ISSN:0143-1161    

DOI:10.1080/01431169508954458

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Abstract. A number of sets of high resolution (001 μm or better) spectra are described which span the major part to the visible short-wave infrared spectrum (0.4-2.5μm). These data sets include soils, both wet and dry, conventional agriculture, grasses, and shrubs, igneous and sedimentary rocks, minerals, and a variety of fabrics, building materials, and metals. Most are from the laboratory, some are field measurements. These collections do not include bi-directional reflectance data sets, nor limited domain (∼0.4-l.0μm) visible near-infrared spectral data sets. To facilitate intercomparisons and spectral matching with remotely-sensed data such as the aircraft instrument (AVIRIS) a standardized collection is described in which all spectra are presented at 0.01μm intervals, in a common format. This collection is available for research studies on a PC diskette.

ISSN:0143-1161    

DOI:10.1080/01431169508954459

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Abstract. Many volcanic eruptions go essentially unmonitored. Potentially the Advanced Very High Resolution Radiometer (AVHRR), with its global coverage, frequent return period, and sensitivity in the thermal infrared, represents a data source capable of monitoring surface volcanic activity unrecorded by ground observations or other satellite sensors. In this study an attempt is made to demonstrate this potential by extracting information for the 1984 eruption at Krafla, Iceland. Seven cloud-free AVHRR images were available for the 14 day period of eruptive activity. The surface activity was detectable as a major thermal anomaly in all three of the longer wavelength channels and was vigorous enough during one night-time pass to be detectable in the near-infrared channel (0.725-1.1μm). Channel 2 and 4 radiance data were used to calculate the size and temperature of sub-pixel heat sources within the lava flow field, and a heat source at 1050° C was estimated as occupying an area of approximately 240000 m2, which was distributed across 20 pixels. Detection and measurement of volcanic heat sources at such short wavelengths using low spatial resolution data has rarely been reported before. Field reports and maps were used to guide and confirm the analysis. Digital number variations within the anomaly could be related to various known features of the eruption. To monitor the eruption a weighted average method was derived and used to sharpen up the images, and the density sliced sharpened images enabled the development of the eruption to be mapped. Results compared well with field reports, suggesting that AVHRR and similar systems could be a useful source of data for monitoring eruptions where contemporaneous field observations are unavailable or incomplete.

ISSN:0143-1161    

DOI:10.1080/01431169508954460

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Jasperoid, an important indicator of disseminated gold deposits, is mapped in the Cedar Mountains, Utah U.S.A. using data gathered by the Airborne Visible Infra-Red Imaging Spectrometer (AVIRIS). Ratio analysis is employed to detect the sharp rise in reflectance between 1000 nm and 1700 nm in the jasperoid spectrum due to iron absorption at about 900 nm in association with quartz and bound water. A pre-requisite is to remove the effects of dead and senescent vegetation from the ratio image. This is achieved using a mask of dead vegetation created by absorption band-depth analysis of ligno-cellulose absorptions in the Short-Wave Infra-red (SWIR). The absorption feature at about 2080 nm was used, but this choice is partly dictated by the limestone host rocks which exhibit a strong absorption feature which overlaps with the longer wavelength lingo-cellulose absorptions. Validation of the ratio map is accomplished by overlaying a geologic boundary which defined an area of jasperoid in the field.

ISSN:0143-1161    

DOI:10.1080/01431169508954461

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Visible and near-infrared laboratory reflectance spectra of soils sampled over the southern contact metamorphic aureole of the Los Pedroches granodiorite north of Cordoba in the southern-central part of the Iberian Peninsula are characterized in terms of relative albedo, depth, width, asymmetry, and wavelength position of absorption features. A decrease in albedo and relative depth of the Al-OH absorption feature (near 2.2μm), the H20 feature (near 1.9μm), and the OH feature (near 1.4μm) is observed with distance to the contact metamorphic domain. This effect is attributed to spectra quenching related to the absorbing capacity of finely disseminated carbonaceous material in soils which opacity increases with increasing temperature related to metamor-phism. Fe+2and Fe+3cause absorption features near l.0μm. 0.55μm, and 0.46 μm and also, a decrease of reflectivity in the 0.8-0.4μm wavelength region. These absorption features, however, are unaffected by the amount of carbonaceous material. Landsat-TM images were used for mapping variations in iron, water, and hydroxyl absorption features over the contact zone using ratio and normalized difTerence images with TM-3:1 for Fe and TM-5:7 for H20. TM-5 was added as blue component in a colour ratio component image mapping the effect of spectral quenching. Ratios enhanced the spectral variability between individual bands resulting in correlation coefficients of the order of (plus or minus) 0-2.

ISSN:0143-1161    

DOI:10.1080/01431169508954462

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The discovery of uranium deposits is more likely if we can identify favourable setting and target areas on the basis of related geological features, such as favourable host rocks, altered zones and structural lineaments. The synoptic view of the enhanced Landsat-TM imagery covering the Central Eastern Desert enabled the author to recognize and interpret these geological features. The coloured composite ratio image produced from combination of 2/4 × 7 (red), 5/7 × 3 (green) and 5/3 × 7 (blue) band ratios was used to classify the exposed younger granitic masses into three groups, namely Gl, G2 and G3. Each of the granitic groups possesses certain image characteristics, such as colour and surface texture. Moreover, the major tectonic features associated with younger granitic bodies were identified from the Landsat image.

ISSN:0143-1161    

DOI:10.1080/01431169508954463

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In this study, the wheat (triticum) and barley (hordeurn) planted areas in the province of Adana were determined by using Landsat-5 TM data in 1991. To classify the wheat and barley fields in this region, Landsat bands 3, 4 and 5 were used. Reflectance distribution in these bands has been expected to have an ellipsoidal shape, and a method was developed to make classification for such distribution. To check the accuracy of the classification, test areas in the province were selected and the classification results were compared with ground-truth. Consequently, it was found that the error estimated wheat and barley planted areas was around 15% and the results of the acreage estimation for wheat and barley fields were 218000 ±32000 hectare in 1991.

ISSN:0143-1161    

DOI:10.1080/01431169508954464

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Spectral data can supply useful information on soil spatial variability even when the soil surface is partially masked by vegetation. This paper reports the first results of research aiming to assess the possibilities and limits of satellite remote sensing data for studying soils in the Apennine Mountains of Southern Italy. This region is characterized by the presence of large areas of bare soils during certain times of the year, but also by the dissected terrain which strongly influences the spectral response of soils. The results presented show the potential of satellite remotely-sensed data to broadly predict certain soil parameters, such as organic matter (OM) and calcium carbonate content (CACAR), from radiance values. However, the results of a sub-scene spectral classification, illustrate a greater potential for satellite data to provide useful reconnaisance soil mapping information, which can be tested by limited ground checks

ISSN:0143-1161    

DOI:10.1080/01431169508954465

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431169508954466

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Central Africa contains the second largest contiguous rain forest in the world. The current state of this forest is poorly known. The most recent comprehensive national forest distribution maps of the central African region are from the period between 1950-1980 and are not representative of more recent forest degradation or conversion. In this study NOAA-AVHRR data at 1km resolution have been used to develop current maps of the dense humid forest extent for Zaire and Cameroon. Preliminary estimates of the areal extent of the rain forest are made. Validation of the AVHRR maps is performed through comparison with high resolution satellite imagery (Landsat-MSS) and existing maps. Forest cover maps generated by this study are a fundamental step leading to multi-scale mapping and monitoring of global tropical forests.

ISSN:0143-1161    

DOI:10.1080/01431169508954467

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor