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101.
复种指数遥感监测方法 总被引:36,自引:6,他引:36
复种指数是反映水土光与自然资源利用程度的指标 ,其实质是沿时间序列 ,反映某一种植制度对耕地的利用程度。联系复种指数与时间序列NDVI曲线的纽带是农作物年内的循环规律。时间序列的NDVI值蕴涵着植被的生长和枯萎的年循环节律 ,经时间序列谐函数分析法 (HarmonicAnalysisofTimeSeries ,HANTS)重构的NDVI曲线 ,可以准确地反映农作物的出苗、拔节、抽穗、收获等物理过程。因此 ,根据时间序列的NDVI曲线的周期性 ,可以反向捕捉到耕地农作物动态的信息 ,进而得到耕地的复种指数。本文依据上述原理 ,提出复种指数遥感监测的方法 ,然后用 1999年至 2 0 0 2年 4年的VGT(SPOT4卫星vegetation数据 )旬合成NDVI时间序列数据集提取了复种指数 ,并利用地面样区观测结果和统计数据进行检验 ,取得很高的精度。 相似文献
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基于通量均衡基准的地壳垂直形变场分析模型 总被引:1,自引:0,他引:1
根据全球通量均衡假说建立了地壳垂直形变场的分析模型,在球面近似下求得了该模型的球谐函数级数解并拟合了两个不同区域的地壳垂直形变场,编绘了等值线图,继而在密切平面坐标系下导出了该模型的Fourier级数解。结果表明,该方法不仅具有几何意义,而且具有一定的地球动力学意义。 相似文献
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Introduction The anisotropy of the Earth crust medium is a common phenomenon(Crampin,1984).More and more observation materials and study results have proved that on most of the Earth′s upper crust is spread fluid-filled cracks and microcracks,which are aligned according to the contempo-rary stress-field.Such distributions of aligned cracks show effectively anisotropy to seismic wave and the phenomenon is called extensive-dilatancy anisotropy(EDA)(Crampin et al,1984).At the same time,it is … 相似文献
107.
ZHANG Renhua LI Zhaoliang SUN Xiaomin ZHU Zhilin & WANG Weimin Institute of Geographical Sciences Natural Resources Research Chinese Academy of Sciences Beijing China LSIIT 《中国科学D辑(英文版)》2005,(1)
This paper proposes a basic equation of thermal radiation interaction between surface objects on the basis of the principle of heat balance in the interface. The solution of this equation takes account of the contribution of sensible heat flux and latent heat flux more completely, compared with traditional solution for surface cooling and heating processes. By the aid of the experimental data conducted in the Xiaotangshan experimental site, Beijing, both the non-applicability of Kirchoff's law and the measurability of surface emissivity in a non-isothermal system have been highlighted. Two methods called ventilation and time-delay compensations have been proposed to reduce the error induced by change of surface temperatures of non-isothermal objects during the measurement of emissivity. Based on the solution of the basic equation, this paper has analyzed and pointed out the misunderstanding in comprehension and application of Kirchoff's law published in literature. 相似文献
108.
Although Eddy Covariance (EC) technique is one of the best methods for estimating the energy and mass exchanges between underlying surface and atmosphere in micrometeorology, errors and uncertainties still exist without necessary corrections. In this paper, we will focus on the effect of coordinate system on the eddy fluxes. Based on the data observed over four sites (one farmland site, one grassland site and two forest sites), the effects of three coordinate system transforming methods (Double Rotation-DR, Triple Rotation-TR and Planar Fit-PF)on the turbulent fluxes are analyzed. It shows that (i) the corrected fluxes are more or less than the uncorrected fluxes, which is related mainly to the sloping degree of surface, wind speed and wind direction; and (ii) pitch angle has a sinusoidal dependence on wind direction, especially in the regular sloping terrain; and (iii) PF method is something like the simplification of TR or DR,and there are not obvious distinctions in correction in sloping grassland and flat farmland, but PF method is not suitable for uneven and irregular forest sites. 相似文献
109.
鲁东南岚山头含柯石英榴辉岩主要产于花岗质片麻岩内,是苏鲁超高压变质带主要榴辉岩体密集分布区之一。流体包裹体研究表明,榴辉岩矿物及细脉石英中捕获有四种类型包裹体:在超高压-高压榴辉岩相条件下捕获的 N_2±CO_2包裹体;在高压榴辉宕重结晶阶段被捕获的 CO_2-H_2O 包裹体和含子矿物高盐度 H_2O 溶液包裹体:在超高压岩石折返过程中的最晚(角闪岩相退变质甚至更晚)阶段捕获的低盐度 H_2O 溶液包裹体。利用榴辉岩矿物及脉体石英中捕获的流体包裹体相互期次关系,可以对本区超高压变质作用板片折返过程中的流体演化史进行重建。 相似文献
110.
Influence of a coarse interlayer on seawater intrusion and contaminant migration in coastal aquifers 下载免费PDF全文
Vertical 2D slice laboratory experiments were carried out in homogenous and layered sand tanks to elucidate the effects of a highly permeable (coarse‐grained sand) interlayer on seawater intrusion and transport of contaminants to a coastal sea. Tidal fluctuations produced oscillations in the seawater–freshwater transition zone, fluctuations of the contaminant infiltration rate and a zigzag contaminant plume outline. The seawater wedge became discontinuous at the (vertical) edges of the interlayer because of increased lateral movement of the seawater–freshwater interface within the interlayer. The contaminant plume formed a tail within the interlayer depending on the tidal stage, and similar to the wedge, its movement was accentuated. A simple analytical model that neglected vertical flow reliably predicted steady‐state seawater intrusion into the coastal aquifer. Numerical modeling was used to gain insight into the groundwater hydrodynamics and contaminant migration. The numerical results confirmed the experimental findings, i.e. that a highly permeable interlayer can provide a rapid transit path for contaminants to reach the seaward boundary and that the interlayer amplifies the effects of tidal fluctuations, resulting in wider transition zones for the seawater wedge and contaminant plume. Numerical simulations further showed that, with increasing interlayer hydraulic conductivity, the maximum seawater intrusion distance inside the interlayer increases approximately linearly. For the fixed‐head contaminant injection condition used, the model showed that contaminant infiltration increases approximately logarithmically with increasing interlayer hydraulic conductivity (other factors held fixed). Copyright © 2013 John Wiley & Sons, Ltd. 相似文献