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Using near simultaneously acquired Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and Earth Observing-1 Advanced Land Imager (ALI) data we assess the relative radiant responses over active lava flows from the Mt. Etna July/August 2001 flank eruption. By assessing the extent of saturation between the two instruments and using the dual-band method of extracting sub pixel thermal information, we show that the ALI represents an improvement over the ETM+ in the present ability to assess temperatures of hot active lava flows for a number of reasons. (1) The extra spectral channels provided by ALI compliment the current SWIR channels on ETM+ by providing a greater number of paired channel combinations for input into the dual-band method. Thus, dual-band temperature solutions can be determined for a greater range of lava flow types than previously possible using the two paired channel combinations available with the ETM+. (2) The ALI instrument is less susceptible than ETM+ to saturation within the SWIR, especially when using channels 5, 5p and 4p at wavelengths of 1.65, 1.25 and 0.87 μm respectively. (3) The greater radiometric sensitivity of the ALI 12 bit electronics coupled with a significantly higher signal to noise ratio aid in obtaining successful dual-band solutions. 相似文献
263.
Wetland vegetation biomass estimation and mapping from Landsat ETM data: a case study of poyang lake 总被引：1，自引：0，他引：1
Poyang Lake is the largest freshwater lake in China. This paper conducted a digital and rapid investigation of the lake’s
wetland vegetation biomass using Landsat ETM data acquired on April 16, 2000. First, utilizing the false color composite derived
from the ETM data as one of the main references, the authors designed a reasonable sampling route for field measurement of
the biomass, and carried it out on April 18–28, 2000. Then after both the sampling data and the ETM data were geometrically
corrected to an equal-area projection of Albers, linear relationships among the sampling data and some transformed data derived
from the ETM data and the ETM 4 were calculated. The results show that the sampling data is best relative to the band 4 data
with a high correlation coefficient of 0.86, followed by the DVI and NDVI data with 0.83 and 0.80 respectively. Therefore,
a linear regression model, which was based on the field data and band 4 data, was used to estimate the total biomass of entire
Poyang Lake, and then the map of the biomass distribution was compiled. 相似文献
264.
Alteration is regarded as significant information for mineral exploration. In this study, ETM remote sensing data are used for recognizing and extracting alteration zones in northwestern Yunnan (云南), China. The principal component analysis (PCA) of ETM bands 1, 4, 5, and 7 was employed for OH- alteration extractions. The PCA of ETM bands 1, 3, 4, and 5 was used for extracting Fe2 (Fe3 ) alterations. Interfering factors, such as vegetation, snow, and shadows, were masked. Alteration components were defined in the principal components (PCs) by the contributions of their diagnostic spectral bands. The zones of alteration identified from remote sensing were analyzed in detail along with geological surveys and field verification. The results show that the OH" alteration is a main indicator of K-feldspar, phyllic, and prophilized alterations. These alterations are closely related to porphyry copper deposits. The Fe2 (Fe3 ) alteration indicates pyritization, which is mainly related to hydrothermal or skarn type polymetallic deposits. 相似文献
265.
In this study, a parameterization method based on Landsat‐7 Enhanced Thematic Mapper (ETM) data and field observations is presented and tested for deriving the regional land surface variables, vegetation variables and land surface heat fluxes over a heterogeneous landscape. As a case study, the method and two Landsat‐7 ETM images are applied to the Jiddah area of Saudi Arabia. The regional distribution maps of surface reflectance, normalized difference vegetation index, modified soil adjusted vegetation index (MSAVI), vegetation coverage, leaf area index, surface temperature, net radiation flux, soil heat flux, sensible heat flux and latent heat flux have been determined over the Jiddah area. The derived results have been validated by using the ‘ground truth’. The results show that the more reasonable regional distributions of land surface variables (surface reflectance, surface temperature), vegetation variables (MSAVI and vegetation coverage), net radiation, soil heat flux and sensible heat flux can be obtained by using the method proposed in this study. Further improvement of the method is also discussed. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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耐震时程法（ETM）是一种基于动力时程的结构抗震分析方法,其典型表征在于随着持续时间的增加,地震动强度逐渐增大。本文合成了基于中国抗震反应谱的耐震时程曲线,并以此作为输入,对一个8层3跨钢框架结构的抗震性能进行了分析和评估。采用增量动力分析方法（IDA）对结构在不同耐震持时下的整体响应进行了评估;以大震下天然地震动分析结果为标准,对比了结构在耐震时程曲线（ETA）作用下的塑性铰分布概率、形成顺序和延性分布。研究结果表明：耐震时程法能较好地预测钢框架结构的非线性动力响应及破坏过程,且分析次数少,这为钢框架结构的抗震性能快速分析与评估提供了一种新的手段。 相似文献
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Since the atmospheric correction is a necessary preprocessing step of remote sensing image before detecting green tide, the introduced error directly affects the detection precision. Therefore, the detection method of green tide is presented from Landsat TM/ETM plus image which needs not the atmospheric correction. In order to achieve an automatic detection of green tide, a linear relationship(y =0.723 x+0.504) between detection threshold y and subtraction x(x=λ_(nir)–λ_(red)) is found from the comparing Landsat TM/ETM plus image with the field surveys.Using this relationship, green tide patches can be detected automatically from Landsat TM/ETM plus image.Considering there is brightness difference between different regions in an image, the image will be divided into a plurality of windows(sub-images) with a same size firstly, and then each window will be detected using an adaptive detection threshold determined according to the discovered linear relationship. It is found that big errors will appear in some windows, such as those covered by clouds seriously. To solve this problem, the moving step k of windows is proposed to be less than the window width n. Using this mechanism, most pixels will be detected[n/k]×[n/k] times except the boundary pixels, then every pixel will be assigned the final class(green tide or sea water) according to majority rule voting strategy. It can be seen from the experiments, the proposed detection method using multi-windows and their adaptive thresholds can detect green tide from Landsat TM/ETM plus image automatically. Meanwhile, it avoids the reliance on the accurate atmospheric correction. 相似文献