摘要:

Simultaneous collocated observations from two different orbits lead to several advantages. These advantages are: (i) During times of collocation two sensors can be cross-calibrated at various look angles within the commonly imaged scenes. The solar zenith angle will also usually vary from encounter to encounter thus providing a wide range of radiance conditions, (ii) When the two satellites are not collocated they can provide a wide range of sensor look angles for a given scene which they both image prior to and after passing through the encounter position. These data are useful for determining the bidirectional reflectance distribution function (BRDF). The problem of determining the number of times per year (on the average) that the subsatellite points of two satellites come within D km of each other is addressed in this paper. For the space station (altitude: 500km, inclination: 28°) and a Sun-synchronous satellite (altitude: 705 km, inclination: 98-21°) the answers are 16, 41 and 82 times per year for encounter distancesDof 20, 50 and 100 km, respectively. The relationship between encounters per year and distance D is linear. The answers were obtained in two ways: (i) a closed-form statistical approach which led to a simple algebraic expression and (ii) a 'Monte Carlo’ type computer solution. The largest difference between the two solutions was less than 12 per cent.

ISSN:0143-1161    

DOI:10.1080/01431168608948910

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The Advanced Very High Resolution Radiometer (AVHRR-2) has two channels in the 10-13/mi window region. These channels are used for remote sensing of the sea surface temperature corrected for atmospheric absorption. The brightness temperature difference between the channels can be directly related to the atmospheric absorption due to water vapour. The problem of water-vapour retrieval from satellite data is examined in detail. The best evaluation of the water-vapour content is obtained from the spectrometric data of the Infrared Interferometer Spectrometer (IRIS), with an error of about + 3kg/m2. It is, however, feasible to obtain the water-vapour content from AVHRR data with an algorithm derived from radiative transfer model simulations. The retrieved water vapour has an error of ±5kg/m2when compared with ship data. It is possible to use the remotely sensed water vapour for the inference of the boundary-layer structure. The information is, however, limited for water vapour contained near the surface.

ISSN:0143-1161    

DOI:10.1080/01431168608948911

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A soil map of parts of the Bundelkhand region and its adjoining areas in Uttar Pradesh (northern India), covering an area of 41 000 km2, was prepared following a collative approach that used visual interpretation of LANDSAT imagery in conjunction with lithological, topographical and other collateral data and information from field work. The soil map was found to be better than the conventional map in terms of soil landscape boundary delineation. The study has demonstrated the usefulness of LANDSAT imagery for small-scale soil mapping. An overall accuracy of 93-3 per cent with respect to soil landscape boundary delineation has been achieved.

ISSN:0143-1161    

DOI:10.1080/01431168608948912

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A procedure to estimate wheat (Triticum aestivum L) area using a sampling technique based on aerial photographs and digital LANDSAT MSS data was developed. Aerial photographs covering 720km2 were visually analysed. Computer classification of LANDSAT MSS data acquired on 4 September 1979 was performed using unsupervised and supervised algorithms and the classification results were spatially filtered using a post-processing technique. To estimate wheal area, a regression approach was applied using different sample sizes and various sampling units. Based on four decision criteria proposed in this study, it was concluded that (i) as the size of the sampling unit decreased, the percentage of the sample area required to obtain a similar estimation performance also decreased, (ii) the lowest percentage of the area sampled for wheat estimation under established precision and accuracy criteria through regression estimation was 13-09 per cent using 10 km2 as the sampling unit and (iii) wheat-area estimation obtained by regression estimation was more precise and accurate than those obtained by a direct expansion method.

ISSN:0143-1161    

DOI:10.1080/01431168608948913

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The weekly global vegetation index (GVI) derived from the NOAA AVHRR instrument has been analysed for the 1982-1985 period over a wide range of vegetation formations of Asia. Temporal development curves of the index are presented for environments ranging from the desert of central Asia to the tropical forest of Borneo. The paper shows that, despite the coarse resolution of the GVI product, a large set of useful information on ecosystem dynamics and cropping practices can be consistently derived from time series of such data. In addition, it is shown that the impact of the 1982-1983 El Nino Southern Oscillation-related drought can be detected in the GVI data through an analysis of anomalies in the development of selected vegetation formations. The relevance of such analysis for global vegetation monitoring and change detection is then underlined.

ISSN:0143-1161    

DOI:10.1080/01431168608948914

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

This paper gives a summary of current activities and future programmes of the Remote Sensing Applications Centre (RESACENT) of the Pakistan Space and Upper Atmosphere Research Commission, Karachi, Pakistan.

ISSN:0143-1161    

DOI:10.1080/01431168608948915

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Expressions are presented for Doppler frequency shift, Doppler bandwidth, zero Doppler offset angle in spacecraft yaw and, in the SAR mode, the rate of Doppler frequency modulation, azimuth time-bandwidth product, resolution, available integration time and the location of principal azimuth ambiguities. The equations are simply expressed with virtually no approximations based on angles referenced to the satellite. Earth rotation is included, as is the geosynchronous case. (These results differ from expressions to be found elsewhere in the literature, most of which have been derived using flat-Earth approximations.).

ISSN:0143-1161    

DOI:10.1080/01431168608948916

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

In this article, which reviews the official report of the European Communities’ ARCHIMEDES 1 experiment, the main objectives and methods of experimentation used in the experiment are described. This experiment was intended to carry out an exhaustive test of microwave equipment (both passive and active), together with ancillary instruments, for the detecting and measuring of oil slicks at sea. The performance of the various instruments, in terms of the minimum thickness of a slick for that slick to be capable of being detected, was determined. Comparisons have been made of the performances of the various systems and certain general conclusions about their performances were obtained. Recommendations for any future campaign were also produced.

ISSN:0143-1161    

DOI:10.1080/01431168608948917

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431168608948918

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431168608948920

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor