THE GEOGRAPHY OF MASTODON EXTINCTION     

《The Professional geographer》2013,65(4):425-429

Geographic Software Reviewed in this article:

LIFE TABLES and the LESLIE MATRIX. CONDUIT

MENTMAP2. Lawrence W. Carstensen Jr.

PC-MATLAB, Version 1.0. The Math Works, Inc.

QUICKMAP, version 1.0. Sammamish Data Systems, Inc.

SYSTAT: THE SYSTEM FOR STATISTICS, Version 2.1, Systat Inc.

USA DISPLAY. Instant Tecall  相似文献   

Updating estimates of low-streamflow statistics to account for possible trends     

Annalise G. Blum  Stacey A. Archfield  Robert M. Hirsch  Richard M. Vogel  Julie E. Kiang  Robert W. Dudley 《水文科学杂志》2013,58(12):1404-1414

ABSTRACT

Accurate estimators of streamflow statistics are critical to the design, planning, and management of water resources. Given increasing evidence of trends in low-streamflow, new approaches to estimating low-streamflow statistics are needed. Here we investigate simple approaches to select a recent subset of the low-flow record to update the commonly used statistic of 7Q10, the annual minimum 7-day streamflow exceeded in 9 out of 10 years on average. Informed by low-streamflow records at 174 US Geological Survey streamgages, Monte Carlo simulation experiments evaluate competing approaches. We find that a strategy which estimates 7Q10 using the most recent 30 years of record when a trend is detected, reduces error and bias in 7Q10 estimators compared to use of the full record. This simple rule-based approach has potential as the basis for a framework for updating frequency-based statistics in the context of possible trends.  相似文献   

高阶统计量在探地雷达数据处理中的应用     

谢尚平  张阔 《物探与化探》2012,(1):122-125,132

用高阶统计量方法对探地雷达数据进行处理,基本思路是采用信号识别与检测中的高阶统计量参数,对不同模型的探地雷达数据记录进行处理与重构,结果表明不同模型具有不同阶数的高阶统计量特征。模型实验与实际应用都表明,高阶统计量对压制背景噪声和多次反射波有较好的效果。  相似文献   

基于地理信息系统的空间统计学方法在地震统计中的应用     

廖微  姚琪  廖林  张微  姜祥华  杨文 《中国地震》2021,37(3):695-703

传统的地震统计学多局限于规则的统计范围,或是需要较多的人工干预,本文引入了基于地理信息系统的空间统计学方法,将其应用于地震空间统计中,能够高效、快速地挖掘含有地理信息的各要素之间的相互联系。本文以川滇地区2019年发生的ML≥1.0地震数量的空间统计为例,详述了对地震数据进行空间统计的流程。统计结果表明,0.5°×0.5°是最适合该地震数据集空间统计的矩形范围,发生地震次数最多的区域位于四川盆地西南缘的威远?长宁地区,此外龙门山断裂带、龙门山断裂带与鲜水河?小江断裂系交汇处、丽江?小金河断裂沿线以及滇南地区均为地震发生次数较高的区域。此外,还利用该方法计算了2015—2019年全国各省地震能量释放情况。结果显示在该时间段内,释放地震能量总量最多的省份为四川省,新疆维吾尔自治区和西藏自治区次之,而台湾地区陆地区域、四川省、西藏自治区等地区具有较高的每万平方公里地震能量释放量和每万人地震能量承受量。并通过上述应用实例,探索了地理信息系统在地震统计领域的初步应用。  相似文献   

统计预测技术的回顾和展望   总被引：1，自引：0，他引：1       下载免费PDF全文

马开玉 《热带气象学报》2003,19(4):436-441

对我国近几十年来的统计预测技术进行了回顾，并对未来的发展提出了一些看法。  相似文献   

1949-2007年登陆我国变性热带气旋的特征统计及合成分析   总被引：1，自引：2，他引：1  

袁娟娟  丁治英  王莉 《热带气象学报》2011,27(4):529-541

利用1949-2007年热带气旋年鉴等资料,统计分析登陆中国并在我国或附近变性的热带气旋的特征,着重分析不同区域及路径的变性气旋特征.分析结果得出,登陆我国的热带气旋很多,但在我国及附近沿海变性的却较少,大多数热带气旋变性后不发展或迅速衰减,只有约17％的变性热带气旋继续发展.热带气旋变性大多发生在114°E以东,移动...  相似文献   

REVIEWS OF GEOGRAPHIC SOFTWARE     

《The Professional geographer》1987,39(2):229-237

CHAOS CLlM 3.77 LP88 and TPR088 MAPEDIT PRODESIGN II RANDMAP SPATIAL AUTOCORRELATION SIMULATION GAME . Daniel A. Griffith STATA THINKTANK NOTEBOOK II  相似文献   

Differences in paleomagnetic interpretations due to the choice of statistical, demagnetization and correction techniques: Kapuskasing Structural Zone, northern Ontario, Canada     

Graham J. Borradaile  Tomasz Werner  France Lagroix   《Tectonophysics》2003,363(1-2):103-125

The Kapuskasing Structural Zone (KSZ) reveals a section through the Archean lower crustal granoblastic gneisses. Our new paleomagnetic data largely agree with previous work but we show that interpretations vary according to the choices of statistical, demagnetization and field-correction techniques. First, where the orientation distribution of characteristic remanence directions on the sphere is not symmetrically circular, the commonly used statistical model is invalid [Fisher, R.A., Proc. R. Soc. A217 (1953) 295]. Any tendency to form an elliptical distribution indicates that the sample is drawn from a Bingham-type population [Bingham, C., 1964. Distributions on the sphere and on the projective plane. PhD thesis, Yale University]. Fisher and Bingham statistics produce different confidence estimates from the same data and the traditionally defined mean vector may differ from the maximum eigenvector of an orthorhombic Bingham distribution. It seems prudent to apply both models wherever a non-Fisher population is suspected and that may be appropriate in any tectonized rocks. Non-Fisher populations require larger sample sizes so that focussing on individual sites may not be the most effective policy in tectonized rocks. More dispersed sampling across tectonic structures may be more productive. Second, from the same specimens, mean vectors isolated by thermal and alternating field (AF) demagnetization differ. Which treatment gives more meaningful results is difficult to decipher, especially in metamorphic rocks where the history of the magnetic minerals is not easily related to the ages of tectonic and petrological events. In this study, thermal demagnetization gave lower inclinations for paleomagnetic vectors and thus more distant paleopoles. Third, of more parochial significance, tilt corrections may be unnecessary in the KSZ because magnetic fabrics and thrust ramp are constant in orientation to the depth at which they level off, at approximately 15-km depth. With Archean geothermal gradients, primary remanences were blocked after the foliation was tilted to rise on the thrust ramp. Therefore, the rocks were probably magnetized in their present orientation; tilting largely or entirely predates magnetization.  相似文献   

Developing local measures of spatial association for categorical data   总被引：2，自引：0，他引：2  

Barry?BootsEmail author 《Journal of Geographical Systems》2003,5(2):139-160

This paper describes a procedure for extending local statistics to categorical spatial data. The approach is based on the notion that there are two fundamental characteristics of categorical spatial data; composition and configuration. Further, it is argued that, when considered locally, the latter should be measured conditionally with respect to the former. These ideas are developed for binary, gridded data. Local composition is measured by counting the numbers of cells of a particular type, while local configuration is measured by join counts. The approach is illustrated using a small, empirical data set and an ad hoc procedure is developed to deal with the impact of global spatial autocorrelation on the local statistics.The author gratefully acknowledges financial support from the GEOIDE Network of Centres of Excellence (ENV #4) and the helpful comments of three anonymous reviewers.  相似文献   

Turbulence Statistics Measurements in a Northern Hardwood Forest   总被引：3，自引：0，他引：3  

M. G. Villani  H. P. Schmid  H.-B. Su  J. L. Hutton  C. S. Vogel 《Boundary-Layer Meteorology》2003,108(3):343-364

Tower-based turbulence measurements were collected in and over a mixed hardwood forest at the University of Michigan BiologicalStation (UMBS) UMBSflux site in the northern summerof 2000. Velocity and temperature fluctuations were measured at five levels within the canopy (up to the canopy height, H = 21.4 m), using one- and three-dimensional sonic anemometers and fine-wire thermocouples. Six additional thermocouples were distributed over the canopy-layer depth. Three-dimensional velocities and sonic temperatures were also measured above the canopy at 1.6H and at 2.15H on the AmeriFlux tower located at the UMBSflux site. Vertical profiles of buoyancy flux, mean horizontal velocity, Reynolds stress, and standard deviation and skewness of velocity components were calculated. The analysis of these measurements aims at a multi-layer parameterization framework of turbulence statistics forimplementation in Lagrangian stochastic models. Turbulence profiles and power spectra above the canopy were analyzed in the context of Monin-Obukhov similarity theory (MOST) and Kolmogorov theory, as determined by stability at the top level (2.15H), to assess the extent to which surface scaling is valid as the canopy top is approached. Velocity spectra were computed to explore the potential of estimating the viscous dissipation rate, and results show that the high frequency range of the spectra above the canopy exhibits the roll-off predicted by Kolmogorov theory. Similarly, velocity standard deviations above the canopy converge to MOST predicted values toward the top level, and spectral peaks shift with stability, as expected. Within the canopy, both turbulence statistics profiles and spectral distributions follow the general known characteristics inside forests.  相似文献