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Geoscience and Remote Sensing, IEEE Transactions on

Issue 2 • Date Mar 1996

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Displaying Results 1 - 25 of 30
  • Observations of ship-generated internal waves in SAR images from Loch Linnhe, Scotland, and comparison with theory and in situ internal wave measurements

    Publication Year: 1996 , Page(s): 532 - 542
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1752 KB)  

    In the 1989 Loch Linnhe experiment, ship-generated internal waves were imaged from airborne synthetic aperture radars (SARs) operating at various frequencies. In this paper, we examine Ka, Ku , X, and C-band images at moderate incidence angles (21-30°) where peak-to-peak modulations of 3.3, 1.6, 1.3, and 0.7 dB, respectively, were observed. In situ time-series measurements of the internal-wave induced currents were made from a spar buoy. The SAR and current-meter data sets were compared by using the images to estimate the equivalent image intensity time series at the location of the spar. This was accomplished using linear internal wave theory with the Keller-Munk formulation of the wave-wake kinematics. The validity of this approach is confirmed by the good agreement obtained between predicted and observed wake geometries. Quantitative comparisons were made between measured radar modulations and predictions from wave-current interaction and radar scattering models. These comparisons indicate that the observed phase relationships between the radar modulation and the current are well predicted for each of the four radar frequencies, but that the magnitude of the predicted modulations is too low at the higher frequencies View full abstract»

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  • Atmospheric corrections in the thermal infrared: global and water vapor dependent split-window algorithms-applications to ATSR and AVHRR data

    Publication Year: 1996 , Page(s): 457 - 470
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1348 KB)  

    The split-window method is an appropriate way to perform atmospheric corrections of satellite brightness temperatures in order to retrieve the surface temperature. A climatological data set of 1761 different radio soundings, the TIGR database, has been used to develop two different split-window methods. A global quadratic (QUAD) method, with global coefficients to be applied on a worldwide scale, and a water vapor dependent (WVD) algorithm. The first method includes a quadratic term in the split-window equation that roughly accounts for the water vapor amount. The other method explicitly includes the water vapor amount in each split-window coefficient. When applied to the 1761 radio soundings, the latter method gives better results than the global one, especially when the surface emissivity is far from unity (0.95 or less) and when the water vapor reaches great values. Both algorithms have been tested on ATSR/ERSI and AVHRR/NOAA data over sea pixels. The QUAD algorithm gives correct results for simulations (the standard error is 0.2 K) and experimental data (the bias ranges from -0.1 to 0.4 K). The WVD algorithm appears to be more accurate for both simulations (the standard error is less than 0.1 K) and AVHRR experimental data when climatological water vapor contents are used (the bias ranges from -0.2 to 0.1 K) View full abstract»

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  • Remote sensing of forest change using artificial neural networks

    Publication Year: 1996 , Page(s): 398 - 404
    Cited by:  Papers (57)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (760 KB)  

    A prolonged drought in the Lake Tahoe Basin in California has resulted in extensive conifer mortality. This phenomenon can be analyzed using (multitemporal) remote sensing data. Prior research in the same region used more traditional methods of change detection. The present paper introduces a third approach to change detection in remote sensing based on artificial neural networks. The neural network architecture used is a multilayer feedforward network. The results of the study indicate that the artificial neural network (ANN) estimates conifer mortality more accurately than the other approaches. Further, an analysis of its architecture reveals that it uses identifiable scene characteristics-the same as those used by a Gramm-Schmidt transformation. ANN models offer a viable alternative for change detection in remote sensing View full abstract»

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  • Stochastic theory of temperature distribution and thermal emission of half-space with random time-dependent surface temperature

    Publication Year: 1996 , Page(s): 582 - 587
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    On the basis of results of simultaneous solution of thermal emission transfer and thermal conductivity equations, the stochastic theory of temperature distribution and thermal radioemission of medium (half-space) has been developed. Expressions for covariance functions of temperature profile and brightness temperature as functions of statistical parameters of half-space surface temperature, which was considered as a random function of time, have been obtained View full abstract»

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  • Surface temperature and soil moisture retrieval in the Sahel from airborne multifrequency microwave radiometry

    Publication Year: 1996 , Page(s): 588 - 600
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1260 KB)  

    Bipolarized microwave brightness temperatures of Sahel semiarid landscapes are analyzed at two frequencies: 5.05 and 36.5 GHz. These measurements were performed in Niger, West Africa, by the radiometer PORTOS in the framework of the Hydrologic Atmospheric Pilot Experiment in the Sahel (HAPEX-Sahel), during the end of the rainy season (August-September 1992). The airborne microwave data were collected simultaneously with radiosoundings of the atmosphere, and ground measurements of surface temperature, soil moisture, and biomass of several vegetation types. After estimating the soil roughness parameters, it is shown that two kinds of vegetation canopies must be considered: sparse canopies and patchy canopies including bare soil strips. The mixed soil vegetation microwave emission is analyzed using a random continuous approach. The sparse canopy emission is efficiently described by considering the vegetation layer as homogeneous. Conversely, a simple soil-vegetation mixing equation must be used for the patchy canopies. The problem with retrieving the canopy temperature and the near-surface soil moisture is addressed. For every canopy, soil moisture retrieval is possible. Soil moisture maps are proposed. The canopy temperature can also be retrieved with good accuracy provided both vertical (v) and horizontal (h) polarizations are available. It is shown that the retrieved variables can be used to separate landscape units through a classification procedure View full abstract»

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  • Simultaneous wavelet estimation and deconvolution of reflection seismic signals

    Publication Year: 1996 , Page(s): 377 - 384
    Cited by:  Papers (29)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    The problem of simultaneous wavelet estimation and deconvolution is investigated with a Bayesian approach under the assumption that the reflectivity obeys a Bernoulli-Gaussian distribution. Unknown quantities, including the seismic wavelet, the reflection sequence, and the statistical parameters of reflection sequence and noise are all treated as realizations of random variables endowed with suitable prior distributions. Instead of deterministic procedures that can be quite computationally burdensome, a simple Monte Carlo method, called Gibbs sampler, is employed to produce random samples iteratively from the joint posterior distribution of the unknowns. Modifications are made in the Gibbs sampler to overcome the ambiguity problems inherent in seismic deconvolution. Simple averages of the random samples are used to approximate the minimum mean-squared error (MMSE) estimates of the unknowns. Numerical examples are given to demonstrate the performance of the method View full abstract»

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  • Pulse coding techniques for ST/MST radar systems: a general approach based on a matrix formulation

    Publication Year: 1996 , Page(s): 304 - 316
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1024 KB)  

    An approach based on matrix formulation used for the representation and analysis of the signals and processes in ST/MST radar systems using a series of polyphase code sequences is presented. Expressions of the appropriate signals at various stages of the transmitting/receiving and processing channels of the system are given, using mostly matrix formulation, which has the advantage, among other things, of compactness. The expressions of the powers of the various components of the received signal, including the geophysical signal and interference signals, are obtained in order to derive expressions for performance parameters such as those related to the degradation of signal-to-noise ratio in the truncated ranges and interference suppression. Analysis tools for obtaining optimum solutions to the full decoding of truncated ranges, interference suppression, and reduction of sidelobes resulting from atmospheric characteristics are developed View full abstract»

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  • Opposite side ERS-1 SAR stereo mapping over rolling topography

    Publication Year: 1996 , Page(s): 543 - 549
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1244 KB)  

    Opposite-side radar stereo images have been considered unsuitable for stereo viewing due to illumination differences which limit the ability to identify the same features in the image pair. In some contexts, like a rolling topography (slope less than 10°), the shadow, layover, and foreshortening effects, specific to radar images, will not be overwhelming with an opposite-side stereo pair. This paper reports on some issues of stereo viewing and plotting, as well as on quantitative results of mapping and features extraction from ascending and descending orbit ERS-1 SAR stereo images. Planimetric accuracy of 17 m and altimetric accuracy of 23.9 m have been achieved for lake shorelines and DEM extractions, respectively. Impacts of different parameters on the accuracy are also evaluated View full abstract»

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  • Microwave permittivity of dry snow

    Publication Year: 1996 , Page(s): 573 - 581
    Cited by:  Papers (40)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (756 KB)  

    The relative dielectric constant, or relative permittivity, ε of dry snow, is independent of frequency from about 1 MHz up to the microwave range of at least 10 GHz. New measurements of with improved accuracy were made with a specially designed resonator operating near 1 GHz. The coaxial sensor accurately defines the sample volume whose actual mass can be determined to give the density of the snow sample. A special electronic instrument, called a resometer, enabled accurate and rapid measurements under field conditions. Some 90 measurements of different kinds of dry snow (fresh, old, wind-pressed snow, depth hear, and refrozen crusts) were made at test sites in the Swiss and Austrian Alps. The data indicate that ε is a function of snow density only, given that the standard deviation of 0.006 from the fitted curve is just due to the expected measurement errors. The interpretation of these data in terms of physical mixing theory favors the effective medium formula of Polder and van Santen (1946). The data allow to relate the average axial ratio X as a function of ice volume fraction. Both prolate and oblate spheroids can explain the data. Independent reasoning gives preference to oblate particles. In both cases, the axial ratio increases with increasing fraction up to a critical value of 0.33, followed by a decrease at still higher fractions. The destructive metamorphism of slowly compacting snow explains the increase of X, while the following decrease might be due to sintering. So far, no effect on ε by a liquid-like surface layer on the ice grains at temperatures between -10°C and 0°C has been observed View full abstract»

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  • Optimal survey design using focused resistivity arrays

    Publication Year: 1996 , Page(s): 358 - 366
    Cited by:  Papers (9)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (732 KB)  

    The first problem which needs to be solved when planning any geoelectrical survey is a choice of a particular electrode configuration that can give the maximal response from a target inhomogeneity. The authors formulate a problem of maximizing the response as an optimization problem for an applied current intensity distribution on the surface. The solution of this problem is the optimal intensity distribution of the current, which maximizes the response from the inclusion. This problem is solved numerically with singular value decomposition of an impedance matrix. The optimal current array is modeled as a current of varying optimal intensity injected at different electrodes. The problem does not need any information about the inclusion but its measured impedance matrix. Thus an optimal current array can be designed for every particular resistivity distribution. The optimal current patterns are found for a number of models of a conductive inclusion, and responses due to the optimal current are compared with responses due to conventional arrays. This method can be applied to any background and inclusion resistivity distribution View full abstract»

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  • A numerical simulation of scattering from one-dimensional inhomogeneous dielectric random surfaces

    Publication Year: 1996 , Page(s): 425 - 432
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB)  

    An efficient numerical solution for the scattering problem of inhomogeneous dielectric rough surfaces is presented. The inhomogeneous dielectric random surface represents a bare soil surface and is considered to be comprised of a large number of randomly positioned dielectric humps of different sizes, shapes, and dielectric constants above an impedance surface. Clods with nonuniform moisture content and rocks are modeled by inhomogeneous dielectric humps and the underlying smooth wet soil surface is modeled by an impedance surface. In this technique, an efficient numerical solution for the constituent dielectric humps over an impedance surface is obtained using Green's function derived by the exact image theory in conjunction with the method of moments. The scattered field from a sample of the rough surface is obtained by summing the scattered fields from all the individual humps of the surface coherently ignoring the effect of multiple scattering between the humps. The statistical behavior of the scattering coefficient σ° is obtained from the calculation of scattered fields of many different realizations of the surface. Numerical results are presented for several different roughnesses and dielectric constants of the random surfaces. The numerical technique is verified by comparing the numerical solution with the solution based on the small perturbation method and the physical optics model for homogeneous rough surfaces. This technique can be used to study the behavior of scattering coefficient and phase difference statistics of rough soil surfaces for which no analytical solution exists View full abstract»

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  • Measurement and modeling of the millimeter-wave backscatter response of soil surfaces

    Publication Year: 1996 , Page(s): 561 - 572
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (932 KB)  

    The millimeter-wave (MMW) backscatter response of bare-soil was examined by conducting experimental measurements at 35 and 94 GHz using a truck-mounted polarimetric scatterometer and by developing appropriate models to relate the backscattering coefficient to the soil's surface and volume properties. The experimental measurements were conducted for three soil surfaces with different roughnesses under both dry and wet conditions. The experimental measurements indicate that in general the backscattering coefficient is comprised of a surface scattering component σs and a volume scattering component σ v. For wet soil conditions, the backscatter is dominated by surface scattering, while for dry conditions both surface and volume scattering are significant, particularly at 94 GHz. Because theoretical surface scattering models were found incapable of predicting the measured backscatter, a semiempirical surface scattering model was developed that relates the surface scattering component of the total backscatter to the roughness parameter ks, where k=2π/λ and s is the rms height, and the dielectric constant of the soil surface. Volume scattering was modeled using radiative transfer theory with the packed soil particles acting as the host material and the air voids as the scattering particles. The combined contribution of surface and volume scattering was found to provide good agreement between the model calculations and the experimental observations View full abstract»

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  • A multiscale, statistically based inversion scheme for linearized inverse scattering problems

    Publication Year: 1996 , Page(s): 346 - 357
    Cited by:  Papers (36)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1352 KB)  

    The application of multiscale and stochastic techniques to the solution of a linearized inverse scattering problem is presented. This approach allows for the explicit and easy handling of many difficulties associated with problems of this type. Regularization is accomplished via the use of a multiscale prior stochastic model which offers considerable flexibility for the incorporation of prior knowledge and constraints. the authors use the relative error covariance matrix (RECM), introduced by E.L. Miller et al. (1995), as a tool for quantitatively evaluating the manner in which data contribute to the structure of a reconstruction. Given a set of scattering experiments, the RECM is used for understanding and analyzing the process of data fusion and allows the authors to define the space-varying optimal scale for reconstruction as a function of the nature (resolution, quality, and distribution of observation points) of the available measurement sets. Examples of the authors' multiscale inversion algorithm are presented using the Born approximation of an inverse electrical conductivity problem formulated so as to illustrate many of the features associated with inverse scattering problems arising in fields such as geophysical prospecting and medical imaging View full abstract»

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  • Statistics of the Stokes parameters and of the complex coherence parameters in one-look and multilook speckle fields

    Publication Year: 1996 , Page(s): 519 - 531
    Cited by:  Papers (47)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (840 KB)  

    Barakat [1987] derived the Stokes parameter statistics, applicable to one-look synthetic aperture radar (SAR) images, of a partially polarized wave backscattered from a Gaussian area. In this paper, the statistics of the Stokes parameters and of the phase difference are derived as a function of the mean effective phase difference and the degree of coherence for one-look and multilook SAR data. The statistics of the degree of coherence are also derived for multilook SAR data. It is shown that the estimator currently used for calculation of the degree of coherence is biased under low coherence conditions View full abstract»

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  • Use of ERS-1 wind scatterometer data over land surfaces

    Publication Year: 1996 , Page(s): 550 - 560
    Cited by:  Papers (38)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1328 KB)  

    The capability of ERS-1 wind scatterometer (WSC) data for land surface studies at regional and global scales is investigated. Calibrated data, available since April 1992, consist of backscattering coefficient σ° values estimated over a 50 km ground resolution cell within a 18-59° incidence range. The WSC covers latitudes between 80°S and 85°N. Data quality is investigated. Results show a good radiometric stability throughout a two-year period (April 1992-March 1994), a good measurement accuracy and a very good intercalibration between antennas. A global backscattering coefficient image of the world is presented and statistics of σ° are extracted for the main land surfaces. A strong dependence between this image and global vegetation and elevation map is observed. Finally, WSC and Seasat-A Scatterometer System (SASS) data of typical regions are compared. Results indicate the high capability of ERS-1 WSC data for land surfaces monitoring at global and regional scales View full abstract»

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  • Complementary sequences with high sidelobe suppression factors for ST/MST radar applications

    Publication Year: 1996 , Page(s): 317 - 329
    Cited by:  Papers (9)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1316 KB)  

    Under ideal conditions, complementary code pairs produce no sidelobes. In practice, sidelobes are produced, among other things, when the period of the Doppler frequency shift as well as the time of coherence of clear air turbulence are comparable (or smaller) than the interpulse period. The intensity of sidelobes increases with the radar operating frequency and becomes a real problem in the upper VHF and UHF bands. In this paper, a new technique for reducing sidelobes originating from atmospheric characteristics for clear air radar systems using pulse coding is presented. For this, a generalized analytic expression for a sidelobe suppression factor applicable to any number of binary code sequences is first derived. This is then used to develop the technique, which in the case of complementary codes consists of manipulating the order of transmission of the code sequences. For such codes, improvements in sidelobe suppression of the order of 80 dB on the VHF frequency band are obtained. The modifications required to implement the technique into existing systems are very few and simple View full abstract»

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  • Calibration of spaceborne scatterometers using tropical rain forests

    Publication Year: 1996 , Page(s): 413 - 424
    Cited by:  Papers (29)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1480 KB)  

    Wind scatterometers are radar systems designed specifically to measure the normalized radar backscatter coefficient (σ°) of the ocean's surface in order to determine the near-surface wind vector. Postlaunch calibration of a wind scatterometer can be performed with an extended-area natural target such as the Amazon tropical rain forest. Rain forests exhibit a remarkably high degree of homogeneity in their radar response over a very large area though some spatial and temporal variability exist. The authors present a simple technique for calibrating scatterometer data using tropical rain forests, Using a polynomial model for the rolloff of σ° with incidence angle, the technique determines gain corrections to ensure consistency between different antennas and processing channels. Corrections for the time varying instrument gain are made consistent with a seasonally fixed rain forest response; however, without ground stations or aircraft flights, it is difficult to uniquely distinguish between seasonal variations in the rain forest and slow variations of the system gain. Applying the corrections, the intrinsic variability of the σ° of the rain forest is estimated to be ±0.15 dB, which is the limit of the accuracy of calibration using the rain forest. The technique is illustrated with Seasat scatterometer (SASS) data and applied to ERS-1 Active Microwave Instrument scatterometer (Escat) data. Gain corrections of up to several tenths of a decibel are estimated for SASS. Corrections for Escat data are found to be very small, suggesting that Escat data is well calibrated View full abstract»

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  • Optimal range and Doppler centroid estimation for a ScanSAR system

    Publication Year: 1996 , Page(s): 479 - 488
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (824 KB)  

    This paper presents a new range and Doppler centroid estimation algorithm for a ScanSAR system. This algorithm is based on processing the image data in the overlapped region of two bursts of the same beam or adjacent beams. It leads to highly accurate radar pointing angles that are paramount to achieving good radiometric performance in ScanSAR imagery. The achievable accuracy is derived theoretically and verified by tests performed using SIR-C ScanSAR data and ERS data. This algorithm is computationally efficient and easy to implement. The proposed Doppler centroid estimation algorithm is also an excellent candidate for a strip mode SAR system View full abstract»

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  • Passive microwave remote sensing of forests: a model investigation

    Publication Year: 1996 , Page(s): 433 - 443
    Cited by:  Papers (79)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (988 KB)  

    A model, based on the radiative transfer theory and the matrix doubling algorithm, is described and used to compute the emissivity e of forests. According to model simulations, the L-band emissivity trend versus forest biomass is more gradual than that of the backscatter coefficient. This gradual behavior is observed, in absence of leaves, also at C- and X-bands, while leaves anticipate saturation and make e higher in coniferous forests and lower in deciduous forests. Model results are successfully validated by some available experimental data. Operational aspects, concerning the potential of airborne and spaceborne radiometers in identifying forest type and estimating biomass, are discussed View full abstract»

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  • The ratio of the arithmetic to the geometric mean: a first-order statistical test for multilook SAR image homogeneity

    Publication Year: 1996 , Page(s): 604 - 606
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1052 KB)  

    The ratio of the arithmetic to the geometric mean is introduced as a general index to test SAR image homogeneity. Application to a multilook airborne SAR image shows that this first-order statistical measure compares advantageously and in some typical cases outperforms the coefficient of variation for the detection of random and structural heterogeneity View full abstract»

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  • A review of target decomposition theorems in radar polarimetry

    Publication Year: 1996 , Page(s): 498 - 518
    Cited by:  Papers (633)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2668 KB)  

    In this paper, we provide a review of the different approaches used for target decomposition theory in radar polarimetry. We classify three main types of theorem; those based on the Mueller matrix and Stokes vector, those using an eigenvector analysis of the covariance or coherency matrix, and those employing coherent decomposition of the scattering matrix. We unify the formulation of these different approaches using transformation theory and an eigenvector analysis. We show how special forms of these decompositions apply for the important case of backscatter from terrain with generic symmetries View full abstract»

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  • Scattering from a metallic object embedded near the randomly rough surface of a lossy dielectric

    Publication Year: 1996 , Page(s): 367 - 376
    Cited by:  Papers (35)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1692 KB)  

    Two-dimensional electromagnetic scattering from a perfectly conducting target embedded near the randomly rough surface of an isotropic lossy dielectric is investigated. The randomly rough surface is illuminated by a finite width beam from an antenna in the free space above the surface, with off-normal incidence. Standard integral equation methods are applied and include all subsurface interactions between the object and rough surface. For a chosen embedded target, Monte Carlo simulations are performed for a selection of ensembles of rough surface types intended to be suggestive of natural ground. Far field scattering coefficient distributions and corresponding synthetic images suggest when the buried object should be discernible. Sensitivities are explored in terms of surface type, polarization of the incident field, depth and orientation of target, soil characteristics, incidence angle, and beamwidth. Many of the scattering features identified should also apply in 3D View full abstract»

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  • A waveform model for surface and volume scattering from ice and snow

    Publication Year: 1996 , Page(s): 444 - 456
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1248 KB)  

    A method for combining surface and volume scattering effects to model the radar altimeter power waveforms recorded over continental ice and snow, such as that present on Greenland and Antarctica, is discussed. The surface model that is used is a variant of the well-known impulse response based method that is capable of modeling the returns for an altimeter having a general configuration of altitude, antenna beamwidth, transmitted pulsewidth, and pointing angle. The newly formulated volume model is also an impulse response based method that differs from previously introduced versions in that it can also be applied to a general altimeter configuration. The two models are added together assuming completely incoherent scattering. An example of fitting this combined model to altimeter data is given to illustrate the importance of accounting for the volume scattering present in ice/snow data. An optimization method can then be used to achieve a least-squares fit to actual altimeter data, providing an estimate of the parameters for that area on the ice shelf View full abstract»

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  • Multispectral data compression using bidirectional interband prediction

    Publication Year: 1996 , Page(s): 385 - 397
    Cited by:  Papers (12)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1604 KB)  

    The introduction of high spatial and spectral resolution sensors on-board remote-sensing spacecraft has increased, by orders of magnitude, the data rates which need to be sustained on the down-link or cross-link transmission channels. Since these channels are severely limited in capacity, the need arises to perform on-board compression to reduce the volume of data which would need to be down-linked. This paper discusses the development and refinement of a low complexity lossy spectral/spatial compression method which provides high compression ratios at low levels of distortion. The developed techniques uses pixels in adjacent bands to predict the intensity of pixels in the band being compressed via a simple linear prediction model. This prediction method when combined with a low-distortion discrete cosine transform (DCT) block coding method yields performance comparable to block-adaptive Karhunen-Loeve Transform (KLT)-DCT methods without incurring the complexity penalty of the KLT. The methods' performance suffers under misregistration. A fractional-pixel interpolation enhancement to the basic technique significantly improves the performance in the case of misregistered bands View full abstract»

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  • The microwave radiometer aboard ERS-1. II. Validation of the geophysical products

    Publication Year: 1996 , Page(s): 291 - 303
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1148 KB)  

    For pt.I see ibid., vol.31, no.6, p.1186-98 (1993). The ERS-1 microwave radiometer was designed to correct the satellite altimeter data for the excess path delay due to tropospheric humidity. The brightness temperature calibration was tested using two radiative transfer models, applied to the same coincident meteorological profiles over ocean. Differences were analyzed by similarly comparing calculated brightness temperatures with SSM/I data, for the same meteorological data set, extracted from ECMWF (European Center for Medium range Weather Forecasting) analyses. The calibration of the two channels of the ERS-1 microwave radiometer required correction of a few Kelvin. The final water vapor and altimeter path delay validation was performed by comparing routine radiosonde measurements with the retrieved water vapor and altimeter path corrections over a one-year period View full abstract»

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Aims & Scope

 

IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING (TGRS) is a monthly publication that focuses on the theory, concepts, and techniques of science and engineering as applied to sensing the land, oceans, atmosphere, and space; and the processing, interpretation, and dissemination of this information.

 

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Meet Our Editors

Editor-in-Chief
Antonio J. Plaza
University of Extremadura