摘要:

LANDSAT provides synoptic imagery for the study of large ice masses in the inaccessible polar regions. Even minor ice surface topographic detail can be identified as differences in relative brightness. However, radiance from such surfaces can be greater than the maximum MSS detector calibration. This results in detector saturation and consequent loss of information. Using MSS digital data from snow surfaces in both polar regions, corrected to radiance values to account for detector calibration changes, a model relating detector saturation in each MSS band to changes in Sun elevation is presented. Band 5 becomes saturated at the lowest Sun angles whereas band 7 remains unsaturated in all imagery examined. Secondary factors affecting detector saturation are atmospheric haze, the magnitude and orientation of surface slopes, variations in detector calibration and the character of the surface. Given a knowledge of the Sun elevation at which each band becomes saturated over large ice masses (of low gradient and snow-covered surface), and information on variations in Sun elevation with latitude and time of year, the spatial and temporal pattern of detector saturation can be predicted. This information is useful in the selection of MSS images for future glaciological studies, and in the scheduling by NASA of the optimum periods to acquire unsaturated MSS data of the polar regions.

ISSN:0143-1161    

DOI:10.1080/01431168608954667

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431168608954668

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431168608954670

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431168608954671

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Muirhead and Cracknell (1985) presented an interesting application of AVHRR thermal data. They proposed that a checking system could be developed to determine the effect of legislation on the practice of strawburning. When the issues behind strawburning are analysed in conjunction with the availability of cloud free data, it is clear that such a system would be difficult to implement.

ISSN:0143-1161    

DOI:10.1080/01431168608954672

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A problem in using radiometric data for v`getation studies is that most vegetation canopies are non-Lambertian reflectors and view angle can influence spectral response. Results are presented which indicate that wind tolerance has an appreciable effect on the spectral response of a crop and any derived indicators of vegetative vigour. In some studies it may not be sufficient to consider the plant position as constant during measurement.

ISSN:0143-1161    

DOI:10.1080/01431168608954673

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor