ISSN:0143-1161    

DOI:10.1080/01431169208904198

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper investigates the automated detection of jet contrails using data from the Advanced Very High Resolution Radiometer (AVHRR). A preliminary algorithm subtracts the 11·8  image from the 10·8  image, creating a difference image on which contrails are enhanced. Then a three-stage algorithm searches the difference image for the nearly-straight line segments which characterize contrails. First, the algorithm searches for elevated, linear patterns called ‘ridges’. Second, it applies a Hough Transform to the detected ridges to locate nearly-straight lines. Third, the algorithm determines which of the nearly-straight lines are likely to be contrails. The paper applies this technique to several test scenes.

ISSN:0143-1161    

DOI:10.1080/01431169208904199

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The Burger distribution is investigated by examining the way in which this novel method of characterizing a frequency distribution represents cloud amount and sky opacity in Canada and Australia. It is shown that the Burger parameters, mean cloud amount and scale distance (C, r), provide an acceptable means of representing cloud frequency distributions and that the Burger distribution may be preferable to previously employed distributions because both parameters have interpretable meaning and because the Burger distribution permits representation and/or prediction of clear and overcast conditions. For the Canadian and Australian stations studied, the seasonal cycle of cloud type is found to be reflected in the computed seasonal cycle in the Burger scale distance but there are problems in interpreting the meaning of these variations in r because the area of observation for a surface observer changes as a function of cloud type. The real potential lies in the application of the Burger distribution to satellite-derived cloudiness where the area of observation is well defined and remains constant. The Burger characterization offers a unique feature, namely the possibility of areal reseating to spatial dimensions different from those over which the original observations were made. Specific testing of this possibility for the Canadian cloud data considered here leads to the conclusion that reseating to smaller areas is successful. Frequency distributions for ground areas commensurate with individual geostationary satellite pixels are achievable, the results are robust and lie only just beyond the demonstrated range of validity. Overall, the Burger distribution is a valid and useful method of characterizing cloudiness which has the demonstrable potential as a means of representing the spatial nature of cloud parameters derived from satellites.

ISSN:0143-1161    

DOI:10.1080/01431169208904200

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Landsat Thematic Mapper images and aerial photographs were used in the detection of kimberlile-derived materials in the Redondao test site. In this area kimberlite-derived soils show a flora constituted mainly by grasses and shrubs, which differ from the surrounding savanna-park (cerrado) vegetation cover. Band-ratio images were able to distinguish kimberlite-derived materials by enhancing areas with different vegetation covers. However, the coarse spatial resolution of Landsat-TM images compared with the spatial variability of the study area, and the removal of topographic shadowing effects on ratio images blurred several landscape features. To increase discrimination, Landsat Thematic Mapper ratio images were merged with digitized aerial photographs through intensity, hue and saturation (IHS) colour transforms. The resulting merged colour composite highlighted the spatial and spectral features of the study area permitting an accurate definition of the kimberlite-derived materials within the Redondao diatreme.

ISSN:0143-1161    

DOI:10.1080/01431169208904201

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A two-stage classification procedure has been applied to extract land use in a rural-urban fringe environment from SPOT High Resolution Visible (HRV) multi-spectral data. In this procedure, the SPOT HRV data were first classified into twelve land-cover types using a supervised maximum-likelihood classification (MLC). In the second stage, cover frequencies were extracted by moving a pixel window over the land-cover map obtained at the first stage. These cover frequencies were then employed in the classification of 14 land-use classes using a supervised minimum-city-block classifier. Results obtained with the cover-frequency method have been compared with those obtained using the conventional MLC approach. The overall accuracy measured by the Kappa coefficient was 0·462 for the MLC method; it was significantly improved to 0·663 with the cover-frequency method.

ISSN:0143-1161    

DOI:10.1080/01431169208904202

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The objective of this study was to use Indian Remote Sensing Satellite-IA (IRS-1A) Linear Imaging Self Scanning-I (LISS-I) digital data in combination with field measurement for the estimation of suspended solids concentration in an inland water body (reservoir). For this purpose, a small reservoir (Tawa), on the Tawa river of the Narmada basin in Central India, was studied.

ISSN:0143-1161    

DOI:10.1080/01431169208904203

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Landsat-MSS satellite data and corresponding water quality measurements of suspended sediment concentration for Lake Chicot, Arkansas, were used to evaluate several possible models For the relation between these two data types. Satellite data were converted to physical values of radiance and reflectance using both the NASA standard curve and the spectrum recommended by the World Radiation Center. Incorporation of an orbital eccentricity correction factor into the computation of solar spectral irradiance was also tested.

ISSN:0143-1161    

DOI:10.1080/01431169208904204

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A 15-ha field of cotton(Gossypium hirsuiutn L,)with an erratic pattern of soil salinity was overflown twice during the 1989 growing season with each of two sensor systems, a multispectral videography system and the High Resolution Visible (HRV) scanner of the French polar-orbiting satellite SPOT. The objectives were to compare the responses of the two sensor systems and to relate vegetation indices calculated from them to plant cover and lint yield (kgha−1) observations for 36 sites located at the intersections of a square 60 m grid laid off in the field. The range in responses, expressed as digital counts, was much greater for the video than for the HRV. For paired dates of acquisitions, the agreement between near-infrared and red bands between systems was almost as good as within systems. Yield and plant cover could also be estimated about equally well from vegetation indices calculated from both systems. Consequently, it is concluded that the video observations provided essentially the same information as SPOT-1 HRV observations and could be used in lieu of, or to supplement, SPOT observations. Videography could also be used to obtain high resolution samples within Landsat Multispectral Scanner (MSS) and NOAA AVHRR scenes or to augment those coverages.

ISSN:0143-1161    

DOI:10.1080/01431169208904205

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The study was carried out (i) to monitor the spatial extent of salt-affected soils and (ii) to assess the efTect of image scale on the delineation of these soils using Landsat data in the Indo-Gangetic plains of Uttar Pradesh, northern India. Monoscopic visual interpretation of standard false colour composile (FCC) prints of Landsat-MSS data acquired in 1975 and of Landsat-TM data acquired in 1986 was carried out to delineate salt-affcted soils during these two periods. Salt-affected soils could be categorized as saline sodic soils and key out as Typic Natrustalfs, A shrinkage in the areal extent of salt-affected soils to the extent of 9–9 per cent was observed during an 11-year period which could be attributed to ameliorative efforts by the farmers and to state and central Government agencies.

ISSN:0143-1161    

DOI:10.1080/01431169208904206

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The accuracy of a calibration of a water-vapour channel of a radiometer on board a satellite by using a radiative transfer code with radiosonde profiles was examined with the aid of the calibrated WV channel data of the Visible and Thermal Infrared Radiometer (VTIR) on the MOS-1 satellite. It has been verified that the assumption that a linear extrapolation for the relative humidity in the upper troposphere was reasonable for estimating the radiances in the water-vapour channel by a comparison of the brightness temperatures of the channel measured by the calibrated VTIR with those calculated by the radiative transfer code. An error in water-vapour distribution or radiosonde data considerably affected the estimated brightness temperature by the radiance calculation in the water vapour absorption band. The accuracy of the calibration of the water-vapour channel by the radiance calculation was with the root-mean-square (rms) temperature difference of 3–96°C.

ISSN:0143-1161    

DOI:10.1080/01431169208904207

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor