摘要:

Radiometric measurements on snow in LANDSAT MSS wavebands have shown a correlation between snow condition and the ratio of green/infrared (band 4/band 7) wavebands. Systematic changes from wet dense snow at tow altitudes to dry less dense snow at higher altitudes should be revealed by a decrease in the intensity ratio band 4/band 7 with altitude. However, analysis of spring LANDSAT MSS images for the Cairngorm Mountains shows that the intensity ratio band 4/band 7 actually increases with altitude. A mixed-pixel hypothesis is invoked to account for this pattern. The results suggest that only in areas where the snow cover is continuous can information on snow condition be reliably obtained from LANDSAT MSS data.

ISSN:0143-1161    

DOI:10.1080/01431168608948894

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A clustering algorithm based on the commonly used least-squared Euclidean distance performs poorly on AVHRR images of clouds. This is primarily due to the data inadequately fitting the assumptions on which such an algorithm is based. Algorithms based on two modified clustering criteria are shown to be convergent within the same algorithm shell. These modified criteria have been developed elsewhere to allow generalized Gaussian clusters and also to account for differences in the populations of the different clusters. The new algorithms are tested on satellite data and found to give much improved results.

ISSN:0143-1161    

DOI:10.1080/01431168608948895

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Various cloud-detection schemes are applied to 1.1 km Advanced Very High Resolution Radiometer (AVHRR) day- and night-time data to determine an optimum automated scheme for deriving cloud-free radiances over both land and sea. A combination of the spatial coherence method at infrared wavelengths (11 μm) and dynamic visible threshold methods proved to be the most effective scheme for day-time use. Uniform thin cirrus (i.e. reflectance less than 15 per cent) was difficult to detect with all methods. Problems were also encountered over regions with a changing underlying surface type (e.g. coastal areas) where the automated scheme was not as effective as over uniform surfaces. At night a combination of the spatial coherence method and a scheme based on the differences in brightness temperatures between the three infrared channels at 37, II and 12 μm wavelength was successfully used. Results obtained by applying these algorithms to AVHRR data are presented and the different problems encountered with each algorithm are discussed.

ISSN:0143-1161    

DOI:10.1080/01431168608948896

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

When using multispectral techniques that exploit the channels of the Advanced Very-High Resolution Radiometer (AVHRR), it is assumed that the radiation measured in the different channels emanates from the same place. Evidence is presented to suggest that for one particular pass of NOAA-7, there was a mis-registration of about one-quarter of a pixel between AVHRR channels 3 and 4. A simple correction is shown to be effective in this case.

ISSN:0143-1161    

DOI:10.1080/01431168608948897

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A simple and fast algorithm for image referencing of the NOAA (National Oceanic and Atmospheric Administration) AVHRR (Advanced Very High Resolution Radiometer) data has been derived to facilitate the identification of geographic co-ordinates corresponding to any pixel on an NOAA image and vice versa. The procedure assumes a spherical Earth and circular orbit and takes into account the effects due to the Earth's rotation and oblateness and the scan skew. Inputs to the procedure are the ascending nodal longitude and lime, the time of the first scan line and one ground control point (GCP). The effects of an ellipsoid Earth and an elliptical orbit are corrected by using the GCP to adjust the spacecraft altitude and inclination angle. No detailed emphemeris data arc required. The average r.m.s. errors obtained by comparing with independent sets of well-distributed GCPs for each image are about 2 pixels and 2 lines or 3 km displacement. Results from the procedure are illustrated by the rectification of NOAA images over France.

ISSN:0143-1161    

DOI:10.1080/01431168608948898

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The interpretation of LANDSAT imagery of a coastal embayment in the north-western Aegean Sea is compared with numerical model outputs, representing the same environmental conditions. It is demonstrated that the remotely sensed data and output from the hydrodynamic and dispersion models can be integrated usefully, to enhance the understanding of coastal processes.

ISSN:0143-1161    

DOI:10.1080/01431168608948899

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Remote sensing has recently become a rapidly expanding area of activity and employment in higher education and research sectors in the U.K. This article considers the range of professional employment opportunities available for postgraduate remote-sensing specialists. Currently, there are very few employers who can accommodate professional staff with a full-time commitment to remote sensing. However, an increasing number of employers offer a range of jobs involving certain aspects of remote sensing, which often lead to commercially successful career progression in wider aspects of research administration, the computing industry and consultancy in space technology and resource assessment. Job descriptions, employers and career potentials are evaluated in the context of the U.K. economy in 1985.

ISSN:0143-1161    

DOI:10.1080/01431168608948900

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431168608948901

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

We have conducted a cloud-cover analysis of AVHRR scenes of Britain for April-September for the years 1982-1985 and interpreted the results in terms of the usefulness of the data for the studying of agricultural strawburning.

ISSN:0143-1161    

DOI:10.1080/01431168608948902

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor