基于EOS/MODIS 数据的NDVI 与 EVI 比较研究   总被引：24，自引：0，他引：24  

李红军  郑力  雷玉平  李春强  周戡 《地理科学进展》2007,26(1):26-32

作为NOAA/AVHRR 归一化植被指数(NDVI) 的延续和发展, EOS/MODIS 归一化植被指 数(NDVI) 和增强植被指数( EVI) 在许多领域得到广泛应用。应用数理统计和地统计学方法对二 者进行的对比研究表明: NDVI 在植被生长旺盛期容易达到饱和, 而EVI 则能克服这一现象, 比 较真实地反映植被的生长变化过程; 相同空间分辨率下, EVI 取值范围、标准差与变异系数均高 于NDVI, NDVI 数据比较均一, 其空间相关性高于EVI, EVI 更能反映研究区域内植被空间差异。 关键词:MODIS; 归一化植被指数(NDVI) ; 增强植被指数( EVI) ; 对比  相似文献   

中国高技术产业投入产出有效性地区差异分析   总被引：6，自引：0，他引：6  

张纯  葛幼松 《地理与地理信息科学》2007,23(3):59-63,77

运用DEA方法,从综合有效性、技术有效性和规模有效性3方面对全国30个省(市、区)(缺失西藏数据)的高技术产业投入产出有效性进行实证分析,根据技术有效性和规模有效性对其发展状态进行分类并提出相应对策。结果表明,我国高技术产业在现有的发展水平上存在投入产出效率不高、总体规模偏大等问题,各省市需针对自身特点制定相应发展策略。  相似文献   

GMS—5多通道高温差的高度分布特征   总被引：2，自引：0，他引：2       下载免费PDF全文

李浩  余怒涛等 《气象科学》2002,22(3):329-336

本文从GMS－5红外通道探测原理出发，得到多通道亮温差DT12，DT1W随高度的分布特征，分析结果表明，所得的DT12，DT1W的高度分布特征具有明确的物理意义，它们与局地降雨概率及强度还存在一定的相关关系。  相似文献   

复杂地质构造波动方程数值模拟   总被引：3，自引：2，他引：3  

单延明  吴清岭  于承业  王建民  陈斌 《物探化探计算技术》2002,24(1):24-26

利用全声波方程进行地震波场的数值模拟，虽然可以计算全声波波场值，但是也常常会出现层间多次波，给资料解释造成一定的困难。作者在本文中根据无反射声波方程，采用有限差分数值解法，实现了自激自收时间剖面的制作，避免了层间多次波的产生。本方法不但允许速度有纵向变化，而且允许速度有横向变化，这使得模拟复杂地质构造的地震响应成为可能。实际计算结果表明，该方法是一种行之有效的自激自收时间剖面的计算机数值模拟方法。  相似文献   

裂隙(EDA)介质P波地震记录数值模拟及波场特征分析     

杜正聪  何义中  贺振华  桂志先 《新疆地质》2002,20(Z1):117-120

通过对潜山面和内幕EDA介质地面地震记录数值模拟及其波场特征分析,在了解地震波场的动力学特征对裂缝介质的敏感性基础上,确定主要以振幅,其次是频率的地震波动力学特征为裂缝检测被检参数,以均方振幅与中心频率作为检验检测结果正确与否的评价参数,为建立裂缝检测方法奠定了理论基础.  相似文献   

A FRAMEWORK FOR AUTOMATED CHANGE DETECTION SYSTEM     

SUI Haigang LI Deren 《地球空间信息科学学报》2001,4(3):29-34

1Ｃｕｒｒｅｎｔｃｈａｎｇｅｄｅｔｅｃｔｉｏｎｔｅｃｈ ｎｉｑｕｅｓＡｕｔｏｍａｔｉｃｃｈａｎｇｅｄｅｔｅｃｔｉｏｎｉｎｉｍａｇｅｓｏｆａｇｉｖｅｎｓｃｅｎｅａｃｑｕｉｒｅｄａｔｄｉｆｆｅｒｅｎｔｔｉｍｅｓｉｓｏｎｅｏｆｔｈｅｍｏｓｔｉｎｔｅｒｅｓｔｉｎｇｔｏｐｉｃｓｏｆｉｍａｇｅｐｒｏｃｅｓｓｉｎｇ .Ｉｔｆｉｎｄｓｉｍ ｐｏｒｔａｎｔａｐｐｌｉｃａｔｉｏｎｓｗｉｔｈｉｎｄｉｆｆｅｒｅｎｔｃｏｎｔｅｘｔｓ,ｒａｎｇ ｉｎｇｆｒｏｍｖｉｓｕａｌｓｕｒｖｅｉｌｌａｎｃｅａｎｄｖｉｄｅｏｃｏｄｉｎｇｔｏｔ…  相似文献   

两种反映东亚夏季风异常的指数的比较研究   总被引：3，自引：3，他引：3  

李峰  孙秀荣等 《气象科学》2001,21(2):178-185

本文利用文献^ [4]提出的一种新的反映东亚夏季风异常的海陆温差指数分析了夏季风异常时我国气温、降水异常以及东亚环流状况，通过分析指出，东亚夏季风偏强，则中国东部夏季气温偏高，江淮干旱，华北多雨；夏季风偏弱则夏季气温偏低，江淮多雨，易涝，华北少雨。通过两种夏季风指数的对比，海陆温差指数能更好地反映东亚夏季环流及天气气候异常。文中还指出，海陆温差指数能更好的反映夏季风异常的原因是它的定义方法更科学，更全面的反映东亚海陆热力差异，既包含了东亚纬向海陆热力差异的影响，又考虑了东亚经向海陆热力差异的因素，并用地表气温和海表温度差来表示海陆热力差，好于以往用海平面气压差来反映海陆热力差。  相似文献   

Estimation Of Sensible Heat Flux From The Surface Temperature Wave And One-Time-Of-Day Air Temperature Observation, Part Ii – Heterogeneous Surfaces     

K. Blümel 《Boundary-Layer Meteorology》2001,98(2):183-218

By means of the algorithm presented in Part I of this study, the temporal course H(t) and the daily mean H of the sensible heat flux H can be determined from measurements of the thermodynamic surface temperature (as a function of time) and from a one-time-of-day air temperature observation. Inaddition to these temperatures, one needs estimates of daily mean wind speed,of the roughness lengths of momentum and heat transfer, and of the displacementheight. In Part I, the algorithm was derived for areas with homogeneous surfaces,i.e., with uniform surface temperature, and the method was verified with measurements taken during several field campaigns. The root mean square error for the temperature difference between surface and air, in the comparison between measurement and model, amounted to one or two kelvin, and the error of H was 10 to 25 per cent. The method can be used to determine the sensible heat flux from measurements of surface temperatures by satellites, but can also be applied to ground based measurements.In Part II, the procedure is generalized for areas that consist of various surface types (sub-regions) with different surface temperatures, and can be usedwhen only a few (at least one) air temperature measurements per day are available over only one of the different sub-regions. This generalization should allow improvements to the estimates for H(t) by means of temperature measurements from, e.g., NOAA/AVHRR or LANDSAT/TM, taking into account the heterogeneity of the area contained in one METEOSAT pixel. Criteria are given as to whether effective (areal mean) surface temperatures and roughness lengths may be used for the computation of H or if the above mentioned generalized procedure has to be applied. The new algorithm is verified by measurements sampled during the field campaigns EFEDA 91 (Spain) and HIBE 89 (Hildesheimer Börde in Germany), and by using synthetic data (due to the lack of measured data) for one further combined surfacetype [soil and water (lakes)].  相似文献   

REGIONAL DIFFERENCES OF TEMPORAL-SPATIAL CHARACTERISTICS OF AIR-SEA INTERACTIONS IN TROPICAL OCEANS   总被引：3，自引：0，他引：3  

王盘兴  何金海  郭品文  马丽萍 《Acta Meteorologica Sinica》2001,(4)

The singular value decomposition (SVD) of air-sea interaction in the tropical western,central,and eastern Pacific,and the tropical Atlantic and Indian Oceans has been conducted by using theNCEP/NCAR 40-year reanalysis 1000 hPa monthly wind field and COADS monthly sea surfacetemperature (SST).Comparisons of the results suggest that these areas can be divided into threetypes from the viewpoint of air-sea interaction:tropical central-eastern Pacific belongs to monistictype,in which ENSO is the sole important process;tropical western Pacific and Indian Oceansbelong to dualistic type,in which in addition to ENSO.there should be an another importantprocess;tropical Atlantic Ocean belongs to pluralistic type,in which the process is complicatedand the ENSO cycle is not evident.  相似文献   

Numerical modeling calculation for the spatial distribution characteristics of horizontal field transfer functions     

龚绍京  陈化然 《地震学报(英文版)》2001,14(6):676-684

Introduction There are two kinds of methods for the mathematic study on electro-magnetic induction in geo-field: one is analytic method, such as integral equation method; the other is numerical model-ing method, such as finite difference method and finite element method. The analytic method can only be applied to the conductor with very simple shape, such as sphere, circular cylinder, etc. With the increasing of computing speed and popularity of computer, the numerical modeling methods are use…  相似文献