ISSN:0143-1161    

DOI:10.1080/01431169208909098

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431169208904154

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An analysis of remotely sensed imagery of the Exxon Valdez oil spill is described and the usefulness of the various wavelengths and platforms available (Landsat, AVHRR, SPOT) is discussed. The spill was sufficiently large that the main body could be detected by the low resolution (I km) AVHRR system. However the higher resolution of Landsat TM and SPOT (30 m and 10 m) was required to identify individual features such as windrows, etc. The utility and uniqueness of a multispectral TM signature developed lo identify spilled oil is discussed in detail with reference to direct terrestrial measurements of oil reflectance and the possibility of other sources of the signature such as ocean vegetation and direct reflectance from some beach materials. Other directly observable ocean parameters such as sea surface temperature and suspended sediment were noted and incorporated into the analysis in terms of ocean circulation and the creation of weathered spill products such as 'tar balls’. The 'mid-infrared’ (TM band 5) provided the strongest component of the oil signature. However, the spill was observable in other wavelengths as well, including the thermal infrared where at various times and locations it appeared either warmer or cooler than the surrounding waters. These observations are discussed in terms of oil emissivity and reflected solar radiation.

ISSN:0143-1161    

DOI:10.1080/01431169208904155

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In this paper 1 review the reasons why it is desirable to place a remote-sensing satellite into an orbit which periodically repeats its path. Such exactly-repeating orbits are often used for Earth remote-sensing satellites, but the most appropriate orbit depends upon the likely application of the data. If they are to be used to study a rapidly changing phenomenon a short repeat period is obviously preferable, whereas if a dense grid of subsatellite tracks is required (e.g., for a large mapping project) a long repeat period is required. The increasing tendency to design multi-purpose remote sensing satellite missions means that these requirements are more likely to come into conflict. 11 is however sometimes possible to choose an orbit which, while exactly repeating itself only after a long period, almost repeats itself at much shorter intervals. These orbits are often called orbital subcycles or drifting subcycles and this paper sets out their theory in sufficient detail, it is hoped, to enable remote sensing scientists lo assist space agencies in selecting orbits which satisfy as many users as possible.

ISSN:0143-1161    

DOI:10.1080/01431169208904156

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Most implementations of Bayesian classification assume fixed a priori probabilities. These implementations can be placed into two general categories: (1) those that assume equal a priori probabilities and (2) those that assume unequal but fixed a priori probabilities. We report here on results of classifying polarimetric SAR images using a scheme in which the classification is done iteratively. The first classification is done assuming fixed (but not necessarily equal) a priori probabilities. The results of this first classification are then used in successive iterations to change the a priori probabilities adaptively. The results show that only a few iterations are necessary to improve the classification accuracy dramatically.

ISSN:0143-1161    

DOI:10.1080/01431169208904157

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An effort was made to produce the best Thematic Mapper colour image for detailed geological visual interpretation. Northern Somalia sedimentary rocks, ranging in age from Jurassic to Quaternary, were chosen as test-object, Bands 7 and 1 were selected as giving the best colour composite; decorrelation stretching with spatial filtering of principal components was chosen as the most suitable enhancement technique. Improved image characteristics facilitate recognition and mapping of lithologic units which can be used to frame ongoing stratigraphical studies for the area under investigation.

ISSN:0143-1161    

DOI:10.1080/01431169208904158

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The variation in the influence of the atmosphere on ground reflectance appears to be small for a stable atmosphere al different haze conditions in the study area. For a comparison of field with simulated and actual satellite data the model of Verhoef was used, which requires as input the ratio of measured diffuse to total irradiation. Relative difference in planetary reflectance of Landsat TM predicted with an atmospheric model for a specific ground reflectance and the observed range of stable atmospheric conditions turned out to be small. In situ measured ground reflectance and the ground reflectance derived from planetary actual TM reflectance are in good agreement.

ISSN:0143-1161    

DOI:10.1080/01431169208904159

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A thermal scanner in the 2-μm waveband is used for airborne studies of urban temperature patterns. The urban geometry is modelled by the Sky View-Factor (SVF). Comparisons of surface temperature and SVF show a good correlation. The largest difference in surface temperature (4°C) was recorded between dense canyons and open areas. Ground measurements correspond well with the temperature calculated from the infrared images. Different examples of inlra-urban thermal variations and the utility of the instrument and software for the determination of differences in temperature arc discussed.

ISSN:0143-1161    

DOI:10.1080/01431169208904160

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Satellite remote sensing of ocean and lake surface temperature is of considerable importance for climate research, but the main problem with thermal infrared measurements is the determination of the atmospheric correction. We present a novel extension to the split-window method to retrieve the total atmospheric transmittance, and demonstrate the use of this information in improved algorithms for sea surface temperature (SST) and total column content of water vapour. Simulation studies, using radiosonde profiles and an atmospheric transmission model, show that the new SST algorithm has an intrinsic precision of ∼01 degKr.m.s. (representing an improvement by a factor of 2-4 over conventional algorithms) and that atmospheric water vapour content can be retrieved with an accuracy of ∼ 5 per cent independent of its absolute value. We also discuss potential sources of error and future applications of the technique.

ISSN:0143-1161    

DOI:10.1080/01431169208904161

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A new method is proposed which allows for reasonably accurate cloud classification based upon Gaussian approximation of cloud emission and using a pair of visible-infrared, high resolution METEOSAT images. Its most important characteristic is the very low amount of CPU time required for a single classification. It becomes then suitable for application in very short range weather forecasting (nowcasting) by ensuring the adequate time coverage and necessary rapidity of use for the operational environment. Two classifications of summer and winter meteorological situations are presented.

ISSN:0143-1161    

DOI:10.1080/01431169208904162

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor