiment (CaPE) in 1991, in which the dual-wavelength airborne radar was coordinated with in situ aircraft particle observations and ground-based radar measurements. Having carefully co-registered the data obtained from the different platforms, the airborne radar-derived size distributions are then compared with the in-situ measurements and ground-based radar. Good agreement is found for these comparisons despite the uncertainties resulting from mismatches of the sample volumes among the different sensors as well as spatial and temporal offsets.

78 FR 19063 - Airworthiness Approval for Aircraft Forward-Looking Windshear and Turbulence Radar Systems

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-28

... Technical Standard Order (TSO)-C63d, Airborne Weather Radar Equipment. The objective is to leverage the..., Airborne Weather and Ground Mapping Pulsed Radars. The FAA and industry collaborated on the end-to-end...

Recent Advances in Radar Polarimetry and Polarimetric SAR Interferometry

DTIC Science & Technology

2005-02-01

Hensley, H. A. Zebker, F. H. Webb, and E. Fielding, 1996, "Surface deformation and coherence measurements of Kilauea Volcano , Hawaii from SIR-C radar...topography, tectonic surface deformation, bulging and subsidence (earthquakes, volcanoes , geo-thermal fields and artesian irrigation, ice fields), glacial...J.J. and Y-J. Kim, 2000, "The relationship between radar polarimetric and interferometric phase," Presented at IGARSS�, Honolulu, Hawaii , July

Comparison of surface wind stress measurements - Airborne radar scatterometer versus sonic anemometer

NASA Technical Reports Server (NTRS)

Brucks, J. T.; Leming, T. D.; Jones, W. L.

1980-01-01

Sea surface wind stress measurements recorded by a sonic anemometer are correlated with airborne scatterometer measurements of ocean roughness (cross section of radar backscatter) to establish the accuracy of remotely sensed data and assist in the definition of geophysical algorithms for the scatterometer sensor aboard Seasat A. Results of this investigation are as follows: Comparison of scatterometer and sonic anemometer wind stress measurements are good for the majority of cases; however, a tendency exists for scatterometer wind stress to be somewhat high for higher wind conditions experienced in this experiment (6-9 m/s). The scatterometer wind speed algorithm tends to overcompute the higher wind speeds by approximately 0.5 m/s. This is a direct result of the scatterometer overestimate of wind stress from which wind speeds are derived. Algorithmic derivations of wind speed and direction are, in most comparisons, within accuracies defined by Seasat A scatterometer sensor specifications.

Englacial layer mapping correlation and consistency techniques: an example from airborne ice penetrating radar profiles in West Antarctica

NASA Astrophysics Data System (ADS)

Sudunagunta, V.; Ballal, S.; Albach, R.; Muldoon, G.; Quartini, E.; Cavitte, M. G.; Young, D. A.; Blankenship, D. D.

2016-12-01

Ice sheets are important considerations in projections of sea level rise and studies of climate history. Satellite imagery, ice-penetrating radar, and ground penetrating radar are commonly used to understand the dynamics and health of ice sheets. We focus on how to accurately interpret ice-penetrating radar data by tracing isochrones dated by comparison to deep ice cores so that an extensive knowledge of the West Antarctic Ice Sheet's internal stratigraphy is obtained. The radar data shows englacial reflectors and isochrones are interpreted englacial reflectors. We analyze these features and attempt to understand their possible origins. Accurate interpretation of radar data is crucial because the data will be used to evaluate ice flow evolution and boundary conditions. It can also be used to validate simulated ice sheet models. However to do so, isochrones must be traced and connected correctly. Our approach accomplishes this and has the potential to be applied to other ice sheets on Earth and in extraterrestrial systems. We discuss the methodology utilized by our team to interpret data from the West Antarctic Ice Sheet collected using airborne ice-penetrating radar. The seismic reflection interpretation environment Landmark DecisionSpace was adapted to display and interpret the radar returns. When tracing isochrones, a group approach is used to maximize accuracy. In gridded surveys, loops are used to continuously check isochrones, in addition to retracing of isochrones by different group members to check for errors in interpretation. As loops are made, areas of possible scientific merit, such as isochrone drawdowns or Raymond bumps, are documented. A key aspect of this approach is the ability to work in a shared environment with a collaborative database like DecisionSpace. We will explore how we identified these features, their root causes, and subsequent implications for understanding ice sheet dynamics.

Strain Partitioning and Localization within Dobe Graben Using Differential Interferometric Synthetic Aperture Radar (D-INSAR) and Shuttle Radar Terrain Model

NASA Astrophysics Data System (ADS)

Demissie, Z. S.; Abdelsalam, M. G.; Byrnes, J. M.; Bridges, D.

2014-12-01

The Dobe graben is a northwestern trending, Quaternary continental rift found within the east-central block of the Afar Depression (AD), Ethiopia. The AD is one of only few places where three active tectonic rift arms meet on land. Extensional rifting is ongoing in the Dobe graben as evident by the 1989 swarm of intermediate magnitude (5.7 < Ms < 6.3) earthquakes. Dobe graben extension occurs on steeply dipping faults, where the maximum displacement, fault length, heave and spacing spans in three orders of magnitude. Crustal deformation within the graben was measured through ascending and descending interferograms using the Advanced Synthetic Aperture Radar (ASAR), C- Band (l = 5.6 cm) of the ENVISAT satellite. Results from the Differential Interferometric Synthetic Aperture Radar (D-INSAR) over a period of four years (05/20/2005 to 03/05/2010) suggests that the vertical component of deformation is distributed along a 50 km long NW trending zone in the Dobe graben. The vertical component of deformation is -0.5 to -0.3 cm along the graben axial rift floor likely representing subsidence due to riftingand +0.6 cm to 0.9 cm at the middle of the Dobe relay zone due to uplifting along the border escarpment faults. An estimate for the extension rate has been calculated from twelve traverses across the Dobe graben using Shuttle Rader Terrain Model (SRTM). Results show a deformation elongation (e) value ranging from 0.225 to 0.348. A fractal dimension of 0.03 from the graben floor was obtained for the measured population of fault throws (n= 162) in 12 traverses totaling 172 km. This value is interpreted to represent the dominant contribution to extension from faults with large throw. Moreover, frequency distribution of a natural fault population along the graben floor revealed a negative exponential law distribution indicating a strong strain partitioning within the active axial graben floor. A fractal dimension of 0.01 from the graben shoulder escarpment was obtained for

A Wing Pod-based Millimeter Wave Cloud Radar on HIAPER

NASA Astrophysics Data System (ADS)

Vivekanandan, Jothiram; Tsai, Peisang; Ellis, Scott; Loew, Eric; Lee, Wen-Chau; Emmett, Joanthan

2014-05-01

One of the attractive features of a millimeter wave radar system is its ability to detect micron-sized particles that constitute clouds with lower than 0.1 g m-3 liquid or ice water content. Scanning or vertically-pointing ground-based millimeter wavelength radars are used to study stratocumulus (Vali et al. 1998; Kollias and Albrecht 2000) and fair-weather cumulus (Kollias et al. 2001). Airborne millimeter wavelength radars have been used for atmospheric remote sensing since the early 1990s (Pazmany et al. 1995). Airborne millimeter wavelength radar systems, such as the University of Wyoming King Air Cloud Radar (WCR) and the NASA ER-2 Cloud Radar System (CRS), have added mobility to observe clouds in remote regions and over oceans. Scientific requirements of millimeter wavelength radar are mainly driven by climate and cloud initiation studies. Survey results from the cloud radar user community indicated a common preference for a narrow beam W-band radar with polarimetric and Doppler capabilities for airborne remote sensing of clouds. For detecting small amounts of liquid and ice, it is desired to have -30 dBZ sensitivity at a 10 km range. Additional desired capabilities included a second wavelength and/or dual-Doppler winds. Modern radar technology offers various options (e.g., dual-polarization and dual-wavelength). Even though a basic fixed beam Doppler radar system with a sensitivity of -30 dBZ at 10 km is capable of satisfying cloud detection requirements, the above-mentioned additional options, namely dual-wavelength, and dual-polarization, significantly extend the measurement capabilities to further reduce any uncertainty in radar-based retrievals of cloud properties. This paper describes a novel, airborne pod-based millimeter wave radar, preliminary radar measurements and corresponding derived scientific products. Since some of the primary engineering requirements of this millimeter wave radar are that it should be deployable on an airborne platform

Operations Manager Tim Miller checks out software for the Airborne Synthetic Aperature Radar (AIRSAR

NASA Technical Reports Server (NTRS)

1998-01-01

Tim Miller checks out software for the Airborne Synthetic Aperture Radar (AIRSAR). He was the AIRSAR operations manager for NASA's Jet Propulsion Laboratory. The AIRSAR produces imaging data for a range of studies conducted by the DC-8. NASA is using a DC-8 aircraft as a flying science laboratory. The platform aircraft, based at NASA's Dryden Flight Research Center, Edwards, Calif., collects data for many experiments in support of scientific projects serving the world scientific community. Included in this community are NASA, federal, state, academic and foreign investigators. Data gathered by the DC-8 at flight altitude and by remote sensing have been used for scientific studies in archeology, ecology, geography, hydrology, meteorology, oceanography, volcanology, atmospheric chemistry, soil science and biology.

An examination of along-track interferometry for detecting ground moving targets

NASA Technical Reports Server (NTRS)

Chen, Curtis W.; Chapin, Elaine; Muellerschoen, Ron; Hensley, Scott

2005-01-01

Along-track interferometry (ATI) is an interferometric synthetic aperture radar technique primarily used to measure Earth-surface velocities. We present results from an airborne experiment demonstrating phenomenology specific to the context of observing discrete ground targets moving admidst a stationary clutter background.

High Resolution Displacement Monitoring for Urban Environments in Seattle, Washington using Terrestrial Radar Interferometry

NASA Astrophysics Data System (ADS)

Lowry, B. W.; Schrock, G.; Werner, C. L.; Zhou, W.; Pugh, N.

2015-12-01

Displacement monitoring using Terrestrial Radar Interferometry (TRI) over an urban environment was conducted to monitor for potential movement of buildings, roadways, and urban infrastructure in Seattle, Washington for a 6 week deployment in March and April of 2015. A Gamma Portable Radar Interferometer was deployed on a the lower roof of the Smith Tower at an elevation of about 100 m, overlooking the historical district of Pioneer Square. Radar monitoring in this context provides wide area coverage, sub millimeter precision, near real time alarming, and reflectorless measurement. Image georectification was established using a previously collected airborne lidar scan which was used to map the radar image onto a 3D 1st return elevation model of downtown Seattle. Platform stability concerns were monitored using high rate GPS and a 3-axis accelerometer to monitor for building movement or platform instability. Displacements were imaged at 2 minute intervals and stacked into 2 hour averages to aid in noise characterization. Changes in coherence are characterized based on diurnal fluctuations of temperature, cultural noise, and target continuity. These informed atmospheric and image selection filters for optimizing interferogram generation and displacement measurement quality control. An urban monitoring workflow was established using point target interferometric analysis to create a monitoring set of approximately 100,000 stable monitoring points measured at 2 minute to 3 hour intervals over the 6 week deployment. Radar displacement measurements were verified using ongoing survey and GPS monitoring program and with corner reflector tests to verify look angle corrections to settlement motion. Insights from this monitoring program can be used to design TRI monitoring programs for underground tunneling, urban subsidence, and earthquake damage assessment applications.

Airborne In Situ and Ground-based Polarimetric Radar Measurements of Tropical Convection in Support of CRYSTAL-FACE

NASA Technical Reports Server (NTRS)

Poellot, Michael R.; Kucera, Paul A.

2004-01-01

This report describes the work performed by the University of North Dakota (UND) under NASA Grant NAG5-11509, titled Airborne In Situ and Ground-based Polarimetric Radar Measurements of Tropical Convection in Support of CRYSTAL-FACE. This work focused on the collection of data by two key platforms: the UND Citation II research aircraft and the NASA NPOL radar system. The CRYSTAL-FACE (C-F) mission addresses several key issues from the NASA Earth System Enterprise, including the variability of water in the atmosphere, the forcing provided by tropical cirrus and the response of the Earth system to this forcing. In situ measurements and radar observations of tropical convection, cirrus clouds and their environment are core elements of C-F. One of the primary issues that C-F is addressing is the relationship of tropical cirrus anvils to precipitating deep convection. The in situ measurements from C-F are being used to validate remote sensing of Earth-Atmosphere properties, increase our knowledge of upper tropospheric water vapor and its distribution, and increase our knowledge of tropical cirrus cloud morphology and composition. Radar measurements, especially polarimetric diversity observations available fiom the NASA NPOL radar, are providing essential information about the initiation, modulation, and dissipation of convective cores and the generation of associated anvils in tropical convection. Specifically, NPOL radar measurements contain information about convective intensity and its vertical structure for comparison with thermodynamic and kinematic environmental measurements observed from soundings. Because of the polarimetric diversity of MOL, statistics on bulk microphysical properties can be retrieved and compared to the other characteristics of convection and associated cirrus anvils. In summary, the central objectives of this proposal were to deploy the UND Citation research aircraft as an in situ sensing platform for this mission and to provide collaborative

Interferometric Synthetic Aperture Radar to capture spatial variability of local land-based subsidence

NASA Astrophysics Data System (ADS)

Bekaert, D. P.; Hamlington, B.; Buzzanga, B. A.; Jones, C. E.

2017-12-01

The rate of relative sea level rise results from a combination of land subsidence and rising seas associated with global warming on long timescales and exacerbated by shifts in ocean dynamics on shorter timescales. An understanding of the current-day magnitude of each component is needed to create accurate projections of future relative sea level rise upon which to base planning efforts. Current day land-based subsidence rates derived from GPS often lack the spatial resolution to capture the local spatial variability needed when assessing the impact of relative sea-level rise. Interferometric Synthetic Aperture Radar (InSAR) is an attractive technique that has the potential to provide a measurement every 20-30m when good signal coherence is maintained. In practice, coastal regions are challenging for InSAR due to variable vegetation cover and soil moisture, which can be in part mitigated by applying advanced time-series InSAR techniques. After applying time-series InSAR, derived rates need to be combined with GPS to tie relative subsidence rates into a geodetic reference frame. Given the need to make projections of relative sea-level rise it is particularly important to propagate all uncertainties during the different processing stages. Here we provide results from ALOS and Sentinel-1 over Hampton Roads area in the Chesapeake Bay region, which is experiencing one of the highest rates of relative sea level rise on the Atlantic coast of the United States. Although the current derived subsidence rates have large uncertainties, it is expected that this will improve with the decadal observations from Sentinel-1.

14 CFR 135.173 - Airborne thunderstorm detection equipment requirements.

Code of Federal Regulations, 2011 CFR

2011-01-01

... weather radar equipment. (b) No person may operate a helicopter that has a passenger seating configuration... approved airborne weather radar equipment. (c) No person may begin a flight under IFR or night VFR...

Reconfigurable L-Band Radar

NASA Technical Reports Server (NTRS)

Rincon, Rafael F.

2008-01-01

The reconfigurable L-Band radar is an ongoing development at NASA/GSFC that exploits the capability inherently in phased array radar systems with a state-of-the-art data acquisition and real-time processor in order to enable multi-mode measurement techniques in a single radar architecture. The development leverages on the L-Band Imaging Scatterometer, a radar system designed for the development and testing of new radar techniques; and the custom-built DBSAR processor, a highly reconfigurable, high speed data acquisition and processing system. The radar modes currently implemented include scatterometer, synthetic aperture radar, and altimetry; and plans to add new modes such as radiometry and bi-static GNSS signals are being formulated. This development is aimed at enhancing the radar remote sensing capabilities for airborne and spaceborne applications in support of Earth Science and planetary exploration This paper describes the design of the radar and processor systems, explains the operational modes, and discusses preliminary measurements and future plans.

Ground Deformation from Chilean Volcanic Eruption Shown by Satellite Radar Image

NASA Image and Video Library

2015-04-29

This satellite interferometric synthetic aperture radar image-pair shows relative deformation of the Earth surface when nn April 22-23, 2015, significant explosive eruptions occurred at Calbuco volcano, Chile.

Evaluation of LIDAR for Automating Recognition of Roads and Trails Beneath Forest Canopy

DTIC Science & Technology

2011-09-01

Measurement Unit InSAR Interferometric Synthetic Aperture Radar ISS International Space Station JALBTCX Joint Airborne LiDAR Bathymetry Technical Center of...California police arrest 100 over marijuana growing. Retrieved July 29, 2011, from http://www.bbc.co.uk/news/world–us–canada–14351501 Contreras, M

Simultaneous dual-band radar development

NASA Technical Reports Server (NTRS)

Liskow, C. L.

1974-01-01

Efforts to design and construct an airborne imaging radar operating simultaneously at L band and X band with an all-inertial navigation system in order to form a dual-band radar system are described. The areas of development include duplex transmitters, receivers, and recorders, a control module, motion compensation for both bands, and adaptation of a commercial inertial navigation system. Installation of the system in the aircraft and flight tests are described. Circuit diagrams, performance figures, and some radar images are presented.

Coherent Doppler Laser Radar: Technology Development and Applications

NASA Technical Reports Server (NTRS)

Kavaya, Michael J.; Arnold, James E. (Technical Monitor)

2000-01-01

NASA's Marshall Space Flight Center has been investigating, developing, and applying coherent Doppler laser radar technology for over 30 years. These efforts have included the first wind measurement in 1967, the first airborne flights in 1972, the first airborne wind field mapping in 1981, and the first measurement of hurricane eyewall winds in 1998. A parallel effort at MSFC since 1982 has been the study, modeling and technology development for a space-based global wind measurement system. These endeavors to date have resulted in compact, robust, eyesafe lidars at 2 micron wavelength based on solid-state laser technology; in a factor of 6 volume reduction in near diffraction limited, space-qualifiable telescopes; in sophisticated airborne scanners with full platform motion subtraction; in local oscillator lasers capable of rapid tuning of 25 GHz for removal of relative laser radar to target velocities over a 25 km/s range; in performance prediction theory and simulations that have been validated experimentally; and in extensive field campaign experience. We have also begun efforts to dramatically improve the fundamental photon efficiency of the laser radar, to demonstrate advanced lower mass laser radar telescopes and scanners; to develop laser and laser radar system alignment maintenance technologies; and to greatly improve the electrical efficiency, cooling technique, and robustness of the pulsed laser. This coherent Doppler laser radar technology is suitable for high resolution, high accuracy wind mapping; for aerosol and cloud measurement; for Differential Absorption Lidar (DIAL) measurements of atmospheric and trace gases; for hard target range and velocity measurement; and for hard target vibration spectra measurement. It is also suitable for a number of aircraft operations applications such as clear air turbulence (CAT) detection; dangerous wind shear (microburst) detection; airspeed, angle of attack, and sideslip measurement; and fuel savings through

Interferometric Meteor Head Echo Observations using the Southern Argentina Agile Meteor Radar (SAAMER)

NASA Technical Reports Server (NTRS)

Janches, D.; Hocking, W.; Pifko, S.; Hormaechea, J. L.; Fritts, D. C.; Brunini, C; Michell, R.; Samara, M.

2013-01-01

A radar meteor echo is the radar scattering signature from the free-electrons in a plasma trail generated by entry of extraterrestrial particles into the atmosphere. Three categories of scattering mechanisms exist: specular, nonspecular trails, and head-echoes. Generally, there are two types of radars utilized to detect meteors. Traditional VHF meteor radars (often called all-sky1radars) primarily detect the specular reflection of meteor trails traveling perpendicular to the line of sight of the scattering trail, while High Power and Large Aperture (HPLA) radars efficiently detect meteor head-echoes and, in some cases, non-specular trails. The fact that head-echo measurements can be performed only with HPLA radars limits these studies in several ways. HPLA radars are very sensitive instruments constraining the studies to the lower masses, and these observations cannot be performed continuously because they take place at national observatories with limited allocated observing time. These drawbacks can be addressed by developing head echo observing techniques with modified all-sky meteor radars. In addition, the fact that the simultaneous detection of all different scattering mechanisms can be made with the same instrument, rather than requiring assorted different classes of radars, can help clarify observed differences between the different methodologies. In this study, we demonstrate that such concurrent observations are now possible, enabled by the enhanced design of the Southern Argentina Agile Meteor Radar (SAAMER) deployed at the Estacion Astronomica Rio Grande (EARG) in Tierra del Fuego, Argentina. The results presented here are derived from observations performed over a period of 12 days in August 2011, and include meteoroid dynamical parameter distributions, radiants and estimated masses. Overall, the SAAMER's head echo detections appear to be produced by larger particles than those which have been studied thus far using this technique.

Small-scale loess landslide monitoring with small baseline subsets interferometric synthetic aperture radar technique-case study of Xingyuan landslide, Shaanxi, China

NASA Astrophysics Data System (ADS)

Zhao, Chaoying; Zhang, Qin; He, Yang; Peng, Jianbing; Yang, Chengsheng; Kang, Ya

2016-04-01

Small baseline subsets interferometric synthetic aperture radar technique is analyzed to detect and monitor the loess landslide in the southern bank of the Jinghe River, Shaanxi province, China. Aiming to achieve the accurate preslide time-series deformation results over small spatial scale and abrupt temporal deformation loess landslide, digital elevation model error, coherence threshold for phase unwrapping, and quality of unwrapping interferograms must be carefully checked in advance. In this experience, land subsidence accompanying a landslide with the distance <1 km is obtained, which gives a sound precursor for small-scale loess landslide detection. Moreover, the longer and continuous land subsidence has been monitored while deformation starting point for the landslide is successfully inverted, which is key to monitoring the similar loess landslide. In addition, the accelerated landslide deformation from one to two months before the landslide can provide a critical clue to early warning of this kind of landslide.

Characterizing Englacial Attenuation and Grounding Zone Geometry Using Airborne Radar Sounding

NASA Astrophysics Data System (ADS)

Schroeder, D. M.; Grima, C.; Blankenship, D. D.

2014-12-01

The impact of warm ocean water on ice sheet retreat and stability is a one of the primary drivers and sources of uncertainty for the rate of global sea level rise. One critical but challenging observation required to understand and model this impact is the location and extent of grounding ice sheet zones. However, existing surface topography based techniques do not directly detect the location where ocean water reaches (or breaches) grounded ice at the bed, which can significantly affect ice sheet stability. The primary geophysical tool for directly observing the basal properties of ice sheets is airborne radar sounding. However, uncertainty in englacial attenuation from unknown ice temperature and chemistry can lead to erroneous interpretation of subglacial conditions from bed echo strengths alone . Recently developed analysis techniques for radar sounding data have overcome this challenge by taking advantage of information in the angular distribution of bed echo energy and joint modeling of radar returns and water routing. We have developed similar approaches to analyze the spatial pattern and character of echoes to address the problems of improved characterization of grounding zone geometry and englacial attenuation. The spatial signal of the transition from an ice-bed interface to an ice-ocean interface is an increase in bed echo strength. However, rapidly changing attenuation near the grounding zone prevents the unambiguous interpretation of this signal in typical echo strength profiles and violates the assumptions of existing empirical attenuation correction techniques. We present a technique that treat bed echoes as continuous signals to take advantage of along-profile ice thickness and echo strength variations to constrain the spatial pattern of attenuation and detect the grounding zone transition. The transition from an ice-bed interface to an ice-ocean interface will also result in a change in the processes that determine basal interface morphology (e

Radar Range Sidelobe Reduction Using Adaptive Pulse Compression Technique

NASA Technical Reports Server (NTRS)

Li, Lihua; Coon, Michael; McLinden, Matthew

2013-01-01

Pulse compression has been widely used in radars so that low-power, long RF pulses can be transmitted, rather than a highpower short pulse. Pulse compression radars offer a number of advantages over high-power short pulsed radars, such as no need of high-power RF circuitry, no need of high-voltage electronics, compact size and light weight, better range resolution, and better reliability. However, range sidelobe associated with pulse compression has prevented the use of this technique on spaceborne radars since surface returns detected by range sidelobes may mask the returns from a nearby weak cloud or precipitation particles. Research on adaptive pulse compression was carried out utilizing a field-programmable gate array (FPGA) waveform generation board and a radar transceiver simulator. The results have shown significant improvements in pulse compression sidelobe performance. Microwave and millimeter-wave radars present many technological challenges for Earth and planetary science applications. The traditional tube-based radars use high-voltage power supply/modulators and high-power RF transmitters; therefore, these radars usually have large size, heavy weight, and reliability issues for space and airborne platforms. Pulse compression technology has provided a path toward meeting many of these radar challenges. Recent advances in digital waveform generation, digital receivers, and solid-state power amplifiers have opened a new era for applying pulse compression to the development of compact and high-performance airborne and spaceborne remote sensing radars. The primary objective of this innovative effort is to develop and test a new pulse compression technique to achieve ultrarange sidelobes so that this technique can be applied to spaceborne, airborne, and ground-based remote sensing radars to meet future science requirements. By using digital waveform generation, digital receiver, and solid-state power amplifier technologies, this improved pulse compression

DATA ACQUISITION AND APPLICATIONS OF SIDE-LOOKING AIRBORNE RADAR IN THE U. S. GEOLOGICAL SURVEY.

USGS Publications Warehouse

Jones, John Edwin; Kover, Allan N.

1985-01-01

The Side-Looking Airborne Radar (SLAR) program encompasses a multi-discipline effort involving geologists, hydrologists, engineers, geographers, and cartographers of the U. S. Geological Survey (USGS). Since the program began in 1980, more than 520,000 square miles of aerial coverage of SLAR data in the conterminous United States and Alaska have been acquired or contracted for acquisition. The Geological Survey has supported more than 60 research and applications projects addressing the use of this technology in the earth sciences since 1980. These projects have included preparation of lithographic reproductions of SLAR mosaics, research to improve the cartographic uses of SLAR, research for use of SLAR in assessing earth hazards, and studies using SLAR for energy and mineral exploration through improved geologic mapping.

Borehole radar interferometry revisited

USGS Publications Warehouse

Liu, Lanbo; Ma, Chunguang; Lane, John W.; Joesten, Peter K.

2014-01-01

Single-hole, multi-offset borehole-radar reflection (SHMOR) is an effective technique for fracture detection. However, commercial radar system limitations hinder the acquisition of multi-offset reflection data in a single borehole. Transforming cross-hole transmission mode radar data to virtual single-hole, multi-offset reflection data using a wave interferometric virtual source (WIVS) approach has been proposed but not fully demonstrated. In this study, we compare WIVS-derived virtual single-hole, multi-offset reflection data to real SHMOR radar reflection profiles using cross-hole and single-hole radar data acquired in two boreholes located at the University of Connecticut (Storrs, CT USA). The field data results are similar to full-waveform numerical simulations developed for a two-borehole model. The reflection from the adjacent borehole is clearly imaged by both the real and WIVS-derived virtual reflection profiles. Reflector travel-time changes induced by deviation of the two boreholes from the vertical can also be observed on the real and virtual reflection profiles. The results of this study demonstrate the potential of the WIVS approach to improve bedrock fracture imaging for hydrogeological and petroleum reservoir development applications.

The need for separate operational and engineering user interfaces for command and control of airborne synthetic aperture radar systems

NASA Astrophysics Data System (ADS)

Klein, Laura M.; McNamara, Laura A.

2017-05-01

In this paper, we address the needed components to create usable engineering and operational user interfaces (UIs) for airborne Synthetic Aperture Radar (SAR) systems. As airborne SAR technology gains wider acceptance in the remote sensing and Intelligence, Surveillance, and Reconnaissance (ISR) communities, the need for effective and appropriate UIs to command and control these sensors has also increased. However, despite the growing demand for SAR in operational environments, the technology still faces an adoption roadblock, in large part due to the lack of effective UIs. It is common to find operational interfaces that have barely grown beyond the disparate tools engineers and technologists developed to demonstrate an initial concept or system. While sensor usability and utility are common requirements to engineers and operators, their objectives for interacting with the sensor are different. As such, the amount and type of information presented ought to be tailored to the specific application.

Ground displacements caused by aquifer-system water-level variations observed using interferometric synthetic aperture radar near Albuquerque, New Mexico

USGS Publications Warehouse

Heywood, Charles E.; Galloway, Devin L.; Stork, Sylvia V.

2002-01-01

Six synthetic aperture radar (SAR) images were processed to form five unwrapped interferometric (InSAR) images of the greater metropolitan area in the Albuquerque Basin. Most interference patterns in the images were caused by range displacements resulting from changes in land-surface elevation. Loci of land- surface elevation changes correlate with changes in aquifer-system water levels and largely result from the elastic response of the aquifer-system skeletal material to changes in pore-fluid pressure. The magnitude of the observed land-surface subsidence and rebound suggests that aquifer-system deformation resulting from ground-water withdrawals in the Albuquerque area has probably remained in the elastic (recoverable) range from July 1993 through September 1999. Evidence of inelastic (permanent) land subsidence in the Rio Rancho area exists, but its relation to compaction of the aquifer system is inconclusive because of insufficient water-level data. Patterns of elastic deformation in both Albuquerque and Rio Rancho suggest that intrabasin faults impede ground- water-pressure diffusion at seasonal time scales and that these faults are probably important in controlling patterns of regional ground-water flow.

Eyeballing oscillators for pulsed Doppler radar

NASA Astrophysics Data System (ADS)

Goldman, S.

1985-03-01

The visibility of small targets to a Doppler radar system in the presence of large targets is limited by phase noise. Such limitations occur when an airborne radar searches the ground for a mobile vehicle. Under these conditions, the performance of the Doppler radar depends greatly on the specifications of its phased-locked oscillator. Goldman (1984) has discussed the steps required to evaluate the noise resulting from a pulsed Doppler radar system. In the present investigation, these techniques are applied in reverse to determine system specifications for oscillator noise. A 95-GHz pulsed Doppler radar system is used as an example of specifying system phase noise.

Detecting and mitigating wind turbine clutter for airspace radar systems.

PubMed

Wang, Wen-Qin

2013-01-01

It is well recognized that a wind turbine has a large radar cross-section (RCS) and, due to the movement of the blades, the wind turbine will generate a Doppler frequency shift. This scattering behavior may cause severe interferences on existing radar systems including static ground-based radars and spaceborne or airborne radars. To resolve this problem, efficient techniques or algorithms should be developed to mitigate the effects of wind farms on radars. Herein, one transponder-based mitigation technique is presented. The transponder is not a new concept, which has been proposed for calibrating high-resolution imaging radars. It modulates the radar signal in a manner that the retransmitted signals can be separated from the scene echoes. As wind farms often occupy only a small area, mitigation processing in the whole radar operation will be redundant and cost inefficient. Hence, this paper uses a transponder to determine whether the radar is impacted by the wind farms. If so, the effects of wind farms are then mitigated with subsequent Kalman filtering or plot target extraction algorithms. Taking airborne synthetic aperture radar (SAR) and pulse Doppler radar as the examples, this paper provides the corresponding system configuration and processing algorithms. The effectiveness of the mitigation technique is validated by numerical simulation results.

Detecting and Mitigating Wind Turbine Clutter for Airspace Radar Systems

PubMed Central

2013-01-01

It is well recognized that a wind turbine has a large radar cross-section (RCS) and, due to the movement of the blades, the wind turbine will generate a Doppler frequency shift. This scattering behavior may cause severe interferences on existing radar systems including static ground-based radars and spaceborne or airborne radars. To resolve this problem, efficient techniques or algorithms should be developed to mitigate the effects of wind farms on radars. Herein, one transponder-based mitigation technique is presented. The transponder is not a new concept, which has been proposed for calibrating high-resolution imaging radars. It modulates the radar signal in a manner that the retransmitted signals can be separated from the scene echoes. As wind farms often occupy only a small area, mitigation processing in the whole radar operation will be redundant and cost inefficient. Hence, this paper uses a transponder to determine whether the radar is impacted by the wind farms. If so, the effects of wind farms are then mitigated with subsequent Kalman filtering or plot target extraction algorithms. Taking airborne synthetic aperture radar (SAR) and pulse Doppler radar as the examples, this paper provides the corresponding system configuration and processing algorithms. The effectiveness of the mitigation technique is validated by numerical simulation results. PMID:24385880

Oil Spill Detection in Terma-Side-Looking Airborne Radar Images Using Image Features and Region Segmentation

PubMed Central

Alacid, Beatriz

2018-01-01

This work presents a method for oil-spill detection on Spanish coasts using aerial Side-Looking Airborne Radar (SLAR) images, which are captured using a Terma sensor. The proposed method uses grayscale image processing techniques to identify the dark spots that represent oil slicks on the sea. The approach is based on two steps. First, the noise regions caused by aircraft movements are detected and labeled in order to avoid the detection of false-positives. Second, a segmentation process guided by a map saliency technique is used to detect image regions that represent oil slicks. The results show that the proposed method is an improvement on the previous approaches for this task when employing SLAR images. PMID:29316716

Measurement of Attenuation with Airborne and Ground-Based Radar in Convective Storms Over Land Its Microphysical Implications

NASA Technical Reports Server (NTRS)

Tian, Lin; Heymsfield, G. M.; Srivastava, R. C.; O'C.Starr, D. (Technical Monitor)

2001-01-01

Observations by the airborne X-band Doppler radar (EDOP) and the NCAR S-band polarimetric (S-Pol) radar from two field experiments are used to evaluate the surface reference technique (SRT) for measuring the path integrated attenuation (PIA) and to study attenuation in deep convective storms. The EDOP, flying at an altitude of 20 km, uses a nadir beam and a forward pointing beam. It is found that over land, the surface scattering cross-section is highly variable at nadir incidence but relatively stable at forward incidence. It is concluded that measurement by the forward beam provides a viable technique for measuring PIA using the SRT. Vertical profiles of peak attenuation coefficient are derived in two deep convective storms by the dual-wavelength method. Using the measured Doppler velocity, the reflectivities at the two wavelengths, the differential reflectivity and the estimated attenuation coefficients, it is shown that: supercooled drops and (dry) ice particles probably co-existed above the melting level in regions of updraft, that water-coated partially melted ice particles probably contributed to high attenuation below the melting level.

A Comparative Study of Radar Stereo and Interferometry for DEM Generation

NASA Astrophysics Data System (ADS)

Gelautz, M.; Paillou, P.; Chen, C. W.; Zebker, H. A.

2004-06-01

In this experiment, we derive and compare radar stereo and interferometric elevation models (DEMs) of a study site in Djibouti, East Africa. As test data, we use a Radarsat stereo pair and ERS-2 and Radarsat interferometric data. Comparison of the reconstructed DEMs with a SPOT reference DEM shows that in regions of high coherence the DEMs produced by interferometry are of much better quality than the stereo result. However, the interferometric error histograms also show some pronounced outliers due to decorrelation and phase unwrapping problems on forested mountain slopes. The more robust stereo result is able to capture the general terrain shape, but finer surface details are lost. A fusion experiment demonstrates that merging the stereoscopic and interferometric DEMs by utilizing coherence- derived weights can significantly improve the accuracy of the computed elevation maps.

Airborne Visible Laser Optical Communications Program (AVLOC)

NASA Technical Reports Server (NTRS)

Ward, J. H.

1975-01-01

The design, development, and operation of airborne and ground-based laser communications and laser radar hardware is described in support of the Airborne Visible Laser Optical Communication program. The major emphasis is placed on the development of a highly flexible test bed for the evaluation of laser communications systems techniques and components in an operational environment.

Remote sensing of ocean wave spectra by interferometric synthetic aperture radar

NASA Technical Reports Server (NTRS)

Marom, M.; Thornton, E. B.; Goldstein, R. M.; Shemer, L.

1990-01-01

Ocean surface waves can be clearly observed by SAR in the interferometric configuration (INSAR) due to the ability of INSAR to provide images of the local surface velocity field. It is shown here that INSAR can be used to obtain wavenumber spectra that are in agreement with power spectra measured in situ. This new method has considerable potential to provide instantaneous spatial information about the structure of ocean wave fields.

Space Radar Image of Kilauea, Hawaii - interferometry 1

NASA Technical Reports Server (NTRS)

1994-01-01

This X-band image of the volcano Kilauea was taken on October 4, 1994, by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar. The area shown is about 9 kilometers by 13 kilometers (5.5 miles by 8 miles) and is centered at about 19.58 degrees north latitude and 155.55 degrees west longitude. This image and a similar image taken during the first flight of the radar instrument on April 13, 1994 were combined to produce the topographic information by means of an interferometric process. This is a process by which radar data acquired on different passes of the space shuttle is overlaid to obtain elevation information. Three additional images are provided showing an overlay of radar data with interferometric fringes; a three-dimensional image based on altitude lines; and, finally, a topographic view of the region. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI), with the Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.V.(DLR), the major partner in science, operations and data processing of X-SAR. The Instituto Ricerca Elettromagnetismo

Designing clutter rejection filters with complex coefficients for airborne pulsed Doppler weather radar

NASA Technical Reports Server (NTRS)

Jamora, Dennis A.

1993-01-01

Ground clutter interference is a major problem for airborne pulse Doppler radar operating at low altitudes in a look-down mode. With Doppler zero set at the aircraft ground speed, ground clutter rejection filtering is typically accomplished using a high-pass filter with real valued coefficients and a stopband notch centered at zero Doppler. Clutter spectra from the NASA Wind Shear Flight Experiments of l991-1992 show that the dominant clutter mode can be located away from zero Doppler, particularly at short ranges dominated by sidelobe returns. Use of digital notch filters with complex valued coefficients so that the stopband notch can be located at any Doppler frequency is investigated. Several clutter mode tracking algorithms are considered to estimate the Doppler frequency location of the dominant clutter mode. From the examination of night data, when a dominant clutter mode away from zero Doppler is present, complex filtering is able to significantly increase clutter rejection over use of a notch filter centered at zero Doppler.

An adaptive angle-doppler compensation method for airborne bistatic radar based on PAST

NASA Astrophysics Data System (ADS)

Hang, Xu; Jun, Zhao

2018-05-01

Adaptive angle-Doppler compensation method extract the requisite information based on the data itself adaptively, thus avoiding the problem of performance degradation caused by inertia system error. However, this method requires estimation and egiendecomposition of sample covariance matrix, which has a high computational complexity and limits its real-time application. In this paper, an adaptive angle Doppler compensation method based on projection approximation subspace tracking (PAST) is studied. The method uses cyclic iterative processing to quickly estimate the positions of the spectral center of the maximum eigenvector of each range cell, and the computational burden of matrix estimation and eigen-decompositon is avoided, and then the spectral centers of all range cells is overlapped by two dimensional compensation. Simulation results show the proposed method can effectively reduce the no homogeneity of airborne bistatic radar, and its performance is similar to that of egien-decomposition algorithms, but the computation load is obviously reduced and easy to be realized.

Progress in coherent laser radar

NASA Technical Reports Server (NTRS)

Vaughan, J. M.

1986-01-01

Considerable progress with coherent laser radar has been made over the last few years, most notably perhaps in the available range of high performance devices and components and the confidence with which systems may now be taken into the field for prolonged periods of operation. Some of this increasing maturity was evident at the 3rd Topical Meeting on Coherent Laser Radar: Technology and Applications. Topics included in discussions were: mesoscale wind fields, nocturnal valley drainage and clear air down bursts; airborne Doppler lidar studies and comparison of ground and airborne wind measurement; wind measurement over the sea for comparison with satellite borne microwave sensors; transport of wake vortices at airfield; coherent DIAL methods; a newly assembled Nd-YAG coherent lidar system; backscatter profiles in the atmosphere and wavelength dependence over the 9 to 11 micrometer region; beam propagation; rock and soil classification with an airborne 4-laser system; technology of a global wind profiling system; target calibration; ranging and imaging with coherent pulsed and CW system; signal fluctuations and speckle. Some of these activities are briefly reviewed.

Mission Analysis and Orbit Control of Interferometric Wheel Formation Flying

NASA Astrophysics Data System (ADS)

Fourcade, J.

Flying satellite in formation requires maintaining the specific relative geometry of the spacecraft with high precision. This requirement raises new problem of orbit control. This paper presents the results of the mission analysis of a low Earth observation system, the interferometric wheel, patented by CNES. This wheel is made up of three receiving spacecraft, which follow an emitting Earth observation radar satellite. The first part of this paper presents trades off which were performed to choose orbital elements of the formation flying which fulfils all constraints. The second part presents orbit positioning strategies including reconfiguration of the wheel to change its size. The last part describes the station keeping of the formation. Two kinds of constraints are imposed by the interferometric system : a constraint on the distance between the wheel and the radar satellite, and constraints on the distance between the wheel satellites. The first constraint is fulfilled with a classical chemical station keeping strategy. The second one is fulfilled using pure passive actuators. Due to the high stability of the relative eccentricity of the formation, only the relative semi major axis had to be controlled. Differential drag due to differential attitude motion was used to control relative altitude. An autonomous orbit controller was developed and tested. The final accuracy is a relative station keeping better than few meters for a wheel size of one kilometer.

The Glacier and Land Ice Surface Topography Interferometer: An Airborne Proof-of-concept Mapping Sensor

NASA Astrophysics Data System (ADS)

Moller, D.; Hensley, S.; Chuang, C.; Fisher, C.; Muellerschoen, R.; Milligan, L.; Sadowy, G.; Rignot, E. J.

2009-12-01

In May 2009 a new radar technique for mapping ice surface topography was demonstrated in a Greenland campaign as part of the NASA International Polar Year activities. This was achieved by integrating a Ka-band single-pass interferometric synthetic radar on the NASA Dryden Gulfstream III for a coordinated deployment. Although the technique of using radar interferometry for mapping terrain has been demonstrated before, this is the first such application at millimeter-wave frequencies. This proof-of-concept demonstration was motivated by the Glacier and Land Ice Surface Topography Interferometer (GLISTIN) Instrument Incubator Program and furthermore, highly leveraged existing ESTO hardware and software assets (the Unmanned Airborne Vehicle Synthetic Aperture Radar (UAVSAR) and processor and the PR2 (precipitation radar 2) RF assembly and power amplifier). Initial Ka-band test flights occurred in March and April of 2009 followed by the Greenland deployment. Instrument performance indicates swath widths over the ice between 5-7km, with height precisions ranging from 30cm-3m at a posting of 3m x 3m. However, for this application the electromagnetic wave will penetrate an unknown amount into the snow cover thus producing an effective bias that must be calibrated. This penetration will be characterized as part of this program and is expected to vary as a function of snow wetness and radar incidence angle. To evaluate this, we flew a coordinated collection with the NASA Wallops Airborne Topographic Mapper on a transect from Greenland’s Summit its West coast. This flight included two field calibration sites at Colorado Institute for Research in Environmental Science’s Swiss Camp and the National Science Foundation’s Summit station. Additional collections entailed flying a grid over Jakobshavn glacier which were repeated after 6 days to reveal surface dynamics. In this time frame we were able to observe horizontal motion of over 1km on the glacier. While developed for

Storm Surge Measurement with an Airborne Scanning Radar Altimeter

NASA Technical Reports Server (NTRS)

Wright, C. W.; Walsh, E. J.; Krabill, W. B.; Shaffer, W. A.; Baig, S. R.; Peng, M.; Pietrafesa, L. J.; Garcia, A. W.; Marks, F. D., Jr.; Black, P. G.;

A comparison of forest canopy models derived from LIDAR and INSAR data in a Pacific Northwest conifer forest.

Treesearch

Hans-Erik Andersen; Robert J. McGaughey; Ward W. Carson; Stephen E. Reutebuch; Bryan Mercer; Jeremy Allan

2004-01-01

Active remote sensing technologies, including interferometric radar (InSAR) and airborne laser scanning (LIDAR) have the potential to provide accurate information relating to three-dimensional forest canopy structure over extensive areas of the landscape. In order to assess the capabilities of these alternative systems for characterizing the forest canopy dimensions,...

Characterizing the Precipitation Processes in Hurricane Karl (2010) Through Analysis of Airborne Doppler Radar Data and Numerical Simulations

NASA Astrophysics Data System (ADS)

DeHart, J.; Houze, R.

2016-12-01

Airborne radar data and numerical simulations are employed to investigate the structure of Hurricane Karl (2010). Karl peaked in intensity as a major hurricane in the Gulf of Mexico before making landfall on the mountainous coast of Veracruz, Mexico. Multiple aircraft extensively sampled Karl during the NASA GRIP campaign, including NASA's DC-8 aircraft instrumented with the Advanced Precipitation Radar 2 (APR-2), which is a high-resolution, dual-frequency Doppler radar. Data from APR-2 provide a unique opportunity to characterize the precipitation structure of Karl as it underwent orographic modification. As Karl made landfall on 17 September 2010, the vertical structure of the precipitation echo varied spatially around the Mexican terrain. The precipitation variation was linked to several factors: landfall, orientation of flow relative to the topographic features, and differing characteristics inherent to the eyewall and rainbands. Despite the differences in the reflectivity intensity across the storm, we show that low-level reflectivity enhancement occurred only where upslope flow was favorable. The radar data indicate that the processes initially contributing to the reflectivity enhancement were warm-cloud processes, either through collection of orographically-generated cloud water or shallow convection. But as Karl weakened, the low-level enhancement processes were overshadowed by deep convection that developed along the terrain. Analysis of the radar data is complemented by a series of numerical simulations, which reasonably reproduce the track, intensity and structure of Karl. The simulated thermodynamic and kinematic patterns provide a holistic view of Karl's evolution during landfall. We use terrain modification experiments to examine the sensitivity of the orographic enhancement processes to the three-dimensional terrain and land surface characteristics. Consistent with the radar analysis, warm-cloud enhancement processes are visible in the spatial

Multifunction Radar for Airborne Applications.

DTIC Science & Technology

1986-07-01

de rapport ( doo roSarvre o ntn orcp tion To de 0 & TR. Pour chaque valour de To, on calculo de la m~me faqon quo prdcdmment PS lo rIpporr - pour...senseur primordial dfalts les aviotts militaires. (in certain ttimbreC de caracteristiulues imptirtantes donne anl radar Ia supuirioritui sur Ics...muitcoroliugiques 1ironillard. nuagesi. 1estimation de distance et lestimatitin Douppler. - la sonplesse de at ]’orientatiiin ilectritnique des

Satellite and airborne IR sensor validation by an airborne interferometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gumley, L.E.; Delst, P.F. van; Moeller, C.C.

1996-11-01

The validation of in-orbit longwave IR radiances from the GOES-8 Sounder and inflight longwave IR radiances from the MODIS Airborne Simulator (MAS) is described. The reference used is the airborne University of Wisconsin High Resolution Interferometer Sounder (HIS). The calibration of each sensor is described. Data collected during the Ocean Temperature Interferometric Survey (OTIS) experiment in January 1995 is used in the comparison between sensors. Detailed forward calculations of at-sensor radiance are used to account for the difference in GOES-8 and HIS altitude and viewing geometry. MAS radiances and spectrally averaged HIS radiances are compared directly. Differences between GOES-8 andmore » HIS brightness temperatures, and GOES-8 and MAS brightness temperatures, are found to be with 1.0 K for the majority of longwave channels examined. The same validation approach will be used for future sensors such as the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS). 11 refs., 2 figs., 4 tabs.« less

Seismic migration for SAR focusing: Interferometrical applications

NASA Astrophysics Data System (ADS)

Prati, C.; Montiguarnieri, A.; Damonti, E.; Rocca, F.

SAR (Synthetic Aperture Radar) data focusing is analyzed from a theoretical point of view. Two applications of a SAR data processing algorithm are presented, where the phases of the returns are used for the recovery of interesting parameters of the observed scenes. Migration techniques, similar to those used in seismic signal processing for oil prospecting, were implemented for the determination of the terrain altitude map from a satellite and the evaluation of the sensor attitude for an airplane. A satisfying precision was achieved, since it was shown how an interferometric system is able to detect variations of the airplane roll angle of a small fraction of a degree.

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.

Ice shelf snow accumulation rates from the Amundsen-Bellingshausen Sea sector of West Antarctica derived from airborne radar

NASA Astrophysics Data System (ADS)

Medley, B.; Kurtz, N. T.; Brunt, K. M.

2015-12-01

The large ice shelves surrounding the Antarctic continent buttress inland ice, limiting the grounded ice-sheet flow. Many, but not all, of the thick ice shelves located along the Amundsen-Bellingshausen Seas are experiencing rapid thinning due to enhanced basal melting driven by the intrusion of warm circumpolar deep water. Determination of their mass balance provides an indicator as to the future of the shelves buttressing capability; however, measurements of surface accumulation are few, limiting the precision of the mass balance estimates. Here, we present new radar-derived measurements of snow accumulation primarily over the Getz and Abbott Ice Shelves, as well as the Dotson and Crosson, which have been the focus of several of NASA's Operation IceBridge airborne surveys between 2009 and 2014. Specifically, we use the Center for Remote Sensing of Ice Sheets (CReSIS) snow radar to map the near-surface (< 30 m) internal stratigraphy to measure snow accumulation. Due to the complexities of the local topography (e.g., ice rises and rumples) and their relative proximity to the ocean, the spatial pattern of accumulation can be equally varied. Therefore, atmospheric models might not be able to reproduce these small-scale features because of their limited spatial resolution. To evaluate whether this is the case over these narrow shelves, we will compare the radar-derived accumulation rates with those from atmospheric models.

Interferometric estimation of ice sheet motion and topography

NASA Technical Reports Server (NTRS)

Joughlin, Ian; Kwok, Ron; Fahnestock, Mark; Winebrenner, Dale; Tulaczyk, Slawek; Gogenini, Prasad

1997-01-01

With ERS-1/2 satellite radar interferometry, it is possible to make measurements of glacier motion with high accuracy and fine spatial resolution. Interferometric techniques were applied to map velocity and topography for several outlet glaciers in Greenland. For the Humboldt and Petermann glaciers, data from several adjacent tracks were combined to make a wide-area map that includes the enhanced flow regions of both glaciers. The discharge flux of the Petermann glacier upstream of the grounding line was estimated, thereby establishing the potential use of ERS-1/2 interferometric data for monitoring ice-sheet discharge. Interferograms collected along a single track are sensitive to only one component of motion. By utilizing data from ascending and descending passes and by making a surface-parallel flow assumption, it is possible to measure the full three-dimensional vector flow field. The application of this technique for an area on the Ryder glacier is demonstrated. Finally, ERS-1/2 interferograms were used to observe a mini-surge on the Ryder glacier that occurred in autumn of 1995.

Contribution to the glaciology of northern Greenland from satellite radar interferometry

NASA Technical Reports Server (NTRS)

Rignot, E.; Gogineni, S.; Joughin, I.; Krabill, W.

2001-01-01

Interferometric synthetic aperture radar (InSAR) data from the ERS-1 and ERS-2 satellites are used to measure the surface velocity, topography, and grounding line position of the major outletglaciers in the northern sector of the Greenland ice sheet.

A Dual-Wavelength Radar Technique to Detect Hydrometeor Phases

NASA Technical Reports Server (NTRS)

Liao, Liang; Meneghini, Robert

2016-01-01

This study is aimed at investigating the feasibility of a Ku- and Ka-band space/air-borne dual wavelength radar algorithm to discriminate various phase states of precipitating hydrometeors. A phase-state classification algorithm has been developed from the radar measurements of snow, mixed-phase and rain obtained from stratiform storms. The algorithm, presented in the form of the look-up table that links the Ku-band radar reflectivities and dual-frequency ratio (DFR) to the phase states of hydrometeors, is checked by applying it to the measurements of the Jet Propulsion Laboratory, California Institute of Technology, Airborne Precipitation Radar Second Generation (APR-2). In creating the statistically-based phase look-up table, the attenuation corrected (or true) radar reflectivity factors are employed, leading to better accuracy in determining the hydrometeor phase. In practice, however, the true radar reflectivities are not always available before the phase states of the hydrometeors are determined. Therefore, it is desirable to make use of the measured radar reflectivities in classifying the phase states. To do this, a phase-identification procedure is proposed that uses only measured radar reflectivities. The procedure is then tested using APR-2 airborne radar data. Analysis of the classification results in stratiform rain indicates that the regions of snow, mixed-phase and rain derived from the phase-identification algorithm coincide reasonably well with those determined from the measured radar reflectivities and linear depolarization ratio (LDR).

Mission design for NISAR repeat-pass Interferometric SAR

NASA Astrophysics Data System (ADS)

Alvarez-Salazar, Oscar; Hatch, Sara; Rocca, Jennifer; Rosen, Paul; Shaffer, Scott; Shen, Yuhsyen; Sweetser, Theodore; Xaypraseuth, Peter

2014-10-01

The proposed spaceborne NASA-ISRO SAR (NISAR) mission would use the repeat-pass interferometric Synthetic Aperture Radar (InSAR) technique to measure the changing shape of Earth's surface at the centimeter scale in support of investigations in solid Earth and cryospheric sciences. Repeat-pass InSAR relies on multiple SAR observations acquired from nearly identical positions of the spacecraft as seen from the ground. Consequently, there are tight constraints on the repeatability of the orbit, and given the narrow field of view of the radar antenna beam, on the repeatability of the beam pointing. The quality and accuracy of the InSAR data depend on highly precise control of both orbital position and observatory pointing throughout the science observation life of the mission. This paper describes preliminary NISAR requirements and rationale for orbit repeatability and attitude control in order to meet science requirements. A preliminary error budget allocation and an implementation approach to meet these allocations are also discussed.

Using temporarily coherent point interferometric synthetic aperture radar for land subsidence monitoring in a mining region of western China

NASA Astrophysics Data System (ADS)

Fan, Hongdong; Xu, Qiang; Hu, Zhongbo; Du, Sen

2017-04-01

Yuyang mine is located in the semiarid western region of China where, due to serious land subsidence caused by underground coal exploitation, the local ecological environment has become more fragile. An advanced interferometric synthetic aperture radar (InSAR) technique, temporarily coherent point InSAR, is applied to measure surface movements caused by different mining conditions. Fifteen high-resolution TerraSAR-X images acquired between October 2, 2012, and March 27, 2013, were processed to generate time-series data for ground deformation. The results show that the maximum accumulated values of subsidence and velocity were 86 mm and 162 mm/year, respectively; these measurements were taken above the fully mechanized longwall caving faces. Based on the dynamic land subsidence caused by the exploitation of one working face, the land subsidence range was deduced to have increased 38 m in the mining direction with 11 days' coal extraction. Although some mining faces were ceased in 2009, they could also have contributed to a small residual deformation of overlying strata. Surface subsidence of the backfill mining region was quite small, the maximum only 21 mm, so backfill exploitation is an effective method for reducing the land subsidence while coal is mined.

Forest height estimation from mountain forest areas using general model-based decomposition for polarimetric interferometric synthetic aperture radar images

NASA Astrophysics Data System (ADS)

Minh, Nghia Pham; Zou, Bin; Cai, Hongjun; Wang, Chengyi

2014-01-01

The estimation of forest parameters over mountain forest areas using polarimetric interferometric synthetic aperture radar (PolInSAR) images is one of the greatest interests in remote sensing applications. For mountain forest areas, scattering mechanisms are strongly affected by the ground topography variations. Most of the previous studies in modeling microwave backscattering signatures of forest area have been carried out over relatively flat areas. Therefore, a new algorithm for the forest height estimation from mountain forest areas using the general model-based decomposition (GMBD) for PolInSAR image is proposed. This algorithm enables the retrieval of not only the forest parameters, but also the magnitude associated with each mechanism. In addition, general double- and single-bounce scattering models are proposed to fit for the cross-polarization and off-diagonal term by separating their independent orientation angle, which remains unachieved in the previous model-based decompositions. The efficiency of the proposed approach is demonstrated with simulated data from PolSARProSim software and ALOS-PALSAR spaceborne PolInSAR datasets over the Kalimantan areas, Indonesia. Experimental results indicate that forest height could be effectively estimated by GMBD.

UAVSAR Program: Initial Results from New Instrument Capabilities

NASA Technical Reports Server (NTRS)

Lou, Yunling; Hensley, Scott; Moghaddam, Mahta; Moller, Delwyn; Chapin, Elaine; Chau, Alexandra; Clark, Duane; Hawkins, Brian; Jones, Cathleen; Marks, Phillip;

Turbulence in breaking mountain waves and atmospheric rotors estimated from airborne in situ and Doppler radar measurements.

PubMed

Strauss, Lukas; Serafin, Stefano; Haimov, Samuel; Grubišić, Vanda

2015-10-01

Atmospheric turbulence generated in flow over mountainous terrain is studied using airborne in situ and cloud radar measurements over the Medicine Bow Mountains in southeast Wyoming, USA. During the NASA Orographic Clouds Experiment (NASA06) in 2006, two complex mountain flow cases were documented by the University of Wyoming King Air research aircraft carrying the Wyoming Cloud Radar. The structure of turbulence and its intensity across the mountain range are described using the variance of vertical velocity σw2 and the cube root of the energy dissipation rate ɛ 1/3 (EDR). For a quantitative analysis of turbulence from the cloud radar, the uncertainties in the Doppler wind retrieval have to be taken into account, such as the variance of hydrometeor fall speed and the contamination of vertical Doppler velocity by the horizontal wind. A thorough analysis of the uncertainties shows that 25% accuracy or better can be achieved in regions of moderate to severe turbulence in the lee of the mountains, while only qualitative estimates of turbulence intensity can be obtained outside the most turbulent regions. Two NASA06 events exhibiting large-amplitude mountain waves, mid-tropospheric wave breaking, and rotor circulations are examined. Moderate turbulence is found in a wave-breaking region with σw2 and EDR reaching 4.8 m 2 s -2 and 0.25 m 2/3 s -1 , respectively. Severe turbulence is measured within the rotor circulations with σw2 and EDR respectively in the ranges of 7.8-16.4 m 2 s -2 and 0.50-0.77 m 2/3 s -1 . A unique result of this study is the quantitative estimation of the intensity of turbulence and its spatial distribution in the interior of atmospheric rotors, provided by the radar-derived turbulence fields.

Sparsity-driven coupled imaging and autofocusing for interferometric SAR

NASA Astrophysics Data System (ADS)

Zengin, Oǧuzcan; Khwaja, Ahmed Shaharyar; ćetin, Müjdat

2018-04-01

We propose a sparsity-driven method for coupled image formation and autofocusing based on multi-channel data collected in interferometric synthetic aperture radar (IfSAR). Relative phase between SAR images contains valuable information. For example, it can be used to estimate the height of the scene in SAR interferometry. However, this relative phase could be degraded when independent enhancement methods are used over SAR image pairs. Previously, Ramakrishnan et al. proposed a coupled multi-channel image enhancement technique, based on a dual descent method, which exhibits better performance in phase preservation compared to independent enhancement methods. Their work involves a coupled optimization formulation that uses a sparsity enforcing penalty term as well as a constraint tying the multichannel images together to preserve the cross-channel information. In addition to independent enhancement, the relative phase between the acquisitions can be degraded due to other factors as well, such as platform location uncertainties, leading to phase errors in the data and defocusing in the formed imagery. The performance of airborne SAR systems can be affected severely by such errors. We propose an optimization formulation that combines Ramakrishnan et al.'s coupled IfSAR enhancement method with the sparsity-driven autofocus (SDA) approach of Önhon and Çetin to alleviate the effects of phase errors due to motion errors in the context of IfSAR imaging. Our method solves the joint optimization problem with a Lagrangian optimization method iteratively. In our preliminary experimental analysis, we have obtained results of our method on synthetic SAR images and compared its performance to existing methods.

The USGS Side-Looking Airborne Radar (SLAR) program: CD-ROMs expand potential for petroleum exploration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kover, A.N.; Schoonmaker, J.W. Jr.; Pohn. H.A.

1991-03-01

The United States Geological Survey (USGS) began the systematic collection of Side-Looking Airborne Radar (SLAR) data in 1980. The SLAR image data, useful for many geologic applications including petroleum exploration, are compiled into mosaics using the USGS 1:250,000-scale topographic map series for format and control. Mosaics have been prepared for over 35% of the United States. Image data collected since 1985 are also available as computer compatible tapes (CCTs) for digital analysis. However, the use of tapes is often cumbersome. To make digital data more readily available for use on a microcomputer, the USGS has started to prepare compact discs-readmore » only memory (CD-ROM). Several experimental discs have been compiled to demonstrate the utility of the medium to make available very large data sets. These discs include necessary nonproprietary software text, radar, and other image data. The SLAR images selected for these discs show significantly different geologic features and include the Long Valley caldera, a section of the San Andreas fault in the Monterey area, the Grand Canyon, and glaciers in southeastern Alaska. At present, several CD-ROMs are available as standard products distributed by the USGS EROS Data Center in Sioux Falls, South Dakota 57198. This is also the source for all USGS SLAR photographic and digital material.« less

Impact of the ionosphere on an L-band space based radar

NASA Technical Reports Server (NTRS)

Chapin, Elaine; Chan, Samuel F.; Chapman, Bruce D.; Chen, Curtis W.; Martin, Jan M.; Michel, Thierry R.; Muellerschoen, Ronald J.; Pi, Xiaoqing; Rosen, Paul A.

2006-01-01

We have quantified the impact that the ionosphere would have on a L-band interferometric Synthetic Aperture Radar (SAR) mission using a combination of simulation, modeling, Global Positioning System (GPS) data collected during the last solar maximum, and existing spaceborne SAR data.

Hurricane Georges' Landfall in the Dominican Republic: Detailed Airborne Doppler Radar Imagery

NASA Technical Reports Server (NTRS)

Geerts, B.; Heymsfield, G. M.; Tian, L.; Halverson, J. B.; Guillory, A.; Mejia, M. I.

1999-01-01

Current understanding of landfalling tropical cyclones is limited, especially with regard to convective scale processes. On 22 September 1998 Hurricane Georges made landfall on the island of Hispaniola, leaving behind a trail of death and devastation, largely the result of excessive rainfall, not sea level surge or wind. Detailed airborne measurements were taken as part of the Third Convection and Moisture Experiment (CAMEX-3). Of Particular interest are the ER-2 nadir X-band Doppler radar (EDOP) data, which provide a first-time high-resolution view of the precipitation and airflow changes as a hurricane interacts with mountainous terrain. The circulation of hurricane Georges underwent an obvious transition during landfall, evident in the rapid increase in minimum sea-level pressure, the subsidence of the eyewall anvil, and a decrease in average ice concentrations in the eyewall. The eye, as seen in satellite imagery, disappeared, but contrary to current understanding, this was not due to eyewall contraction but rather to convective eruption within the eye. The main convective event within the eye, with upper-level updraft magnitudes near 20 m/s and 89 GHz brightness temperatures below 100 K, occurred when the eye moved over the Cordillera Central, the island's main mountain chain. The location, intensity and evolution of this convection indicate that it was coupled to the surface orography. It is likely that surface rain rates increased during landfall, because of effective droplet collection, both in the convection and in the more widespread stratiform rainfall areas over the island. Evidence for this is the increase in radar reflectivity below the bright band of 1-2 dB/km down to ground-level. Such increase was absent offshore. Such low-level rain enhancement, which cannot be detected in satellite images of upwelling infrared or microwave radiation, must be due to the ascent of boundary-layer air over the topography.

Exploiting Synthetic Aperture Radar data to map and observe landslides

NASA Astrophysics Data System (ADS)

Bekaert, D. P.; Agram, P. S.; Fattahi, H.; Kirschbaum, D.; Amatya, P. M.; Stanley, T.

2017-12-01

Synthetic Aperture Radar instruments onboard satellites or airborne platforms are a powerful means to study landslides. How to best exploit the data and which techniques to apply strongly depend on the region of study and the landslide type which occurs. The amount of vegetation, snowfall, and steepness of the terrain, as well the shadowing effects of the mountain will determine if SAR is suitable to map a given landslide. Fast moving landslides occurring over a large area (e.g. >100 m) could benefit from pixel or feature tracking, while for slower moving landslides Interferometric SAR could be a more favorable approach. However, neither of those methods would work for critical landslide failures which do not preserve surface features. This type of slides would benefit from a change detection approach. Here we look at these three different cases and utilize Sentinel-1 space-borne SAR data and state-of-the-art processing techniques to map multiple landslides along the California State Route 1 and the Trishuli highway in the Langtang valley of Nepal. Our findings correlate with existing landslide catalogues and also identify landslides in regions earlier mapped to be dormant.

Space Radar Image Isla Isabela in 3-D

NASA Technical Reports Server (NTRS)

1999-01-01

This is a three-dimensional view of Isabela, one of the Galapagos Islands located off the western coast of Ecuador, South America. This view was constructed by overlaying a Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) image on a digital elevation map produced by TOPSAR, a prototype airborne interferometric radar which produces simultaneous image and elevation data. The vertical scale in this image is exaggerated by a factor of 1.87. The SIR-C/X-SAR image was taken on the 40th orbit of space shuttle Endeavour. The image is centered at about 0.5 degree south latitude and 91 degrees west longitude and covers an area of 75 by 60 kilometers (47 by 37 miles). The radar incidence angle at the center of the image is about 20 degrees. The western Galapagos Islands, which lie about 1,200 kilometers (750 miles)west of Ecuador in the eastern Pacific, have six active volcanoes similar to the volcanoes found in Hawaii and reflect the volcanic processes that occur where the ocean floor is created. Since the time of Charles Darwin's visit to the area in 1835, there have been more than 60 recorded eruptions on these volcanoes. This SIR-C/X-SAR image of Alcedo and Sierra Negra volcanoes shows the rougher lava flows as bright features, while ash deposits and smooth pahoehoe lava flows appear dark. Vertical exaggeration of relief is a common tool scientists use to detect relationships between structure (for example, faults, and fractures) and topography. Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data

Interferometric detection of nanoparticles

NASA Astrophysics Data System (ADS)

Hayrapetyan, Karen

Interferometric surfaces enhance light scattering from nanoparticles through constructive interference of partial scattered waves. By placing the nanoparticles on interferometric surfaces tuned to a special surface phase interferometric condition, the particles are detectable in the dilute limit through interferometric image contrast in a heterodyne light scattering configuration, or through diffraction in a homodyne scattering configuration. The interferometric enhancement has applications for imaging and diffractive biosensors. We present a modified model based on Double Interaction (DI) to explore bead-based detection mechanisms using imaging, scanning and diffraction. The application goal of this work is to explore the trade-offs between the sensitivity and throughput among various detection methods. Experimentally we use thermal oxide on silicon to establish and control surface interferometric conditions. Surface-captured gold beads are detected using Molecular Interferometric Imaging (MI2) and Spinning-Disc Interferometry (SDI). Double-resonant enhancement of light scattering leads to high-contrast detection of 100 nm radius gold nanoparticles on an interferometric surface. The double-resonance condition is achieved when resonance (or anti-resonance) from an asymmetric Fabry-Perot substrate coincides with the Mie resonance of the gold nanoparticle. The double-resonance condition is observed experimentally using molecular interferometric imaging (MI2). An invisibility condition is identified for which the gold nanoparticles are optically cloaked by the interferometric surface.

Present and Future Airborne and Space-borne Systems

DTIC Science & Technology

2007-02-01

Present and Future Airborne and Space-borne Systems Wolfgang Keydel Microwaves and Radar Institute German Aerospace Research Centre (DLR...airborne and space-borne SAR systems with polarimetric interferometry capability, their technological, system technical and application related...interferometry accuracies in the cm range have been obtained. In order to reach these values an exact system calibration is indispensable. The calibration of

Radar systems for a polar mission, volume 1

NASA Technical Reports Server (NTRS)

Moore, R. K.; Claassen, J. P.; Erickson, R. L.; Fong, R. K. T.; Komen, M. J.; Mccauley, J.; Mcmillan, S. B.; Parashar, S. K.

1977-01-01

The application of synthetic aperture radar (SAR) in monitoring and managing earth resources is examined. Synthetic aperture radars form a class of side-looking airborne radar, often referred to as coherent SLAR, which permits fine-resolution radar imagery to be generated at long operating ranges by the use of signal processing techniques. By orienting the antenna beam orthogonal to the motion of the spacecraft carrying the radar, a one-dimensional imagery ray system is converted into a two-dimensional or terrain imaging system. The radar's ability to distinguish - or resolve - closely spaced transverse objects is determined by the length of the pulse. The transmitter components receivers, and the mixer are described in details.

Antarctic meteor observations using the Davis MST and meteor radars

NASA Astrophysics Data System (ADS)

Holdsworth, David A.; Murphy, Damian J.; Reid, Iain M.; Morris, Ray J.

2008-07-01

This paper presents the meteor observations obtained using two radars installed at Davis (68.6°S, 78.0°E), Antarctica. The Davis MST radar was installed primarily for observation of polar mesosphere summer echoes, with additional transmit and receive antennas installed to allow all-sky interferometric meteor radar observations. The Davis meteor radar performs dedicated all-sky interferometric meteor radar observations. The annual count rate variation for both radars peaks in mid-summer and minimizes in early Spring. The height distribution shows significant annual variation, with minimum (maximum) peak heights and maximum (minimum) height widths in early Spring (mid-summer). Although the meteor radar count rate and height distribution variations are consistent with a similar frequency meteor radar operating at Andenes (69.3°N), the peak heights show a much larger variation than at Andenes, while the count rate maximum-to-minimum ratios show a much smaller variation. Investigation of the effects of the temporal sampling parameters suggests that these differences are consistent with the different temporal sampling strategies used by the Davis and Andenes meteor radars. The new radiant mapping procedure of [Jones, J., Jones, W., Meteor radiant activity mapping using single-station radar observations, Mon. Not. R. Astron. Soc., 367(3), 1050-1056, doi: 10.1111/j.1365-2966.2006.10025.x, 2006] is investigated. The technique is used to detect the Southern delta-Aquarid meteor shower, and a previously unknown weak shower. Meteoroid speeds obtained using the Fresnel transform are presented. The diurnal, annual, and height variation of meteoroid speeds are presented, with the results found to be consistent with those obtained using specular meteor radars. Meteoroid speed estimates for echoes identified as Southern delta-Aquarid and Sextantid meteor candidates show good agreement with the theoretical pre-atmospheric speeds of these showers (41 km s -1 and 32 km s -1

Radar research at University of Oklahoma (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zhang, Yan R.; Weber, Mark E.

2017-05-01

This abstract is for the academic institution profiles session This presentation will focus on radar research programs at the University of Oklahoma, the radar research in OU has more than 50 years history of collaboration with NOAA, and has been through tremendous growth since early 2000. Before 2010, the focus was weather radar and weather surveillance, and since the Defense, Security and Intelligence (DSI) initiative in 2011, there have many new efforts on the defense and military radar applications. This presentation will focus on the following information: (1) The history, facilities and instrumentations of Advanced Radar Research Center, (2) Focus area of polarimetric phased array systems, (3) Focus area of airborne and spaceborne radars, (4) Intelligent radar information processing, (5) Innovative antenna and components.

Seeing the unseen: Complete volcano deformation fields by recursive filtering of satellite radar interferograms

NASA Astrophysics Data System (ADS)

Gonzalez, Pablo J.

2017-04-01

Automatic interferometric processing of satellite radar data has emerged as a solution to the increasing amount of acquired SAR data. Automatic SAR and InSAR processing ranges from focusing raw echoes to the computation of displacement time series using large stacks of co-registered radar images. However, this type of interferometric processing approach demands the pre-described or adaptive selection of multiple processing parameters. One of the interferometric processing steps that much strongly influences the final results (displacement maps) is the interferometric phase filtering. There are a large number of phase filtering methods, however the "so-called" Goldstein filtering method is the most popular [Goldstein and Werner, 1998; Baran et al., 2003]. The Goldstein filter needs basically two parameters, the size of the window filter and a parameter to indicate the filter smoothing intensity. The modified Goldstein method removes the need to select the smoothing parameter based on the local interferometric coherence level, but still requires to specify the dimension of the filtering window. An optimal filtered phase quality usually requires careful selection of those parameters. Therefore, there is an strong need to develop automatic filtering methods to adapt for automatic processing, while maximizing filtered phase quality. Here, in this paper, I present a recursive adaptive phase filtering algorithm for accurate estimation of differential interferometric ground deformation and local coherence measurements. The proposed filter is based upon the modified Goldstein filter [Baran et al., 2003]. This filtering method improves the quality of the interferograms by performing a recursive iteration using variable (cascade) kernel sizes, and improving the coherence estimation by locally defringing the interferometric phase. The method has been tested using simulations and real cases relevant to the characteristics of the Sentinel-1 mission. Here, I present real examples

A revised calibration of the interferometric mode of the CryoSat-2 radar altimeter improves ice height and height change measurements in western Greenland

NASA Astrophysics Data System (ADS)

Gray, Laurence; Burgess, David; Copland, Luke; Dunse, Thorben; Langley, Kirsty; Moholdt, Geir

2017-05-01

We compare geocoded heights derived from the interferometric mode (SARIn) of CryoSat to surface heights from calibration-validation sites on Devon Ice Cap and western Greenland. Comparisons are included for both the heights derived from the first return (the point-of-closest-approach or POCA) and heights derived from delayed waveform returns (swath processing). While swath-processed heights are normally less precise than edited POCA heights, e.g. standard deviations of ˜ 3 and ˜ 1.5 m respectively for the western Greenland site, the increased coverage possible with swath data complements the POCA data and provides useful information for both system calibration and improving digital elevation models (DEMs). We show that the pre-launch interferometric baseline coupled with an additional roll correction ( ˜ 0.0075° ± 0.0025°), or equivalent phase correction ( ˜ 0.0435 ± 0.0145 radians), provides an improved calibration of the interferometric SARIn mode. We extend the potential use of SARIn data by showing the influence of surface conditions, especially melt, on the return waveforms and that it is possible to detect and measure the height of summer supraglacial lakes in western Greenland. A supraglacial lake can provide a strong radar target in the waveform, stronger than the initial POCA return, if viewed at near-normal incidence. This provides an ideal situation for swath processing and we demonstrate a height precision of ˜ 0.5 m for two lake sites, one in the accumulation zone and one in the ablation zone, which were measured every year from 2010 or 2011 to 2016. Each year the lake in the ablation zone was viewed in June by ascending passes and then 5.5 days later by descending passes, which allows an approximate estimate of the filling rate. The results suggest that CryoSat waveform data and measurements of supraglacial lake height change could complement the use of optical satellite imagery and be helpful as proxy indicators for surface

Advanced Antenna Design for NASA's EcoSAR Instrument

NASA Technical Reports Server (NTRS)

Du Toit, Cornelis F.; Deshpande, Manohar; Rincon, Rafael F.

2016-01-01

Advanced antenna arrays were designed for NASA's EcoSAR airborne radar instrument. EcoSAR is a beamforming synthetic aperture radar instrument designed to make polarimetric and "single pass" interferometric measurements of Earth surface parameters. EcoSAR's operational requirements of a 435MHz center frequency with up to 200MHz bandwidth, dual polarization, high cross-polarization isolation (> 30 dB), +/- 45deg beam scan range and antenna form-factor constraints imposed stringent requirements on the antenna design. The EcoSAR project successfully developed, characterized, and tested two array antennas in an anechoic chamber. EcoSAR's first airborne campaign conducted in the spring of 2014 generated rich data sets of scientific and engineering value, demonstrating the successful operation of the antennas.

Multibaseline interferometric SAR at millimeterwaves test of an algorithm on real data and a synthetic scene

NASA Astrophysics Data System (ADS)

Essen, Helmut; Brehm, Thorsten; Boehmsdorff, Stephan

2007-10-01

Interferometric Synthetic Aperture Radar has the capability to provide the user with the 3-D-Information of land surfaces. To gather data with high height estimation accuracy it is necessary to use a wide interferometric baseline or a high radar frequency. However the problem of resolving the phase ambiguity at smaller wavelengths is more critical than at longer wavelengths, as the unambiguous height interval is inversely proportional to the radar wavelength. To solve this shortcoming, a multiple baseline approach can be used with a number of neighbouring horns and an increasing baselength going from narrow to wide. The narrowest, corresponding to adjacent horns, is then assumed to be unambiguous in phase. This initial interferogram is used as a starting point for the algorithm, which in the next step, unwraps the interferogram with the next wider baseline using the coarse height information to solve the phase ambiguities. This process is repeated consecutively until the interferogram with highest precision is unwrapped. On the expense of this multi-channel-approach the algorithm is simple and robust, and even the amount of processing time is reduced considerably, compared to traditional methods. The multiple baseline approach is especially adequate for millimeterwave radars as antenna horns with relatively small aperture can be used, while a sufficient 3-dB beamwidth is maintained. The paper describes the multiple baseline algorithm and shows the results of tests on real data and a synthetic area. Possibilities and limitations of this approach are discussed. Examples of digital elevation maps derived from measured data at millimeterwaves are shown.

Understanding Volcanic Inflation of Long Valley Caldera, California, from Differential Synthetic Aperture Radar observations

NASA Technical Reports Server (NTRS)

Webb, F.; Hensley, S.; Rosen, P.; Langbein, J.

1994-01-01

The results using interferometric synthetic aperture radar(SAR) to measure the co-seismic displacement from the June 28, 1992 Landers earthquake suggest that this technique may be applicable to other problems in crustal deformation.

a Study of Precipitation Using Dual-Frequency and Interferometric Doppler Radars.

NASA Astrophysics Data System (ADS)

Chilson, Phillip Bruce

The primary focus of this dissertation involves the investigation of precipitation using Doppler radar but using distinctly different methods. Each method will be treated separately. The first part describes an investigation of a tropical thunderstorm that occurred in the summer of 1991 over the National Astronomy and Ionosphere Center in Arecibo, Puerto Rico. Observations were made using a vertically pointing, dual-wavelength, collinear beam Doppler radar which permits virtually simultaneous observations of the same pulse volume using transmission and reception of coherent UHF and VHF signals on alternate pulses. This made it possible to measure directly the vertical wind within the sampling volume using the VHF signal while using the UHF signal to study the nature of the precipitation. The observed storm showed strong similarities with systems observed in the Global Atmospheric Research Program's (GARP) Atlantic Tropical Experiment (GATE) study. The experiment provided a means of determining various parameters associated with the storm, such as the vertical air velocity, the mean fall speeds of the precipitation, and the reflectivity. Rogers proposed a means of deducing the mean fall speed of precipitation particles using the radar reflectivity factor. Using the data from our experiment, the mean precipitation fall speeds were calculated and compared with those that would be inferred from Rogers' method. The results suggest the Rogers method of estimating mean precipitation fall speeds to be unreliable in turbulent environments. The second part reports observations made with the 50 MHz Middle and Upper Atmosphere (MU) radar located at Shigaraki, Japan during May of 1992. The facility was operated in a spatial interferometry (SI) mode while observing frontal precipitation. The data suggest that the presence of precipitation can produce a bias in the SI cross-spectral phase that in turn creates an overestimation of the horizontal wind. The process is likened to

A Radar/Radiometer Instrument for Mapping Soil Moisture and Ocean Salinity

NASA Technical Reports Server (NTRS)

Hildebrand, Peter H.; Hilliard, Laurence; Rincon, Rafael; LeVine, David; Mead, James

2003-01-01

The RadSTAR instrument combines an L-band, digital beam-forming radar with an L-band synthetic aperture, thinned array (STAR) radiometer. The RadSTAR development will support NASA Earth science goals by developing a novel, L-band scatterometer/ radiometer that measures Earth surface bulk material properties (surface emissions and backscatter) as well as surface characteristics (backscatter). Present, real aperture airborne L-Band active/passive measurement systems such as the JPUPALS (Wilson, et al, 2000) provide excellent sampling characteristics, but have no scanning capabilities, and are extremely large; the huge JPUPALS horn requires a the C-130 airborne platform, operated with the aft loading door open during flight operation. The approach used for the upcoming Aquarius ocean salinity mission or the proposed Hydros soil mission use real apertures with multiple fixed beams or scanning beams. For real aperture instruments, there is no upgrade path to scanning over a broad swath, except rotation of the whole aperture, which is an approach with obvious difficulties as aperture size increases. RadSTAR will provide polarimetric scatterometer and radiometer measurements over a wide swath, in a highly space-efficient configuration. The electronic scanning approaches provided through STAR technology and digital beam forming will enable the large L-band aperture to scan efficiently over a very wide swath. RadSTAR technology development, which merges an interferometric radiometer with a digital beam forming scatterometer, is an important step in the path to space for an L-band scatterometer/radiometer. RadSTAR couples a patch array antenna with a 1.26 GHz digital beam forming radar scatterometer and a 1.4 GHz STAR radiometer to provide Earth surface backscatter and emission measurements in a compact, cross-track scanning instrument with no moving parts. This technology will provide the first L-band, emission and backscatter measurements in a compact aircraft instrument

CLASS: Coherent Lidar Airborne Shear Sensor. Windshear avoidance

NASA Technical Reports Server (NTRS)

Targ, Russell

1991-01-01

The coherent lidar airborne shear sensor (CLASS) is an airborne CO2 lidar system being designed and developed by Lockheed Missiles and Space Company, Inc. (LMSC) under contract to NASA Langley Research Center. The goal of this program is to develop a system with a 2- to 4-kilometer range that will provide a warning time of 20 to 40 seconds, so that the pilot can avoid the hazards of low-altitude wind shear under all weather conditions. It is a predictive system which will warn the pilot about a hazard that the aircraft will experience at some later time. The ability of the system to provide predictive warnings of clear air turbulence will also be evaluated. A one-year flight evaluation program will measure the line-of-sight wind velocity from a wide variety of wind fields obtained by an airborne radar, an accelerometer-based reactive wind-sensing system, and a ground-based Doppler radar. The success of the airborne lidar system will be determined by its correlation with the windfield as indicated by the onboard reactive system, which indicates the winds actually experienced by the NASA Boeing 737 aircraft.

Simulation Studies of Forest Structure using 3D Lidar and Radar Models

NASA Technical Reports Server (NTRS)

Sun, Guoqing; Ranson, K. Jon; Koetz, Benjamin; Liu, Dawei

2007-01-01

The use of lidars and radars to measure forest structure attributes such as height and biomass are being considered for future Earth Observation missions. Large footprint lidar makes a direct measurement of the heights of scatterers in the illuminated footprint and can yield information about the vertical profile of the canopy. Synthetic Aperture Radar (SAR) is known to sense the canopy volume, especially at longer wavelengths and is useful for estimating biomass. Interferometric SAR (InSAR) has been shown to yield forest canopy height information. For example, the height of scattering phase retrieved from InSAR data is considered to be correlated with the three height and the spatial structure of the forest stand. There is much interest in exploiting these technologies separately and together to get important information for carbon cycle and ecosystem science. More detailed information of the electromagnetic radiation interactions within forest canopies is needed. And backscattering models can be of much utility here. As part of a NASA funded project to explore data fusion, a three-dimensional (3D) coherent radar backscattering model and a 3D lidar backscatter models were used to investigate the use of large footprint lidar, SAR and InSAR for characterizing realistic forest scenes. For this paper, we use stem maps and other forest measurements to develop a realistic spatial structure of a spruce-hemlock forest canopy found in Maine, USA. The radar and lidar models used measurements of the 3D forest scene as input and simulated the coherent radar backscattering signature and 1064nm energy backscatter, respectively. The relationships of backscatter derived forest structure were compared with field measurements. In addition, we also had detailed airborne lidar (Laser Imaging Vegetation Sensor, LVIS) data available over the stem map sites that was used to study the accuracies of tree height derived from modeled SAR backscatter and the scattering phase center retrieved

Non-Cooperative Air Target Identification Using Radar (l’Identification radar des cibles aeriennes non cooperatives)

DTIC Science & Technology

1998-11-01

are already operational in the radar domain , e.g. in airborne radars. NATO fighter aircraft are equipped with transponder systems answering on...Mise en forme et 6talonnage des donn6es SER moyenne pour un domaine de fr6quence (bande passante du code utilis6) et un secteur Ce module extrait les...cooperatives) Papers presented at the Symposium of the RTO Systems Concepts and Integration Panel (SCI) held in Mannheim, Germany, 22-24 April 1998. 1

Description, characteristics and testing of the NASA airborne radar

NASA Technical Reports Server (NTRS)

Jones, W. R.; Altiz, O.; Schaffner, P.; Schrader, J. H.; Blume, H. J. C.

1991-01-01

Presented here is a description of a coherent radar scattermeter and its associated signal processing hardware, which have been specifically designed to detect microbursts and record their radar characteristics. Radar parameters, signal processing techniques and detection algorithms, all under computer control, combine to sense and process reflectivity, clutter, and microburst data. Also presented is the system's high density, high data rate recording system. This digital system is capable of recording many minutes of the in-phase and quadrature components and corresponding receiver gains of the scattered returns for selected spatial regions, as well as other aircraft and hardware related parameters of interest for post-flight analysis. Information is given in viewgraph form.

Airborne gravity measurement over sea-ice: The western Weddel Sea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brozena, J.; Peters, M.; LaBrecque, J.

1990-10-01

An airborne gravity study of the western Weddel Sea, east of the Antarctic Peninsula, has shown that floating pack-ice provides a useful radar altimetric reference surface for altitude and vertical acceleration corrections surface for alititude and vertical acceleration corrections to airborne gravimetry. Airborne gravimetry provides an important alternative to satellite altimetry for the sea-ice covered regions of the world since satellite alimeters are not designed or intended to provide accurate geoidal heights in areas where significant sea-ice is present within the radar footprint. Errors in radar corrected airborne gravimetry are primarily sensitive to the variations in the second derivative ofmore » the sea-ice reference surface in the frequency pass-band of interest. With the exception of imbedded icebergs the second derivative of the pack-ice surface closely approximates that of the mean sea-level surface at wavelengths > 10-20 km. With the airborne method the percentage of ice coverage, the mixture of first and multi-year ice and the existence of leads and pressure ridges prove to be unimportant in determining gravity anomalies at scales of geophysical and geodetic interest, provided that the ice is floating and not grounded. In the Weddell study an analysis of 85 crosstrack miss-ties distributed over 25 data tracks yields an rms error of 2.2 mGals. Significant structural anomalies including the continental shelf and offsets and lineations interpreted as fracture zones recording the early spreading directions within the Weddell Sea are observed in the gravity map.« less

Fly eye radar or micro-radar sensor technology

NASA Astrophysics Data System (ADS)

Molchanov, Pavlo; Asmolova, Olga

2014-05-01

To compensate for its eye's inability to point its eye at a target, the fly's eye consists of multiple angularly spaced sensors giving the fly the wide-area visual coverage it needs to detect and avoid the threats around him. Based on a similar concept a revolutionary new micro-radar sensor technology is proposed for detecting and tracking ground and/or airborne low profile low altitude targets in harsh urban environments. Distributed along a border or around a protected object (military facility and buildings, camp, stadium) small size, low power unattended radar sensors can be used for target detection and tracking, threat warning, pre-shot sniper protection and provides effective support for homeland security. In addition it can provide 3D recognition and targets classification due to its use of five orders more pulses than any scanning radar to each space point, by using few points of view, diversity signals and intelligent processing. The application of an array of directional antennas eliminates the need for a mechanical scanning antenna or phase processor. It radically decreases radar size and increases bearing accuracy several folds. The proposed micro-radar sensors can be easy connected to one or several operators by point-to-point invisible protected communication. The directional antennas have higher gain, can be multi-frequency and connected to a multi-functional network. Fly eye micro-radars are inexpensive, can be expendable and will reduce cost of defense.

Measurement of Attenuation with Airborne and Ground-Based Radar in Convective Storms Over Land and Its Microphysical Implications

NASA Technical Reports Server (NTRS)

Tian, Lin; Heymsfield, G. M.; Srivastava, R. C.; Starr, D. OC. (Technical Monitor)

2001-01-01

Observations by the airborne X-band Doppler radar (EDOP) and the NCAR S-band polarimetric (S-POL) radar from two field experiments are used to evaluate the Surface ref'ercnce technique (SRT) for measuring the path integrated attenuation (PIA) and to study attenuation in deep convective storms. The EDOP, flying at an altitude of 20 km, uses a nadir beam and a forward pointing beam. It is found that over land, the surface scattering cross-section is highly variable at nadir incidence but relatively stable at forward incidence. It is concluded that measurement by the forward beam provides a viable technique for measuring PIA using the SRT. Vertical profiles of peak attenuation coefficient are derived in vxo deep convective storms by the dual-wavelength method. Using the measured Doppler velocity, the reflectivities at. the two wavelengths, the differential reflectivity and the estimated attenuation coefficients, it is shown that: supercooled drops and dry ice particles probably co-existed above the melting level in regions of updraft, that water-coated partially melted ice particles probably contributed to high attenuation below the melting level, and that the data are not readil explained in terms of a gamma function raindrop size distribution.

Shuttle Radar Topography Mission (SRTM) Flight System Design and Operations Overview

NASA Technical Reports Server (NTRS)

Shen, Yuhsyen; Shaffer, Scott J.; Jordan, Rolando L.

2000-01-01

This paper provides an overview of the Shuttle Radar Topography Mission (SRTM), with emphasis on flight system implementation and mission operations from systems engineering perspective. Successfully flown in February, 2000, the SRTM's primary payload consists of several subsystems to form the first spaceborne dual-frequency (C-band and X-band) fixed baseline interferometric synthetic aperture radar (InSAR) system, with the mission objective to acquire data sets over 80% of Earth's landmass for height reconstruction. The paper provides system architecture, unique design features, engineering budgets, design verification, in-flight checkout and data acquisition of the SRTM payload, in particular for the C-band system. Mission operation and post-mission data processing activities are also presented. The complexity of the SRTM as a system, the ambitious mission objective, the demanding requirements and the high interdependency between multi-disciplined subsystems posed many challenges. The engineering experience and the insight thus gained have important implications for future spaceborne interferometric SAR mission design and implementation.

Monitoring subsurface coal fires in Jharia coalfield using observations of land subsidence from differential interferometric synthetic aperture radar (DInSAR)

NASA Astrophysics Data System (ADS)

Gupta, Nishant; Syed, Tajdarul H.; Athiphro, Ashiihrii

2013-10-01

Coal fires in the Jharia coalfield pose a serious threat to India's vital resource of primary coking coal and the regional environment. In order to undertake effective preventative measures, it is critical to detect the occurrence of subsurface coal fires and to monitor the extent of the existing ones. In this study, Differential Interferometric Synthetic Aperature Radar (DInSAR) technique has been utilized to monitor subsurface coal fires in the Jharia coalfield. Results showed that majority of the coal fire-related subsidence were concentrated on the eastern and western boundaries of the coalfield. The magnitude of subsidence observed was classified into high (10-27.8 mm), low (0-10 mm) and upliftment (-10-0 mm). The results were strongly supported by in situ observations and satellite-based thermal imagery analysis. Major subsidence was observed in the areas with repeated sightings of coal fire. Further, the study highlighted on the capability of the methodology for predicting potential coal fire zones on the basis of land surface subsidence only. The results from this study have major implications for demarcating the hazardous coal fire areas as well as effective implementation of public safety measures.

Application of a Threshold Method to Airborne-Spaceborne Attenuating-Wavelength Radars for the Estimation of Space-Time Rain-Rate Statistics.

NASA Astrophysics Data System (ADS)

Meneghini, Robert

1998-09-01

A method is proposed for estimating the area-average rain-rate distribution from attenuating-wavelength spaceborne or airborne radar data. Because highly attenuated radar returns yield unreliable estimates of the rain rate, these are eliminated by means of a proxy variable, Q, derived from the apparent radar reflectivity factors and a power law relating the attenuation coefficient and the reflectivity factor. In determining the probability distribution function of areawide rain rates, the elimination of attenuated measurements at high rain rates and the loss of data at light rain rates, because of low signal-to-noise ratios, leads to truncation of the distribution at the low and high ends. To estimate it over all rain rates, a lognormal distribution is assumed, the parameters of which are obtained from a nonlinear least squares fit to the truncated distribution. Implementation of this type of threshold method depends on the method used in estimating the high-resolution rain-rate estimates (e.g., either the standard Z-R or the Hitschfeld-Bordan estimate) and on the type of rain-rate estimate (either point or path averaged). To test the method, measured drop size distributions are used to characterize the rain along the radar beam. Comparisons with the standard single-threshold method or with the sample mean, taken over the high-resolution estimates, show that the present method usually provides more accurate determinations of the area-averaged rain rate if the values of the threshold parameter, QT, are chosen in the range from 0.2 to 0.4.

Sea Ice Thickness Estimates from Data Collected Using Airborne Sensors and Coincident In Situ Data

NASA Astrophysics Data System (ADS)

Gardner, J. M.; Brozena, J. M.; Abelev, A.; Hagen, R. A.; Liang, R.; Ball, D.

2016-12-01

The Naval Research Laboratory collected data using Airborne sensors and coincident in-situ measurements over multiple sites of floating, but land-fast ice north of Barrow, AK. The in-situ data provide ground-truth for airborne measurements from a scanning LiDAR (Riegl Q 560i), digital photogrammetry (Applanix DSS-439), a low-frequency SAR (P-band in 2014 and P and L bands in 2015 and 2016) and a snow/Ku radar procured from the Center for Remote Sensing of Ice Sheets of the University of Kansas. The CReSIS radar was updated in 2015 to integrate the snow and Ku radars into a single continuous chirp, thus improving resolution. The objective of the surveys was to aid our understanding of the accuracy of ice thickness estimation via the freeboard method using the airborne sensor suite. Airborne data were collected on multiple overflights of the transect areas. The LiDAR measured total freeboard (ice + snow) referenced to leads in the ice, and produced swaths 200-300 m wide. The SAR imaged the ice beneath the snow and the snow/Ku radar measured snow thickness. The freeboard measurements and snow thickness are used to estimate ice thickness via isostasy and density estimates. Comparisons and processing methodology will be shown using data from three field seasons (2014-2016). The results of this ground-truth experiment will inform our analysis of grids of airborne data collected over areas of sea-ice illuminated by Cryosat-2.

Replacing missing data between airborne SAR coherent image pairs

DOE PAGES

Musgrove, Cameron H.; West, James C.

2017-07-31

For synthetic aperture radar systems, missing data samples can cause severe image distortion. When multiple, coherent data collections exist and the missing data samples do not overlap between collections, there exists the possibility of replacing data samples between collections. For airborne radar, the known and unknown motion of the aircraft prevents direct data sample replacement to repair image features. Finally, this paper presents a method to calculate the necessary phase corrections to enable data sample replacement using only the collected radar data.

Replacing missing data between airborne SAR coherent image pairs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Musgrove, Cameron H.; West, James C.

For synthetic aperture radar systems, missing data samples can cause severe image distortion. When multiple, coherent data collections exist and the missing data samples do not overlap between collections, there exists the possibility of replacing data samples between collections. For airborne radar, the known and unknown motion of the aircraft prevents direct data sample replacement to repair image features. Finally, this paper presents a method to calculate the necessary phase corrections to enable data sample replacement using only the collected radar data.

Remote sensing with laser spectrum radar

NASA Astrophysics Data System (ADS)

Wang, Tianhe; Zhou, Tao; Jia, Xiaodong

2016-10-01

The unmanned airborne (UAV) laser spectrum radar has played a leading role in remote sensing because the transmitter and the receiver are together at laser spectrum radar. The advantages of the integrated transceiver laser spectrum radar is that it can be used in the oil and gas pipeline leak detection patrol line which needs the non-contact reflective detection. The UAV laser spectrum radar can patrol the line and specially detect the swept the area are now in no man's land because most of the oil and gas pipelines are in no man's land. It can save labor costs compared to the manned aircraft and ensure the safety of the pilots. The UAV laser spectrum radar can be also applied in the post disaster relief which detects the gas composition before the firefighters entering the scene of the rescue.

Investigation of Advanced Radar Techniques for Atmospheric Hazard Detection with Airborne Weather Radar

NASA Technical Reports Server (NTRS)

Pazmany, Andrew L.

2014-01-01

In 2013 ProSensing Inc. conducted a study to investigate the hazard detection potential of aircraft weather radars with new measurement capabilities, such as multi-frequency, polarimetric and radiometric modes. Various radar designs and features were evaluated for sensitivity, measurement range and for detecting and quantifying atmospheric hazards in wide range of weather conditions. Projected size, weight, power consumption and cost of the various designs were also considered. Various cloud and precipitation conditions were modeled and used to conduct an analytic evaluation of the design options. This report provides an overview of the study and summarizes the conclusions and recommendations.

Airborne radar and radiometer experiment for quantitative remote measurements of rain

NASA Technical Reports Server (NTRS)

Kozu, Toshiaki; Meneghini, Robert; Boncyk, Wayne; Wilheit, Thomas T.; Nakamura, Kenji

1989-01-01

An aircraft experiment has been conducted with a dual-frequency (10 GHz and 35 GHz) radar/radiometer system and an 18-GHz radiometer to test various rain-rate retrieval algorithms from space. In the experiment, which took place in the fall of 1988 at the NASA Wallops Flight Facility, VA, both stratiform and convective storms were observed. A ground-based radar and rain gauges were also used to obtain truth data. An external radar calibration is made with rain gauge data, thereby enabling quantitative reflectivity measurements. Comparisons between path attenuations derived from the surface return and from the radar reflectivity profile are made to test the feasibility of a technique to estimate the raindrop size distribution from simultaneous radar and path-attenuation measurements.

Radar activities of the DFVLR Institute for Radio Frequency Technology

NASA Technical Reports Server (NTRS)

Keydel, W.

1983-01-01

Aerospace research and the respective applications microwave tasks with respect to remote sensing, position finding and communication are discussed. The radar activities are directed at point targets, area targets and volume targets; they center around signature research for earth and ocean remote sensing, target recognition, reconnaissance and camouflage and imaging and area observation radar techniques (SAR and SLAR). The radar activities cover a frequency range from 1 GHz up to 94 GHz. The radar program is oriented to four possible application levels: ground, air, shuttle orbits and satellite orbits. Ground based studies and measurements, airborne scatterometers and imaging radars, a space shuttle radar, the MRSE, and follow on experiments are considered.

CBSIT 2009: Airborne Validation of Envisat Radar Altimetry and In Situ Ice Camp Measurements Over Arctic Sea Ice

NASA Technical Reports Server (NTRS)

Connor, Laurence; Farrell, Sinead; McAdoo, David; Krabill, William; Laxon, Seymour; Richter-Menge, Jacqueline; Markus, Thorsten

2010-01-01

The past few years have seen the emergence of satellite altimetry as valuable tool for taking quantitative sea ice monitoring beyond the traditional surface extent measurements and into estimates of sea ice thickness and volume, parameters that arc fundamental to improved understanding of polar dynamics and climate modeling. Several studies have now demonstrated the use of both microwave (ERS, Envisat/RA-2) and laser (ICESat/GLAS) satellite altimeters for determining sea ice thickness. The complexity of polar environments, however, continues to make sea ice thickness determination a complicated remote sensing task and validation studies remain essential for successful monitoring of sea ice hy satellites. One such validation effort, the Arctic Aircraft Altimeter (AAA) campaign of2006. included underflights of Envisat and ICESat north of the Canadian Archipelago using NASA's P-3 aircraft. This campaign compared Envisat and ICESat sea ice elevation measurements with high-resolution airborne elevation measurements, revealing the impact of refrozen leads on radar altimetry and ice drift on laser altimetry. Continuing this research and validation effort, the Canada Basin Sea Ice Thickness (CBSIT) experiment was completed in April 2009. CBSIT was conducted by NOAA. and NASA as part of NASA's Operation Ice Bridge, a gap-filling mission intended to supplement sea and land ice monitoring until the launch of NASA's ICESat-2 mission. CBIST was flown on the NASA P-3, which was equipped with a scanning laser altimeter, a Ku-band snow radar, and un updated nadir looking photo-imaging system. The CB5IT campaign consisted of two flights: an under flight of Envisat along a 1000 km track similar to that flown in 2006, and a flight through the Nares Strait up to the Lincoln Sea that included an overflight of the Danish GreenArc Ice Camp off the coast of northern Greenland. We present an examination of data collected during this campaign, comparing airborne laser altimeter measurements

Big data managing in a landslide early warning system: experience from a ground-based interferometric radar application

NASA Astrophysics Data System (ADS)

Intrieri, Emanuele; Bardi, Federica; Fanti, Riccardo; Gigli, Giovanni; Fidolini, Francesco; Casagli, Nicola; Costanzo, Sandra; Raffo, Antonio; Di Massa, Giuseppe; Capparelli, Giovanna; Versace, Pasquale

2017-10-01

A big challenge in terms or landslide risk mitigation is represented by increasing the resiliency of society exposed to the risk. Among the possible strategies with which to reach this goal, there is the implementation of early warning systems. This paper describes a procedure to improve early warning activities in areas affected by high landslide risk, such as those classified as critical infrastructures for their central role in society. This research is part of the project LEWIS (Landslides Early Warning Integrated System): An Integrated System for Landslide Monitoring, Early Warning and Risk Mitigation along Lifelines. LEWIS is composed of a susceptibility assessment methodology providing information for single points and areal monitoring systems, a data transmission network and a data collecting and processing center (DCPC), where readings from all monitoring systems and mathematical models converge and which sets the basis for warning and intervention activities. The aim of this paper is to show how logistic issues linked to advanced monitoring techniques, such as big data transfer and storing, can be dealt with compatibly with an early warning system. Therefore, we focus on the interaction between an areal monitoring tool (a ground-based interferometric radar) and the DCPC. By converting complex data into ASCII strings and through appropriate data cropping and average, and by implementing an algorithm for line-of-sight correction, we managed to reduce the data daily output without compromising the capability for performing.

Developing tools for digital radar image data evaluation

NASA Technical Reports Server (NTRS)

Domik, G.; Leberl, F.; Raggam, J.

1986-01-01

The refinement of radar image analysis methods has led to a need for a systems approach to radar image processing software. Developments stimulated through satellite radar are combined with standard image processing techniques to create a user environment to manipulate and analyze airborne and satellite radar images. One aim is to create radar products for the user from the original data to enhance the ease of understanding the contents. The results are called secondary image products and derive from the original digital images. Another aim is to support interactive SAR image analysis. Software methods permit use of a digital height model to create ortho images, synthetic images, stereo-ortho images, radar maps or color combinations of different component products. Efforts are ongoing to integrate individual tools into a combined hardware/software environment for interactive radar image analysis.

The development of a power spectral density processor for C and L band airborne radar scatterometer sensor systems

NASA Technical Reports Server (NTRS)

Harrison, D. A., III; Chladek, J. T.

1983-01-01

A real-time signal processor was developed for the NASA/JSC L-and C-band airborne radar scatterometer sensor systems. The purpose of the effort was to reduce ground data processing costs. Conversion of two quadrature channels of data (like and cross polarized) was made to obtain Power Spectral Density (PSD) values. A chirp-z transform (CZT) approach was used to filter the Doppler return signal and improved high frequency and angular resolution was realized. The processors have been tested with record signals and excellent results were obtained. CZT filtering can be readily applied to scatterometers operating at other wavelengths by altering the sample frequency. The design of the hardware and software and the results of the performance tests are described in detail.

Spectrum Modal Analysis for the Detection of Low-Altitude Windshear with Airborne Doppler Radar

NASA Technical Reports Server (NTRS)

Kunkel, Matthew W.

1992-01-01

A major obstacle in the estimation of windspeed patterns associated with low-altitude windshear with an airborne pulsed Doppler radar system is the presence of strong levels of ground clutter which can strongly bias a windspeed estimate. Typical solutions attempt to remove the clutter energy from the return through clutter rejection filtering. Proposed is a method whereby both the weather and clutter modes present in a return spectrum can be identified to yield an unbiased estimate of the weather mode without the need for clutter rejection filtering. An attempt will be made to show that modeling through a second order extended Prony approach is sufficient for the identification of the weather mode. A pattern recognition approach to windspeed estimation from the identified modes is derived and applied to both simulated and actual flight data. Comparisons between windspeed estimates derived from modal analysis and the pulse-pair estimator are included as well as associated hazard factors. Also included is a computationally attractive method for estimating windspeeds directly from the coefficients of a second-order autoregressive model. Extensions and recommendations for further study are included.

Coded continuous wave meteor radar

NASA Astrophysics Data System (ADS)

Chau, J. L.; Vierinen, J.; Pfeffer, N.; Clahsen, M.; Stober, G.

2016-12-01

The concept of a coded continuous wave specular meteor radar (SMR) is described. The radar uses a continuously transmitted pseudorandom phase-modulated waveform, which has several advantages compared to conventional pulsed SMRs. The coding avoids range and Doppler aliasing, which are in some cases problematic with pulsed radars. Continuous transmissions maximize pulse compression gain, allowing operation at lower peak power than a pulsed system. With continuous coding, the temporal and spectral resolution are not dependent on the transmit waveform and they can be fairly flexibly changed after performing a measurement. The low signal-to-noise ratio before pulse compression, combined with independent pseudorandom transmit waveforms, allows multiple geographically separated transmitters to be used in the same frequency band simultaneously without significantly interfering with each other. Because the same frequency band can be used by multiple transmitters, the same interferometric receiver antennas can be used to receive multiple transmitters at the same time. The principles of the signal processing are discussed, in addition to discussion of several practical ways to increase computation speed, and how to optimally detect meteor echoes. Measurements from a campaign performed with a coded continuous wave SMR are shown and compared with two standard pulsed SMR measurements. The type of meteor radar described in this paper would be suited for use in a large-scale multi-static network of meteor radar transmitters and receivers. Such a system would be useful for increasing the number of meteor detections to obtain improved meteor radar data products, such as wind fields. This type of a radar would also be useful for over-the-horizon radar, ionosondes, and observations of field-aligned-irregularities.

Radar Interferometer for Topographic Mapping of Glaciers and Ice Sheets

NASA Technical Reports Server (NTRS)

Moller, Delwyn K.; Sadowy, Gregory A.; Rignot, Eric J.; Madsen, Soren N.

2007-01-01

A report discusses Ka-band (35-GHz) radar for mapping the surface topography of glaciers and ice sheets at high spatial resolution and high vertical accuracy, independent of cloud cover, with a swath-width of 70 km. The system is a single- pass, single-platform interferometric synthetic aperture radar (InSAR) with an 8-mm wavelength, which minimizes snow penetration while remaining relatively impervious to atmospheric attenuation. As exhibited by the lower frequency SRTM (Shuttle Radar Topography Mission) AirSAR and GeoSAR systems, an InSAR measures topography using two antennas separated by a baseline in the cross-track direction, to view the same region on the ground. The interferometric combination of data received allows the system to resolve the pathlength difference from the illuminated area to the antennas to a fraction of a wavelength. From the interferometric phase, the height of the target area can be estimated. This means an InSAR system is capable of providing not only the position of each image point in along-track and slant range as with a traditional SAR but also the height of that point through interferometry. Although the evolution of InSAR to a millimeter-wave center frequency maximizes the interferometric accuracy from a given baseline length, the high frequency also creates a fundamental problem of swath coverage versus signal-to-noise ratio. While the length of SAR antennas is typically fixed by mass and stowage or deployment constraints, the width is constrained by the desired illuminated swath width. As the across-track beam width which sets the swath size is proportional to the wavelength, a fixed swath size equates to a smaller antenna as the frequency is increased. This loss of antenna size reduces the two-way antenna gain to the second power, drastically reducing the signal-to-noise ratio of the SAR system. This fundamental constraint of high-frequency SAR systems is addressed by applying digital beam-forming (DBF) techniques to

Electromagnetic Model Reliably Predicts Radar Scattering Characteristics of Airborne Organisms

NASA Astrophysics Data System (ADS)

Mirkovic, Djordje; Stepanian, Phillip M.; Kelly, Jeffrey F.; Chilson, Phillip B.

2016-10-01

The radar scattering characteristics of aerial animals are typically obtained from controlled laboratory measurements of a freshly harvested specimen. These measurements are tedious to perform, difficult to replicate, and typically yield only a small subset of the full azimuthal, elevational, and polarimetric radio scattering data. As an alternative, biological applications of radar often assume that the radar cross sections of flying animals are isotropic, since sophisticated computer models are required to estimate the 3D scattering properties of objects having complex shapes. Using the method of moments implemented in the WIPL-D software package, we show for the first time that such electromagnetic modeling techniques (typically applied to man-made objects) can accurately predict organismal radio scattering characteristics from an anatomical model: here the Brazilian free-tailed bat (Tadarida brasiliensis). The simulated scattering properties of the bat agree with controlled measurements and radar observations made during a field study of bats in flight. This numerical technique can produce the full angular set of quantitative polarimetric scattering characteristics, while eliminating many practical difficulties associated with physical measurements. Such a modeling framework can be applied for bird, bat, and insect species, and will help drive a shift in radar biology from a largely qualitative and phenomenological science toward quantitative estimation of animal densities and taxonomic identification.

Electromagnetic Model Reliably Predicts Radar Scattering Characteristics of Airborne Organisms.

PubMed

Mirkovic, Djordje; Stepanian, Phillip M; Kelly, Jeffrey F; Chilson, Phillip B

2016-10-20

The radar scattering characteristics of aerial animals are typically obtained from controlled laboratory measurements of a freshly harvested specimen. These measurements are tedious to perform, difficult to replicate, and typically yield only a small subset of the full azimuthal, elevational, and polarimetric radio scattering data. As an alternative, biological applications of radar often assume that the radar cross sections of flying animals are isotropic, since sophisticated computer models are required to estimate the 3D scattering properties of objects having complex shapes. Using the method of moments implemented in the WIPL-D software package, we show for the first time that such electromagnetic modeling techniques (typically applied to man-made objects) can accurately predict organismal radio scattering characteristics from an anatomical model: here the Brazilian free-tailed bat (Tadarida brasiliensis). The simulated scattering properties of the bat agree with controlled measurements and radar observations made during a field study of bats in flight. This numerical technique can produce the full angular set of quantitative polarimetric scattering characteristics, while eliminating many practical difficulties associated with physical measurements. Such a modeling framework can be applied for bird, bat, and insect species, and will help drive a shift in radar biology from a largely qualitative and phenomenological science toward quantitative estimation of animal densities and taxonomic identification.

Two antenna, two pass interferometric synthetic aperture radar

DOEpatents

Martinez, Ana; Doerry, Armin W.; Bickel, Douglas L.

2005-06-28

A multi-antenna, multi-pass IFSAR mode utilizing data driven alignment of multiple independent passes can combine the scaling accuracy of a two-antenna, one-pass IFSAR mode with the height-noise performance of a one-antenna, two-pass IFSAR mode. A two-antenna, two-pass IFSAR mode can accurately estimate the larger antenna baseline from the data itself and reduce height-noise, allowing for more accurate information about target ground position locations and heights. The two-antenna, two-pass IFSAR mode can use coarser IFSAR data to estimate the larger antenna baseline. Multi-pass IFSAR can be extended to more than two (2) passes, thereby allowing true three-dimensional radar imaging from stand-off aircraft and satellite platforms.

Accuracy of Flight Altitude Measured with Low-Cost GNSS, Radar and Barometer Sensors: Implications for Airborne Radiometric Surveys.

PubMed

Albéri, Matteo; Baldoncini, Marica; Bottardi, Carlo; Chiarelli, Enrico; Fiorentini, Giovanni; Raptis, Kassandra Giulia Cristina; Realini, Eugenio; Reguzzoni, Mirko; Rossi, Lorenzo; Sampietro, Daniele; Strati, Virginia; Mantovani, Fabio

2017-08-16

Flight height is a fundamental parameter for correcting the gamma signal produced by terrestrial radionuclides measured during airborne surveys. The frontiers of radiometric measurements with UAV require light and accurate altimeters flying at some 10 m from the ground. We equipped an aircraft with seven altimetric sensors (three low-cost GNSS receivers, one inertial measurement unit, one radar altimeter and two barometers) and analyzed ~3 h of data collected over the sea in the (35-2194) m altitude range. At low altitudes (H < 70 m) radar and barometric altimeters provide the best performances, while GNSS data are used only for barometer calibration as they are affected by a large noise due to the multipath from the sea. The ~1 m median standard deviation at 50 m altitude affects the estimation of the ground radioisotope abundances with an uncertainty less than 1.3%. The GNSS double-difference post-processing enhanced significantly the data quality for H > 80 m in terms of both altitude median standard deviation and agreement between the reconstructed and measured GPS antennas distances. Flying at 100 m the estimated uncertainty on the ground total activity due to the uncertainty on the flight height is of the order of 2%.

Accuracy of Flight Altitude Measured with Low-Cost GNSS, Radar and Barometer Sensors: Implications for Airborne Radiometric Surveys

PubMed Central

Baldoncini, Marica; Chiarelli, Enrico; Fiorentini, Giovanni; Raptis, Kassandra Giulia Cristina; Realini, Eugenio; Reguzzoni, Mirko; Rossi, Lorenzo; Sampietro, Daniele; Strati, Virginia

2017-01-01

Flight height is a fundamental parameter for correcting the gamma signal produced by terrestrial radionuclides measured during airborne surveys. The frontiers of radiometric measurements with UAV require light and accurate altimeters flying at some 10 m from the ground. We equipped an aircraft with seven altimetric sensors (three low-cost GNSS receivers, one inertial measurement unit, one radar altimeter and two barometers) and analyzed ~3 h of data collected over the sea in the (35–2194) m altitude range. At low altitudes (H < 70 m) radar and barometric altimeters provide the best performances, while GNSS data are used only for barometer calibration as they are affected by a large noise due to the multipath from the sea. The ~1 m median standard deviation at 50 m altitude affects the estimation of the ground radioisotope abundances with an uncertainty less than 1.3%. The GNSS double-difference post-processing enhanced significantly the data quality for H > 80 m in terms of both altitude median standard deviation and agreement between the reconstructed and measured GPS antennas distances. Flying at 100 m the estimated uncertainty on the ground total activity due to the uncertainty on the flight height is of the order of 2%. PMID:28813023

Airborne precursor missions in support of SIR-C/X-SAR

NASA Technical Reports Server (NTRS)

Evans, D.; Oettl, H.; Pampaloni, P.

1991-01-01

The NASA DC-8 and DLR E-SAR airborne imaging radars have been deployed over several sites in Europe and the U.S. in support of SIR-C/X-SAR (Shuttle Imaging Radar-C/X-Synthetic Aperture Radar) science team investigations. To date, data have been acquired in support of studies of alpine glaciers, forests, geology, oceanography, and calibration. An experimental campaign with airborne sensors will take place in Europe in June to July 1991 which will allow multitemporal surveys of several Europeans sites. Current plans are for calibration and ecology experiments to be undertaken in Germany, the Netherlands, Italy, France, and the United Kingdom. Coordinated multitemporal aircraft and ground campaigns are planned in support of hydrology experiments in Italy, the United Kingdom, and Austria. Data will also be acquired in support of oceanogrqhy in the Gulf of Genova, North Atlantic, Straits of Messina and the North Sea. Geology sites will include Campi Flegrei and Vesuvio, Italy.

InSAR datum connection using GNSS-augmented radar transponders

NASA Astrophysics Data System (ADS)

Mahapatra, Pooja; der Marel, Hans van; van Leijen, Freek; Samiei-Esfahany, Sami; Klees, Roland; Hanssen, Ramon

2018-01-01

Deformation estimates from Interferometric Synthetic Aperture Radar (InSAR) are relative: they form a `free' network referred to an arbitrary datum, e.g. by assuming a reference point in the image to be stable. However, some applications require `absolute' InSAR estimates, i.e. expressed in a well-defined terrestrial reference frame, e.g. to compare InSAR results with those of other techniques. We propose a methodology based on collocated InSAR and Global Navigation Satellite System (GNSS) measurements, achieved by rigidly attaching phase-stable millimetre-precision compact active radar transponders to GNSS antennas. We demonstrate this concept through a simulated example and practical case studies in the Netherlands.

Adaptive clutter rejection filters for airborne Doppler weather radar applied to the detection of low altitude windshear

NASA Technical Reports Server (NTRS)

Keel, Byron M.

1989-01-01

An optimum adaptive clutter rejection filter for use with airborne Doppler weather radar is presented. The radar system is being designed to operate at low-altitudes for the detection of windshear in an airport terminal area where ground clutter returns may mask the weather return. The coefficients of the adaptive clutter rejection filter are obtained using a complex form of a square root normalized recursive least squares lattice estimation algorithm which models the clutter return data as an autoregressive process. The normalized lattice structure implementation of the adaptive modeling process for determining the filter coefficients assures that the resulting coefficients will yield a stable filter and offers possible fixed point implementation. A 10th order FIR clutter rejection filter indexed by geographical location is designed through autoregressive modeling of simulated clutter data. Filtered data, containing simulated dry microburst and clutter return, are analyzed using pulse-pair estimation techniques. To measure the ability of the clutter rejection filters to remove the clutter, results are compared to pulse-pair estimates of windspeed within a simulated dry microburst without clutter. In the filter evaluation process, post-filtered pulse-pair width estimates and power levels are also used to measure the effectiveness of the filters. The results support the use of an adaptive clutter rejection filter for reducing the clutter induced bias in pulse-pair estimates of windspeed.

Electromagnetic Model Reliably Predicts Radar Scattering Characteristics of Airborne Organisms

PubMed Central

Mirkovic, Djordje; Stepanian, Phillip M.; Kelly, Jeffrey F.; Chilson, Phillip B.

2016-01-01

The radar scattering characteristics of aerial animals are typically obtained from controlled laboratory measurements of a freshly harvested specimen. These measurements are tedious to perform, difficult to replicate, and typically yield only a small subset of the full azimuthal, elevational, and polarimetric radio scattering data. As an alternative, biological applications of radar often assume that the radar cross sections of flying animals are isotropic, since sophisticated computer models are required to estimate the 3D scattering properties of objects having complex shapes. Using the method of moments implemented in the WIPL-D software package, we show for the first time that such electromagnetic modeling techniques (typically applied to man-made objects) can accurately predict organismal radio scattering characteristics from an anatomical model: here the Brazilian free-tailed bat (Tadarida brasiliensis). The simulated scattering properties of the bat agree with controlled measurements and radar observations made during a field study of bats in flight. This numerical technique can produce the full angular set of quantitative polarimetric scattering characteristics, while eliminating many practical difficulties associated with physical measurements. Such a modeling framework can be applied for bird, bat, and insect species, and will help drive a shift in radar biology from a largely qualitative and phenomenological science toward quantitative estimation of animal densities and taxonomic identification. PMID:27762292

Integrated Airborne and In-Situ Measurements Over Land-Fast Ice Near Barrow, AK.

NASA Astrophysics Data System (ADS)

Gardner, J. M.; Brozena, J. M.; Richter-Menge, J.; Abelev, A.; Liang, R.; Ball, D.; Claffey, K. J.; Hebert, D. A.; Jones, K.

2015-12-01

The Naval Research Laboratory has collected two field seasons of integrated airborne and in-situ measurements over multiple sites of floating, but land-fast ice north of Barrow, AK. During the first season in March of 2014 the Cold Regions Research and Engineering Laboratory led the on-ice group including NRL personnel and Naval Academy midshipmen. The second season (March 2015) included only NRL scientists and midshipmen. The in-situ data provided ground-truth for airborne measurements from a scanning LiDAR (Riegl Q 560i), digital photogrammetry (Applanix DSS-439), a low-frequency SAR (P-band in 2014 and P and L bands in 2015) and a snow/Ku radar procured from the Center for Remote Sensing of Ice Sheets of the University of Kansas. The CReSIS radar was updated in 2015 to integrate the snow and Ku radars into a single continuous chirp, thus improving resolution. The objective of the survey was to aid our understanding of the use of the airborne data to calibrate/validate Cryosat-2 data. Sampling size or "footprint" plays a critical role in the attempt to compare in-situ measurements with airborne (or satellite) measurements. Thus the in-situ data were arranged to minimize aliasing. Ground measurements were collected along transects a sites generally consisting of a 2 km long profile of Magnaprobe and EM31 measurements with periodic boreholes. A 60 m x 400 m swath of Magnaprobe measurements was centered on this profile. Airborne data were collected on multiple overflights of the transect areas. The LiDAR measured total freeboard (ice + snow) referenced to leads in the ice, and produced swaths 200-300 m wide. The SAR imaged the ice beneath the snow and the snow/Ku radar measured snow thickness. The freeboard measurements and snow thickness are used to estimate ice thickness via isostasy and density estimates. Comparisons and processing methodology will be shown. The results of this ground-truth experiment will inform our analysis of grids of airborne data collected

Monitoring of civil infrastructures by interferometric radar: a review.

PubMed

Pieraccini, Massimiliano

2013-01-01

Ground-based radar interferometry is an increasingly popular technique for monitoring civil infrastructures. Many research groups, professionals, and companies have tested it in different operative scenarios, so it is time for a first systematic survey of the case studies reported in the literature. This review is addressed especially to the engineers and scientists interested to consider the applicability of the technique to their practice, so it is focused on the issues of the practical cases rather than on theory and principles, which are now well consolidated.

Fault Creep along the Southern San Andreas from Interferometric Synthetic Aperture Radar, Permanent Scatterers, and Stacking

NASA Technical Reports Server (NTRS)

Lyons, Suzanne; Sandwell, David

2003-01-01

Interferometric synthetic aperture radar (InSAR) provides a practical means of mapping creep along major strike-slip faults. The small amplitude of the creep signal (less than 10 mm/yr), combined with its short wavelength, makes it difficult to extract from long time span interferograms, especially in agricultural or heavily vegetated areas. We utilize two approaches to extract the fault creep signal from 37 ERS SAR images along the southem San Andreas Fault. First, amplitude stacking is utilized to identify permanent scatterers, which are then used to weight the interferogram prior to spatial filtering. This weighting improves correlation and also provides a mask for poorly correlated areas. Second, the unwrapped phase is stacked to reduce tropospheric and other short-wavelength noise. This combined processing enables us to recover the near-field (approximately 200 m) slip signal across the fault due to shallow creep. Displacement maps fiom 60 interferograms reveal a diffuse secular strain buildup, punctuated by localized interseismic creep of 4-6 mm/yr line of sight (LOS, 12-18 mm/yr horizontal). With the exception of Durmid Hill, this entire segment of the southern San Andreas experienced right-lateral triggered slip of up to 10 cm during the 3.5-year period spanning the 1992 Landers earthquake. The deformation change following the 1999 Hector Mine earthquake was much smaller (4 cm) and broader than for the Landers event. Profiles across the fault during the interseismic phase show peak-to-trough amplitude ranging from 15 to 25 mm/yr (horizontal component) and the minimum misfit models show a range of creeping/locking depth values that fit the data.

UAV-based Radar Sounding of Antarctic Ice

NASA Astrophysics Data System (ADS)

Leuschen, Carl; Yan, Jie-Bang; Mahmood, Ali; Rodriguez-Morales, Fernando; Hale, Rick; Camps-Raga, Bruno; Metz, Lynsey; Wang, Zongbo; Paden, John; Bowman, Alec; Keshmiri, Shahriar; Gogineni, Sivaprasad

2014-05-01

We developed a compact radar for use on a small UAV to conduct measurements over the ice sheets in Greenland and Antarctica. It operates at center frequencies of 14 and 35 MHz with bandwidths of 1 MHz and 4 MHz, respectively. The radar weighs about 2 kgs and is housed in a box with dimensions of 20.3 cm x 15.2 cm x 13.2 cm. It transmits a signal power of 100 W at a pulse repletion frequency of 10 kHz and requires average power of about 20 W. The antennas for operating the radar are integrated into the wings and airframe of a small UAV with a wingspan of 5.3 m. We selected the frequencies of 14 and 35 MHz based on previous successful soundings of temperate ice in Alaska with a 12.5 MHz impulse radar [Arcone, 2002] and temperate glaciers in Patagonia with a 30 MHz monocycle radar [Blindow et al., 2012]. We developed the radar-equipped UAV to perform surveys over a 2-D grid, which allows us to synthesize a large two-dimensional aperture and obtain fine resolution in both the along- and cross-track directions. Low-frequency, high-sensitivity radars with 2-D aperture synthesis capability are needed to overcome the surface and volume scatter that masks weak echoes from the ice-bed interface of fast-flowing glaciers. We collected data with the radar-equipped UAV on sub-glacial ice near Lake Whillans at both 14 and 35 MHz. We acquired data to evaluate the concept of 2-D aperture synthesis and successfully demonstrated the first successful sounding of ice with a radar on an UAV. We are planning to build multiple radar-equipped UAVs for collecting fine-resolution data near the grounding lines of fast-flowing glaciers. In this presentation we will provide a brief overview of the radar and UAV, as well as present results obtained at both 14 and 35 MHz. Arcone, S. 2002. Airborne-radar stratigraphy and electrical structure of temperate firn: Bagley Ice Field, Alaska, U.S.A. Journal of Glaciology, 48, 317-334. Blindow, N., C. Salat, and G. Casassa. 2012. Airborne GPR sounding of

Enhanced Weather Radar (EWxR) System

NASA Technical Reports Server (NTRS)

Kronfeld, Kevin M. (Technical Monitor)

2003-01-01

An airborne weather radar system, the Enhanced Weather Radar (EWxR), with enhanced on-board weather radar data processing was developed and tested. The system features additional weather data that is uplinked from ground-based sources, specialized data processing, and limited automatic radar control to search for hazardous weather. National Weather Service (NWS) ground-based Next Generation Radar (NEXRAD) information is used by the EWxR system to augment the on-board weather radar information. The system will simultaneously display NEXRAD and on-board weather radar information in a split-view format. The on-board weather radar includes an automated or hands-free storm-finding feature that optimizes the radar returns by automatically adjusting the tilt and range settings for the current altitude above the terrain and searches for storm cells near the atmospheric 0-degree isotherm. A rule-based decision aid was developed to automatically characterize cells as hazardous, possibly-hazardous, or non-hazardous based upon attributes of that cell. Cell attributes are determined based on data from the on-board radar and from ground-based radars. A flight path impact prediction algorithm was developed to help pilots to avoid hazardous weather along their flight plan and their mission. During development the system was tested on the NASA B757 aircraft and final tests were conducted on the Rockwell Collins Sabreliner.

Hardware Design for a Fixed-Wing Airborne Gravity Measurement System

DTIC Science & Technology

1986-12-22

worldwide navigation system currently available that is sufficiently accurate for deter- mining Eotvos correction in airborne gravimetry is the Global...better in defining the strength of precipitation . The radar display is compact enough to be mounted on the cockpit, thus giving the pilots better...of the proposed AGMS version 3 MISCELLANEOUS AIRCRAFT CONSIDERATIONS Autopilot One of the most important considerations in airborne gravimetry is

Multi-frequency fine resolution imaging radar instrumentation and data acquisition. [side-looking radar for airborne imagery

NASA Technical Reports Server (NTRS)

Rendleman, R. A.; Champagne, E. B.; Ferris, J. E.; Liskow, C. L.; Marks, J. M.; Salmer, R. J.

1974-01-01

Development of a dual polarized L-band radar imaging system to be used in conjunction with the present dual polarized X-band radar is described. The technique used called for heterodyning the transmitted frequency from X-band to L-band and again heterodyning the received L-band signals back to X-band for amplification, detection, and recording.

Radar Observation of Large Attenuation in Convective Storms: Implications for the Dropsize Distribution

NASA Technical Reports Server (NTRS)

Tian, Lin; Heymsfield, G. M.; Srivastava, R. C.

2000-01-01

Airborne meteorological radars typically operate at attenuating wavelengths. The path integrated attenuation (PIA) can be estimated using the surface reference technique (SRT). In this method, an initial value is determined for the radar cross section of the earth surface in a rain-free area in relatively close proximity to the rain cloud. During subsequent observations of precipitation any decrease 'in the observed surface cross section from the reference value s assumed to be a result of the two-way attenuation along the propagation path. In this paper we present selected instances of high PIA observed over land by an airborne radar. The observations were taken in Brazil and Florida during TRMM (Tropical Rainfall Measurement Mission) field campaigns. We compared these observations with collocated and nearly simultaneous ground-based radar observations by an S-band radar that is not subject to significant attenuation. In this preliminary evaluation, a systematic difference in the attenuation in the two storms is attributed to a difference in the raindrop size distributions; this is supported by observations of ZDR (differential reflectivity).

Monitoring of Civil Infrastructures by Interferometric Radar: A Review

PubMed Central

Pieraccini, Massimiliano

2013-01-01

Ground-based radar interferometry is an increasingly popular technique for monitoring civil infrastructures. Many research groups, professionals, and companies have tested it in different operative scenarios, so it is time for a first systematic survey of the case studies reported in the literature. This review is addressed especially to the engineers and scientists interested to consider the applicability of the technique to their practice, so it is focused on the issues of the practical cases rather than on theory and principles, which are now well consolidated. PMID:24106454

Atmospheric corrections in interferometric synthetic aperture radar surface deformation - a case study of the city of Mendoza, Argentina

NASA Astrophysics Data System (ADS)

Balbarani, S.; Euillades, P. A.; Euillades, L. D.; Casu, F.; Riveros, N. C.

2013-09-01

Differential interferometry is a remote sensing technique that allows studying crustal deformation produced by several phenomena like earthquakes, landslides, land subsidence and volcanic eruptions. Advanced techniques, like small baseline subsets (SBAS), exploit series of images acquired by synthetic aperture radar (SAR) sensors during a given time span. Phase propagation delay in the atmosphere is the main systematic error of interferometric SAR measurements. It affects differently images acquired at different days or even at different hours of the same day. So, datasets acquired during the same time span from different sensors (or sensor configuration) often give diverging results. Here we processed two datasets acquired from June 2010 to December 2011 by COSMO-SkyMed satellites. One of them is HH-polarized, and the other one is VV-polarized and acquired on different days. As expected, time series computed from these datasets show differences. We attributed them to non-compensated atmospheric artifacts and tried to correct them by using ERA-Interim global atmospheric model (GAM) data. With this method, we were able to correct less than 50% of the scenes, considering an area where no phase unwrapping errors were detected. We conclude that GAM-based corrections are not enough for explaining differences in computed time series, at least in the processed area of interest. We remark that no direct meteorological data for the GAM-based corrections were employed. Further research is needed in order to understand under what conditions this kind of data can be used.

Radar detection of pedestrian-induced vibrations on Michelangelo's David.

PubMed

Pieraccini, Massimiliano; Betti, Michele; Forcellini, Davide; Dei, Devis; Papi, Federico; Bartoli, Gianni; Facchini, Luca; Corazzi, Riccardo; Kovacevic, Vladimir Cerisano

2017-01-01

This paper summarizes the results of a two-day dynamic monitoring of Michelangelo's David subject to environmental loads (city traffic and pedestrian loading induced by tourists visiting the Accademia Gallery). The monitoring was carried out by a no-contact technique using an interferometric radar, whose effectiveness in measuring the resonant frequencies of structures and historic monuments has proved over the last years through numerous monitoring activities. Owing to the dynamic behavior of the measurement system (radar and tripod), an accelerometer has been installed on the radar head to filter out the movement component of the measuring instrument from the measurement of the David's displacement. Measurements were carried out in the presence and absence of visitors, to assess their influence on the dynamic behavior of the statue. A numerical model of the statue was employed to evaluate the experimental results.

Radar detection of pedestrian-induced vibrations on Michelangelo's David

PubMed Central

2017-01-01

This paper summarizes the results of a two-day dynamic monitoring of Michelangelo's David subject to environmental loads (city traffic and pedestrian loading induced by tourists visiting the Accademia Gallery). The monitoring was carried out by a no-contact technique using an interferometric radar, whose effectiveness in measuring the resonant frequencies of structures and historic monuments has proved over the last years through numerous monitoring activities. Owing to the dynamic behavior of the measurement system (radar and tripod), an accelerometer has been installed on the radar head to filter out the movement component of the measuring instrument from the measurement of the David's displacement. Measurements were carried out in the presence and absence of visitors, to assess their influence on the dynamic behavior of the statue. A numerical model of the statue was employed to evaluate the experimental results. PMID:28394932

Radar monitoring of oil pollution

NASA Technical Reports Server (NTRS)

Guinard, N. W.

1970-01-01

Radar is currently used for detecting and monitoring oil slicks on the sea surface. The four-frequency radar system is used to acquire synthetic aperature imagery of the sea surface on which the oil slicks appear as a nonreflecting area on the surface surrounded by the usual sea return. The value of this technique was demonstrated, when the four-frequency radar system was used to image the oil spill of tanker which has wrecked. Imagery was acquired on both linear polarization (horizontal, vertical) for frequencies of 428, 1228, and 8910 megahertz. Vertical returns strongly indicated the presence of oil while horizontal returns failed to detect the slicks. Such a result is characteristic of the return from the sea and cannot presently be interpreted as characteristics of oil spills. Because an airborne imaging radar is capable of providing a wide-swath coverage under almost all weather conditions, it offers promise in the development of a pollution-monitoring system that can provide a coastal watch for oil slicks.

Azimuthal Signature of Coincidental Brightness Temperature and Normalized Radar Cross-Section Obtained Using Airborne PALS Instrument

NASA Technical Reports Server (NTRS)

Colliander, Andreas; Kim, Seungbum; Yueh, Simon; Cosh, Mike; Jackson, Tom; Njoku, Eni

2010-01-01

Coincidental airborne brightness temperature (TB) and normalized radar-cross section (NRCS) measurements were carried out with the PALS (Passive and Active L- and S-band) instrument in the SMAPVEX08 (SMAP Validation Experiment 2008) field campaign. This paper describes results obtained from a set of flights which measured a field in 45(sup o) steps over the azimuth angle. The field contained mature soy beans with distinct row structure. The measurement shows that both TB and NRCS experience modulation effects over the azimuth as expected based on the theory. The result is useful in development and validation of land surface parameter forward models and retrieval algorithms, such as the soil moisture algorithm for NASA's SMAP (Soil Moisture Active and Passive) mission. Although the footprint of the SMAP will not be sensitive to the small resolution scale effects as the one presented in this paper, it is nevertheless important to understand the effects at smaller scale.

(abstract) Mount Rainier: New Remote Sensing Observations of a Decade Volcano

NASA Technical Reports Server (NTRS)

Realmuto, V. J.; Zebker, H. A.; Frank, D.

1994-01-01

Mount Rainier was selected as a Decade Volcano by the International Association of Volcanology and Chemistry of the Earth's Interior. The purpose of this selection is to focus scientific and public attention on Mount Rainier during the current decade, the United Nations-designated International Decade of Natural Hazard Reduction. The Mount Rainier science plan calls for remote sensing surveys to monitor the volcano. To date, we have conducted airborne surveys with visible and near-infrared, thermal infrared, and interferometric radar instruments. Our preliminary analysis of some night-time time-series thermal infrared survey data sets of the summit suggests that, aside from seasonal variations in snow cover, there have been no qualitative changes in the size or pattern of the summit hot spots. Day-time airborne surveys were done to record the current surface appearance of the volcano and map hydrothermal alteration in the summit region. An interferometric radar survey yielded a high-resolution digital elevation model (DEM) which serves as a base for the registration of the other remote sensing data sets. More importantly, the DEM documents the current topography of glaciers and valleys. Planned biannual radar survey of mount rainier will produce a data set from which seasonal changes in glacier and valley topography can be characterized. Such characterization is essential if we are to recognize geothermally induced changes in snow and ice cover.

Airborne lidar wind detection at 2 μm

NASA Astrophysics Data System (ADS)

Targ, Russell; Hawley, James G.; Steakley, Bruce C.; Ames, Lawrence L.; Robinson, Paul A.

1995-06-01

NASA and the FAA have expressed interest in laser radar's capabilities to detect wind profiles at altitude. A number of programs have been addressing the technical feasibility and utility of laser radar atmospheric backscatter data to determine wind profiles and wind hazards for aircraft guidance and navigation. In addition, the U.S. Air Force is investigating the use of airborne lidar to achieve precision air drop capability, and to increase the accuracy of the AC- 130 gunship and the B-52 bomber by measuring the wind field from the aircraft to the ground. There are emerging capabilities of airborne laser radar to measure wind velocities and detect turbulence and other atmospheric disturbances out in front of an aircraft in real time. The measurement of these parameters can significantly increase fuel efficiency, flight safety, airframe lifetime, and terminal area capacity for new and existing aircraft. This is achieved through wind velocity detection, turbulence avoidance, active control utilization to alleviate gust loading, and detection of wingtip wake vortices produced by landing aircraft. This paper presents the first flight test results of an all solid-state 2-micrometers laser radar system measuring the wind field profile 1 to 2 km in front of an aircraft in real time. We find 0.7-m/s wind measurement accuracy for the system which is configured in a rugged, light weight, high- performance ARINC package.

The flight test of Pi-SAR(L) for the repeat-pass interferometric SAR

NASA Astrophysics Data System (ADS)

Nohmi, Hitoshi; Shimada, Masanobu; Miyawaki, Masanori

2006-09-01

This paper describes the experiment of the repeat pass interferometric SAR using Pi-SAR(L). The air-borne repeat-pass interferometric SAR is expected as an effective method to detect landslide or predict a volcano eruption. To obtain a high-quality interferometric image, it is necessary to make two flights on the same flight pass. In addition, since the antenna of the Pi-SAR(L) is secured to the aircraft, it is necessary to fly at the same drift angle to keep the observation direction same. We built a flight control system using an auto pilot which has been installed in the airplane. This navigation system measures position and altitude precisely with using a differential GPS, and the PC Navigator outputs a difference from the desired course to the auto pilot. Since the air density is thinner and the speed is higher than the landing situation, the gain of the control system is required to be adjusted during the repeat pass flight. The observation direction could be controlled to some extent by adjusting a drift angle with using a flight speed control. The repeat-pass flight was conducted in Japan for three days in late November. The flight was stable and the deviation was within a few meters for both horizontal and vertical direction even in the gusty condition. The SAR data were processed in time domain based on range Doppler algorism to make the complete motion compensation. Thus, the interferometric image processed after precise phase compensation is shown.

Integrated Airborne and In-Situ Measurements over Land-Fast Ice near Barrow, AK.

NASA Astrophysics Data System (ADS)

Brozena, J. M.; Gardner, J. M.; Liang, R.; Ball, D.; Richter-Menge, J.; Claffey, K. J.; Abelev, A.; Hebert, D. A.; Jones, K.

2014-12-01

During March of 2014, the Naval Research Laboratory and the Cold Regions Research and Engineering Laboratory collected an integrated set of airborne and in-situ measurements over two areas of floating, but land-fast ice near the coast of Barrow, AK. The near-shore site was just north of Point Barrow, and the "offshore" site was ~ 20 km east of Point Barrow. The in-situ data provided ground-truth for airborne measurements from a scanning LiDAR (Riegl Q 560i), digital photogrammetry (Applanix DSS-439) and a snow radar procured from the Center for Remote Sensing of Ice Sheets of the University of Kansas. The objective of the survey was to aid our understanding of the use of the airborne data to calibrate/validate Cryosat-2 data. Sampling size or "footprint" plays a critical role in the attempt to compare in-situ measurements with airborne (or satellite) measurements. Thus the in-situ data were arranged to minimize aliasing. Ground measurements were collected along transects at both sites consisting of a 2 km long profile of snow depth and ice thickness measurements with periodic boreholes. A 60 m x 400 m swath of snow depth measurements was centered on this profile. Airborne data were collected on five overflights of the two transect areas. The LiDAR measured total freeboard (ice + snow) referenced to leads in the ice, and produced swaths 200-300 m wide. The radar measured snow thickness. The freeboard and snow thickness measurements are used to estimate ice thickness via isostasy and density estimates. The central swath of in situ snow depth data allows examination of the effects of cross-track variations considering the relatively large footprint of the snow radar. Assuming a smooth, flat surface the radar range resolution in air is < 4 cm, but the along-track sampling distance is ~ 3 m after unfocussed SAR processing. The width of the footprint varies from ~ 9 m up to about 40 m (beam-limited) for uneven surfaces. However, the radar could not resolve snow thickness

Radar polarimetry - Analysis tools and applications

NASA Technical Reports Server (NTRS)

Evans, Diane L.; Farr, Tom G.; Van Zyl, Jakob J.; Zebker, Howard A.

1988-01-01

The authors have developed several techniques to analyze polarimetric radar data from the NASA/JPL airborne SAR for earth science applications. The techniques determine the heterogeneity of scatterers with subregions, optimize the return power from these areas, and identify probable scattering mechanisms for each pixel in a radar image. These techniques are applied to the discrimination and characterization of geologic surfaces and vegetation cover, and it is found that their utility varies depending on the terrain type. It is concluded that there are several classes of problems amenable to single-frequency polarimetric data analysis, including characterization of surface roughness and vegetation structure, and estimation of vegetation density. Polarimetric radar remote sensing can thus be a useful tool for monitoring a set of earth science parameters.

Radar Thickness Measurements over the Southern Part of the Greenland Ice Sheet

NASA Technical Reports Server (NTRS)

Chuah, Teong Sek; Gogineni, Siva Prasad; Allen, Christopher; Wohletz, Brad; Wong, Y. C.; Ng, P. Y.; Ajayi, E.

1996-01-01

We performed ice thickness measurements over the southern part of the Greenland ice sheet during June and July 1993. We used an airborne coherent radar depth sounder for these measurements. The radar was operated from a NASA P-3 aircraft equipped with GPS receivers. Radar data were collected in conjunction with laser altimeter and microwave altimeter measurements of ice surface elevation. This report provides radio echograms and thickness profiles from data collected during 1993.

Use of radar in urban studies

NASA Technical Reports Server (NTRS)

Bryan, M. L.

1976-01-01

The use of side-looking airborne radar for urban studies is reviewed with attention given to the work of Moore (1969) and Lewis (1968) which may be summarized as follows: (1) linear elements of the transportation net were easily defined, (2) gross patterns of industry, residential and open space land were identified, but it was not possible to map the land use boundaries in great detail, (3) commercial land areas were often difficult to identify, and (4) multiple polarized imagery was helpful in correctly interpreting the total scene. It is found that the sensitivity of radar to surface roughness and the availability of multiple wavelength data allow the discrimination of variations in the surface roughness of intra-urban areas. An L-band imaging radar (25 cm; 1215-1225 GHz) of 25 m resolution will be operating from satellite altitudes in 1978 and will increase the availability of radar data.

TRMM Precipitation Radar Reflectivity Profiles Compared to High-Resolution Airborne and Ground-Based Radar Measurements

NASA Technical Reports Server (NTRS)

Heymsfield, G. M.; Geerts, B.; Tian, L.

1999-01-01

In this paper, TRMM (Tropical Rainfall Measuring Mission Satellite) Precipitation Radar (PR) products are evaluated by means of simultaneous comparisons with data from the high-altitude ER-2 Doppler Radar (EDOP), as well as ground-based radars. The comparison is aimed primarily at the vertical reflectivity structure, which is of key importance in TRMM rain type classification and latent heating estimation. The radars used in this study have considerably different viewing geometries and resolutions, demanding non-trivial mapping procedures in common earth-relative coordinates. Mapped vertical cross sections and mean profiles of reflectivity from the PR, EDOP, and ground-based radars are compared for six cases. These cases cover a stratiform frontal rainband, convective cells of various sizes and stages, and a hurricane. For precipitating systems that are large relative to the PR footprint size, PR reflectivity profiles compare very well to high-resolution measurements thresholded to the PR minimum reflectivity, and derived variables such as bright band height and rain types are accurate, even at high PR incidence angles. It was found that for, the PR reflectivity of convective cells small relative to the PR footprint is weaker than in reality. Some of these differences can be explained by non-uniform beam filling. For other cases where strong reflectivity gradients occur within a PR footprint, the reflectivity distribution is spread out due to filtering by the PR antenna illumination pattern. In these cases, rain type classification may err and be biased towards the stratiform type, and the average reflectivity tends to be underestimated. The limited sensitivity of the PR implies that the upper regions of precipitation systems remain undetected and that the PR storm top height estimate is unreliable, usually underestimating the actual storm top height. This applies to all cases but the discrepancy is larger for smaller cells where limited sensitivity is compounded

Radar scattering from desert terrains, Pisgah/Lavic Region, California: Implications for Magellan

NASA Technical Reports Server (NTRS)

Plaut, J. J.; Arvidson, R. E.; Wall, S.

1989-01-01

A major component of the 1988 Mojave Field Experiment involved the simultaneous acquisition of quad-polarization multifrequency airborne Synthetic Aperture Radar (SAR) imaging radar data and ground measurements thought to be relevant to the radar scattering behavior of a variety of desert surfaces. In preparation for the Magellan mission to Venus, the experiment was designed to explore the ability of SAR to distinguish types of geological surfaces, and the effects of varying incidence angles on the appearance of such surfaces. The airborne SAR system acquired images at approx. 10 m resolution, at 3 incidence angles (30, 40, 50 degs) and at 3 wavelengths (P:68 cm, L:24 cm, C:5.6 cm). The polarimetric capabilities of the instrument allow the simulation of any combination of transmit and receive polarizations during data reduction. Calibrated trihedral corner reflectors were deployed within each scene to permit absolute radiometric calibration of the image data. Initial analyses of this comprehensive radar data set is reported, with emphasis on implications for interpretation of Magellan data.

Radar velocity determination using direction of arrival measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doerry, Armin W.; Bickel, Douglas L.; Naething, Richard M.

The various technologies presented herein relate to utilizing direction of arrival (DOA) data to determine various flight parameters for an aircraft A plurality of radar images (e.g., SAR images) can be analyzed to identify a plurality of pixels in the radar images relating to one or more ground targets. In an embodiment, the plurality of pixels can be selected based upon the pixels exceeding a SNR threshold. The DOA data in conjunction with a measurable Doppler frequency for each pixel can be obtained. Multi-aperture technology enables derivation of an independent measure of DOA to each pixel based on interferometric analysis.more » This independent measure of DOA enables decoupling of the aircraft velocity from the DOA in a range-Doppler map, thereby enabling determination of a radar velocity. The determined aircraft velocity can be utilized to update an onboard INS, and to keep it aligned, without the need for additional velocity-measuring instrumentation.« less

Identification of corn fields using multidate radar data

NASA Technical Reports Server (NTRS)

Shanmugan, K. S.; Ulaby, F. T.; Narayanan, V.; Dobson, C.

1983-01-01

Airborne C- and L-band radar data acquired over a test site in western kansas were analyzed to determine corn-field identification accuracies obtainable using single-channel, multichannel, and multidate radar data. An automated pattern-recognition procedure was used to classify 144 fields into three categories: corn, pasture land, and bare soil (including wheat stubble and fallow). Corn fields were identified with accuracies ranging from 85 percent for single channel, single-date data to 100 percent for single-channel, multidate data. The effects of radar parameters such as frequency, polarization, and look angle as well as the effects of soil moisture on the classification accuracy are also presented.

Partitioning Ocean Wave Spectra Obtained from Radar Observations

NASA Astrophysics Data System (ADS)

Delaye, Lauriane; Vergely, Jean-Luc; Hauser, Daniele; Guitton, Gilles; Mouche, Alexis; Tison, Celine

2016-08-01

2D wave spectra of ocean waves can be partitioned into several wave components to better characterize the scene. We present here two methods of component detection: one based on watershed algorithm and the other based on a Bayesian approach. We tested both methods on a set of simulated SWIM data, the Ku-band real aperture radar embarked on the CFOSAT (China- France Oceanography Satellite) mission which launch is planned mid-2018. We present the results and the limits of both approaches and show that Bayesian method can also be applied to other kind of wave spectra observations as those obtained with the radar KuROS, an airborne radar wave spectrometer.

Tropical-Forest Structure and Biomass Dynamics from TanDEM-X Radar Interferometry

Treesearch

Robert Treuhaft; Yang Lei; Fabio Gonçalves; Michael Keller; João Santos; Maxim Neumann; André Almeida

2017-01-01

Changes in tropical-forest structure and aboveground biomass (AGB) contribute directly to atmospheric changes in CO2, which, in turn, bear on global climate. This paper demonstrates the capability of radar-interferometric phase-height time series at X-band (wavelength = 3 cm) to monitor changes in vertical structure and AGB, with sub-hectare and monthly spatial and...

77 FR 53962 - Technical Standard Order (TSO)-C68a, Airborne Automatic Dead Reckoning Computer Equipment...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-04

..., Airborne Automatic Dead Reckoning Computer Equipment Utilizing Aircraft Heading and Doppler Ground Speed.... ACTION: Notice of cancellation of Technical Standard Order (TSO)-C68a, Airborne Automatic Dead Reckoning... . SUPPLEMENTARY INFORMATION: Background Doppler radar is a semiautomatic self-contained dead reckoning navigation...

Directional ocean wave measurements in a coastal setting using a focused array imaging radar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frasier, S.J.; Liu, Y.; Moller, D.

1995-03-01

A unique focused array imaging Doppler radar was used to measure directional spectra of ocean surface waves in a nearshore experiment performed on the North Carolina Outer Banks. Radar images of the ocean surface`s Doppler velocity were used to generate two dimensional spectra of the radial component of the ocean surface velocity field. These are compared to simultaneous in-situ measurements made by a nearby array of submerged pressure sensors. Analysis of the resulting two-dimensional spectra include comparisons of dominant wave lengths, wave directions, and wave energy accounting for relative differences in water depth at the measurement locations. Limited estimates ofmore » the two-dimensional surface displacement spectrum are derived from the radar data. The radar measurements are analogous to those of interferometric synthetic aperture radars (INSAR), and the equivalent INSAR parameters are shown. The agreement between the remote and in-situ measurements suggests that an imaging Doppler radar is effective for these wave measurements at near grazing incidence angles.« less

Radar image and data fusion for natural hazards characterisation

USGS Publications Warehouse

Lu, Zhong; Dzurisin, Daniel; Jung, Hyung-Sup; Zhang, Jixian; Zhang, Yonghong

2010-01-01

Fusion of synthetic aperture radar (SAR) images through interferometric, polarimetric and tomographic processing provides an all - weather imaging capability to characterise and monitor various natural hazards. This article outlines interferometric synthetic aperture radar (InSAR) processing and products and their utility for natural hazards characterisation, provides an overview of the techniques and applications related to fusion of SAR/InSAR images with optical and other images and highlights the emerging SAR fusion technologies. In addition to providing precise land - surface digital elevation maps, SAR - derived imaging products can map millimetre - scale elevation changes driven by volcanic, seismic and hydrogeologic processes, by landslides and wildfires and other natural hazards. With products derived from the fusion of SAR and other images, scientists can monitor the progress of flooding, estimate water storage changes in wetlands for improved hydrological modelling predictions and assessments of future flood impacts and map vegetation structure on a global scale and monitor its changes due to such processes as fire, volcanic eruption and deforestation. With the availability of SAR images in near real - time from multiple satellites in the near future, the fusion of SAR images with other images and data is playing an increasingly important role in understanding and forecasting natural hazards.

Internal wave observations made with an airborne synthetic aperture imaging radar

NASA Technical Reports Server (NTRS)

Elachi, C.; Apel, J. R.

1976-01-01

Synthetic aperture L-band radar flown aboard the NASA CV-990 has observed periodic striations on the ocean surface off the coast of Alaska which have been interpreted as tidally excited oceanic internal waves of less than 500 m length. These radar images are compared to photographic imagery of similar waves taken from Landsat 1. Both the radar and Landsat images reveal variations in reflectivity across each wave in a packet that range from low to high to normal. The variations point to the simultaneous existence of two mechanisms for the surface signatures of internal waves: roughening due to wave-current interactions, and smoothing due to slick formation.

Snowpack displacement measured by terrestrial radar interferometry as precursor for wet snow avalanches

NASA Astrophysics Data System (ADS)

Caduff, Rafael; Wiesmann, Andreas; Bühler, Yves

2016-04-01

Wet snow and full depth gliding avalanches commonly occur on slopes during springtime when air temperatures rise above 0°C for longer time. The increase in the liquid water content changes the mechanical properties of the snow pack. Until now, forecasts of wet snow avalanches are mainly done using weather data such as air and snow temperatures and incoming solar radiation. Even tough some wet snow avalanche events are indicated before the release by the formation of visible signs such as extension cracks or compressional bulges in the snow pack, a large number of wet snow avalanches are released without any previously visible signs. Continuous monitoring of critical slopes by terrestrial radar interferometry improves the scale of reception of differential movement into the range of millimetres per hour. Therefore, from a terrestrial and remote observation location, information on the mechanical state of the snow pack can be gathered on a slope wide scale. Recent campaigns in the Swiss Alps showed the potential of snow deformation measurements with a portable, interferometric real aperture radar operating at 17.2 GHz (1.76 cm wavelength). Common error sources for the radar interferometric measurement of snow pack displacements are decorrelation of the snow pack at different conditions, the influence of atmospheric disturbances on the interferometric phase and transition effects from cold/dry snow to warm/wet snow. Therefore, a critical assessment of those parameters has to be considered in order to reduce phase noise effects and retrieve accurate displacement measurements. The most recent campaign in spring 2015 took place in Davos Dorf/GR, Switzerland and its objective was to observe snow glide activity on the Dorfberg slope. A validation campaign using total station measurements showed good agreement to the radar interferometric line of sight displacement measurements in the range of 0.5 mm/h. The refinement of the method led to the detection of numerous gliding

Polarimetric Measurements Over the Sea-Surface with the Airborne STORM Radar in the Context of the Geophysical Validation of the ENVISAT ASAR

NASA Astrophysics Data System (ADS)

Podvin, D. Hauser. T.; Dechambre, M.; Valentin, R.; Caudal, G.; Daloze, J.-F.; Mouche, A.

2003-04-01

Among the new specificities of the ENVISAT/ASAR particular polarization diversity make the instrument very promising, but require complementary studies in addition to those already completed with the ERS data. Moreover, in the context of the preparation of other missions which will embark polarimetric SAR (e.g. RADARSAT2) it is important to better assess the benefit of multi-polarization or polarimetric SAR systems. In particular, over the ocean the question remains open regarding the estimate of wind speed, directional spectra of surface ocean waves and maybe other parameters related to wave breaking. CETP has designed and developed a new airborne radar called STORM], which has a full polarimetric capability. STORM is a new-version of the RESSAC airborne radar already used in previous experiments (Hauser et al, JGR 1992). STORM is a real-aperture, C-Band system with a FM/CW transmission and with a rotating antenna to explore in azimuth. In addition to RESSAC (which was mono-polarized) it offers a polarization diversity (receiving simultaneously in H and V polarizations) which enables us to analyze the radar cross- section in HH, VV, HV, and other cross-polarized terms related to the scattering matrix. In the context of the validation of the ASAR wave mode of ENVISAT, a field experiment will be carried out in October and November 2002 over the ocean (offshore the coasts of Brittany, France), with STORM] embarked on the MERLIN-IV aircraft of Meteo-France. We intend to perform about 20 flights under the ENVISAT SAR swath during a one-month experiment, with overpasses over a directional wave buoy also equipped with wind measurements. The ASAR image mode (in HH or VV) or alternating polarization mode will be requested during these flights. STORM will be used in a mode which will permit to measure the full complex scattering matrix over the sea surface at incidence angles ranging from 10 to 35°. In addition to conventional analysis of the radar cross-sections in HH

Doppler synthetic aperture radar interferometry: a novel SAR interferometry for height mapping using ultra-narrowband waveforms

NASA Astrophysics Data System (ADS)

Yazıcı, Birsen; Son, Il-Young; Cagri Yanik, H.

2018-05-01

This paper introduces a new and novel radar interferometry based on Doppler synthetic aperture radar (Doppler-SAR) paradigm. Conventional SAR interferometry relies on wideband transmitted waveforms to obtain high range resolution. Topography of a surface is directly related to the range difference between two antennas configured at different positions. Doppler-SAR is a novel imaging modality that uses ultra-narrowband continuous waves (UNCW). It takes advantage of high resolution Doppler information provided by UNCWs to form high resolution SAR images. We introduce the theory of Doppler-SAR interferometry. We derive an interferometric phase model and develop the equations of height mapping. Unlike conventional SAR interferometry, we show that the topography of a scene is related to the difference in Doppler frequency between two antennas configured at different velocities. While the conventional SAR interferometry uses range, Doppler and Doppler due to interferometric phase in height mapping; Doppler-SAR interferometry uses Doppler, Doppler-rate and Doppler-rate due to interferometric phase in height mapping. We demonstrate our theory in numerical simulations. Doppler-SAR interferometry offers the advantages of long-range, robust, environmentally friendly operations; low-power, low-cost, lightweight systems suitable for low-payload platforms, such as micro-satellites; and passive applications using sources of opportunity transmitting UNCW.

Space Radar Image of Long Valley, California -Interferometry/Topography

NASA Image and Video Library

1999-05-01

These four images of the Long Valley region of east-central California illustrate the steps required to produced three dimensional data and topographics maps from radar interferometry. All data displayed in these images were acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour during its two flights in April and October, 1994. The image in the upper left shows L-band (horizontally transmitted and received) SIR-C radar image data for an area 34 by 59 kilometers (21 by 37 miles). North is toward the upper right; the radar illumination is from the top of the image. The bright areas are hilly regions that contain exposed bedrock and pine forest. The darker gray areas are the relatively smooth, sparsely vegetated valley floors. The dark irregular patch near the lower left is Lake Crowley. The curving ridge that runs across the center of the image from top to bottom is the northeast rim of the Long Valley Caldera, a remnant crater from a massive volcanic eruption that occurred about 750,000 years ago. The image in the upper right is an interferogram of the same area, made by combining SIR-C L-band data from the April and October flights. The colors in this image represent the difference in the phase of the radar echoes obtained on the two flights. Variations in the phase difference are caused by elevation differences. Formation of continuous bands of phase differences, known as interferometric "fringes," is only possible if the two observations were acquired from nearly the same position in space. For these April and October data takes, the shuttle tracks were less than 100 meters (328 feet) apart. The image in the lower left shows a topographic map derived from the interferometric data. The colors represent increments of elevation, as do the thin black contour lines, which are spaced at 50-meter (164-foot) elevation intervals. Heavy contour lines show 250-meter intervals (820-foot). Total relief in

Radar Determination of Fault Slip and Location in Partially Decorrelated Images

NASA Astrophysics Data System (ADS)

Parker, Jay; Glasscoe, Margaret; Donnellan, Andrea; Stough, Timothy; Pierce, Marlon; Wang, Jun

2017-06-01

Faced with the challenge of thousands of frames of radar interferometric images, automated feature extraction promises to spur data understanding and highlight geophysically active land regions for further study. We have developed techniques for automatically determining surface fault slip and location using deformation images from the NASA Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR), which is similar to satellite-based SAR but has more mission flexibility and higher resolution (pixels are approximately 7 m). This radar interferometry provides a highly sensitive method, clearly indicating faults slipping at levels of 10 mm or less. But interferometric images are subject to decorrelation between revisit times, creating spots of bad data in the image. Our method begins with freely available data products from the UAVSAR mission, chiefly unwrapped interferograms, coherence images, and flight metadata. The computer vision techniques we use assume no data gaps or holes; so a preliminary step detects and removes spots of bad data and fills these holes by interpolation and blurring. Detected and partially validated surface fractures from earthquake main shocks, aftershocks, and aseismic-induced slip are shown for faults in California, including El Mayor-Cucapah (M7.2, 2010), the Ocotillo aftershock (M5.7, 2010), and South Napa (M6.0, 2014). Aseismic slip is detected on the San Andreas Fault from the El Mayor-Cucapah earthquake, in regions of highly patterned partial decorrelation. Validation is performed by comparing slip estimates from two interferograms with published ground truth measurements.

NASA Radar Images Show Continued Deformation from Mexico Quake

NASA Image and Video Library

2010-08-04

This image shows a UAVSAR interferogram swath overlaid atop a Google Earth image. New NASA airborne radar images show the continuing deformation in Earth surface resulting from the magnitude 7.2 temblor in Baja California on April 4, 2010.

Frequency Agility Radar,

DTIC Science & Technology

1982-12-06

different model aircraft in different wave bands (P,L, S and X). Yet, the obtained results were relatively complex and it was not easy to find regularity...hertz for the S wave band . This type of narrow wave band signifies that the drift velocity of the target viewed in the reflection center is very low... Band of Airborne Radar With Pulse Width of 0.02)4 s and Grazing Angle of 470) Key: 1. Probability exceeding horizontal coordinates 2. Clutter section 3

Airborne surveys in the Arctic and Antarctic for geophysics, sea-ice thickness, and CryoSat validation

NASA Astrophysics Data System (ADS)

Forsberg, R.; Olesen, A. V.; Hvidegaard, S.; Skourup, H.

2010-12-01

Airborne laser and radar measurements over the Greenland ice sheet, Svalbard, and adjacent parts of the Arctic Ocean have been carried out by DTU-Space in a number of recent Danish/Greenlandic and European project campaigns, with the purpose to monitor ice sheet and sea-ice changes, support of Greenland societal needs (oil exploration and hydropower), and support of CryoSat pre-launch calibration and validation campaigns. The Arctic campaigns have been done using a Twin-Otter aircraft, carrying laser scanners and various radars. Since 2009 a new program of long-range gravity and magnetic surveys have been initiated using a Basler DC3 aircraft for large-scale surveys in the Arctic Ocean and Antarctica, with the 2010 cooperative Danish-Argentinean-Chilean-US ICEGRAV survey of the Antarctic Peninsula additionally including a UTIG 60 MHz ice-penetrating radar. In the paper we outline the recent and upcoming airborne survey activities, outline the usefulness of the airborne data for satellite validation (CryoSat and GOCE), and give examples of measurements and comparisons to satellite and in-situ data.

Study on analysis from sources of error for Airborne LIDAR

NASA Astrophysics Data System (ADS)

Ren, H. C.; Yan, Q.; Liu, Z. J.; Zuo, Z. Q.; Xu, Q. Q.; Li, F. F.; Song, C.

2016-11-01

With the advancement of Aerial Photogrammetry, it appears that to obtain geo-spatial information of high spatial and temporal resolution provides a new technical means for Airborne LIDAR measurement techniques, with unique advantages and broad application prospects. Airborne LIDAR is increasingly becoming a new kind of space for earth observation technology, which is mounted by launching platform for aviation, accepting laser pulses to get high-precision, high-density three-dimensional coordinate point cloud data and intensity information. In this paper, we briefly demonstrates Airborne laser radar systems, and that some errors about Airborne LIDAR data sources are analyzed in detail, so the corresponding methods is put forwarded to avoid or eliminate it. Taking into account the practical application of engineering, some recommendations were developed for these designs, which has crucial theoretical and practical significance in Airborne LIDAR data processing fields.

Radar measurement of L-band signal fluctuations caused by propagation through trees

NASA Technical Reports Server (NTRS)

Durden, Stephen L.; Klein, Jeffrey D.; Zebker, Howard A.

1991-01-01

Fluctuations of an L-band, horizontally polarized signal that was transmitted from the ground through a coniferous forest canopy to an airborne radar are examined. The azimuth synthetic aperture radar (SAR) impulse response in the presence of the measured magnitude fluctuations shows increased sidelobes over the case with no trees. Statistics of the observed fluctuations are similar to other observations.

Radar reflectivity of bare and vegetation-covered soil

NASA Technical Reports Server (NTRS)

Ulaby, F. T.; Dobson, M. C.; Bradley, G. A.

1981-01-01

Radar sensitivity to soil moisture content has been investigated experimentally for bare and vegetation-covered soil using detailed spectral measurements obtained by a truck-mounted radar spectrometer in the 1-8 GHz band and by airborne scatterometer observations at 1.6, 4.75, and 13.3 GHz. It is shown that radar can provide quantitative information on the soil moisture content of both bare and vegetation-covered soil. The observed soil moisture is in the form of the soil matric potential or a related quantity such as the percent of field capacity. The depth of the monitored layer varies from 1 cm for very wet soil to about 15 cm for very dry soil.

Rupture parameters of the 2003 Zemmouri (Mw 6.8), Algeria, earthquake from joint inversion of interferometric synthetic aperture radar, coastal uplift, and GPS

USGS Publications Warehouse

Belabbes, S.; Wicks, Charles; Cakir, Z.; Meghraoui, M.

2009-01-01

We study the surface deformation associated with the 21 May 2003 (M w = 6.8) Zemmouri (Algeria) earthquake, the strongest seismic event felt in the Algiers region since 1716. The thrust earthquake mechanism and related surface deformation revealed an average 0.50 m coastal uplift along ??55-km-long coastline. We obtain coseismic interferograms using Envisat advanced synthetic aperture radar (ASAR) (IS2) and RADARSAT standard beam (ST4) data from both the ascending and descending orbits of Envisat satellite, whereas the RADARSAT data proved useful only in the descending mode. While the two RADARSAT interferograms cover the earthquake area, Envisat data cover only the western half of the rupture zone. Although the interferometric synthetic aperture radar (InSAR) coherence in the epicenter area is poor, deformation fringes are observed along the coast in different patches. In the Boumerdes area, the maximum coseismic deformation is indicated by the high gradient of fringes visible in all interferograms in agreement with field measurements (tape, differential GPS, leveling, and GPS). To constrain the earthquake rupture parameters, we model the interferograms and uplift measurements using elastic dislocations on triangular fault patches in an elastic and homogeneous half-space. We invert the coseismic slip using first, a planar surface and second, a curved fault, both constructed from triangular elements using Poly3Dinv program that uses a damped least square minimization. The best fit of InSAR, coastal uplift, and GPS data corresponds to a 65-km-long fault rupture dipping 40?? to 50?? SE, located at 8 to 13 km offshore with a change in strike west of Boumerdes from N60??-65?? to N95??-105??. The inferred rupture geometry at depth correlates well with the seismological results and may have critical implications for the seismic hazard assessment of the Algiers region. Copyright 2009 by the American Geophysical Union.

Summaries of the Sixth Annual JPL Airborne Earth Science Workshop. Volume 1; AVIRIS Workshop

NASA Technical Reports Server (NTRS)

Green, Robert O. (Editor)

1996-01-01

This publication contains the summaries for the Sixth Annual JPL Airborne Earth Science Workshop, held in Pasadena, California, on March 4-8, 1996. The main workshop is divided into two smaller workshops as follows: (1) The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) workshop, on March 4-6. The summaries for this workshop appear in Volume 1; (2) The Airborne Synthetic Aperture Radar (AIRSAR) workshop, on March 6-8. The summaries for this workshop appear in Volume 2.

Operation of a Radar Altimeter over the Greenland Ice Sheet

NASA Technical Reports Server (NTRS)

Grund, Matthew D.

1996-01-01

This thesis presents documentation for the Advanced Application Flight Experiment (AAFE) pulse compression radar altimeter and its role in the NASA Multisensor Airborne Altimetry Experiment over Greenland in 1993. The AAFE Altimeter is a Ku-band microwave radar which has demonstrated 14 centimeter range precision in operation over arctic ice. Recent repairs and improvements were required to make the Greenland missions possible. Transmitter, receiver and software modifications, as well as the integration of a GPS receiver are thoroughly documented. Procedures for installation, and operation of the radar are described. Finally, suggestions are made for further system improvements.

Space-Time Adaptive Processing for Airborne Radar

DTIC Science & Technology

1994-12-13

horizontal plane Uniform linear antenna array (possibly columns of a planar array) Identical element patterns 13 14 15 9 7 7,33 7 7 Target Model ...Parameters for Example Scenario 31 3 Assumptions Made for Radar System and Signal Model 52 4 Platform and Interference Scenario for Baseline Scenario. 61 5...pulses, is addressed first. Fully adaptive STAP requires the solution to a system of linear equations of size MN, where N is the number of array

Integrated Airborne and In-Situ Measurements over Land-Fast Ice near Barrow, AK

NASA Astrophysics Data System (ADS)

Brozena, J. M.; Gardner, J. M.; Liang, R.; Vermillion, M.; Ball, D.; Stoudt, C. A.; Geiger, C. A.; Woods, J. E.; Samluk, J.; Deliberty, T. L.

2013-12-01

During March of 2013, the Naval Research Laboratory, the University of Delaware and the US Naval Academy collected an integrated set of measurements over the largely floating, but land-fast ice near the coast of Barrow, AK. The purpose of the collection was to compare airborne remote sensing methods of collection to in-situ ground-truth measurements. Airborne measurements include scanning LiDAR (Riegl Q 680i), digital photogrammetry (Applanix DSS-439) and a short-pulse (~ 1 nsec) 10 GHz radar altimeter. The LiDAR measures total freeboard (ice + snow) referenced to leads in the ice. The radar measures approximate ice freeboard with the difference with the LiDAR providing an estimate of snow thickness. The freeboard measurements are aimed at estimating ice thickness via estimates of densities and isostasy. The photogrammetry was used to measure ice motion over free-floating sea-ice, but provided only a velocity calibration and general situational awareness over the land-fast ice. Ground measurements were collected along a transect, and included boreholes, snow-thickness (Magnaprobe), and ice thickness (EM31). Airborne data were collected on six overflights of this transect over a three week period. LiDAR swath widths ranged from 200-300m (depending on altitude) and encompassed three grounded ridges which remained essentially stationary over the collection period, that together with the shoreline, provided fixed reference points to compare the heights of the floating ice that varied with the tide (and to some extent the snow conditions). Sampling size or 'footprint' plays a critical role in the attempt to compare in-situ measurements with airborne (or satellite) measurements. Boreholes are point measurements and are difficult enough to obtain, that only a limited number are practical during a survey period. EM31 and Magnaprobe instrumentation allows collection of snow and ice thickness along one-dimensional profiles, and several adjacent profiles can be collected to

SLAPex Freeze/Thaw 2015: The First Dedicated Soil Freeze/Thaw Airborne Campaign

NASA Technical Reports Server (NTRS)

Kim, Edward; Wu, Albert; DeMarco, Eugenia; Powers, Jarrett; Berg, Aaron; Rowlandson, Tracy; Freeman, Jacqueline; Gottfried, Kurt; Toose, Peter; Roy, Alexandre;

Radar Image with Color as Height, Sman Teng, Temple, Cambodia

NASA Image and Video Library

2002-10-11

This image, taken by NASA Airborne Synthetic Aperture Radar AIRSAR in 2002, is of Cambodia Angkor region revealing a temple upper-right not depicted on early 19th Century French archeological survey maps and American topographic maps.

Single-pass Airborne InSAR for Wide-swath, High-Resolution Cryospheric Surface Topography Mapping

NASA Astrophysics Data System (ADS)

Moller, D.; Hensley, S.; Wu, X.; Muellerschoen, R.

2014-12-01

In May 2009 a mm-wave single-pass interferometric synthetic aperture radar (InSAR) for the first time demonstrated ice surface topography swath-mapping in Greenland. This was achieved with the airborne Glacier and Ice Surface Topography Interferometer (GLISTIN-A). Ka-band (35.6GHz) was chosen for high-precision topographic mapping from a compact sensor with minimal surface penetration. In recent years, the system was comprehensively upgraded for improved performance, stability and calibration. In April 2013, after completing the upgrades, GLISTIN-A flew a brief campaign to Alaska. The primary purpose was to demonstrate the InSAR's ability to generate high-precision, high resolution maps of ice surface topography with swaths in excess of 10km. Comparison of GLISTIN-A's elevations over glacial ice with lidar verified the precision requirements and established elevation accuracies to within 2 m without tie points. Feature tracking of crevasses on Columbia Glacier using data acquired with a 3-day separation exhibit an impressive velocity mapping capability. Furthermore, GLISTIN-A flew over the Beaufort sea to determine if we could not only map sea ice, but also measure freeboard. Initial analysis has established we can measure sea-ice freeboard using height differences from the top of the sea-ice and the sea surface in open leads. In the future, a campaign with lidar is desired for a quantitative validation. Another proof-of-concept collection mapped snow-basins for hydrology. Snow depth measurements using summer and winter collections in the Sierras were compared with lidar measurements. Unsurprisingly when present, trees complicate the interpretation, but additional filtering and processing is in work. For each application, knowledge of the interferometric penetration is important for scientific interpretation. We present analytical predictions and experimental data to upper bound the elevation bias of the InSAR measurements over snow and snow-covered ice.

An observation of sea-spray microphysics by airborne Doppler radar

NASA Astrophysics Data System (ADS)

Fairall, C. W.; Pezoa, S.; Moran, K.; Wolfe, D.

2014-05-01

This paper describes observations and analysis of Doppler radar data from a down-looking 94 GHz (W-Band) system operated from a NOAA WP-3 Orion research aircraft in Tropical Storm (TS) Karen. The flight took place on 5 October 2013; Karen had weakened with maximum winds around 20 m s-1. Doppler spectral moments from the radar were processed to retrieve sea-spray microphysical properties (drop size and liquid water mass concentration) profiles in the height range 75-300 m above the sea surface. In the high wind speed regions of TS Karen (U10 > 15 m s-1), sea spray was observed with a nominal mass-mode radius of about 40 µm, a radar-weighted gravitational fall velocity of about 1 m s-1, and a mass concentration of about 10-3 gm-3 at 75 m. Spray-drop mass concentration declined with height to values of about 10-4 gm-3 at 300 m. Drop mass decreased slightly more slowly with increasing height than predicted by surface-layer similarity theory for a balance of turbulent diffusion vs fall velocity.

MAJOR SOURCE OF NEW RADAR DATA FOR EXPLORATION RESEARCH.

USGS Publications Warehouse

Kover, Allan N.; Jones, John Edwin; Southworth, C. Scott

1984-01-01

In 1980, the U. S. Geological Survey (USGS) initiated a program to acquire high-quality, side-looking, airborne-radar (SLAR) imagery of selected areas of the United States. The program goals were to demonstrate the usefulness of SLAR imagery for geologic exploration and geoscience applications and to make radar data readily available to the public for additional research and economic applications. Considerable SLAR imagery has been acquired already since 1980 under a mandate from the U. S. Congress. The U. S. Geological Survey is actively engaged in demonstrating the usefulness of radar imagery, and since 1980 has started more than 50 studies addressing geologic, cartographic, and hydrologic applications. All of the radar-imagery products acquired by the USGS during 1980 and 1982 have been archived and are available for public sale.

14 CFR 135.173 - Airborne thunderstorm detection equipment requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Airborne thunderstorm detection equipment requirements. 135.173 Section 135.173 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... weather radar equipment. (b) No person may operate a helicopter that has a passenger seating configuration...

14 CFR 135.173 - Airborne thunderstorm detection equipment requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Airborne thunderstorm detection equipment requirements. 135.173 Section 135.173 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... weather radar equipment. (b) No person may operate a helicopter that has a passenger seating configuration...

14 CFR 135.173 - Airborne thunderstorm detection equipment requirements.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Airborne thunderstorm detection equipment requirements. 135.173 Section 135.173 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... weather radar equipment. (b) No person may operate a helicopter that has a passenger seating configuration...

Analysis of Interferometric Synthetic Aperture Radar Phase Data at Brady Hot Springs, Nevada, USA Using Prior Information

NASA Astrophysics Data System (ADS)

Reinisch, E. C.; Ali, S. T.; Cardiff, M. A.; Morency, C.; Kreemer, C.; Feigl, K. L.; Team, P.

2016-12-01

Time-dependent deformation has been observed at Brady Hot Springs using interferometric synthetic aperture radar (InSAR) [Ali et al. 2016, http://dx.doi.org/10.1016/j.geothermics.2016.01.008]. Our goal is to evaluate multiple competing hypotheses to explain the observed deformation at Brady. To do so requires statistical tests that account for uncertainty. Graph theory is useful for such an analysis of InSAR data [Reinisch, et al. 2016, http://dx.doi.org/10.1007/s00190-016-0934-5]. In particular, the normalized edge Laplacian matrix calculated from the edge-vertex incidence matrix of the graph of the pair-wise data set represents its correlation and leads to a full data covariance matrix in the weighted least squares problem. This formulation also leads to the covariance matrix of the epoch-wise measurements, representing their relative uncertainties. While the formulation in terms of incidence graphs applies to any quantity derived from pair-wise differences, the modulo-2π ambiguity of wrapped phase renders the problem non-linear. The conventional practice is to unwrap InSAR phase before modeling, which can introduce mistakes without increasing the corresponding measurement uncertainty. To address this issue, we are applying Bayesian inference. To build the likelihood, we use three different observables: (a) wrapped phase [e.g., Feigl and Thurber 2009, http://dx.doi.org/10.1111/j.1365-246X.2008.03881.x]; (b) range gradients, as defined by Ali and Feigl [2012, http://dx.doi.org/10.1029/2012GC004112]; and (c) unwrapped phase, i.e. range change in mm, which we validate using GPS data. We apply our method to InSAR data taken over Brady Hot Springs geothermal field in Nevada as part of a project entitled "Poroelastic Tomography by Adjoint Inverse Modeling of Data from Seismology, Geodesy, and Hydrology" (PoroTomo) [ http://geoscience.wisc.edu/feigl/porotomo].

Measuring ocean coherence time with dual-baseline interferometry

NASA Technical Reports Server (NTRS)

Carande, Richard E.

1992-01-01

Using the Jet Propulsion Laboratory (JPL) Airborne Synthetic Aperture Radar (AIRSAR) interferometer, measurements of the ocean coherence time at L and C band can be made at high spatial resolution. Fundamental to this measurement is the ability to image the ocean interferometrically at two different time-lags, or baselines. By modifying the operating procedure of the existing two antenna interferometer, a technique was developed make these measurements. L band coherence times are measured and presented.

ESA airborne campaigns in support of Earth Explorers

NASA Astrophysics Data System (ADS)

Casal, Tania; Davidson, Malcolm; Schuettemeyer, Dirk; Perrera, Andrea; Bianchi, Remo

2013-04-01

In the framework of its Earth Observation Programmes the European Space Agency (ESA) carries out ground based and airborne campaigns to support geophysical algorithm development, calibration/validation, simulation of future spaceborne earth observation missions, and applications development related to land, oceans and atmosphere. ESA has been conducting airborne and ground measurements campaigns since 1981 by deploying a broad range of active and passive instrumentation in both the optical and microwave regions of the electromagnetic spectrum such as lidars, limb/nadir sounding interferometers/spectrometers, high-resolution spectral imagers, advanced synthetic aperture radars, altimeters and radiometers. These campaigns take place inside and outside Europe in collaboration with national research organisations in the ESA member states as well as with international organisations harmonising European campaign activities. ESA campaigns address all phases of a spaceborne missions, from the very beginning of the design phase during which exploratory or proof-of-concept campaigns are carried out to the post-launch exploitation phase for calibration and validation. We present four recent campaigns illustrating the objectives and implementation of such campaigns. Wavemill Proof Of Concept, an exploratory campaign to demonstrate feasibility of a future Earth Explorer (EE) mission, took place in October 2011 in the Liverpool Bay area in the UK. The main objectives, successfully achieved, were to test Astrium UKs new airborne X-band SAR instrument capability to obtain high resolution ocean current and topology retrievals. Results showed that new airborne instrument is able to retrieve ocean currents to an accuracy of ± 10 cms-1. The IceSAR2012 campaign was set up to support of ESA's EE Candidate 7,BIOMASS. Its main objective was to document P-band radiometric signatures over ice-sheets, by upgrading ESA's airborne POLARIS P-band radar ice sounder with SAR capability. Campaign

Summaries of the Third Annual JPL Airborne Geoscience Workshop. Volume 1: AVIRIS Workshop

NASA Technical Reports Server (NTRS)

Green, Robert O. (Editor)

1992-01-01

This publication contains the preliminary agenda and summaries for the Third Annual JPL Airborne Geoscience Workshop, held at the Jet Propulsion Laboratory, Pasadena, California, on 1-5 June 1992. This main workshop is divided into three smaller workshops as follows: (1) the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) workshop, on June 1 and 2; (2) the Thermal Infrared Multispectral Scanner (TIMS) workshop, on June 3; and (3) the Airborne Synthetic Aperture Radar (AIRSAR) workshop, on June 4 and 5. The summaries are contained in Volumes 1, 2, and 3, respectively.

Applicability of interferometric SAR technology to ground movement and pipeline monitoring

NASA Astrophysics Data System (ADS)

Grivas, Dimitri A.; Bhagvati, Chakravarthy; Schultz, B. C.; Trigg, Alan; Rizkalla, Moness

1998-03-01

This paper summarizes the findings of a cooperative effort between NOVA Gas Transmission Ltd. (NGTL), the Italian Natural Gas Transmission Company (SNAM), and Arista International, Inc., to determine whether current remote sensing technologies can be utilized to monitor small-scale ground movements over vast geographical areas. This topic is of interest due to the potential for small ground movements to cause strain accumulation in buried pipeline facilities. Ground movements are difficult to monitor continuously, but their cumulative effect over time can have a significant impact on the safety of buried pipelines. Interferometric synthetic aperture radar (InSAR or SARI) is identified as the most promising technique of those considered. InSAR analysis involves combining multiple images from consecutive passes of a radar imaging platform. The resulting composite image can detect changes as small as 2.5 to 5.0 centimeters (based on current analysis methods and radar satellite data of 5 centimeter wavelength). Research currently in progress shows potential for measuring ground movements as small as a few millimeters. Data needed for InSAR analysis is currently commercially available from four satellites, and additional satellites are planned for launch in the near future. A major conclusion of the present study is that InSAR technology is potentially useful for pipeline integrity monitoring. A pilot project is planned to test operational issues.

Radar attenuation and temperature within the Greenland Ice Sheet

USGS Publications Warehouse

MacGregor, Joseph A; Li, Jilu; Paden, John D; Catania, Ginny A; Clow, Gary D.; Fahnestock, Mark A; Gogineni, Prasad S.; Grimm, Robert E.; Morlighem, Mathieu; Nandi, Soumyaroop; Seroussi, Helene; Stillman, David E

2015-01-01

The flow of ice is temperature-dependent, but direct measurements of englacial temperature are sparse. The dielectric attenuation of radio waves through ice is also temperature-dependent, and radar sounding of ice sheets is sensitive to this attenuation. Here we estimate depth-averaged radar-attenuation rates within the Greenland Ice Sheet from airborne radar-sounding data and its associated radiostratigraphy. Using existing empirical relationships between temperature, chemistry, and radar attenuation, we then infer the depth-averaged englacial temperature. The dated radiostratigraphy permits a correction for the confounding effect of spatially varying ice chemistry. Where radar transects intersect boreholes, radar-inferred temperature is consistently higher than that measured directly. We attribute this discrepancy to the poorly recognized frequency dependence of the radar-attenuation rate and correct for this effect empirically, resulting in a robust relationship between radar-inferred and borehole-measured depth-averaged temperature. Radar-inferred englacial temperature is often lower than modern surface temperature and that of a steady state ice-sheet model, particularly in southern Greenland. This pattern suggests that past changes in surface boundary conditions (temperature and accumulation rate) affect the ice sheet's present temperature structure over a much larger area than previously recognized. This radar-inferred temperature structure provides a new constraint for thermomechanical models of the Greenland Ice Sheet.

14 CFR 135.173 - Airborne thunderstorm detection equipment requirements.

Code of Federal Regulations, 2010 CFR

2010-01-01

... more in passenger-carrying operations, except a helicopter operating under day VFR conditions, unless..., excluding any pilot seat, of 10 seats or more in passenger-carrying operations, under night VFR when current... approved airborne weather radar equipment. (c) No person may begin a flight under IFR or night VFR...

YSAR: a compact low-cost synthetic aperture radar

NASA Astrophysics Data System (ADS)

Thompson, Douglas G.; Arnold, David V.; Long, David G.; Miner, Gayle F.; Karlinsey, Thomas W.; Robertson, Adam E.

1997-09-01

The Brigham Young University Synthetic Aperture Radar (YSAR) is a compact, inexpensive SAR system which can be flown on a small aircraft. The system has exhibited a resolution of approximately 0.8 m by 0.8 m in test flights in calm conditions. YSAR has been used to collect data over archeological sites in Israel. Using a relatively low frequency (2.1 GHz), we hope to be able to identify walls or other archeological features to assist in excavation. A large data set of radar and photographic data have been collected over sites at Tel Safi, Qumran, Tel Micnah, and the Zippori National Forest in Israel. We show sample images from the archeological data. We are currently working on improved autofocus algorithms for this data and are developing a small, low-cost interferometric SAR system (YINSAR) for operation from a small aircraft.

Calibration Software for Use with Jurassicprok

NASA Technical Reports Server (NTRS)

Chapin, Elaine; Hensley, Scott; Siqueira, Paul

2004-01-01

The Jurassicprok Interferometric Calibration Software (also called "Calibration Processor" or simply "CP") estimates the calibration parameters of an airborne synthetic-aperture-radar (SAR) system, the raw measurement data of which are processed by the Jurassicprok software described in the preceding article. Calibration parameters estimated by CP include time delays, baseline offsets, phase screens, and radiometric offsets. CP examines raw radar-pulse data, single-look complex image data, and digital elevation map data. For each type of data, CP compares the actual values with values expected on the basis of ground-truth data. CP then converts the differences between the actual and expected values into updates for the calibration parameters in an interferometric calibration file (ICF) and a radiometric calibration file (RCF) for the particular SAR system. The updated ICF and RCF are used as inputs to both Jurassicprok and to the companion Motion Measurement Processor software (described in the following article) for use in generating calibrated digital elevation maps.

Summaries of the 4th Annual JPL Airborne Geoscience Workshop. Volume 3: AIRSAR Workshop

NASA Technical Reports Server (NTRS)

Vanzyl, Jakob (Editor)

1993-01-01

This publication contains the summaries for the Fourth Annual JPL Airborne Geoscience Workshop, held in Washington, D.C. on October 25-29, 1993. The main workshop is divided into three smaller workshops as follows: The Airborne Visible/Infrared Spectrometer (AVIRIS) workshop, on October 25-26, whose summaries appear in Volume 1; The Thermal Infrared Multispectral Scanner (TIMS) workshop, on October 27, whose summaries appear in Volume 2; and The Airborne Synthetic Aperture Radar (AIRSAR) workshop, on October 28-29, whose summaries appear in this volume, Volume 3.

Modeling L-band synthetic aperture radar observations through dielectric changes in soil moisture and vegetation over shrublands

USDA-ARS?s Scientific Manuscript database

L-band airborne synthetic aperture radar observations were made over California shrublands to better understand the effects by soil and vegetation parameters on backscatter. Temporal changes in radar backscattering coefficient (s0) of up to 3 dB were highly correlated to surface soil moisture but no...

A comparison of airborne GEMS/SAR with satellite-borne Seasat/SAR radar imagery - The value of archived multiple data sets

NASA Technical Reports Server (NTRS)

Hanson, Bradford C.; Dellwig, Louis F.

1988-01-01

In a study concerning the value of using radar imagery from systems with diverse parameters, X-band images of the Northern Louisiana Salt dome area generated by the airborne Goodyear electronic mapping system (GEMS) are analyzed in conjunction with imagery generated by the satelliteborne Seasat/SAR. The GEMS operated with an incidence angle of 75 to 85 deg and a resolution of 12 m, whereas the Seasat/SAR operated with an incidence angle of 23 deg and a resolution of 25 m. It is found that otherwise unattainable data on land management activities, improved delineation of the drainage net, better definition of surface roughness in cleared areas, and swamp identification, became accessible when adjustments for the time lapse between the two missions were made and supporting ground data concerning the physical and vegetative characteristics of the terrain were acquired.

Retrieve Optically Thick Ice Cloud Microphysical Properties by Using Airborne Dual-Wavelength Radar Measurements

NASA Technical Reports Server (NTRS)

Wang, Zhien; Heymsfield, Gerald M.; Li, Lihua; Heymsfield, Andrew J.

2005-01-01

An algorithm to retrieve optically thick ice cloud microphysical property profiles is developed by using the GSFC 9.6 GHz ER-2 Doppler Radar (EDOP) and the 94 GHz Cloud Radar System (CRS) measurements aboard the high-altitude ER-2 aircraft. In situ size distribution and total water content data from the CRYSTAL-FACE field campaign are used for the algorithm development. To reduce uncertainty in calculated radar reflectivity factors (Ze) at these wavelengths, coincident radar measurements and size distribution data are used to guide the selection of mass-length relationships and to deal with the density and non-spherical effects of ice crystals on the Ze calculations. The algorithm is able to retrieve microphysical property profiles of optically thick ice clouds, such as, deep convective and anvil clouds, which are very challenging for single frequency radar and lidar. Examples of retrieved microphysical properties for a deep convective clouds are presented, which show that EDOP and CRS measurements provide rich information to study cloud structure and evolution. Good agreement between IWPs derived from an independent submillimeter-wave radiometer, CoSSIR, and dual-wavelength radar measurements indicates accuracy of the IWC retrieved from the two-frequency radar algorithm.

Windshear detection radar signal processing studies

NASA Technical Reports Server (NTRS)

Baxa, Ernest G., Jr.

1993-01-01

This final report briefly summarizes research work at Clemson in the Radar Systems Laboratory under the NASA Langley Research Grant NAG-1-928 in support of the Antenna and Microwave Branch, Guidance and Control Division, program to develop airborne sensor technology for the detection of low altitude windshear. A bibliography of all publications generated by Clemson personnel is included. An appendix provides abstracts of all publications.

Fault zone structure and kinematics from lidar, radar, and imagery: revealing new details along the creeping San Andreas Fault

NASA Astrophysics Data System (ADS)

DeLong, S.; Donnellan, A.; Pickering, A.

2017-12-01

Aseismic fault creep, coseismic fault displacement, distributed deformation, and the relative contribution of each have important bearing on infrastructure resilience, risk reduction, and the study of earthquake physics. Furthermore, the impact of interseismic fault creep in rupture propagation scenarios, and its impact and consequently on fault segmentation and maximum earthquake magnitudes, is poorly resolved in current rupture forecast models. The creeping section of the San Andreas Fault (SAF) in Central California is an outstanding area for establishing methodology for future scientific response to damaging earthquakes and for characterizing the fine details of crustal deformation. Here, we describe how data from airborne and terrestrial laser scanning, airborne interferometric radar (UAVSAR), and optical data from satellites and UAVs can be used to characterize rates and map patterns of deformation within fault zones of varying complexity and geomorphic expression. We are evaluating laser point cloud processing, photogrammetric structure from motion, radar interferometry, sub-pixel correlation, and other techniques to characterize the relative ability of each to measure crustal deformation in two and three dimensions through time. We are collecting new and synthesizing existing data from the zone of highest interseismic creep rates along the SAF where a transition from a single main fault trace to a 1-km wide extensional stepover occurs. In the stepover region, creep measurements from alignment arrays 100 meters long across the main fault trace reveal lower rates than those in adjacent, geomorphically simpler parts of the fault. This indicates that deformation is distributed across the en echelon subsidiary faults, by creep and/or stick-slip behavior. Our objectives are to better understand how deformation is partitioned across a fault damage zone, how it is accommodated in the shallow subsurface, and to better characterize the relative amounts of fault creep

Site Characterization for Radar Experiments

DTIC Science & Technology

1990-08-01

accomplished waz "New Mine Detection Technologies," Mr. Jack Stoll, Principal Investigator. The Environmental Systems Division (EST) of the Environmental...Mr. Steve Bong of Hilton Systems visiting the proposed study site in M’rch to select specific locations for the test plots. The field data coll in...Technology/Lincoln Laboratory (MIT/LL) described an airborne 35-Ghz radar imaging system . The MIT/LL would employ various kinds of processing on the

Collation of earth resources data collected by ERIM airborne sensors

NASA Technical Reports Server (NTRS)

Hasell, P. G., Jr.

1975-01-01

Earth resources imagery from nine years of data collection with developmental airborne sensors is cataloged for reference. The imaging sensors include single and multiband line scanners and side-looking radars. The operating wavelengths of the sensors include ultraviolet, visible and infrared band scanners, and X- and L-band radar. Imagery from all bands (radar and scanner) were collected at some sites and many sites had repeated coverage. The multiband scanner data was radiometrically calibrated. Illustrations show how the data can be used in earth resource investigations. References are made to published reports which have made use of the data in completed investigations. Data collection sponsors are identified and a procedure described for gaining access to the data.

Airborne radar technology for windshear detection

NASA Technical Reports Server (NTRS)

Hibey, Joseph L.; Khalaf, Camille S.

1988-01-01

The objectives and accomplishments of the two-and-a-half year effort to describe how returns from on-board Doppler radar are to be used to detect the presence of a wind shear are reported. The problem is modeled as one of first passage in terms of state variables, the state estimates are generated by a bank of extended Kalman filters working in parallel, and the decision strategy involves the use of a voting algorithm for a series of likelihood ratio tests. The performance issue for filtering is addressed in terms of error-covariance reduction and filter divergence, and the performance issue for detection is addressed in terms of using a probability measure transformation to derive theoretical expressions for the error probabilities of a false alarm and a miss.

Current test results for the Athena radar responsive tag

NASA Astrophysics Data System (ADS)

Ormesher, Richard C.; Martinez, Ana; Plummer, Kenneth W.; Erlandson, David; Delaware, Sheri; Clark, David R.

2006-05-01

Sandia National Laboratories has teamed with General Atomics and Sierra Monolithics to develop the Athena tag for the Army's Radar Tag Engagement (RaTE) program. The radar-responsive Athena tag can be used for Blue Force tracking and Combat Identification (CID) as well as data collection, identification, and geolocation applications. The Athena tag is small (~4.5" x 2.4" x 4.2"), battery-powered, and has an integral antenna. Once remotely activated by a Synthetic Aperture Radar (SAR) or Moving Target Indicator (MTI) radar, the tag transponds modulated pulses to the radar at a low transmit power. The Athena tag can operate Ku-band and X-band airborne SAR and MTI radars. This paper presents results from current tag development testing activities. Topics covered include recent field tests results from the AN/APY-8 Lynx, F16/APG-66, and F15E/APG-63 V(1) radars and other Fire Control radars. Results show that the Athena tag successfully works with multiple radar platforms, in multiple radar modes, and for multiple applications. Radar-responsive tags such as Athena have numerous applications in military and government arenas. Military applications include battlefield situational awareness, combat identification, targeting, personnel recovery, and unattended ground sensors. Government applications exist in nonproliferation, counter-drug, search-and-rescue, and land-mapping activities.

Estimation of forest fuel load from radar remote sensing

USGS Publications Warehouse

Saatchi, S.; Halligan, K.; Despain, Don G.; Crabtree, R.L.

2007-01-01

Understanding fire behavior characteristics and planning for fire management require maps showing the distribution of wildfire fuel loads at medium to fine spatial resolution across large landscapes. Radar sensors from airborne or spaceborne platforms have the potential of providing quantitative information about the forest structure and biomass components that can be readily translated to meaningful fuel load estimates for fire management. In this paper, we used multifrequency polarimetric synthetic aperture radar (SAR) imagery acquired over a large area of the Yellowstone National Park by the Airborne SAR sensor to estimate the distribution of forest biomass and canopy fuel loads. Semiempirical algorithms were developed to estimate crown and stem biomass and three major fuel load parameters, namely: 1) canopy fuel weight; 2) canopy bulk density; and 3) foliage moisture content. These estimates, when compared directly to measurements made at plot and stand levels, provided more than 70% accuracy and, when partitioned into fuel load classes, provided more than 85% accuracy. Specifically, the radar-generated fuel parameters were in good agreement with the field-based fuel measurements, resulting in coefficients of determination of R2 = 85 for the canopy fuel weight, R 2 = 0.84 for canopy bulk density, and R2 =0.78 for the foliage biomass. ?? 2007 IEEE.

Structural geologic interpretations from radar imagery

USGS Publications Warehouse

Reeves, Robert G.

1969-01-01

Certain structural geologic features may be more readily recognized on sidelooking airborne radar (SLAR) images than on conventional aerial photographs, other remote sensor imagery, or by ground observations. SLAR systems look obliquely to one or both sides and their images resemble aerial photographs taken at low sun angle with the sun directly behind the camera. They differ from air photos in geometry, resolution, and information content. Radar operates at much lower frequencies than the human eye, camera, or infrared sensors, and thus "sees" differently. The lower frequency enables it to penetrate most clouds and some precipitation, haze, dust, and some vegetation. Radar provides its own illumination, which can be closely controlled in intensity and frequency. It is narrow band, or essentially monochromatic. Low relief and subdued features are accentuated when viewed from the proper direction. Runs over the same area in significantly different directions (more than 45° from each other), show that images taken in one direction may emphasize features that are not emphasized on those taken in the other direction; optimum direction is determined by those features which need to be emphasized for study purposes. Lineaments interpreted as faults stand out on radar imagery of central and western Nevada; folded sedimentary rocks cut by faults can be clearly seen on radar imagery of northern Alabama. In these areas, certain structural and stratigraphic features are more pronounced on radar images than on conventional photographs; thus radar imagery materially aids structural interpretation.

Summaries of the Seventh JPL Airborne Earth Science Workshop January 12-16, 1998. Volume 1; AVIRIS Workshop

NASA Technical Reports Server (NTRS)

Green, Robert O. (Editor)

1998-01-01

This publication contains the summaries for the Seventh JPL Airborne Earth Science Workshop, held in Pasadena, California, on January 12-16, 1998. The main workshop is divided into three smaller workshops, and each workshop has a volume as follows: (1) Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) Workshop; (2) Airborne Synthetic Aperture Radar (AIRSAR) Workshop; and (3) Thermal Infrared Multispectral Scanner (TIMS) Workshop. This Volume 1 publication contains 58 papers taken from the AVIRIS workshop.

UAVSAR Instrument: Current Operations and Planned Upgrades

NASA Technical Reports Server (NTRS)

Lou, Yunling; Hensley, Scott; Chao, Roger; Chapin, Elaine; Heavy, Brandon; Jones, Cathleen; Miller, Timothy; Naftel, Chris; Fratello, David

2011-01-01

The Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) instrument is a pod-based Lband polarimetric synthetic aperture radar (SAR), specifically designed to acquire airborne repeat track SAR data for differential interferometric measurements. This instrument is currently installed on the NASA Gulfstream- III (G-III) aircraft with precision real-time Global Positioning System (GPS) and a sensor-controlled flight management system for precision repeat-pass data acquisitions. UAVSAR has conducted engineering and preliminary science data flights since October 2007 on the G-III. We are porting the radar to the Global Hawk Unmanned Airborne Vehicle (UAV) to enable long duration/long range data campaigns. We plan to install two radar pods (each with its own active array antenna) under the wings of the Global Hawk to enable the generation of precision topographic maps and single pass polarimetric-interferometry (SPI) providing vertical structure of ice and vegetation. Global Hawk's range of 8000 nm will enable regional surveys with far fewer sorties as well as measurements of remote locations without the need for long and complicated deployments. We are also developing P-band polarimetry and Ka-band single-pass interferometry capabilities on UAVSAR by replacing the radar antenna and front-end electronics to operate at these

Randomly iterated search and statistical competency as powerful inversion tools for deformation source modeling: Application to volcano interferometric synthetic aperture radar data

NASA Astrophysics Data System (ADS)

Shirzaei, M.; Walter, T. R.

2009-10-01

Modern geodetic techniques provide valuable and near real-time observations of volcanic activity. Characterizing the source of deformation based on these observations has become of major importance in related monitoring efforts. We investigate two random search approaches, simulated annealing (SA) and genetic algorithm (GA), and utilize them in an iterated manner. The iterated approach helps to prevent GA in general and SA in particular from getting trapped in local minima, and it also increases redundancy for exploring the search space. We apply a statistical competency test for estimating the confidence interval of the inversion source parameters, considering their internal interaction through the model, the effect of the model deficiency, and the observational error. Here, we present and test this new randomly iterated search and statistical competency (RISC) optimization method together with GA and SA for the modeling of data associated with volcanic deformations. Following synthetic and sensitivity tests, we apply the improved inversion techniques to two episodes of activity in the Campi Flegrei volcanic region in Italy, observed by the interferometric synthetic aperture radar technique. Inversion of these data allows derivation of deformation source parameters and their associated quality so that we can compare the two inversion methods. The RISC approach was found to be an efficient method in terms of computation time and search results and may be applied to other optimization problems in volcanic and tectonic environments.

Adaptive Unscented Kalman Filter Phase Unwrapping Method and Its Application on Gaofen-3 Interferometric SAR Data.

PubMed

Gao, Yandong; Zhang, Shubi; Li, Tao; Chen, Qianfu; Li, Shijin; Meng, Pengfei

2018-06-02

Phase unwrapping (PU) is a key step in the reconstruction of digital elevation models (DEMs) and the monitoring of surface deformation from interferometric synthetic aperture radar (SAR, InSAR) data. In this paper, an improved PU method that combines an amended matrix pencil model, an adaptive unscented kalman filter (AUKF), an efficient quality-guided strategy based on heapsort, and a circular median filter is proposed. PU theory and the existing UKFPU method are covered. Then, the improved method is presented with emphasis on the AUKF and the circular median filter. AUKF has been well used in other fields, but it is for the first time applied to interferometric images PU, to the best of our knowledge. First, the amended matrix pencil model is used to estimate the phase gradient. Then, an AUKF model is used to unwrap the interferometric phase based on an efficient quality-guided strategy based on heapsort. Finally, the key results are obtained by filtering the results using a circular median. The proposed method is compared with the minimum cost network flow (MCF), statistical cost network flow (SNAPHU), regularized phase tracking technique (RPTPU), and UKFPU methods using two sets of simulated data and two sets of experimental GF-3 SAR data. The improved method is shown to yield the greatest accuracy in the interferometric phase maps compared to the methods considered in this paper. Furthermore, the improved method is shown to be the most robust to noise and is thus most suitable for PU of GF-3 SAR data in high-noise and low-coherence regions.

Summaries of the 4th Annual JPL Airborne Geoscience Workshop. Volume 1: AVIRIS Workshop

NASA Technical Reports Server (NTRS)

Green, Robert O. (Editor)

1993-01-01

This publication contains the summaries for the Fourth Annual JPL Airborne Geoscience Workshop, held in Washington, D. C. October 25-29, 1993 The main workshop is divided into three smaller workshops as follows: The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) workshop, October 25-26 (the summaries for this workshop appear in this volume, Volume 1); The Thermal Infrared Multispectral Scanner (TMIS) workshop, on October 27 (the summaries for this workshop appear in Volume 2); and The Airborne Synthetic Aperture Radar (AIRSAR) workshop, October 28-29 (the summaries for this workshop appear in Volume 3).

Planetary landing-zone reconnaissance using ice-penetrating radar data: Concept validation in Antarctica

NASA Astrophysics Data System (ADS)

Grima, Cyril; Schroeder, Dustin M.; Blankenship, Donald D.; Young, Duncan A.

2014-11-01

The potential for a nadir-looking radar sounder to retrieve significant surface roughness/permittivity information valuable for planetary landing site selection is demonstrated using data from an airborne survey of the Thwaites Glacier Catchment, West Antarctica using the High Capability Airborne Radar Sounder (HiCARS). The statistical method introduced by Grima et al. (2012. Icarus 220, 84-99. http://dx.doi.org/10.1007/s11214-012-9916-y) for surface characterization is applied systematically along the survey flights. The coherent and incoherent components of the surface signal, along with an internally generated confidence factor, are extracted and mapped in order to show how a radar sounder can be used as both a reflectometer and a scatterometer to identify regions of low surface roughness compatible with a planetary lander. These signal components are used with a backscattering model to produce a landing risk assessment map by considering the following surface properties: Root mean square (RMS) heights, RMS slopes, roughness homogeneity/stationarity over the landing ellipse, and soil porosity. Comparing these radar-derived surface properties with simultaneously acquired nadir-looking imagery and laser-altimetry validates this method. The ability to assess all of these parameters with an ice penetrating radar expands the demonstrated capability of a principle instrument in icy planet satellite science to include statistical reconnaissance of the surface roughness to identify suitable sites for a follow-on lander mission.

Imaging Radar Applications in the Death Valley Region

NASA Technical Reports Server (NTRS)

Farr, Tom G.

1996-01-01

Death Valley has had a long history as a testbed for remote sensing techniques (Gillespie, this conference). Along with visible-near infrared and thermal IR sensors, imaging radars have flown and orbited over the valley since the 1970's, yielding new insights into the geologic applications of that technology. More recently, radar interferometry has been used to derive digital topographic maps of the area, supplementing the USGS 7.5' digital quadrangles currently available for nearly the entire area. As for their shorter-wavelength brethren, imaging radars were tested early in their civilian history in Death Valley because it has a variety of surface types in a small area without the confounding effects of vegetation. In one of the classic references of these early radar studies, in a semi-quantitative way the response of an imaging radar to surface roughness near the radar wavelength, which typically ranges from about 1 cm to 1 m was explained. This laid the groundwork for applications of airborne and spaceborne radars to geologic problems in and regions. Radar's main advantages over other sensors stems from its active nature- supplying its own illumination makes it independent of solar illumination and it can also control the imaging geometry more accurately. Finally, its long wavelength allows it to peer through clouds, eliminating some of the problems of optical sensors, especially in perennially cloudy and polar areas.

Digital Radar-Signal Processors Implemented in FPGAs

NASA Technical Reports Server (NTRS)

Berkun, Andrew; Andraka, Ray

2004-01-01

High-performance digital electronic circuits for onboard processing of return signals in an airborne precipitation- measuring radar system have been implemented in commercially available field-programmable gate arrays (FPGAs). Previously, it was standard practice to downlink the radar-return data to a ground station for postprocessing a costly practice that prevents the nearly-real-time use of the data for automated targeting. In principle, the onboard processing could be performed by a system of about 20 personal- computer-type microprocessors; relative to such a system, the present FPGA-based processor is much smaller and consumes much less power. Alternatively, the onboard processing could be performed by an application-specific integrated circuit (ASIC), but in comparison with an ASIC implementation, the present FPGA implementation offers the advantages of (1) greater flexibility for research applications like the present one and (2) lower cost in the small production volumes typical of research applications. The generation and processing of signals in the airborne precipitation measuring radar system in question involves the following especially notable steps: The system utilizes a total of four channels two carrier frequencies and two polarizations at each frequency. The system uses pulse compression: that is, the transmitted pulse is spread out in time and the received echo of the pulse is processed with a matched filter to despread it. The return signal is band-limited and digitally demodulated to a complex baseband signal that, for each pulse, comprises a large number of samples. Each complex pair of samples (denoted a range gate in radar terminology) is associated with a numerical index that corresponds to a specific time offset from the beginning of the radar pulse, so that each such pair represents the energy reflected from a specific range. This energy and the average echo power are computed. The phase of each range bin is compared to the previous echo

Comparison of interferometric and stereo-radargrammetric 3D metrics in mapping of forest resources

NASA Astrophysics Data System (ADS)

Karila, K.; Karjalainen, M.; Yu, X.; Vastaranta, M.; Holopainen, M.; Hyyppa, J.

2015-04-01

Accurate forest resources maps are needed in diverse applications ranging from the local forest management to the global climate change research. In particular, it is important to have tools to map changes in forest resources, which helps us to understand the significance of the forest biomass changes in the global carbon cycle. In the task of mapping changes in forest resources for wide areas, Earth Observing satellites could play the key role. In 2013, an EU/FP7-Space funded project "Advanced_SAR" was started with the main objective to develop novel forest resources mapping methods based on the fusion of satellite based 3D measurements and in-situ field measurements of forests. During the summer 2014, an extensive field surveying campaign was carried out in the Evo test site, Southern Finland. Forest inventory attributes of mean tree height, basal area, mean stem diameter, stem volume, and biomass, were determined for 91 test plots having the size of 32 by 32 meters (1024 m2). Simultaneously, a comprehensive set of satellite and airborne data was collected. Satellite data also included a set of TanDEM-X (TDX) and TerraSAR-X (TSX) X-band synthetic aperture radar (SAR) images, suitable for interferometric and stereo-radargrammetric processing to extract 3D elevation data representing the forest canopy. In the present study, we compared the accuracy of TDX InSAR and TSX stereo-radargrammetric derived 3D metrics in forest inventory attribute prediction. First, 3D data were extracted from TDX and TSX images. Then, 3D data were processed as elevations above the ground surface (forest canopy height values) using an accurate Digital Terrain Model (DTM) based on airborne laser scanning survey. Finally, 3D metrics were calculated from the canopy height values for each test plot and the 3D metrics were compared with the field reference data. The Random Forest method was used in the forest inventory attributes prediction. Based on the results InSAR showed slightly better

Summaries of the Sixth Annual JPL Airborne Earth Science Workshop, March 4-8, 1996. Volume 2; AIRSAR Workshop

NASA Technical Reports Server (NTRS)

Kim, Yunjin (Editor)

1996-01-01

This publication contains the summaries for the Sixth Annual JPL Airborne Earth Science Workshop, held in Pasadena, California, on March 4-8, 1996. The main workshop is divided into two smaller workshops as follows: The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) workshop, on March 4-6. The summaries for this workshop appear in Volume 1. The Airborne Synthetic Aperture Radar (AIRSAR) workshop, on March 6-8. The summaries for this workshop appear in Volume 2.

Surface Water Detection Using Fused Synthetic Aperture Radar, Airborne LiDAR and Optical Imagery

NASA Astrophysics Data System (ADS)

Braun, A.; Irwin, K.; Beaulne, D.; Fotopoulos, G.; Lougheed, S. C.

2016-12-01

Each remote sensing technique has its unique set of strengths and weaknesses, but by combining techniques the classification accuracy can be increased. The goal of this project is to underline the strengths and weaknesses of Synthetic Aperture Radar (SAR), LiDAR and optical imagery data and highlight the opportunities where integration of the three data types can increase the accuracy of identifying water in a principally natural landscape. The study area is located at the Queen's University Biological Station, Ontario, Canada. TerraSAR-X (TSX) data was acquired between April and July 2016, consisting of four single polarization (HH) staring spotlight mode backscatter intensity images. Grey-level thresholding is used to extract surface water bodies, before identifying and masking zones of radar shadow and layover by using LiDAR elevation models to estimate the canopy height and applying simple geometry algorithms. The airborne LiDAR survey was conducted in June 2014, resulting in a discrete return dataset with a density of 1 point/m2. Radiometric calibration to correct for range and incidence angle is applied, before classifying the points as water or land based on corrected intensity, elevation, roughness, and intensity density. Panchromatic and multispectral (4-band) imagery from Quickbird was collected in September 2005 at spatial resolutions of 0.6m and 2.5m respectively. Pixel-based classification is applied to identify and distinguish water bodies from land. A classification system which inputs SAR-, LiDAR- and optically-derived water presence models in raster formats is developed to exploit the strengths and weaknesses of each technique. The total percentage of water detected in the sample area for SAR backscatter, LiDAR intensity, and optical imagery was 27%, 19% and 18% respectively. The output matrix of the classification system indicates that in over 72% of the study area all three methods agree on the classification. Analysis was specifically targeted

Adaptive Noise Reduction Techniques for Airborne Acoustic Sensors

DTIC Science & Technology

2012-01-01

and Preamplifiers . . . . . . . . . . . . . . . . . . . . 16 3.3.2 Audio Recorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 iv 4...consuming less energy than active systems such as radar, lidar, or sonar [5]. Ground and marine-based acoustic arrays are currently employed in a variety of...factors for the performance of an airborne acoustic array. 3.3.1 Audio Microphones and Preamplifiers An audio microphone is a transducer that converts

Accident investigation: Analysis of aircraft motions from ATC radar recordings

NASA Technical Reports Server (NTRS)

Wingrove, R. C.

1976-01-01

A technique was developed for deriving time histories of an aircraft's motion from air traffic control (ATC) radar records. This technique uses the radar range and azimuth data, along with the downlinked altitude data (from an onboard Mode-C transponder), to derive an expanded set of data which includes airspeed, lift, thrust-drag, attitude angles (pitch, roll, and heading), etc. This method of analyzing aircraft motions was evaluated through flight experiments which used the CV-990 research aircraft and recordings from both the enroute and terminal ATC radar systems. The results indicate that the values derived from the ATC radar records are for the most part in good agreement with the corresponding values obtained from airborne measurements. In an actual accident, this analysis of ATC radar records can complement the flight-data recorders, now onboard airliners, and provide a source of recorded information for other types of aircraft that are equipped with Mode-C transponders but not with onboard recorders.

Forest discrimination with multipolarization imaging radar

NASA Technical Reports Server (NTRS)

Ford, J. P.; Wickland, D. E.

1985-01-01

The use of radar polarization diversity for discriminating forest canopy variables on airborne synthetic-aperture radar (SAR) images is evaluated. SAR images were acquired at L-Band (24.6 cm) simultaneously in four linear polarization states (HH, HV, VH, and VV) in South Carolina on March 1, 1984. In order to relate the polarization signatures to biophysical properties, false-color composite images were compared to maps of forest stands in the timber compartment. In decreasing order, the most useful correlative forest data are stand basal area, forest age, site condition index, and forest management type. It is found that multipolarization images discriminate variation in tree density and difference in the amount of understory, but do not discriminate between evergreen and deciduous forest types.

Joint stars phased array radar antenna

NASA Astrophysics Data System (ADS)

Shnitkin, Harold

1994-10-01

The Joint STARS phased array radar system is capable of performing long range airborne surveillance and was used during the Persian Gulf war on two E8-A aircraft to fly many around-the-clock missions to monitor the Kuwait and Iraq battlefield from a safe distance behind the front lines. This paper is a follow-on to previous publications on the subject of the Joint STARS antenna and deals mainly with mission performance and technical aspects not previously covered. Radar data of troop movements and armament installations will be presented, a brief review of the antenna design is given, followed by technical discussions concerning the three-port interferometry, gain and sidelobe design approach, cost control, range test implementation and future improvements.

Low-frequency radar sounder over Glaciers in Alaska, Greenland and Antarctica

NASA Astrophysics Data System (ADS)

Mouginot, J.; Rignot, E. J.; Gim, Y.; Kirchner, D. L.; Merritt, S.; Robison, W. T.

2009-12-01

Ice-thickness and basal layer topography measurements are needed to calculate fluxes through fast-flowing outlet glaciers in Greenland, Alaska, Patagonia and Antarctica. However, relatively high attenuation of radio waves by dielectric absorption and volume scattering from englacial water restrains detection of the bed through warm deep ice. Using a low-frequency (1-5 MHz) airborne radar, we have sounded outlet fast glaciers over Greenland (Store, Upernavik, Hellheim, …), East Antarctica (David, Mertz, Dibble, Byrd, …) and Alaska (Bering, Maslapina, Bagley, …). We will show that we detected the bed through temperate ice up to 1000m thick over Bering and Maslapina Glaciers and also point out difficulty in detecting bed of other Alaska glaciers due to off-nadir returns. We will also make direct comparison of this radar and previous airborne measurements in Greenland and Antarctica in order to discuss a potential improvement of bedrock detectability in temperate ice.

Development of NASA's Next Generation L-Band Digital Beamforming Synthetic Aperture Radar (DBSAR-2)

NASA Technical Reports Server (NTRS)

Rincon, Rafael; Fatoyinbo, Temilola; Osmanoglu, Batuhan; Lee, Seung-Kuk; Ranson, K. Jon; Marrero, Victor; Yeary, Mark

2014-01-01

NASA's Next generation Digital Beamforming SAR (DBSAR-2) is a state-of-the-art airborne L-band radar developed at the NASA Goddard Space Flight Center (GSFC). The instrument builds upon the advanced architectures in NASA's DBSAR-1 and EcoSAR instruments. The new instrument employs a 16-channel radar architecture characterized by multi-mode operation, software defined waveform generation, digital beamforming, and configurable radar parameters. The instrument has been design to support several disciplines in Earth and Planetary sciences. The instrument was recently completed, and tested and calibrated in a anechoic chamber.

Characterization of airborne transducers by optical tomography

PubMed

Bou Matar O; Pizarro; Certon; Remenieras; Patat

2000-03-01

This paper describes the application of an acousto-optic method to the measurement of airborne ultrasound. The method consists of a heterodyne interferometric probing of the pressure emitted by the transducer combined with a tomographic algorithm. The heterodyne interferometer measures the optical phase shift of the probe laser beam, proportional to the acoustic pressure integrated along the light path. A number of projections of the sound field, e.g. a set of ray integrals obtained along parallel paths, are made in moving the transducer to be tested. The main advantage of the method is its very high sensitivity in air (2 x 10(-4) Pa Hz-1/2), combined with a large bandwidth. Using the same principle as X-ray tomography the ultrasonic pressure in a plane perpendicular to the transducer axis can be reconstructed. Several ultrasonic fields emitted by wide-band home made electrostatic transducers, with operating frequencies between 200 and 700 kHz, have been measured. The sensitivities compared favorably with those of commercial airborne transducers.

Study of Movement and Seepage Along Levees Using DINSAR and the Airborne UAVSAR Instrument

NASA Technical Reports Server (NTRS)

Jones, Cathleen E.; Bawden, Gerald; Deverel, Steven; Dudas, Joel; Hensley, Scott

2012-01-01

We have studied the utility of high resolution SAR (synthetic aperture radar) for levee monitoring using UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar) data collected along the dikes and levees in California's Sacramento-San Joaquin Delta and along the lower Mississippi River. Our study has focused on detecting and tracking changes that are indicative of potential problem spots, namely deformation of the levees, subsidence along the levee toe, and seepage through the levees, making use of polarimetric and interferometric SAR techniques. Here was present some results of those studies, which show that high resolution, low noise SAR imaging could supplement more traditional ground-based monitoring methods by providing early indicators of seepage and deformation.

Summaries of the Fifth Annual JPL Airborne Earth Science Workshop. Volume 3: AIRSAR Workshop

NASA Technical Reports Server (NTRS)

Vanzyl, Jakob (Editor)

1995-01-01

This publication is the third containing summaries for the Fifth Annual JPL Airborne Earth Science Workshop, held in Pasadena, California, on January 23-26, 1995. The main workshop is divided into three smaller workshops as follows: (1) The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) workshop, on January 23-24. The summaries for this workshop appear in Volume 1; (2) The Airborne synthetic Aperture Radar (AIRSAR) workshop, on January 25-26. The summaries for this workshop appear in this volume; and (3) The Thermal Infrared Multispectral Scanner (TIMS) workshop, on January 26. The summaries for this workshop appear in Volume 2.

Summaries of the Fifth Annual JPL Airborne Earth Science Workshop. Volume 1: AVIRIS Workshop

NASA Technical Reports Server (NTRS)

Green, Robert O. (Editor)

1995-01-01

This publication is the first of three containing summaries for the Fifth Annual JPL Airborne Earth Science Workshop, held in Pasadena, California, on January 23-26, 1995. The main workshop is divided into three smaller workshops as follows: (1) The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) workshop, on January 23-24. The summaries for this workshop appear in this volume; (2) The Airborne Synthetic Aperture Radar (AIRSAR) workshop, on January 25-26. The summaries for this workshop appear in Volume 3; and (3) The Thermal Infrared Multispectral Scanner (TIMS) workshop, on January 26. The summaries for this workshop appear in Volume 2.

Summaries of the Fifth Annual JPL Airborne Earth Science Workshop. Volume 2: TIMS Workshop

NASA Technical Reports Server (NTRS)

Realmuto, Vincent J. (Editor)

1995-01-01

This publication is the second volume of the summaries for the Fifth Annual JPL Airborne Earth Science Workshop, held in Pasadena, California, on January 23-26, 1995. The main workshop is divided into three smaller workshops as follows: (1) The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) workshop on January 23-24. The summaries for this workshop appear in Volume 1; (2) The Airborne Synthetic Aperture Radar (AIRSAR) workshop on January 25-26. The summaries for this workshop appear in volume 3; and (3) The Thermal Infrared Multispectral Scanner (TIMS) workshop on January 26. The summaries for this workshop appear in this volume.

Development and Testing of the VAHIRR Radar Product

NASA Technical Reports Server (NTRS)

Barrett, Joe III; Miller, Juli; Charnasky, Debbie; Gillen, Robert; Lafosse, Richard; Hoeth, Brian; Hood, Doris; McNamara, Todd

2008-01-01

Lightning Launch Commit Criteria (LLCC) and Flight Rules (FR) are used for launches and landings at government and commercial spaceports. They are designed to avoid natural and triggered lightning strikes to space vehicles, which can endanger the vehicle, payload, and general public. The previous LLCC and FR were shown to be overly restrictive, potentially leading to costly launch delays and scrubs. A radar algorithm called Volume Averaged Height Integrated Radar Reflectivity (VAHIRR), along with new LLCC and FR for anvil clouds, were developed using data collected by the Airborne Field Mill II research program. VAHIRR is calculated at every horizontal position in the coverage area of the radar and can be displayed similar to a two-dimensional derived reflectivity product, such as composite reflectivity or echo tops. It is the arithmetic product of two quantities not currently generated by the Weather Surveillance Radar 1988 Doppler (WSR-88D): a volume average of the reflectivity measured in dBZ and the average cloud thickness based on the average echo top height and base height. This presentation will describe the VAHIRR algorithm, and then explain how the VAHIRR radar product was implemented and tested on a clone of the National Weather Service's (NWS) Open Radar Product Generator (ORPG-clone). The VAHIRR radar product was then incorporated into the Advanced Weather Interactive Processing System (AWIPS), to make it more convenient for weather forecasters to utilize. Finally, the reliability of the VAHIRR radar product was tested with real-time level II radar data from the WSR-88D NWS Melbourne radar.

Radar and infrared remote sensing of terrain, water resources, arctic sea ice, and agriculture

NASA Technical Reports Server (NTRS)

Biggs, A. W.

1983-01-01

Radar range measurements, basic waveforms of radar systems, and radar displays are initially described. These are followed by backscatter from several types of terrain and vegetation as a function of frequency and grazing angle. Analytical models for this backscatter include the facet models of radar return, with range-angle, velocity-range, velocity-angle, range, velocity, and angular only discriminations. Several side-looking airborne radar geometries are presented. Radar images of Arctic sea ice, fresh water lake ice, cloud-covered terrain, and related areas are presented to identify applications of radar imagery. Volume scatter models are applied to radar imagery from alpine snowfields. Short pulse ice thickness radar for subsurface probes is discussed in fresh-water ice and sea ice detection. Infrared scanners, including multispectral, are described. Diffusion of cold water into a river, Arctic sea ice, power plant discharges, volcanic heat, and related areas are presented in thermal imagery. Multispectral radar and infrared imagery are discussed, with comparisons of photographic, infrared, and radar imagery of the same terrain or subjects.

Detecting and Measuring Land Subsidence in Houston-Galveston, Texas using Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System Data, 2012-2016

NASA Astrophysics Data System (ADS)

Reed, A.; Baker, S.

2016-12-01

Several cities in the Houston-Galveston (HG) region in Texas have subsided up to 13 feet over several decades due to natural and anthropogenic processes [Yu et al. 2014]. Land subsidence, a gradual sinking of the Earth's surface, is an often human-induced hazard and a major environmental problem expedited by activities such as mining, oil and gas extraction, urbanization and excessive groundwater pumping. We are able to detect and measure subsidence in HG using interferometric synthetic aperture radar (InSAR) and global positioning systems (GPS). Qu et al. [2015] used ERS, Envisat, and ALOS-1 to characterize subsidence in HG from 1995 to 2011, but a five-year gap in InSAR measurements exists due to a lack of freely available SAR data. We build upon the previous study by comparing subsidence patterns detected by Sentinel-1 data starting in July 2015. We used GMT5SAR to generate a stack of interferograms with perpendicular baselines less than 100 meters and temporal baselines less than 100 days to minimize temporal and spatial decorrelation. We applied the short baseline subset (SBAS) time series processing using GIAnT and compared our results with GPS measurements. The implications of this work will strengthen land subsidence monitoring systems in HG and broadly aid in the development of effective water resource management policies and strategies.

Lava-flow characterization at Pisgah Volcanic Field, California, with multiparameter imaging radar

USGS Publications Warehouse

Gaddis, L.R.

1992-01-01

Multi-incidence-angle (in the 25?? to 55?? range) radar data aquired by the NASA/JPL Airborne Synthetic Aperture Radar (AIRSAR) at three wavelengths simultaneously and displayed at three polarizations are examined for their utility in characterizing lava flows at Pisgah volcanic field, California. Pisgah lava flows were erupted in three phases; flow textures consist of hummocky pahoehoe, smooth pahoehoe, and aa (with and without thin sedimentary cover). Backscatter data shown as a function of relative age of Pisgah flows indicate that dating of lava flows on the basis of average radar backscatter may yield ambiguous results if primary flow textures and modification processes are not well understood. -from Author

Summaries of the Third Annual JPL Airborne Geoscience Workshop. Volume 2: TIMS Workshop

NASA Technical Reports Server (NTRS)

Realmuto, Vincent J. (Editor)

1992-01-01

This publication contains the preliminary agenda and summaries for the Third Annual JPL Airborne Geoscience Workshop, held at the Jet Propulsion Laboratory, Pasadena, California, on 1-5 June 1992. This main workshop is divided into three smaller workshops as follows: (1) the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) workshop, on June 1 and 2; the summaries for this workshop appear in Volume 1; (2) the Thermal Infrared Multispectral Scanner (TIMS) workshop, on June 3; the summaries for this workshop appear in Volume 2; and (3) the Airborne Synthetic Aperture Radar (AIRSAR) workshop, on June 4 and 5; the summaries for this workshop appear in Volume 3.

Summaries of the Third Annual JPL Airborne Geoscience Workshop. Volume 3: AIRSAR Workshop

NASA Technical Reports Server (NTRS)

Vanzyl, Jakob (Editor)

1992-01-01

This publication contains the preliminary agenda and summaries for the Third Annual JPL Airborne Geoscience Workshop, held at the Jet Propulsion Laboratory, Pasadena, California, on 1-5 June 1992. This main workshop is divided into three smaller workshops as follows: (1) the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) workshop, on June 1 and 2; the summaries for this workshop appear in Volume 1; (2) the Thermal Infrared Multispectral Scanner (TIMS) workshop, on June 3; the summaries for this workshop appear in Volume 2; and (3) the Airborne Synthetic Aperture Radar (AIRSAR) workshop, on June 4 and 5; the summaries for this workshop appear in Volume 3.

Multiband radar characterization of forest biomes

NASA Technical Reports Server (NTRS)

Dobson, M. Craig; Ulaby, Fawwaz T.

1990-01-01

The utility of airborne and orbital SAR in classification, assessment, and monitoring of forest biomes is investigated through analysis of orbital synthetic aperature radar (SAR) and multifrequency and multipolarized airborne SAR imagery relying on image tone and texture. Preliminary airborne SAR experiments and truck-mounted scatterometer observations demonstrated that the three dimensional structural complexity of a forest, and the various scales of temporal dynamics in the microwave dielectric properties of both trees and the underlying substrate would severely limit empirical or semi-empirical approaches. As a consequence, it became necessary to develop a more profound understanding of the electromagnetic properties of a forest scene and their temporal dynamics through controlled experimentation coupled with theoretical development and verification. The concatenation of various models into a physically-based composite model treating the entire forest scene became the major objective of the study as this is the key to development of a series of robust retrieval algorithms for forest biophysical properties. In order to verify the performance of the component elements of the composite model, a series of controlled laboratory and field experiments were undertaken to: (1) develop techniques to measure the microwave dielectric properties of vegetation; (2) relate the microwave dielectric properties of vegetation to more readily measured characteristics such as density and moisture content; (3) calculate the radar cross-section of leaves, and cylinders; (4) improve backscatter models for rough surfaces; and (5) relate attenuation and phase delays during propagation through canopies to canopy properties. These modeling efforts, as validated by the measurements, were incorporated within a larger model known as the Michigan Microwave Canopy Scattering (MIMICS) Model.

Using Airborne Radar Stratigraphy to Model Surface Accumulation Anomaly and Basal Control over Deformed Basal Ice in Greenland

NASA Astrophysics Data System (ADS)

Das, I.; Bell, R. E.; Creyts, T. T.; Wolovick, M.

2013-12-01

Large deformed ice structures have been imaged at the base of northern Greenland ice sheet by IceBridge airborne radar. Numerous deformed structures lie along the base of both Petermann Glacier and Northeast Ice stream catchments covering 10-13% of the catchment area. These structures may be combinations of basal freeze-on and folded ice that overturns and inverts stratigraphy. In the interior, where the ice velocity is low, the radar imaged height of the deformed structures are frequently a significant fraction of the ice thickness. They are related to basal freeze on and stick-slip at the base of the ice sheet and may be triggered by subglacial water, sediments or local geological conditions. The larger ones (at times up to 700 m thick and 140 km long) perturb the ice stratigraphy and create prominent undulations on the ice surface and modify the local surface mass balance. Here, we investigate the relationship between the deformed structures and surface processes using shallow and deep ice radar stratigraphy. The surface undulations caused by the deformed structures modulate the pattern of local surface snow accumulation. Using normalized differences of several near-surface stratigraphic layers, we have calculated the accumulation anomaly over these deformed structures. The accumulation anomalies can be as high as 20% of the local surface accumulation over some of the larger surface depressions caused by these deformed structures. We observe distinct differences in the phases of the near-surface internal layers on the Petermann and Northeast catchments. These differences indicate that the deformed bodies over Petermann are controlled by conditions at the bed different from the Northeast Ice stream. The distinctly different near-surface stratigraphy over the deformed structures in the Petermann and Northeast catchments have opened up a number of questions including their formation and how they influence the ice dynamics, ice stratigraphy and surface mass balance

UAVSAR Active Electronically-Scanned Array

NASA Technical Reports Server (NTRS)

Sadowy, Gregory; Brown, Kyle; Chamberlain, Neil; Figueroa, Harry; Fisher, Charlie; Grando, Maurio; Hamilton, Gary; Vorperian, Vatche; Zawadzki, Mark

2010-01-01

The Uninhabited Airborne Vehicle Synthetic Aperture Radar (UAVSAR) L-band (1.2-1.3 GHz) repeat pass, interferometric synthetic aperture radar (InSAR) used for Earth science applications. Using complex radar images collected during separate passes on time scales of hours to years, changes in surface topography can be measured. The repeat-pass InSAR technique requires that the radar look angle be approximately the same on successive passes. Due to variations in aircraft attitude between passes, antenna beam steering is required to replicate the radar look angle. This paper describes an active, electronically steered array (AESA) that provides beam steering capability in the antenna azimuth plane. The array contains 24 transmit/receive modules generating 2800 W of radiated power and is capable of pulse-to-pulse beam steering and polarization agility. Designed for high reliability as well as serviceability, all array electronics are contained in single 178cm x 62cm x 12 cm air-cooled panel suitable for operation up 60,000 ft altitude.

Space Radar Image of Kilauea Volcano, Hawaii

NASA Image and Video Library

1999-05-01

This three-dimensional image of the volcano Kilauea was generated based on interferometric fringes derived from two X-band Synthetic Aperture Radar data takes on April 13, 1994 and October 4, 1994. The altitude lines are based on quantitative interpolation of the topographic fringes. The level difference between neighboring altitude lines is 20 meters (66 feet). The ground area covers 12 kilometers by 4 kilometers (7.5 miles by 2.5 miles). The altitude difference in the image is about 500 meters (1,640 feet). The volcano is located around 19.58 degrees north latitude and 155.55 degrees west longitude. http://photojournal.jpl.nasa.gov/catalog/PIA01761

An Improved Interferometric Calibration Method Based on Independent Parameter Decomposition

NASA Astrophysics Data System (ADS)

Fan, J.; Zuo, X.; Li, T.; Chen, Q.; Geng, X.

2018-04-01

Interferometric SAR is sensitive to earth surface undulation. The accuracy of interferometric parameters plays a significant role in precise digital elevation model (DEM). The interferometric calibration is to obtain high-precision global DEM by calculating the interferometric parameters using ground control points (GCPs). However, interferometric parameters are always calculated jointly, making them difficult to decompose precisely. In this paper, we propose an interferometric calibration method based on independent parameter decomposition (IPD). Firstly, the parameters related to the interferometric SAR measurement are determined based on the three-dimensional reconstruction model. Secondly, the sensitivity of interferometric parameters is quantitatively analyzed after the geometric parameters are completely decomposed. Finally, each interferometric parameter is calculated based on IPD and interferometric calibration model is established. We take Weinan of Shanxi province as an example and choose 4 TerraDEM-X image pairs to carry out interferometric calibration experiment. The results show that the elevation accuracy of all SAR images is better than 2.54 m after interferometric calibration. Furthermore, the proposed method can obtain the accuracy of DEM products better than 2.43 m in the flat area and 6.97 m in the mountainous area, which can prove the correctness and effectiveness of the proposed IPD based interferometric calibration method. The results provide a technical basis for topographic mapping of 1 : 50000 and even larger scale in the flat area and mountainous area.

Artifacts in Radar Imaging of Moving Targets

DTIC Science & Technology

2012-09-01

CA, USA, 2007. [11] B. Borden, Radar imaging of airborne targets: A primer for Applied mathematicians and Physicists . New York, NY: Taylor and... Project (0704–0188) Washington DC 20503. 1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 21 September 2012 3. REPORT TYPE AND DATES COVERED...CW Continuous Wave DAC Digital to Analog Convertor DFT Discrete Fourier Transform FBP Filtered Back Projection FFT Fast Fourier Transform GPS

Spatial and Temporal Characteristics of Land Deformation in Northern Saudi Arabia: Inferences from Radar Interferometric Applications

NASA Astrophysics Data System (ADS)

Othman, A.; Sultan, M.; Gebremichael, E.; Sefry, S.; Yanar, R.; Alharbi, H.; Albalawi, S.; Emil, M. K.; Pankratz, H. G.

2016-12-01

Over the past two decades, land deformation phenomena and related losses in public and private property were reported from the northern part of the Kingdom of Saudi Arabia in Al Jowf region (100,212 km²; from lat: 29.25°N to 30.90°N, from long: 37.60°E to 40.70°E). We applied an integrated approach (geotechnical, geology, remote sensing, geodesy, hydrogeology, and GIS) to identify areas affected by these phenomena, quantify the nature and magnitude of deformation, investigate the factors controlling the deformation, and recommend solutions for these problems. We applied a three-fold approach in three different areas (Alisawiyah, Wadi Alsarhan, and Sakaka areas) to accomplish the following: (1) assess the spatial distribution of land deformation and quantify deformation rates using InSAR methods Persistent Scatterer Interferometry (PSI) and Small BAseline Subsets (SBAS); (2) generate a GIS database to encompass all relevant data and derived products (e.g., remote sensing, geology, geotechnical, GPS, groundwater extraction rates, distribution of urban areas, etc.), and (3) correlate findings from the InSAR exercise with relevant spatial and temporal datasets in search of causal effects. Findings revealed the following: (1) high and consistent subsidence rates (5 to 13 mm/yr) from multiple interferometric techniques; (2) subsided areas correlated largely with the distribution of irrigated agricultural land over alluvial and unconfined aquifers (e.g., Tawil and Jauf aquifers), areas characterized by high and a progressive increase in groundwater extraction (1.2 bcm/yr) as evidenced from the satellite-based temporal distribution of irrigated lands (area irrigated lands: 1998: 37,737 ha; 2013: 70,869 ha); (3) high subsidence rates ( 8 mm/yr) were also detected over urban areas (e.g., Sakaka, Dumat Aljandal, and Tubarjal ), subsidence being caused by disposal of wastewater in the subsurface leading to rise in water tables, dissolution of substrate rocks/sediments (e

The influence on the interferometry due to the instability of ground-based synthetic aperture radar work platform

NASA Astrophysics Data System (ADS)

Tao, Gang; Wei, Guohua; Wang, Xu; Kong, Ming

2018-03-01

There has been increased interest over several decades for applying ground-based synthetic aperture radar (GB-SAR) for monitoring terrain displacement. GB-SAR can achieve multitemporal surface deformation maps of the entire terrain with high spatial resolution and submilimetric accuracy due to the ability of continuous monitoring a certain area day and night regardless of the weather condition. The accuracy of the interferometric measurement result is very important. In this paper, the basic principle of InSAR is expounded, the influence of the platform's instability on the interferometric measurement results are analyzed. The error sources of deformation detection estimation are analyzed using precise geometry of imaging model. Finally, simulation results demonstrates the validity of our analysis.

Measurements of the radar cross section and Inverse Synthetic Aperture Radar (ISAR) images of a Piper Navajo at 9.5 GHz and 49 GHz

NASA Astrophysics Data System (ADS)

Dinger, R.; Kinzel, G.; Lam, W.; Jones, S.

1993-01-01

Studies were conducted of the enhanced radar cross section (RCS) and improved inverse synthetic aperture radar (ISAR) image quality that may result at millimeter-wave (mmw) frequencies. To study the potential for mmw radar in these areas, a program was initiated in FY-90 to design and fabricate a 49.0- to 49.5-GHz stepped-frequency radar. After conducting simultaneous measurements of the RCS of an airborne Piper Navajo twin-engine aircraft at 9.0 and 49.0 GHz, the RCS at 49.0 GHz was always found to be higher than at 9.0 GHz by an amount that depended on the target aspect angle. The largest increase was 19 dB and was measured at nose-on incidence; at other angles of incidence, the increase ranged from 3 to 10 dB. The increase averaged over a 360-degree aspect-angle change was 7.2 dB. The 49.0-GHz radar has demonstrated a capability to gather well-calibrated millimeter-wave RCS data of flying targets. In addition, the successful ISAR images obtainable with short aperture time suggest that 49.0-GHz radar may have a role to play in noncooperative target identification (NCTI).

Ku-band ocean radar backscatter observations during SWADE

NASA Technical Reports Server (NTRS)

Nghiem, S. V.; Li, F. K.; Lou, S. H.; Neumann, G.

1993-01-01

We present results obtained by an airborne Ku-band scatterometer during the Surface Wave Dynamics Experiment (SWADE). The specific objective of this study is to improve our understanding of the relationship between ocean radar backscatter and near surface winds. The airborne scatterometer, NUSCAT, was flown on the NASA Ames C-130 over an instrumented oceanic area near 37 deg N and 74 deg W. A total of 10 flights from 27 Feb. to 9 Mar. 1991 were conducted. Radar backscatter at incidence angles of 0 to 60 deg were obtained. For each incidence angle, the NUSCAT antenna was azimuthally scanned in multiple complete circles to measure the azimuthal backscatter modulations. Both horizontal and vertical polarization backscatter measurements were made. In some of the flights, the cross-polarization backscatter was measured as well. Internal calibrations were carried out throughout each of the flights. Preliminary results indicate that the radar was stable to +/-0.3 dB for each flight. In this paper, we present studies of the backscatter measurements over several crossings of the Gulf Stream. In these crossings, large air-sea temperature differences were encountered and substantial changes in the radar cross section were observed. We summarize the observations and compare them to the changes of several wind variables across the Gulf Stream boundary. In one of the flights, the apparent wind near the cold side of the Gulf Stream was very low (less than 3 m/s). The behavior of the radar cross sections at such low wind speeds and a comparison with models are presented. A case study of the effects of swell on the absolute cross section and the azimuthal modulation pattern is presented. Significant wave heights larger than m were observed during SWADE. The experimentally observed effects of the swell on the radar backscatter are discussed. The effects are used to assess the uncertainties in wind retrieval due to underlying waves. A summary of azimuthal modulation from our ten

A data assimilation experiment of RASTA airborne cloud radar data during HyMeX IOP16

NASA Astrophysics Data System (ADS)

Saussereau, Gaël; Caumont, Olivier; Delanoë, Julien

2015-04-01

The main goal of HyMeX first special observing period (SOP1), which took place from 5 September to 5 November 2012, was to document the heavy precipitation events and flash floods that regularly affect the north-western Mediterranean coastal areas. In the two-month campaign, around twenty rainfall events were documented in France, Italy, and Spain. Among the instrumental platforms that were deployed during SOP1, the Falcon 20 of the Safire unit (http://www.safire.fr/) made numerous flights in storm systems so as to document their thermodynamic, microphysical, and dynamical properties. In particular, the RASTA cloud radar (http://rali.projet.latmos.ipsl.fr/) was aboard this aircraft. This radar measures vertical profiles of reflectivity and Doppler velocity above and below the aircraft. This unique instrument thus allows us to document the microphysical properties and the speed of wind and hydrometeors in the clouds, quasi-continuously in time and at a 60-m vertical resolution. For this field campaign, a special version of the numerical weather prediction (NWP) Arome system was developed to cover the whole north-western Mediterranean basin. This version, called Arome-WMed, ran in real time during the SOP in order to, notably, schedule the airborne operations, especially in storm systems. Like the operational version, Arome-WMed delivers forecasts at a horizontal resolution of 2.5 km with a one-moment microphysical scheme that predicts the evolution of six water species: water vapour, cloud liquid water, rainwater, pristine ice, snow, and graupel. Its three-dimensional variational (3DVar) data assimilation (DA) system ingests every three hours (at 00 UTC, 03 UTC, etc.) numerous observations (radiosoundings, ground automatic weather stations, radar, satellite, GPS, etc.). In order to provide improved initial conditions to Arome-WMed, especially for heavy precipitation events, RASTA data were assimilated in Arome-WMed 3DVar DA system for IOP16 (26 October 2012), to

Interferometric inversion for passive imaging and navigation

DTIC Science & Technology

2017-05-01

AFRL-AFOSR-VA-TR-2017-0096 Interferometric inversion for passive imaging and navigation Laurent Demanet MASSACHUSETTS INSTITUTE OF TECHNOLOGY Final...COVERED (From - To) Feb 2015-Jan 2017 4. TITLE AND SUBTITLE Interferometric inversion for passive imaging and navigation 5a. CONTRACT NUMBER...Grant title: Interferometric inversion for passive imaging and navigation • Grant number: FA9550-15-1-0078 • Period: Feburary 2015 - January 2017

Radar detection of radiation-induced ionization in air

DOEpatents

Gopalsami, Nachappa; Heifetz, Alexander; Chien, Hual-Te; Liao, Shaolin; Koehl, Eugene R.; Raptis, Apostolos C.

2015-07-21

A millimeter wave measurement system has been developed for remote detection of airborne nuclear radiation, based on electromagnetic scattering from radiation-induced ionization in air. Specifically, methods of monitoring radiation-induced ionization of air have been investigated, and the ionized air has been identified as a source of millimeter wave radar reflection, which can be utilized to determine the size and strength of a radiation source.

Summaries of the 4th Annual JPL Airborne Geoscience Workshop. Volume 2: TIMS Workshop

NASA Technical Reports Server (NTRS)

Realmuto, Vincent J. (Editor)

1993-01-01

This is volume 2 of a three volume set of publications that contain the summaries for the Fourth Annual JPL Airborne Geoscience Workshop, held in Washington, D.C. on October 25-29, 1993. The main workshop is divided into three smaller workshops as follows: The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) workshop, on October 25-26. The summaries for this workshop appear in Volume 1. The Thermal Infrared Multispectral Scanner (TIMS) workshop, on October 27. The summaries for this workshop appear in Volume 2. The Airborne Synthetic Aperture Radar (AIRSAR) workshop, on October 28-29. The summaries for this workshop appear in Volume 3.

Application of multispectral radar and LANDSAT imagery to geologic mapping in death valley

NASA Technical Reports Server (NTRS)

Daily, M.; Elachi, C.; Farr, T.; Stromberg, W.; Williams, S.; Schaber, G.

1978-01-01

Side-Looking Airborne Radar (SLAR) images, acquired by JPL and Strategic Air Command Systems, and visible and near-infrared LANDSAT imagery were applied to studies of the Quaternary alluvial and evaporite deposits in Death Valley, California. Unprocessed radar imagery revealed considerable variation in microwave backscatter, generally correlated with surface roughness. For Death Valley, LANDSAT imagery is of limited value in discriminating the Quaternary units except for alluvial units distinguishable by presence or absence of desert varnish or evaporite units whose extremely rough surfaces are strongly shadowed. In contrast, radar returns are most strongly dependent on surface roughness, a property more strongly correlated with surficial geology than is surface chemistry.

Ground-Truthing a Next Generation Snow Radar

NASA Astrophysics Data System (ADS)

Yan, S.; Brozena, J. M.; Gogineni, P. S.; Abelev, A.; Gardner, J. M.; Ball, D.; Liang, R.; Newman, T.

2016-12-01

During the early spring of 2016 the Naval Research Laboratory (NRL) performed a test of a next generation airborne snow radar over ground truth data collected on several areas of fast ice near Barrow, AK. The radar was developed by the Center for Remote Sensing of Ice Sheets (CReSIS) at the University of Kansas, and includes several improvements compared to their previous snow radar. The new unit combines the earlier Ku-band and snow radars into a single unit with an operating frequency spanning the entire 2-18 GHz, an enormous bandwidth which provides the possibility of snow depth measurements with 1.5 cm range resolution. Additionally, the radar transmits on dual polarizations (H and V), and receives the signal through two orthogonally polarized Vivaldi arrays, each with 128 phase centers. The 8 sets of along-track phase centers are combined in hardware to improve SNR and narrow the beamwidth in the along-track, resulting in 8 cross-track effective phase centers which are separately digitized to allow for beam sharpening and forming in post-processing. Tilting the receive arrays 30 degrees from the horizontal also allows the formation of SAR images and the potential for estimating snow-water equivalent (SWE). Ground truth data (snow depth, density, salinity and SWE) were collected over several 60 m wide swaths that were subsequently overflown with the snow radar mounted on a Twin Otter. The radar could be operated in nadir (by beam steering the receive antennas to point beneath the aircraft) or side-looking modes. Results from the comparisons will be shown.

New observations of Bolivian wind streaks by JPL Airborne SAR: Preliminary results

NASA Technical Reports Server (NTRS)

Blumberg, Dan G.; Greeley, Ronald

1995-01-01

In 1993 NASA's Jet Propulsion Laboratory Airborne Synthetic Aperture Radar system (AIRSAR) was deployed to South America to collect multi-parameter radar data over pre-selected targets. Among the sites targeted was a series of wind streaks located in the Altiplano of Bolivia. The objective of this investigation is to study the effect of wavelength, polarization, and incidence angle on the visibility of wind streaks in radar data. Because this is a preliminary evaluation of the recently acquired data we will focus on one scene and, thus, only on the effects of wavelength and polarization. Wind streaks provide information on the near-surface prevailing winds and on the abundance of winderodible material, such as sand. The potential for a free-flyer radar system that could provide global radar images in multiple wavelengths, polarizations, and incidence angles requires definition of system parameters for mission planning. Furthermore, thousands of wind streaks were mapped from Magellan radar images of Venus; their interpretation requires an understanding of the interaction of radar with wind streaks and the surrounding terrain. Our experiment was conducted on wind streaks in the Altiplano of Bolivia to address these issues.

Combined VHF Dopplar radar and airborne (CV-990) measurements of atmospheric winds on the mesoscale

NASA Technical Reports Server (NTRS)

Fairall, Christopher W.; Thomson, Dennis W.

1989-01-01

Hourly measurements of wind speed and direction obtained using two wind profiling Doppler radars during two prolonged jet stream occurrences over western Pennsylvania were analyzed. In particular, the time-variant characteristics of derived shear profiles were examined. To prevent a potential loss of structural detail and retain statistical significance, data from both radars were stratified into categories based on the location data from the Penn State radar were also compared to data from Pittsburgh radiosondes. Profiler data dropouts were studied in an attempt to determine possible reasons for the apparently reduced performance of profiling radars operating beneath a jet stream. Temperature profiles for the radar site were obtained using an interpolated temperature and dewpoint temperature sounding procedure developed at Penn State. The combination of measured wind and interpolated temperature profiles allowed Richardson number profiles to be generated for the profiler sounding volume. Both Richardson number and wind shear statistics were then examined along with pilot reports of turbulence in the vicinity of the profiler.

Initial assessment of an airborne Ku-band polarimetric SAR.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raynal, Ann Marie; Doerry, Armin Walter

2013-02-01

Polarimetric synthetic aperture radar (SAR) has been used for a variety of dual-use research applications since the 1940s. By measuring the direction of the electric field vector from radar echoes, polarimetry may enhance an analysts understanding of scattering effects for both earth monitoring and tactical surveillance missions. Polarimetry may provide insight into surface types, materials, or orientations for natural and man-made targets. Polarimetric measurements may also be used to enhance the contrast between scattering surfaces such as man-made objects and their surroundings. This report represents an initial assessment of the utility of, and applications for, polarimetric SAR at Ku-band formore » airborne or unmanned aerial systems.« less

Interferometric redatuming by sparse inversion

NASA Astrophysics Data System (ADS)

van der Neut, Joost; Herrmann, Felix J.

2013-02-01

Assuming that transmission responses are known between the surface and a particular depth level in the subsurface, seismic sources can be effectively mapped to this level by a process called interferometric redatuming. After redatuming, the obtained wavefields can be used for imaging below this particular depth level. Interferometric redatuming consists of two steps, namely (i) the decomposition of the observed wavefields into downgoing and upgoing constituents and (ii) a multidimensional deconvolution of the upgoing constituents with the downgoing constituents. While this method works in theory, sensitivity to noise and artefacts due to incomplete acquisition require a different formulation. In this letter, we demonstrate the benefits of formulating the two steps that undergird interferometric redatuming in terms of a transform-domain sparsity-promoting program. By exploiting compressibility of seismic wavefields in the curvelet domain, the method not only becomes robust with respect to noise but we are also able to remove certain artefacts while preserving the frequency content. Although we observe improvements when we promote sparsity in the redatumed data space, we expect better results when interferometric redatuming would be combined or integrated with least-squares migration with sparsity promotion in the image space.

Analysis of synthetic aperture radar data acquired over a variety of land cover

NASA Technical Reports Server (NTRS)

Wu, S.-T.

1984-01-01

The results of Synthetic Aperture Radar (SAR) measurements over Kershaw County, South Carolina, using HH, HV, and VV polarization and two-incidence angle X-band airborne SAR system and over Baldwin County, Alabama, using HH polarization L-band Shuttle Imaging Radar (SIR-A) are presented. The X-band data indicate higher HH than VV radar return for cypress forest with standing water. Multipolarization (HH, HV, and VV) data help delineate several land-cover types that are difficult to delineate by the single polarization (HH) data. The L-band data indicate that radar return signal strength is highly correlated with tree height or age for three types of pine forest. It is found that delineation of urban/residential from deciduous forest is significantly improved by the inclusion of Landsat multispectral scanner data.

Space Radar Image of Kilauea, Hawaii

NASA Image and Video Library

1999-05-01

Data acquired on April 13, 1994 and on October 4, 1994 from the X-band Synthetic Aperture Radar on board the space shuttle Endeavour were used to generate interferometric fringes, which were overlaid on the X-SAR image of Kilauea. The volcano is centered in this image at 19.58 degrees north latitude and 155.55 degrees west longitude. The image covers about 9 kilometers by 13 kilometers (5.6 miles by 8 miles). The X-band fringes correspond clearly to the expected topographic image. The yellow line indicates the area below which was used for the three-dimensional image using altitude lines. The yellow rectangular frame fences the area for the final topographic image. http://photojournal.jpl.nasa.gov/catalog/PIA01762

NASA's DC-8 Airborne Science research aircraft, in new colors and markings, takes off Feb. 24, 2004

NASA Image and Video Library

2004-02-24

NASA's DC-8 Airborne Science research aircraft, in new colors and markings, takes off Feb. 24, 2004. Dark panels on lower fuselage are synthetic aperture radar antennas enabling sophisticated studies of Earth features.

NASA's DC-8 Airborne Science research aircraft, in new colors and markings, in flight Feb. 24, 2004

NASA Image and Video Library

2004-02-24

NASA's DC-8 Airborne Science research aircraft, in new colors and markings, in flight Feb. 24, 2004. Dark panels on lower fuselage are synthetic aperture radar antennas enabling sophisticated studies of Earth features.

Effect of phase errors in stepped-frequency radar systems

NASA Astrophysics Data System (ADS)

Vanbrundt, H. E.

1988-04-01

Stepped-frequency waveforms are being considered for inverse synthetic aperture radar (ISAR) imaging from ship and airborne platforms and for detailed radar cross section (RCS) measurements of ships and aircraft. These waveforms make it possible to achieve resolutions of 1.0 foot by using existing radar designs and processing technology. One problem not yet fully resolved in using stepped-frequency waveform for ISAR imaging is the deterioration in signal level caused by random frequency error. Random frequency error of the stepped-frequency source results in reduced peak responses and increased null responses. The resulting reduced signal-to-noise ratio is range dependent. Two of the major concerns addressed in this report are radar range limitations for ISAR and the error in calibration for RCS measurements caused by differences in range between a passive reflector used for an RCS reference and the target to be measured. In addressing these concerns, NOSC developed an analysis to assess the tolerable frequency error in terms of resulting power loss in signal power and signal-to-phase noise.

Electric Field Magnitude and Radar Reflectivity as a Function of Distance from Cloud Edge

NASA Technical Reports Server (NTRS)

Ward, Jennifer G.; Merceret, Francis J.

2004-01-01

The results of analyses of data collected during a field investigation of thunderstorm anvil and debris clouds are reported. Statistics of the magnitude of the electric field are determined as a function of distance from cloud edge. Statistics of radar reflectivity near cloud edge are also determined. Both analyses use in-situ airborne field mill and cloud physics data coupled with ground-based radar measurements obtained in east-central Florida during the summer convective season. Electric fields outside of anvil and debris clouds averaged less than 3 kV/m. The average radar reflectivity at the cloud edge ranged between 0 and 5 dBZ.

Software for Generating Strip Maps from SAR Data

NASA Technical Reports Server (NTRS)

Hensley, Scott; Michel, Thierry; Madsen, Soren; Chapin, Elaine; Rodriguez, Ernesto

2004-01-01

Jurassicprok is a computer program that generates strip-map digital elevation models and other data products from raw data acquired by an airborne synthetic-aperture radar (SAR) system. This software can process data from a variety of airborne SAR systems but is designed especially for the GeoSAR system, which is a dual-frequency (P- and X-band), single-pass interferometric SAR system for measuring elevation both at the bare ground surface and top of the vegetation canopy. Jurassicprok is a modified version of software developed previously for airborne-interferometric- SAR applications. The modifications were made to accommodate P-band interferometric processing, remove approximations that are not generally valid, and reduce processor-induced mapping errors to the centimeter level. Major additions and other improvements over the prior software include the following: a) A new, highly efficient multi-stage-modified wave-domain processing algorithm for accurately motion compensating ultra-wideband data; b) Adaptive regridding algorithms based on estimated noise and actual measured topography to reduce noise while maintaining spatial resolution; c) Exact expressions for height determination from interferogram data; d) Fully calibrated volumetric correlation data based on rigorous removal of geometric and signal-to-noise decorrelation terms; e) Strip range-Doppler image output in user-specified Doppler coordinates; f) An improved phase-unwrapping and absolute-phase-determination algorithm; g) A more flexible user interface with many additional processing options; h) Increased interferogram filtering options; and i) Ability to use disk space instead of random- access memory for some processing steps.

STS-68 radar image: Kilauea, Hawaii

NASA Image and Video Library

1994-10-10

STS068-S-054 (10 October 1994) --- This is a deformation map of the south flank of Kilauea volcano on the big island of Hawaii, centered at 19.5 degrees north latitude and 155.25 degrees west longitude. The map was created by combining interferometric radar data - that is data acquired on different passes of the Space Shuttle Endeavour which are then overlaid to obtain elevation information - acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) during its first flight in April 1994 and its second flight in October 1994. The area shown is approximately 40 by 80 kilometers (25 by 50 miles). North is toward the upper left of the image. The colors indicate the displacement of the surface in that direction that the radar instrument was pointed (toward the right of the image) in the six months between images. The analysis of ground movement is preliminary, but appears consistent with the motions detected by the Global Positioning System ground receivers that have been used over the past five years. The south flank of the Kilauea volcano is among the most rapidly deforming terrain's on Earth. Several regions show motion over the six-month time period. Most obvious is at the base of Hilina Pali, where 10 centimeters (4 inches) or more of crustal deformation can be seen in a concentrated area near the coastline. On a more localized scale, the currently active Pu'u O'o summit also shows about 10 centimeters (4 inches) of change near the vent area. Finally, there are indications of additional movement along the upper southwest rift zone, just below the Kilauea caldera in the image. Deformation of the south flank is believed to be the result of movements along faults deep beneath the surface of the volcano, as well as injections of magma, or molten rock, into the volcano's "plumbing" system. Detection of ground motions from space has proven to be a unique capability of imaging radar technology. Scientists hope to use deformation data

Definition and fabrication of an airborne scatterometer radar signal processor

NASA Technical Reports Server (NTRS)

1976-01-01

A hardware/software system which incorporates a microprocessor design and software for the calculation of normalized radar cross section in real time was developed. Interface is provided to decommutate the NASA ADAS data stream for aircraft parameters used in processing and to provide output in the form of strip chart and pcm compatible data recording.

The relationship between the microwave radar cross section and both wind speed and stress: Model function studies using Frontal Air-Sea Interaction Experiment data

NASA Astrophysics Data System (ADS)

Weissman, David E.; Davidson, Kenneth L.; Brown, Robert A.; Friehe, Carl A.; Li, Fuk

1994-05-01

The Frontal Air-Sea Interaction Experiment (FASINEX) provided a unique data set with coincident airborne scatterometer measurements of the ocean surface radar cross section (RCS) (at Ku band) and near-surface wind and wind stress. These data have been analyzed to study new model functions which relate wind speed and surface friction velocity (square root of the kinematic wind stress) to the radar cross section and to better understand the processes in the boundary layer that have a strong influence on the radar backscatter. Studies of data from FASINEX indicate that the RCS has a different relation to the friction velocity than to the wind speed. The difference between the RCS models using these two variables depends on the polarization and the incidence angle. The radar data have been acquired from the Jet Propulsion Laboratory airborne scatterometer. These data span 10 different flight days. Stress measurements were inferred from shipboard instruments and from aircraft flying at low altitudes, closely following the scatterometer. Wide ranges of radar incidence angles and environmental conditions needed to fully develop algorithms are available from this experiment.

The relationship between the microwave radar cross section and both wind speed and stress: Model function studies using Frontal Air-Sea Interaction Experiment data

NASA Technical Reports Server (NTRS)

Weissman, David E.; Davidson, Kenneth L.; Brown, Robert A.; Friehe, Carl A.; Li, Fuk

1994-01-01

The Frontal Air-Sea Interaction Experiment (FASINEX) provided a unique data set with coincident airborne scatterometer measurements of the ocean surface radar cross section (RCS)(at Ku band) and near-surface wind and wind stress. These data have been analyzed to study new model functions which relate wind speed and surface friction velocity (square root of the kinematic wind stress) to the radar cross section and to better understand the processes in the boundary layer that have a strong influence on the radar backscatter. Studies of data from FASINEX indicate that the RCS has a different relation to the friction velocity than to the wind speed. The difference between the RCS models using these two variables depends on the polarization and the incidence angle. The radar data have been acquired from the Jet Propulsion Laboratory airborne scatterometer. These data span 10 different flight days. Stress measurements were inferred from shipboard instruments and from aircraft flying at low altitudes, closely following the scatterometer. Wide ranges of radar incidence angles and environmental conditions needed to fully develop algorithms are available from this experiment.

Maximum-likelihood spectral estimation and adaptive filtering techniques with application to airborne Doppler weather radar. Thesis Technical Report No. 20

NASA Technical Reports Server (NTRS)

Lai, Jonathan Y.

1994-01-01

This dissertation focuses on the signal processing problems associated with the detection of hazardous windshears using airborne Doppler radar when weak weather returns are in the presence of strong clutter returns. In light of the frequent inadequacy of spectral-processing oriented clutter suppression methods, we model a clutter signal as multiple sinusoids plus Gaussian noise, and propose adaptive filtering approaches that better capture the temporal characteristics of the signal process. This idea leads to two research topics in signal processing: (1) signal modeling and parameter estimation, and (2) adaptive filtering in this particular signal environment. A high-resolution, low SNR threshold maximum likelihood (ML) frequency estimation and signal modeling algorithm is devised and proves capable of delineating both the spectral and temporal nature of the clutter return. Furthermore, the Least Mean Square (LMS) -based adaptive filter's performance for the proposed signal model is investigated, and promising simulation results have testified to its potential for clutter rejection leading to more accurate estimation of windspeed thus obtaining a better assessment of the windshear hazard.

Vegetation canopy discrimination and biomass assessment using multipolarized airborne SAR

NASA Technical Reports Server (NTRS)

Ulaby, F. T.; Dobson, M. C.; Held, D. N.

1985-01-01

Multipolarized airborne Synthetic Aperture Radar (SAR) data were acquired over a largely agricultural test site near Macomb, Illinois, in conjunction with the Shuttle Imaging Radar (SIR-B) experiment in October 1984. The NASA/JPL L-band SAR operating at 1.225 GHz made a series of daily overflights with azimuth view angles both parallel and orthogonal to those of SIR-B. The SAR data was digitally recorded in the quadpolarization configuration. An extensive set of ground measurements were obtained throughout the test site and include biophysical and soil measurements of approximately 400 agricultural fields. Preliminary evaluation of some of the airborne SAR imagery indicates a great potential for crop discrimination and assessment of canopy condition. False color composites constructed from the combination of three linear polarizations (HH, VV, and HV) were found to be clearly superior to any single polarization for purposes of crop classification. In addition, an image constructed using the HH return to modulate intensity and the phase difference between HH and VV returns to modulate chroma indicates a clear capability for assessment of canopy height and/or biomass. In particular, corn fields heavily damaged by infestations of corn borer are readily distinguished from noninfested fields.

Retrieving mesospheric winds and gravity waves using high resolution radar measurements of polar mesospheric summer echoes with MAARSY

NASA Astrophysics Data System (ADS)

Stober, G.; Sommer, S.; Schult, C.; Chau, J. L.; Latteck, R.

2013-12-01

The Middle Atmosphere Alomar Radar System (MAARSY) located at the northern Norwegian island of Andøya (69.3 ° N, 16° E) observes polar mesosphere summer echoes (PMSE) on a regular basis. This backscatter turned out to be an ideal tracer of atmospheric dynamics and to investigate the wind field at the mesosphere/lower thermosphere (MLT) at high spatial and temporal scales. MAARSY is dedicated to explore the polar mesosphere at such high resolution and employs an active phased array antenna with the capability to steer the beam on a pulse-to-pulse basis, which permits to perform systematic scanning of PMSE and to investigate the horizontal structure of the backscatter. The radar also uses a 16 channel receiver system for interferometric applications e.g. mean angle of arrival analysis or coherent radar imaging. Here we present measurements using these features of MAARSY to study the wind field at the MLT applying sophisticated wind analysis algorithms such as velocity azimuth display or volume velocity processing to derive gravity wave parameters such as horizontal wave length, phase speed and propagation direction. Further, we compare the interferometrically corrected and uncorrected wind measurements to emphasize the importance to account for likely edge effects using PMSE as tracer of the dynamics. The observations indicate huge deviations from the nominal beam pointing direction at the upper and lower edges of the PMSE altering the wind analysis.

Constraining the slip distribution and fault geometry of the Mw 7.9, 3 November 2002, Denali fault earthquake with Interferometric Synthetic Aperture Radar and Global Positioning System data

USGS Publications Warehouse

Wright, Tim J.; Lu, Z.; Wicks, Charles

2004-01-01

The Mw 7.9, Denali fault earthquake (DFE) is the largest continental strike-slip earthquake to occur since the development of Interferometric Synthetic Aperture Radar (InSAR). We use five interferograms, constructed using radar images from the Canadian Radarsat-1 satellite, to map the surface deformation at the western end of the fault rupture. Additional geodetic data are provided by displacements observed at 40 campaign and continuous Global Positioning System (GPS) sites. We use the data to determine the geometry of the Susitna Glacier fault, thrusting on which initiated the DFE, and to determine a slip model for the entire event that is consistent with both the InSAR and GPS data. We find there was an average of 7.3 ± 0.4 m slip on the Susitna Glacier fault, between 1 and 9.5 km depth on a 29 km long fault that dips north at 41 ± 0.7° and has a surface projection close to the mapped rupture. On the Denali fault, a simple model with large slip patches finds a maximum of 8.7 ± 0.7 m of slip between the surface and 14.3 ± 0.2 km depth. A more complex distributed slip model finds a peak of 12.5 ± 0.8 m in the upper 4 km, significantly higher than the observed surface slip. We estimate a geodetic moment of 670 ± 10 × 1018 N m (Mw 7.9), consistent with seismic estimates. Lack of preseismic data resulted in an absence of InSAR coverage for the eastern half of the DFE rupture. A dedicated geodetic InSAR mission could obviate coverage problems in the future.

Development of a Cost-Effective Airborne Remote Sensing System for Coastal Monitoring

PubMed Central

Kim, Duk-jin; Jung, Jungkyo; Kang, Ki-mook; Kim, Seung Hee; Xu, Zhen; Hensley, Scott; Swan, Aaron; Duersch, Michael

2015-01-01

Coastal lands and nearshore marine areas are productive and rapidly changing places. However, these areas face many environmental challenges related to climate change and human-induced impacts. Space-borne remote sensing systems may be restricted in monitoring these areas because of their spatial and temporal resolutions. In situ measurements are also constrained from accessing the area and obtaining wide-coverage data. In these respects, airborne remote sensing sensors could be the most appropriate tools for monitoring these coastal areas. In this study, a cost-effective airborne remote sensing system with synthetic aperture radar and thermal infrared sensors was implemented to survey coastal areas. Calibration techniques and geophysical model algorithms were developed for the airborne system to observe the topography of intertidal flats, coastal sea surface current, sea surface temperature, and submarine groundwater discharge. PMID:26437413

Development of a Cost-Effective Airborne Remote Sensing System for Coastal Monitoring.

PubMed

Kim, Duk-jin; Jung, Jungkyo; Kang, Ki-mook; Kim, Seung Hee; Xu, Zhen; Hensley, Scott; Swan, Aaron; Duersch, Michael

2015-09-30

Coastal lands and nearshore marine areas are productive and rapidly changing places. However, these areas face many environmental challenges related to climate change and human-induced impacts. Space-borne remote sensing systems may be restricted in monitoring these areas because of their spatial and temporal resolutions. In situ measurements are also constrained from accessing the area and obtaining wide-coverage data. In these respects, airborne remote sensing sensors could be the most appropriate tools for monitoring these coastal areas. In this study, a cost-effective airborne remote sensing system with synthetic aperture radar and thermal infrared sensors was implemented to survey coastal areas. Calibration techniques and geophysical model algorithms were developed for the airborne system to observe the topography of intertidal flats, coastal sea surface current, sea surface temperature, and submarine groundwater discharge.

Initial results from SKiYMET meteor radar at Thumba (8.5°N, 77°E): 1. Comparison of wind measurements with MF spaced antenna radar system

NASA Astrophysics Data System (ADS)

Kumar, Karanam Kishore; Ramkumar, Geetha; Shelbi, S. T.

2007-12-01

In the present communication, initial results from the allSKy interferometric METeor (SKiYMET) radar installed at Thumba (8.5°N, 77°E) are presented. The meteor radar system provides hourly zonal and meridional winds in the mesosphere lower thermosphere (MLT) region. The meteor radar measured zonal and meridional winds are compared with nearby MF radar at Tirunalveli (8.7°N, 77.8°E). The present study provided an opportunity to compare the winds measured by the two different techniques, namely, interferometry and spaced antenna drift methods. Simultaneous wind measurements for a total number of 273 days during September 2004 to May 2005 are compared. The comparison showed a very good agreement between these two techniques in the height region 82-90 km and poor agreement above this height region. In general, the zonal winds compare very well as compared to the meridional winds. The observed discrepancies in the wind comparison above 90 km are discussed in the light of existing limitations of both the radars. The detailed analysis revealed the consistency of the measured winds by both the techniques. However, the discrepancies are observed at higher altitudes and are attributed to the contamination of MF radar neutral wind measurements with Equatorial Electro Jet (EEJ) induced inospheric drifts rather than the limitations of the spaced antenna technique. The comparison of diurnal variation of zonal winds above 90 km measured by both the radars is in reasonably good agreement in the absence of EEJ (during local nighttime). It is also been noted that the difference in the zonal wind measurements by both the radars is directly related to the strength of EEJ, which is a noteworthy result from the present study.

Fusing enhanced radar precipitation, in-situ hydrometeorological measurements and airborne LIDAR snowpack estimates in a hyper-resolution hydrologic model to improve seasonal water supply forecasts

NASA Astrophysics Data System (ADS)

Gochis, D. J.; Busto, J.; Howard, K.; Mickey, J.; Deems, J. S.; Painter, T. H.; Richardson, M.; Dugger, A. L.; Karsten, L. R.; Tang, L.

2015-12-01

Scarcity of spatially- and temporally-continuous observations of precipitation and snowpack conditions in remote mountain watersheds results in fundamental limitations in water supply forecasting. These limitationsin observational capabilities can result in strong biases in total snowmelt-driven runoff amount, the elevational distribution of runoff, river basin tributary contributions to total basin runoff and, equally important for water management, the timing of runoff. The Upper Rio Grande River basin in Colorado and New Mexico is one basin where observational deficiencies are hypothesized to have significant adverse impacts on estimates of snowpack melt-out rates and on water supply forecasts. We present findings from a coordinated observational-modeling study within Upper Rio Grande River basin whose aim was to quanitfy the impact enhanced precipitation, meteorological and snowpack measurements on the simulation and prediction of snowmelt driven streamflow. The Rio Grande SNOwpack and streamFLOW (RIO-SNO-FLOW) Prediction Project conducted enhanced observing activities during the 2014-2015 water year. Measurements from a gap-filling, polarimetric radar (NOXP) and in-situ meteorological and snowpack measurement stations were assimilated into the WRF-Hydro modeling framework to provide continuous analyses of snowpack and streamflow conditions. Airborne lidar estimates of snowpack conditions from the NASA Airborne Snow Observatory during mid-April and mid-May were used as additional independent validations against the various model simulations and forecasts of snowpack conditions during the melt-out season. Uncalibrated WRF-Hydro model performance from simulations and forecasts driven by enhanced observational analyses were compared against results driven by currently operational data inputs. Precipitation estimates from the NOXP research radar validate significantly better against independent in situ observations of precipitation and snow-pack increases

Reconfigurable signal processor designs for advanced digital array radar systems

NASA Astrophysics Data System (ADS)

Suarez, Hernan; Zhang, Yan (Rockee); Yu, Xining

2017-05-01

The new challenges originated from Digital Array Radar (DAR) demands a new generation of reconfigurable backend processor in the system. The new FPGA devices can support much higher speed, more bandwidth and processing capabilities for the need of digital Line Replaceable Unit (LRU). This study focuses on using the latest Altera and Xilinx devices in an adaptive beamforming processor. The field reprogrammable RF devices from Analog Devices are used as analog front end transceivers. Different from other existing Software-Defined Radio transceivers on the market, this processor is designed for distributed adaptive beamforming in a networked environment. The following aspects of the novel radar processor will be presented: (1) A new system-on-chip architecture based on Altera's devices and adaptive processing module, especially for the adaptive beamforming and pulse compression, will be introduced, (2) Successful implementation of generation 2 serial RapidIO data links on FPGA, which supports VITA-49 radio packet format for large distributed DAR processing. (3) Demonstration of the feasibility and capabilities of the processor in a Micro-TCA based, SRIO switching backplane to support multichannel beamforming in real-time. (4) Application of this processor in ongoing radar system development projects, including OU's dual-polarized digital array radar, the planned new cylindrical array radars, and future airborne radars.

Generation of topographic terrain models utilizing synthetic aperture radar and surface level data

NASA Technical Reports Server (NTRS)

Imhoff, Marc L. (Inventor)

1991-01-01

Topographical terrain models are generated by digitally delineating the boundary of the region under investigation from the data obtained from an airborne synthetic aperture radar image and surface elevation data concurrently acquired either from an airborne instrument or at ground level. A set of coregistered boundary maps thus generated are then digitally combined in three dimensional space with the acquired surface elevation data by means of image processing software stored in a digital computer. The method is particularly applicable for generating terrain models of flooded regions covered entirely or in part by foliage.

The Multiple Doppler Radar Workshop, November 1979.

NASA Astrophysics Data System (ADS)

Carbone, R. E.; Harris, F. I.; Hildebrand, P. H.; Kropfli, R. A.; Miller, L. J.; Moninger, W.; Strauch, R. G.; Doviak, R. J.; Johnson, K. W.; Nelson, S. P.; Ray, P. S.; Gilet, M.

1980-10-01

the dual Doppler and multiple Doppler cases. Various filters and techniques, including statistical and variational approaches, are mentioned. Emphasis is placed on the importance of experiment design and procedures, technological improvements, incorporation of all information from supporting sensors, and analysis priority for physically simple cases. Integrated reliability is proposed as an objective tool for radar siting.Verification of multiple Doppler-derived vertical velocity is discussed in Part V. Three categories of verification are defined as direct, deductive, and theoretical/numerical. Direct verification consists of zenith-pointing radar measurements (from either airborne or ground-based systems), air motion sensing aircraft, instrumented towers, and tracking of radar chaff. Deductive sources include mesonetworks, aircraft (thermodynamic and microphysical) measurements, satellite observations, radar reflectivity, multiple Doppler consistency, and atmospheric soundings. Theoretical/numerical sources of verification include proxy data simulation, momentum checking, and numerical cloud models. New technology, principally in the form of wide bandwidth radars, is seen as a development that may reduce the need for extensive verification of multiple Doppler-derived vertical air motions. Airborne Doppler radar is perceived as the single most important source of verification within the bounds of existing technology.Nine stages of data processing and display are identified in Part VI. The stages are identified as field checks, archival, selection, editing, coordinate transformation, synthesis of Cartesian fields, filtering, display, and physical analysis. Display of data is considered to be a problem critical to assimilation of data at all stages. Interactive computing systems and software are concluded to be very important, particularly for the editing stage. Three- and 4-dimensional displays are considered essential for data assimilation, particularly at the

Comparison of Shuttle Imaging Radar-B ocean wave image spectra with linear model predictions based on aircraft measurements

NASA Technical Reports Server (NTRS)

Monaldo, Frank M.; Lyzenga, David R.

1988-01-01

During October 1984, coincident Shuttle Imaging Radar-B synthetic aperture radar (SAR) imagery and wave measurements from airborne instrumentation were acquired. The two-dimensional wave spectrum was measured by both a radar ocean-wave spectrometer and a surface-contour radar aboard the aircraft. In this paper, two-dimensional SAR image intensity variance spectra are compared with these independent measures of ocean wave spectra to verify previously proposed models of the relationship between such SAR image spectra and ocean wave spectra. The results illustrate both the functional relationship between SAR image spectra and ocean wave spectra and the limitations imposed on the imaging of short-wavelength, azimuth-traveling waves.

The NRL 2011 Airborne Sea-Ice Thickness Campaign

NASA Astrophysics Data System (ADS)

Brozena, J. M.; Gardner, J. M.; Liang, R.; Ball, D.; Richter-Menge, J.

2011-12-01

In March of 2011, the US Naval Research Laboratory (NRL) performed a study focused on the estimation of sea-ice thickness from airborne radar, laser and photogrammetric sensors. The study was funded by ONR to take advantage of the Navy's ICEX2011 ice-camp /submarine exercise, and to serve as a lead-in year for NRL's five year basic research program on the measurement and modeling of sea-ice scheduled to take place from 2012-2017. Researchers from the Army Cold Regions Research and Engineering Laboratory (CRREL) and NRL worked with the Navy Arctic Submarine Lab (ASL) to emplace a 9 km-long ground-truth line near the ice-camp (see Richter-Menge et al., this session) along which ice and snow thickness were directly measured. Additionally, US Navy submarines collected ice draft measurements under the groundtruth line. Repeat passes directly over the ground-truth line were flown and a grid surrounding the line was also flown to collect altimeter, LiDAR and Photogrammetry data. Five CRYOSAT-2 satellite tracks were underflown, as well, coincident with satellite passage. Estimates of sea ice thickness are calculated assuming local hydrostatic balance, and require the densities of water, ice and snow, snow depth, and freeboard (defined as the elevation of sea ice, plus accumulated snow, above local sea level). Snow thickness is estimated from the difference between LiDAR and radar altimeter profiles, the latter of which is assumed to penetrate any snow cover. The concepts we used to estimate ice thickness are similar to those employed in NASA ICEBRIDGE sea-ice thickness estimation. Airborne sensors used for our experiment were a Reigl Q-560 scanning topographic LiDAR, a pulse-limited (2 nS), 10 GHz radar altimeter and an Applanix DSS-439 digital photogrammetric camera (for lead identification). Flights were conducted on a Twin Otter aircraft from Pt. Barrow, AK, and averaged ~ 5 hours in duration. It is challenging to directly compare results from the swath LiDAR with the

Crustal deformation at long Valley Caldera, eastern California, 1992-1996 inferred from satellite radar interferometry

USGS Publications Warehouse

Thatcher, W.; Massonnet, D.

1997-01-01

Satellite radar interferometric images of Long Valley caldera show a pattern of surface deformation that resembles that expected from analysis of an extensive suite of ground-based geodetic data. Images from 2 and 4 year intervals respectively, are consistent with uniform movement rates determined from leveling surveys. Synthetic interferograms generated from ellipsoidal-inclusion source models based on inversion of the ground-based data show generally good agreement with the observed images. Two interferograms show evidence for a magmatic source southwest of the caldera in a region not covered by ground measurements. Poorer image quality in the 4 year interferogram indicates that temporal decorrelation of surface radar reflectors is progressively degrading the fringe pattern in the Long Valley region. Copyright 1997 by the American Geophysical Union.

2nd Generation Airborne Precipitation Radar (APR-2)

NASA Technical Reports Server (NTRS)

Durden, S.; Tanelli, S.; Haddad, Z.; Im, E.

2012-01-01

Dual-frequency operation with Ku-band (13.4 GHz) and Ka-band (35.6 GHz). Geometry and frequencies chosen to simulate GPM radar. Measures reflectivity at co- and cross-polarizations, and Doppler. Range resolution is approx. 60 m. Horizontal resolution at surface is approx. 1 km. Reflectivity calibration is within 1.5 dB, based on 10 deg sigmaO at Ku-band and Mie scattering calculations in light rain at Ka-band. LDR measurements are OK to near -20 dB; LDR lower than this is likely contaminated by system cross-polarization isolation. Velocity is motion-corrected total Doppler, including particle fall speed. Aliasing can be seen in some places; can usually be dealiased with an algorithm. .

Detecting and Quantifying Forest Change: The Potential of Existing C- and X-Band Radar Datasets.

PubMed

Tanase, Mihai A; Ismail, Ismail; Lowell, Kim; Karyanto, Oka; Santoro, Maurizio

2015-01-01

This paper evaluates the opportunity provided by global interferometric radar datasets for monitoring deforestation, degradation and forest regrowth in tropical and semi-arid environments. The paper describes an easy to implement method for detecting forest spatial changes and estimating their magnitude. The datasets were acquired within space-borne high spatial resolutions radar missions at near-global scales thus being significant for monitoring systems developed under the United Framework Convention on Climate Change (UNFCCC). The approach presented in this paper was tested in two areas located in Indonesia and Australia. Forest change estimation was based on differences between a reference dataset acquired in February 2000 by the Shuttle Radar Topography Mission (SRTM) and TanDEM-X mission (TDM) datasets acquired in 2011 and 2013. The synergy between SRTM and TDM datasets allowed not only identifying changes in forest extent but also estimating their magnitude with respect to the reference through variations in forest height.

Temperate Ice Depth-Sounding Radar

NASA Astrophysics Data System (ADS)

Jara-Olivares, V. A.; Player, K.; Rodriguez-Morales, F.; Gogineni, P.

2008-12-01

. It also digitizes the output signal from the receiver and stores the data in binary format using a portable computer. The RF-section consists of a high- power transmitter and a low-noise receiver with digitally controlled variable gain. The antenna is time-shared between the transmitter and receiver by means of a transmit/receive (T/R) switch. In regards to the antenna, we have made a survey study of various electrically small antennas (ESA) to choose the most suitable radiating structure for this application. Among the different alternatives that provide a good trade-off between electrical performance and small size, we have adopted an ESA dipole configuration for airborne platforms and a half-wavelength radiator for the surface-based version. The airborne antenna solution is given after studying the geometry of the aerial vehicle and its fuselage contribution to the antenna radiation pattern. Dipoles are made of 11.6 mm diameter cables (AWG 0000) or printed patches embedded into the aircraft fuselage, wings, or both. The system is currently being integrated and tested. TIDSoR is expected to be deployed during the spring 2008 either in Alaska or Greenland for surface based observations. In this paper, we will discuss our design considerations and current progress towards the development of this radar system. [1] Center for Remote Sensing of Ice Sheets (Cresis), Sept 2008, [Online]. Available: http://www.cresis.ku.edu

The ZpiM algorithm: a method for interferometric image reconstruction in SAR/SAS.

PubMed

Dias, José M B; Leitao, José M N

2002-01-01

This paper presents an effective algorithm for absolute phase (not simply modulo-2-pi) estimation from incomplete, noisy and modulo-2pi observations in interferometric aperture radar and sonar (InSAR/InSAS). The adopted framework is also representative of other applications such as optical interferometry, magnetic resonance imaging and diffraction tomography. The Bayesian viewpoint is adopted; the observation density is 2-pi-periodic and accounts for the interferometric pair decorrelation and system noise; the a priori probability of the absolute phase is modeled by a compound Gauss-Markov random field (CGMRF) tailored to piecewise smooth absolute phase images. We propose an iterative scheme for the computation of the maximum a posteriori probability (MAP) absolute phase estimate. Each iteration embodies a discrete optimization step (Z-step), implemented by network programming techniques and an iterative conditional modes (ICM) step (pi-step). Accordingly, the algorithm is termed ZpiM, where the letter M stands for maximization. An important contribution of the paper is the simultaneous implementation of phase unwrapping (inference of the 2pi-multiples) and smoothing (denoising of the observations). This improves considerably the accuracy of the absolute phase estimates compared to methods in which the data is low-pass filtered prior to unwrapping. A set of experimental results, comparing the proposed algorithm with alternative methods, illustrates the effectiveness of our approach.

Hurricane structure and wind fields from stereoscopic and infrared satellite observations and radar data

NASA Technical Reports Server (NTRS)

Hasler, A. F.; Morris, K. R.

1986-01-01

Hurricane cloud and precipitation structure have been studied by means of IR and stereoscopic visual satellite data from synchronized scanning GOES-East and -West, in combination with ground-based radar data for Hurricane Frederico and time-composited airborne radar data for Hurricane Allen. It is noted that stereoscopically measured cloudtop height in these hurricanes is not as closely correlated to radar reflectivity at lower levels as it is in intense thunderstorms over land. This and other results obtained imply that satellite precipitation estimation techniques for tropical cyclones that are based on cloudtop measurements will not be accurate with respect to time and place scales that are less than several hours and a few hundred km, respectively.

Global search and rescue - A new concept. [orbital digital radar system with passive reflectors

NASA Technical Reports Server (NTRS)

Sivertson, W. E., Jr.

1976-01-01

A new terrestrial search and rescue concept is defined embodying the use of simple passive radiofreqeuncy reflectors in conjunction with a low earth-orbiting, all-weather, synthetic aperture radar to detect, identify, and position locate earth-bound users in distress. Users include ships, aircraft, small boats, explorers, hikers, etc. Airborne radar tests were conducted to evaluate the basic concept. Both X-band and L-band, dual polarization radars were operated simultaneously. Simple, relatively small, corner-reflector targets were successfully imaged and digital data processing approaches were investigated. Study of the basic concept and evaluation of results obtained from aircraft flight tests indicate an all-weather, day or night, global search and rescue system is feasible.

Relating the microwave radar cross section to the sea surface stress - Physics and algorithms

NASA Technical Reports Server (NTRS)

Weissman, David E.; Plant, William J.; Brown, Robert A.; Davidson, Kenneth L.; Shaw, William J.

1991-01-01

The FASINEX (Frontal Air-Sea Interaction Experiment) provided a unique data set with coincident airborne measurements of the ocean surface radar cross section (at Ku-band) and surface windstress. It is being analyzed to create new algorithms and to better understand the air-sea variables that can have a strong influence on the RCS (radar cross section). Several studies of portions of data from the FASINEX indicate that the RCS is more dependent on the surface stress than on the wind speed. Radar data have been acquired by the JPL and NRL groups. The data span 12 different flight days. Stress measurements can be inferred from ship-board instruments and from aircraft closely following the scatterometers.

Monitoring of urban subsidence with SAR interferometric point target analysis: A case study in Suzhou, China

NASA Astrophysics Data System (ADS)

Zhang, Yonghong; Zhang, Jixian; Wu, Hongan; Lu, Zhong; Guangtong, Sun

2011-10-01

Ground subsidence, mainly caused by over exploitation of groundwater and other underground resources, such as oil, gas and coal, occurs in many cities in China. The annual direct loss associated with subsidence across the country is estimated to exceed 100 million US dollar. Interferometric SAR (InSAR) is a powerful tool to map ground deformation at an unprecedented level of spatial detail. It has been widely used to investigate the deformation resulting from earthquakes, volcanoes and subsidence. Repeat-pass InSAR, however, may fail due to impacts of spatial decorrelation, temporal decorrelation and heterogeneous refractivity of atmosphere. In urban areas, a large amount of natural stable radar reflectors exists, such as buildings and engineering structures, at which radar signals can remain coherent during a long time interval. Interferometric point target analysis (IPTA) technique, also known as persistent scatterers (PS) InSAR is based on these reflectors. It overcomes the shortfalls in conventional InSAR. This paper presents a procedure for urban subsidence monitoring with IPTA. Calculation of linear deformation rate and height residual, and the non-linear deformation estimate, respectively, are discussed in detail. Especially, the former is highlighted by a novel and easily implemented 2-dimensional spatial search algorithm. Practically useful solutions that can significantly improve the robustness of IPTA, are recommended. Finally, the proposed procedure is applied to mapping the ground subsidence in Suzhou city, Jiangsu province, China. Thirty-four ERS-1/2 SAR scenes are analyzed, and the deformation information over 38,881 point targets between 1992 and 2000 are generated. The IPTA-derived deformation estimates correspond well with leveling measurements, demonstrating the potential of the proposed subsidence monitoring procedure based on IPTA technique. Two shortcomings of the IPTA-based procedure, e.g., the requirement of large number of SAR images and

Applications of airborne remote sensing in atmospheric sciences research

NASA Technical Reports Server (NTRS)