摘要:

A low-cost high-quality system for the processing of satellite data received in the WEFAX analogue format is presented. It is composed of a receiver with its antenna connected to a personal computer with digitizing and graphic boards. The software automatically performs the storage of data onto the hard disk, contrast enhancement and false colour display, accurate navigation and animation loops. Interactive features are also available. Such a system is of great use in meteorological education, in weather forecasting and in environmental research. Taking into account the peculiarities of the WEFAX format, some algorithms have been devised lo correct for atmospheric depletion. Ground albedo can therefore be evaluated accurately on a pixel basis as well as global irradiation, cloud coverage and atmospheric global transmission.

ISSN:0143-1161    

DOI:10.1080/01431169208904163

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An artificial neural network based on the multilayer-perceptron model has been used to classify two-date multispectral SPOT High Resolution Visible (HRV) imagery on a test site in the Departement Ardeche, France. A large network consisting of 98 nodes was trained successfully to classify 20 land-cover classes. A ground dataset comprising 1881 pixels was used to verify the accuracy of the classifier. The average accuracy achieved over all classes in the verification dataset was 81 per cent, exceeding the performance of a maximum-likelihood classifier by 28 per cent.

ISSN:0143-1161    

DOI:10.1080/01431169208904164

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Spectral reflectances were measured for the canopies of Pinus eiliouii seedlings that were inoculated versus non-inoculated with the ectomycorrhizal fungus Pisotithus linctorius. Reflectances of the less vigorous, non-inoculated seedlings increased substantially at visible and near-infrared wavelengths compared to the more vigorous, inoculated seedlings. An algorithm was developed to indicate the spectral regions in which reflectance was most sensitive to ectomycorrhizae. The reflectance curve of the more vigorous seedlings was used as a standard of comparison. We denote the spectral regions defined by this algorithm as regions of maximum reflectance sensitivity. Far-red and near-infrared photography filtered to the region of maximum sensitivity (700 nm) were used to enable visualization of a 'blue shift' reflectance response to decreased vigour in the non-inoculated seedlings in response to these differences of mycorrhizal development.

ISSN:0143-1161    

DOI:10.1080/01431169208904165

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This Letter presents an approach for applying atmospheric correction to remotely-sensed data in near-real time. In general, it is applicable to the visible and near-infrared part of the spectrum and in particular, it has been tested with channels 1 and 2 data from the Advanced Very High Resolution Radiometer (AVHRR). This algorithm makes an extensive use of look-up tables and it resulted in the speed of about 3 scanlines per second whereas the AVHRR data reception rate is 6 scanlines per second.

ISSN:0143-1161    

DOI:10.1080/01431169208904166

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Actual evapotranspiration is an important parameter in crop yield models, soil moisture determination and crop stress detection. As actual evapotranspiration is not routinely available, maximum evapotranspiration (ETJ is normally used in agronomic models to calculate watering needs over irrigated areas. For this reason an empirical method has been developed to obtain ETra from albedo and temperature data suplied by the Advanced Very High Resolution Radiometer (AVHRR) sensor on board NOAA satellites. This model has been applied to the La Mancha region, Spain, where barley, vine and maize are the main crops, and ETM was obtained with an acceptable error of ± 1-4 mm of water per day.

ISSN:0143-1161    

DOI:10.1080/01431169208904167

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Two similar Landsat Thematic Mapper images of upland North Wales, U.K. were compared. They were obtained 16 days apart and their main difference was a 6° change in solar elevation. Minor changes in vegetation cover on flatter terrain can be distinguished but the difference in solar elevation is sufficient to prevent accurate radiometric comparisons of steeply sloping areas.

ISSN:0143-1161    

DOI:10.1080/01431169208904168

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We study the feasibility of using a dual linear-polarized radiometer operating at 6 GHz in conjunction with a scatterometer as a method of extracting sea surface temperature. A model, originally developed by Wilheit (1979), is used to investigate the sensitivity of radiometric temperature to changes in wind speed, U, at a height of 20 m; that is, the accuracy of sea temperature depends directly on the accuracy of radiometric temperature. These changes are corrected using this extracted wind speed based on a scatterometer wind accuracy of ± 1 ms−1. We show that a vertically polarized radiometer is less sensitive to wind speed changes than a horizontally polarized one near an incidence angle © = 60°. Furthermore, we quantify the wind variation; δTBH/δU≲;0.12°Cms−1s when U>I0ms−1and δTHB/δU≲;2.0°Cm−1when U>6ms−1for vertical and horizontal polarization, respectively. Thus, the resulting error is ± 0I2°C and ±20°C for TBVand THB, respectively. These results suggest that a scatterometer can be used to correct the wind speed dependence of a vertically polarized radiometer operating near 6 GHz using a pencil antenna beam pointing at an incidence angle near 57°.

ISSN:0143-1161    

DOI:10.1080/01431169208904169

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The objective of this Letter is to-examine the utility of mullispectral video data to supplement image data from satellite sensors in the environmental assessment of New Jersey nearshore waters. Due to the complexity or environmental conditions in nearshore waters, such applications of remote sensing technology may require a wide range of sensors. It was concluded that mullispectral video data are a low cost and useful supplement—particularly when imaging of the water surface from satellite sensors is prohibited by weather conditions.

ISSN:0143-1161    

DOI:10.1080/01431169208904170

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Noise power spectral densities (PSDs) have been derived from the analysis often seamount-free Geosat tracks in the Indian seas. The average noise PSD has been fitted by a model function. The model noise PSD has been used in conjunction with a model seamount signature to construct a matched filter for detecting seamounts in the Arabian Sea. Performance of the technique has been verified by successfully detecting the Somali ridge and the Error Seamount which are located in the Arabian Sea. Several uncharted seamounts have also been predicted.

ISSN:0143-1161    

DOI:10.1080/01431169208904171

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This Letter reports the application of linear mixture modelling of Advanced Very High Resolution Radiometer (AVHRR) time series data for crop area estimation. Results are presented showing the value of a cloud-clearing procedure for the application of the technique over large areas.

ISSN:0143-1161    

DOI:10.1080/01431169208904172

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor