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Geoscience and Remote Sensing, IEEE Transactions on

Issue 4 • Date Oct. 1981

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Displaying Results 1 - 18 of 18
  • [Front cover - IEEE Transactions on Geoscience And Remote Sensing]

    Page(s): c1
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  • IEEE Geoscience And Remote Sensing Society

    Page(s): c2
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  • Table of contents

    Page(s): 177
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  • Regression Techniques for Oceanographic Parameter Retrieval Using Space-Borne Microwave Radiometry

    Page(s): 178 - 189
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    Variations of conventional multiple regression techniques are applied to the problem of remote sensing of oceanographic parameters from space. The techniques are specifically adapted to the scanning multichannel microwave radiometer (SMMR) launched on the Seasat and Nimbus 7 satellites to determine ocean surface temperature, wind speed, and atmospheric water content. The retrievals are studied primarily from a theoretical viewpoint, to illustrate the retrieval error structure, the relative importances of different radiometer channels, and the tradeoffs between spatial resolution and retrieval accuracy. Comparisons between regressions using simulated and actual SMMR data are discussed; they show similar behavior. View full abstract»

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  • Freshwater Ice Thickness Observations Using Passive Microwave Sensors

    Page(s): 189 - 193
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    Walden Reservoir, a freshwater lake in north-central Colorado, was overflown six times by a NASA C-130 aircraft between January 1977 and April 1980. The aircraft was equipped with four microwave radiometers operating between 0.81 and 6.0 cm in wavelength (37.0 to 5.0 GHz). The 6.0-cm radiometer data showed a good relationship (R2 = 0.98) with ice thickness based on a sample of four ice thickness values. The 1.67- and 1.35-cm radiometer data showed weaker relationships with ice thickness. The 0.81-cm sensor data showed no positive relationship with ice thickness. None of the relationships was statistically significant because of the small sample size. The 6.0-cm sensor data in the nadir-viewing mode was found to have the most potential of all the wavelengths studied, for use in remotely determining ice thickness. The 6.0-cm radiometer probably sensed the entire thickness of the ice on the reservoir (ranging from 25.4 to 67.3 cm in thickness) and was apparently not significantly affected by the snow overlying the ice. The shorter wavelengths are scattered by the snow overlying the ice and are more suitable for snow studies than for ice thickness studies. View full abstract»

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  • Direct Determination of the Two-Dimensional Image Spectrum from Raw Synthetic Aperture Radar Data

    Page(s): 194 - 203
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    This paper describes an algorithm which computes two-dimensional Fourier transform of a synthetic aperture radar (SAR) image. This method is intended to replace the whole SAR processing and the two-dimensional Fourier transformation by a specialized processing scheme which, in terms of computational speed and complexity, will be of the order of a single two-dimensional autocorrelation. This processing approach is applied to the estimation of the wave directional spectrum from the raw data of the SAR sensor of Seasat-1. View full abstract»

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  • HF Radio Wave Transmission over Sea Ice And Remote Sensing Possibilities

    Page(s): 204 - 209
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    Ground wave propagation is analyzed for a path where sea water is covered by a uniform layer of sea ice. The source is taken to be a vertical electric dipole on or above the ice layer. The solution indicates that a trapped surface wave is significant at short ranges while, at longer ranges, the usual ground wave modes are dominant. The resulting interference pattern may produce rapid variations of the field at intermediate ranges. These characteristics, as well as the height dependence of the observed field strength, are strongly dependent on the thickness of the ice layer. View full abstract»

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  • HF Ground Wave Propagation over Mixed Land, Sea, And Sea-Ice Paths

    Page(s): 210 - 216
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    Ground wave propagation is analyzed for a two-section path on a spherical earth. Each section can be a two-layer medium which is characterized by a surface impedance. Specific calculations for a land-to-sea path indicate that the well-known recovery effect in amplitude and phase is more extreme at higher frequencies but is reduced for elevated observer heights. Calculations for a sea-to-sea ice path indicate a brief recovery because of the excitation of the trapped surface wave over sea ice. At greater distances from the boundary, the field may be seriously degraded due to the sea ice. View full abstract»

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  • A Fast Optimal Deconvolution Algorithm for Real Seismic Data Using Kalman Predictor Model

    Page(s): 216 - 221
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    The paper is concerned with an application of a recently proposed algorithm for minimal realization of stochastic dynamic systems to the problem of deconvolution of reflection seismograms. Results of real data processing are presented in order to establish the advantages of this algorithm in terms of computational requirements and accuracy of signal estimation vis-à-vis the widely accepted algorithm of Robinson and Treitel. View full abstract»

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  • Application of Prediction Error Filters for the Detection of Weak Teleseismic Events

    Page(s): 222 - 230
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    This paper analyzes how the signal-to-noise ratio (SNR) for digital registrations of weak earthquakes can be enhanced by application of prediction error filters. Two prediction algorithms are considered: A linear prediction filter and an adaptive autoregressive moving average (ARMA) filter. The effects of the filter parameters on the noise suppression rate and on the quality of spectral approximation are discussed. Results are given for broad-band and short period data of the Graefenberg array. The signal-to-noise gains achieved by prediction error filtering are examined for a series of weak events. View full abstract»

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  • Towards a General Theory of Induced Electrical Polarization in Geophysical Exploration

    Page(s): 231 - 234
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    We exploit the concept that the resistivity of earth materials is a complex frequency-dependent quantity. We then present a general macroscopic formulation for the voltage response at two ¿potential¿ electrodes when a current is suddenly applied to two additional electrodes. It is indicated, in a general way, how the transient and the frequency domain results are related. Using a function approach, the apparent complex resistivity is related to the complex resistivities of the constituent media. Hitherto neglected second-order effects are accounted for and their significance is pointed out. Finally, we consider a unified dynamic formulation that allows both induced polarization and electromagnetic coupling to be accounted for. We believe this points the way for a much needed general analytical approach to the macroscopic description of the phenomenon. View full abstract»

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  • Quasi-Static Magnetic-Field Technique for Determining Position And Orientation

    Page(s): 235 - 243
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    Multiaxis generation and sensing of magnetic-dipole fields is used to determine both position and orientation. The effect of conducting ground upon the fields is kept to an acceptably low level by using extremely low-frequency source-excitation signals. This technique can therefore be used in through-the-earth position-finding for applications such as drill guidance and mine rescue. The theory of operation, system-design procedures, and simulated performance data are given. View full abstract»

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  • Miniature Interferometer Terminals for Earth Surveying: Ambiguity And Multipath with Global Positioning System

    Page(s): 244 - 252
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    With the recent launching of several satellites of the global positioning system (GPS), a variety of schemes based on radio interferometry have been proposed for the accurate determination of relative positions of receiving terminals on the ground. Provided that the integer-cycle ambiguities of the interferometric phase observations can be correctly resolved, the baseline vector extending from the antenna of one terminal to that of another should be determinable with uncertainty much smaller than the 19-cm wavelength of the GPS transmissions. We propose a method of ambiguity resolution that is suitable for observations made with antennas of low directive gain. Such antennas are compact, but the feasibility of their use has been questioned because observations with them are susceptible to multipath interference. For short-baseline interferometric observations of GPS our method yields correct ambiguity resolution despite severe multipath interference and significant sky blockage, even when instability of the frequency standards governing the separate receiving terminals limits the time span of coherent integration to five minutes. View full abstract»

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  • Editorial Board for 1980

    Page(s): 253
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  • Author index

    Page(s): 253a - 253b
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  • Subject index

    Page(s): 253b - 253e
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  • Information for authors

    Page(s): 253f
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  • Institutional listings

    Page(s): 253g
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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.

 

Full Aims & Scope

Meet Our Editors

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