ISSN:0143-1161    

DOI:10.1080/01431169308904409

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The paper brings out the theoretical basis and utility of near-infrared band data sets obtained from Earth resources satellites, in the estimation of very high temperatures witnessed during volcanic eruptions. The Landsat Thematic Mapper (TM) and Indian Remote Sensing Satellite (IRS) Linear Imaging Self Scanning System (LISS-II) data sets for the period 4 April 1991-4 August 1991 were used for studying the volcanic eruption at Barren Island (India). The effect of the sub-pixel size vent in the estimation of pixel-integrated temperature has been discussed. The volcanic vent temperature on 6 May 1991 was found to be 1084K. The availability of mid-IR bands (1-55-1-75 μm and 2.08-2.35μm spectral region) in Landsat-TM enabled bringing out the vent region in the false colour composite (FCC) generated using these and the near-IR (0.76-0.90μm) band. The very high or saturated values in mid-IR bands brought a good contrast between vent and its surroundings

ISSN:0143-1161    

DOI:10.1080/01431169308904410

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In July 1991, the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) was flown over Mount Etna and Stromboli, Italy. At the time, magma-filled vents, of subpixel dimensions, occupied the summit craters of both volcanoes. For pixels located over these hot spots, thermal radiation dominates the sensor response between about 1-4 and 2-4μm,the latter figure being the upper limit of spectral coverage. One thermal source within the Northeast Crater of Mount Etna is evident at wavelengths as short as I 0 μm despite this intensity, therc is no saturation of the AVIRIS sensors because of their wide dynamic range. A curve-fitting algorithm is used to match the thermal spectra with Planck radiation models, in order to derive information on temperature distributions at the subpixel scale. Difficulties arise because the sequential readout of detector elements during scanning leads to interband spatial misregistration. Although the standard preprocessing of AVIRIS data includes a linear interpolation of adjacent pairs of cross-track pixels to compensate for the readout delay, this procedure only complicates further the extraction of subpixel resolution thermal information. Only by reconfiguring AVIRIS, such that all spectral channels arc recorded simultaneously, could this problem be completely overcome. Nevertheless, by examining geometrically unprocessed spectra, and selecting from thcm thermal measurements in a few adjacent channels, meaningful radiometric calculations are possible in some cases. In this manner, we estimate that one of the hot spots on Stromboli was at ≈600°C and occupied ≈ 15 m2of ground. The methodologies proposed here are applicable to any hyperspectral record of thermal emission of volcanic or other origin

ISSN:0143-1161    

DOI:10.1080/01431169308904411

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Minerals and rocks show varying spectral reflectances under different spectral ranges of the electromagnetic spectrum and such spectral responses vary because of colour, texture, crystal structure, specific gravity and other physical and optical properties. Hence in order to optimise the spectral ranges which may be used in the recognition of the minerals and the rocks, spectral reflectance measurements were carried out for 29 minerals under the visible and near-infrared ranges of the electromagnetic spectrum covered by the TM bands 1, 2, 3 and 4, IRS bands 1, 2, 3 and 4 and SPOT bands 1, 2 and 3. The analysis of the data identifies the optimum spectral bands for distinguishing the different minerals and the mineral aggregates/rocks

ISSN:0143-1161    

DOI:10.1080/01431169308904412

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The discovery and subsequent mapping of an ancient shoreline at 25 m depth in N-E Brazil by TM-Landsat imagery is described. The study area is located on a technically stable part of the Brazilian shelf which presently shows a minor uplift rate of 0-2 mm year−1, to the north of Natal in the State of Rio Grande do Norte. This submerged shoreline is characterized by the occurrence of a large number of long beachrock outcrops (>3km in length), observed by diving, which are comparable to their analogues seen on the present-day beaches of the adjacent coast. The good state of preservation of this shoreline and the large number of carbonate rock ‘reefs’ on it suggest abruptness of a return to transgressive sea-level trend with high growth rates subsequent to a long-lived sea-level relating to the 11000-9000 yr b.p. band. By reviewing high resolution paleoclimatic data from this period, we conjecture that this stillstand could be a consequence of the Younger Dryas cold event in the north Atlantic, which might have also had importance as a driving morphogenctic process for coasts in a global scale.

ISSN:0143-1161    

DOI:10.1080/01431169308904413

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Rapidly accelerating interest in remote sensing of marine pollution has resulted in the development of a diverse range of appropriate techniques, but remote sensing has yet to reach its zenith in terms of real world applications. To assist in this direction this paper provides an overview of applications. Limitations are outlined and the potential of remote sensing is illustrated by means of case studies. Methods for providing base-line inventories of coastal environments, and measurement of marine properties are reviewed. Pollutants in the marine environment are reviewed and are split into physical, chemical, biological and thermal. The future potential for a more effective use of remote sensing in operational projects is discussed

ISSN:0143-1161    

DOI:10.1080/01431169308904414

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The model which allows one to simulate the Synthetic Aperture Radar (SAR) and the along track Interferometric SAR (INSAR) imagery of a monochromatic ocean wave is presented. The model accounts for the effects of the real aperture radar (RAR) modulation of the radar backscatter cross-section. The comparison of the SAR and the INSAR imagery of the wave system under consideration is carried out and the performance of the two imaging systems is studied under various operational conditions. The results of the study indicate that the interferometric SAR is less sensitive to the RAR modulation as compared lo the regular SAR. This fact further augments the assertion that INSAR has considerable advantages over SAR in its potential of providing quantitative information about the ocean wave lengths, directions and amplitudes

ISSN:0143-1161    

DOI:10.1080/01431169308904415

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The azimuthal resolution of the Synthetic Aperture Radar (SAR) when imaging the permanently moving ocean surface is determined by the coherence time of the imaged scene. The scene coherence time thus constitutes one of the major parameters in SAR imagery of the ocean. The present study shows how the direct estimate of this parameter under the actual experimental conditions can be performed using a two-antenna interferometric SAR. The present results arc in agreement with earlier estimates.

ISSN:0143-1161    

DOI:10.1080/01431169308904416

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Radiometry at the water vapour line with a scanning antenna beam from horizon to horizon through the zenith, in the vertical plane, was shown to be useful in estimating the integrated water vapour content from the zenith angle variation of radiometric temperature. The beam scanning may be made at a rate slower than the radiometer time constant using a Dicke type radiometer. Alternatively, a fast scanning beam may be used in a total power radiometer with a synchronous detection of the radiometer output at the scanning frequency to obtain a space domain Dicke switching for the measurements. A simultaneous scanning beam with 22.235 and 31.4GHz radiometers would allow us to separate the liquid water, if any, from the integrated water vapour content. Theoretical studies of the scanning beam radiometer performance in the estimation of integrated water vapour content from radiosonde data is presented and some typical results of Dicke type scanning beam radiometers at 22.235 and 31.4 GHz are also presented in this paper.

ISSN:0143-1161    

DOI:10.1080/01431169308904417

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

We present here a new scheme that performs geometrical correction for airborne multi-spectral scanner imagery provided that an adequate reference image, i.e., an orthophoto, is available. Instead of the ray-tracing method, we determine the corresponding ground coordinates for each pixel of an input image by integrating feature point matching under Delaunay triangulated networks. The major components of the scheme include progressive generation of registration control points, and image registration. Comprehensive investigation for quantitative error analysis is also included. Experimental results indicate that the corrected images attain an accuracy of better than 09 pixels.

ISSN:0143-1161    

DOI:10.1080/01431169308904418

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor