ISSN:0143-1161    

DOI:10.1080/01431169608949001

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The high resolution of Landsat Thematic Mapper (TM) thermal infrared data can be interesting in applications such as energy balance and crop water stress studies. However, surface temperature measurements are strongly affected by atmospheric effects, particularly by water vapour absorption, therefore a correction method is absolutely necessary. The impossibility of applying a split-window equation and the difficulty of having temporarily coincident radiosondes produce a slight use of Landsat TM data to obtain surface temperature. Vidal et al. show that in a zone with homogeneous climalic conditions, atmospheric correction can be evaluated by using energy balance equation and standard meteorological parameters. Using data of the EFEDA project, a comparison between two different atmospheric correction methods has been made in this paper. The first one was proposed by Vidal et al. and the second one was proposed by Coll et al. in 1994, where atmospheric parameters are calculated from a radiative transfer model, using atmospheric profiles obtained from local temporarily coincident radiosondes. Comparing blackbody temperatures calculated with both methods, a root mean square error of 1·6°C has been obtained. A complete discussion of the sensitivity of both methods is also included in order to explain the differences of blackbody temperatures obtained using each method.

ISSN:0143-1161    

DOI:10.1080/01431169608949002

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

It has been postulated that tropical forests regenerating after deforestation constitute an unmeasured terrestrial sink of atmospheric carbon, and that the strength of this sink is a function of regeneration stage. Such regeneration stages can be characterized by biophysical properties, such as leaf and wood biomass, which influence the radiance emitted and/or reflected from the forest canopy. Remotely sensed data can therefore be used to estimate these biophysical properties and thereby determine the forest regenerative stage. Studies conducted on temperate forests have related biophysical properties successfully with red and near-infrared radiance, particularly within the Normalized Difference Vegetation Index (NDVI). However, only weak correlations have generally been observed for tropical forests and it is suggested here that the relationship between forest biophysical properties and middle and thermal infrared radiance may be stronger than that between those properties and visible and near-infrared radiance.

ISSN:0143-1161    

DOI:10.1080/01431169608949003

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Debate over a forestry incentive scheme in the Gisborne district, New Zealand, highlighted the need for up to date information on the vegetation cover. Maps of vegetation at a scale of 1:100 000 were produced by automatically classifying Landsat Thematic Mapper (TM) imagery. The classified imagery was compared with existing vegetation information (20-years-old) from a GIS database to identify gross errors. Through field checking the discrepancies were identified as either real changes or errors in classification. Correction of errors increased the overall classification accuracy from 84 to 90 per cent.

ISSN:0143-1161    

DOI:10.1080/01431169608949004

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Shadowing is one of the factors that most affects the relation between canopy reflectance and forest light interception efficiency. For Christmas tree plantations, a decreasing exponential function can assess the shadow proportion from canopy SPOT-HRV red or green reflectances. Near-infrared reflectances as well as the wavelength of the inflexion point in the red-edge region (λi) are not affected by shadowing in the canopy. The linear correlation coefficients calculated between the shadow proportion and three common vegetation indices (Normalized Difference Vegetation Index, Perpendicular Vegetation Index and the Transformed Soil Adjusted Vegetation Index) estimated with the SPOT-HRV reflectances are non-significant in the case of PVI and TSAVI (if it is calculated with green reflectances). The limits and possible improvements of such a study are discussed.

ISSN:0143-1161    

DOI:10.1080/01431169608949005

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A goodness-of-fit solution method for spectral mixture modelling is applied to Landsat Multi-Spectral Scanner (MSS) data. The modelled pixel proportions are compared against independent validation data obtained by aerial photographic interpretation. A goodness-of-fit parameter is found to provide an objective means of investigating the impact of both the number of ground-cover components and spatial averaging on the mixture solution.

ISSN:0143-1161    

DOI:10.1080/01431169608949006

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Landsat Thematic Mapper (TM) images of eastern Zagros ranges, Iran, were evaluated for information about the bedrock geology and primary Neogene structures. Digitally processed TM subscenes have been compared with regional tectonic elements. Analysis of these images suggests that the regional geology in the area immediately east of the Zagros fold belt is characterized by thick volcanic piles which were emplaced during several episodes. On the images, these volcanic rocks depict a wide range of colours which correspond to their relative age differences from Jurassic rhyolitic and dacitic lavas to Tertiary tuffs. The Cretaceous-Paleocene carbonate and coloured melanges along with Jurassic volcanics appear to have undergone intensive compressive deformation indicated by the intermingled spectral reflectances of the rocks. Mappable features within the deformed sequence show a persistent N-S structural grain overprinted by a NW-trending fault trace. In the south-east portion of the area two sets of dike swarms dissect the older volcanic rocks. A prominent N-S-trending, steeply eastward-dipping set is truncated and dextrally oMset by faults associated with the north-westerly set. This suggests that the post-collisional tectonic pattern in the area is dominated by an element of dextral transpressional shear.

ISSN:0143-1161    

DOI:10.1080/01431169608949007

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The Chott el Djerid is a large salt playa situated in southern Tunisia. The playa has a brine- type of Na-K-Mg-Cl-SO4and a stable mineral assemblage of gypsum (CaSO4.2H2O), halite (NaCl) and carnallite (KMgCl3.6H2O). From laboratory spectra of the three stable evaporite minerals it was found that gypsum and halite were the only evaporite minerals likely to be differentiated using Landsat TM imagery.

ISSN:0143-1161    

DOI:10.1080/01431169608949008

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The gold mineralization at the Rodalquilar mine in southern Spain is of the acid-sulphate type. We have assessed the ability of AVIRIS imaging spectrometer data to detect the hydrothermal alteration mineralogy mapped using traditional ground-based techniques at Rodalquilar. Four methods of retrieving apparent surface reflectance have been evaluated, the empirical line method and three methods of radiative transfer modelling. This study indicates that radiative transfer modelling, using only atmospheric information derived from the imaging spectrometry data, can satisfactorily correct the atmospheric effects involved in retrieving apparent surface reflectance. The alteration at Rodalquilar is characterized by propylitic (vermiculite), illitic, kaolinitic (pyrophyllitic), alunitic and silicic zones with an increasing degree of alteration towards the formative hydrothermal cells in whose fossil cores the gold mineralization is found. However, several factors act against the usefulness of the AVIRIS data for mapping these mineral zones: the mine site is heavily disturbed with exposed workings, often of high albedo altered rocks, whilst unworked areas have partial iron-rich soil and dry vegetation cover; the alteration itself is highly discontinuous at the scale of 10 m and the shortwave infrared (SWIR) data where much of the diagnostic information for these hydrothermal minerals lies is very noisy. Nevertheless it has proved possible to map successfully, at the individual pixel level, the zones of gold-bearing alunitic alteration using the joint presence of alunite absorption features at 1480 and 1760 nm. The data from the 2000-2400 nm spectral range allow the areas with general absorption features centred around 2200 nm to be mapped but zonation based on individual minerals identification is not possible.

ISSN:0143-1161    

DOI:10.1080/01431169608949009

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The point of maximum slope in the reflectance spectra of leaves occurs around 690-740 nm and is termed the ‘red edge’. Strong correlations have been found between the red edge of leaves and the chlorophyll concentration of those leaves. Imaging spectrometers can record the red edge of canopies and strong correlations have been observed between canopy red edge and the chlorophyll concentration of leaves in those canopies; providing the canopies were optically thick and/or had spatially invariant biomass.

ISSN:0143-1161    

DOI:10.1080/01431169608949010

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor