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121.
沙漠地区土壤质地对不同频点微波地表发射率反演和模拟的影响 总被引:1,自引:0,他引:1
首先运用先进微波扫描辐射仪(AMSR-E)资料反演了北非沙漠地区晴空条件下的地表微波发射率。然后根据不同的土壤类型,进一步分析了沙漠地表微波发射率频谱特性,并将增加土壤质地信息前、后的翁(Weng)氏微波地表发射率模型(2001)的模拟结果和反演结果进行了比较。结果表明,沙漠地表发射率与土壤质地密切相关,随土壤颗粒大小的不同变化明显。在沙漠土壤类型中,以大颗粒为主的土壤类型,其水平(垂直)极化的发射率通常随频率提高而增大(减小);而对于以较小粒子为主的沙漠土壤类型,地表发射率几乎为常数,或水平(垂直)极化的发射率随频率提高略有减小(增大)。并且,发射率的季节性特征明显,特别是以小颗粒组成的土壤,其水平极化的发射率比垂直极化的发射率表现出更强的季节性变化。以上这些发射率特征与翁氏模型模拟结果一致。此外,在翁氏模型的输入参数中增加土壤质地信息(土壤组分含量、粒径尺度)改善了翁氏模型在沙漠地区的模拟结果,特别是对于包含大量小粒子的沙漠土壤类型,如黏土和黏质壤土,模拟误差从6%9%降低至4%以下。由于翁氏模型是美国国家环境预报中心(NCEP)全球同化和预报系统的重要组成部分,对翁氏模型的改进将提高沙漠地区卫星资料的利用率并有望改进数值天气预报的准确度。 相似文献
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对高淳地震台自投入运行以来的分量应变观测资料进行了分析研究,结果表明:该台观测资料精度很高,同时发现分量应变观测对一些大震有明显同震效应. 相似文献
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A low-voltage (≤3.3 V) imaging technology has been developed to enable scientific-grade imagers with low-power complex functions
on chip. A 128 × 128 CCD imager with on-chip clocking and charge-domain analog-to-digital conversion, as well as an exploratory
active pixel sensor have been demonstrated. A 640 × 960 CCD imager with optimized 12 bit charge-domain conversion and an improved
active pixel sensor are presently in fabrication.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
126.
To complement previously published information on E2V CCDs, we present here some less well-known information about Marconi
CCDs. We show details of the performance of deep depletion silicon variants, and discuss other subtleties of performance.
We also present an update on L3vision (sub-electron noise) devices, indicating current availability, options, and ongoing
development work. Finally, we will give a flavour of the range of custom designs that have been made. Many of these are not
commercially available, and may not be familiar to all astronomers or CCD technologists.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Grain-size distribution data,as a substitute for measuring hydraulic conductivity(K),has often been used to get K value indirectly.With grain-size distribution data of 150 sets of samples being input data,this study combined the Artificial Neural Network technology(ANN)and Markov Chain Monte Carlo method(MCMC),which replaced the Monte Carlo method(MC)of Generalized Likelihood Uncertainty Estimation(GLUE),to establish the GLUE-ANN model for hydraulic conductivity prediction and uncertainty analysis.By means of applying the GLUE-ANN model to a typical piedmont region and central region of North China Plain,and being compared with actually measured values of hydraulic conductivity,the relative error ranges are between 1.55%and 23.53%and between 14.08%and 27.22%respectively,the accuracy of which can meet the requirements of groundwater resources assessment.The global best parameter gained through posterior distribution test indicates that the GLUEANN model,which has satisfying sampling efficiency and optimization capability,is able to reasonably reflect the uncertainty of hydrogeological parameters.Furthermore,the influence of stochastic observation error(SOE)in grain-size analysis upon prediction of hydraulic conductivity was discussed,and it is believed that the influence can not be neglected. 相似文献
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《International Journal of Digital Earth》2013,6(4):271-284
Abstract The purpose of this paper is to contribute to the definition of a European perspective on Digital Earth (DE), identify some actions that can contribute to raise the awareness of DE in the European context and thus strengthen the European contribution to the International Society for Digital Earth (ISDE). The paper identifies opportunities and synergies with the current policy priorities in Europe (Europe 2020, Innovation Union and Digital Agenda) and highlights a number of key areas to advance the development of DE from a European perspective: (1) integrating scientific research into DE; (2) exploiting the Observation Web with human-centred sensing; and (3) governance, including the establishment of stronger linkages across the European landscape of funding streams and initiatives. The paper is offered also as a contribution to the development of this new vision of DE to be presented at the next International DE Conference in Perth, Australia, in August 2011. The global recognition of this new vision will then reinforce the European component and build a positive feedback loop for the further implementation of DE across the globe. 相似文献