ISSN:0143-1161    

DOI:10.1080/01431169108929627

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Mid-infrared (IR) orbiting platforms are attractive candidates for monitoring fire on a global basis, as needed for global biogeochemical studies. In the mid IR, fires radiate intensely against a low-energy background. Thus fires occupying a fraction of a percent of a pixel can be detected. Fire size and temperature can, in theory, be calculated from multi-channel IR measurements. The fire record in raw IR data is biased by obscuration by clouds and smoke, sensor saturation, difficulties in gaining a representative sample given the diurnal variation in fire activity and the large role played in global fire emissions by cooking fires, charcoal making and very small burns on agricultural wastes. The bias is spatially variant and its nature is poorly understood. Further research and engineering is required before IR sensing can improve upon current rough estimates of biomass burning based on scattered available data.

ISSN:0143-1161    

DOI:10.1080/01431169108929628

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Some design issues relevant to the adaptation of small satellites for remote sensing applications are presented. Particular emphasis is placed on those areas which will necessitate the advancement of current small satellite technology. The aim of such a programme would be to provide a cost-effective but reliable way of obtaining remotely sensed data from a range of novel sensors, thus complementing the efforts of major missions towards the 21st century.

ISSN:0143-1161    

DOI:10.1080/01431169108929629

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The Microwave Limb Sounder (MLS) to be carried on the Upper Atmosphere Research Satellite (UARS) will measure concentrations of a number of stratospheric constituents. In this paper sample calculations of the forward problem pertaining to the 183 GHz band of MLS are presented. This band is used to infer water vapour and ozone amounts from the 183·3 GHz and 184·4 GHz lines respectively. The calculations include the effects of the antenna field of view and radiometric filter response. Some indications of the sensitivity of the calculated radiances to changes in the constituent concentration are shown. These are closely related to the influence functions which arise in the retrieval or inverse problem.

ISSN:0143-1161    

DOI:10.1080/01431169108929630

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This paper describes an accurate and efficient method for supervised classification of multispectral images. First, a simple derivation of a best linear discriminant function (BLD) is presented through geometrical consideration on ellipses with equi-Mahalanobis distance. It is shown that the function satisfies the Minimax criterion, which implies the robustness with regard to prior probabilities. Then, the binary decision tree (BDT) is introduced in order to make the method efficient, where the BLD is utilized as a decision rule. Care is taken to prevent a decline in the classification accuracy during the process of constructing the BDT. In addition to the theoretical evaluation of the processing speed, the actual performance of the proposed method is shown by applying it to multispectral data of Landsat-5. It is shown that the BDT/BLD becomes more efficient than Fisher's linear discriminant function when the number of classes increases.

ISSN:0143-1161    

DOI:10.1080/01431169108929631

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Digital analysis of Landsat-5 Thematic Mapper (TM) data was evaluated as a mechanism for mapping the distribution of nine land-use/land-cover types found within five regional provinces of Sicily. Digital data from TM wavebands 1, 4, 5 and 7, along with corresponding ground truth data for 280 training sites, were used to characteize the spectral response of the land-use/land-cover categories under study. Training data were then input to supervised and unsupervised classification algorithms to map the distribution of the nine categories within eight Landsat-5 TM quarter-scenes needed for complete coverage of the study area. A quantitative assessment of classification performance was not performed.

ISSN:0143-1161    

DOI:10.1080/01431169108929632

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

In May 1985, synoptic current measurements were made by the Ocean Surface Current Radar (OSCR) high-frequency (HF) system as part of a survey of currents off the coast of North Wales. For most days during this campaign, extensive cloud cover prevented the acquisition of useful infrared imagery over the experimental region by NOAA satellites. However, on 30 and 31 May 1985 cloud-free images were obtained by NOAA-9 and, from these data, contour maps of sea surface temperature were derived. The early afternoon image acquired on 30 May shows that a zone of enhanced temperature gradient passes within the region mapped by the HF radar. As a result of this rare coincidence, a unique view of surface flows in an evolving situation is obtained.

ISSN:0143-1161    

DOI:10.1080/01431169108929633

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A review of Landsat MultiSpectral Scanner ‘Quicklook’ images in the National Remote Sensing Centre archive indicates that, on average, only one satellite pass in six over the United Kingdom results in cloud-free imagery. There are significant regional and inter-annual variations in acquisition of cloud-free imagery. Coastal districts are relatively less cloudy than inland upland areas, while the south-east of Britain and the western coast have the highest percentages of useful imagery. Inter-annual variations suggest that the chances of acquiring data from currently operational satellites within the precise date intervals required for automated crop mapping on a regular basis are very low. A wide range of other operational applications of remote sensing with less rigorous acquisition requirements are possible in the U.K. with current sensors. The study highlights the need for more frequent imaging by sensors of Thematic Mapper and SPOT HRV types, in order to minimize the effect of cloud cover and the longer-term requirement for development of all-weather microwave imaging systems of comparable spatial and spectral resolution to current optical sensors.

ISSN:0143-1161    

DOI:10.1080/01431169108929634

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A multiresolution method for analysing remotely sensed images is described, in which correlation filters, based on two-point differences, are applied over a range of scales with octave separation. When applied to typical Earth backgrounds viewed from space, the measured probability distributions of filter outputs exhibit strongly non-Gaussian statistics and satisfy scaling laws which allow a representation of the imagery in terms of fractal geometry. The method may be used as a basis for image, or image-region, characterization and, using the tails of the resulting normalised distributions, for the identification of those localized image features which are most unusual; that is, have lowest relative probability.

ISSN:0143-1161    

DOI:10.1080/01431169108929635

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A computer program in ANSI Standard FORTRAN 77 language has been developed to simulate waveforms produced by radar altimeters. Single waveforms or trains of waveforms at any pulse interval can be calculated. Antenna characteristics are modelled, including off-nadir pointing. The Earth is modelled as an oblate spheroid upon which any desired topography can be superimposed, either by means of formulae or as numerical data. The angular dependence of scattering coefficients can be treated.

ISSN:0143-1161    

DOI:10.1080/01431169108929636

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor