The High Concentration Tails Of The Probability Density Function Of A Dispersing Scalar In The Atmosphere   总被引：1，自引：0，他引：1  

R. J. Munro  P. C. Chatwin  N. Mole 《Boundary-Layer Meteorology》2001,98(2):315-339

The distribution function for concentrations of a scalar pollutant dispersing in the turbulent atmosphere has a finite domain that is bounded above and below. Three methods, based on extreme value statistics, are used to obtainestimates for the upper bound and to describe the high concentration tailbehaviour of the distribution; all three methods are applied to concentrationdata obtained from experimental atmospheric releases. Quantile quantile (QQ)plots are used to assess the goodness of fit of the resulting estimates of thedistribution, and also to compare the performance of the three methods. Thepredicted values for the upper bound are orders of magnitude less than thesource concentration, illustrating that molecular diffusion has a large effecton the high concentrations.  相似文献   

强弱南海夏季风活动及大气季节内振荡   总被引：26，自引：0，他引：26  

Li Chongyin  Long Zhenxi  Zhang Qingyun 《大气科学进展》2001,18(6):1146-1160

应用ＮＣＥＰ再分析资料和中国降水资料，分析研究了对应南海强、弱夏季风的环流形势及其与之相应的中国东部的降水异常。其结果表明，由强、弱夏季风所引起的中国气候异常是完全不同（甚至反相）的。分析大气季节内振荡（ＩＳＯ）的活动还表明，对应大气强（弱）南海夏季风，南海地区 ８５０ ｈＰａ也有强（弱）大气 ＩＳＯ；而强、弱南海夏季风环流（２００ ｈＰａ和 ８５０ ｈＰａ）主要由异常的大气ＩＳＯ所激发。本研究还揭示了南海地区大气ＩＳＯ的变化往往与江淮地区大气ＩＳＯ的变化反相，例如南海地区的强（弱）大气ＩＳＯ常与江淮流域的弱（强）大气ＩＳＯ相对应。对于大气ＩＳＯ的强度，一般多表现出局地激发特征，经向传播相对较弱。  相似文献   

无线电掩星反演大气参数误差分析及应用进展   总被引：3，自引：1，他引：3  

蒋虎  黄珹  严豪键 《地球物理学进展》2001,16(1):82-88

本文详细分析了影响空间GPS无线电掩星反演大气参数方法的主要误差源，其中包括信噪比误差，精密定轨误差，电离层模制误差，多路径效应和时钟改正等误差，并且介绍了国内外在无线电掩星领域的一些应用研究进展。  相似文献   

Analysis And Simulation Of Surface-Layer Winds Using Multiplicative Cascade Models With Self-Similar Probability Densities   总被引：1，自引：0，他引：1  

Michael K. Lauren  Merab Menabde  Geoffrey L. Austin 《Boundary-Layer Meteorology》2001,100(2):263-286

Statistical analysis techniques based on multiplicative cascades are investigated for use with surface-layer wind data sets collected in the atmospheric boundary layer over flat farm land. The data were found to exhibit multiscaling statistics, allowing the surface-layer winds to be simulated with the use of multiplicative random cascades. The study found evidence that, for the surface-layer at least, these cascade models (andhence the methods of multifractal analysis) should be applied in separate ways to the microscale inertial range, and the mesoscale. This is at odds with the view found in the existing literature, which proposes a `universal multifractal' model to replace the widely held view that there exists separate microscale, mesoscale and synoptic scales for which the processes governing each are different. At least two separate ranges of scaling are suggested for surface-layer wind data, corresponding to the microscale inertial range and the mesoscale. For the case of the mesoscale range, a self-similar distribution of weighting factors was found for the wind speed data themselves, rather than for an intermediate (dissipation) field, as is required for themicroscale data.  相似文献   

MAPINFO下城市地下管网空间分析功能的实现   总被引：1，自引：0，他引：1  

于海龙  谢刚生  李大军 《测绘工程》2001,10(2):48-50

主要对在MAPINFO平台上如何实现管网空间位置分析、拓扑分析、缓冲区分析以及最短路径及事故分析等空间分析功能的实现思路和算法进行较详细的研究，并用实际探测的管线数据进行功能模拟，模拟后得到了较好的效果。  相似文献   

Synoptic circulation and stream discharge in the Great Lakes basin, USA     

R. V. Rohli  A. J. Vega  M. R. Binkley  S. D. Britton  H. E. Heckman  J. M. Jenkins  Y. Ono  D. E. Sheeler 《Applied geography (Sevenoaks, England)》2001,21(4)

Impacts on water resources caused by human activity, natural climate variation and long-term climate change are unclear in the US Great Lakes region. Improved understanding of the impact of atmospheric circulation on stream discharge variability into the Lakes is thus important. In this analysis, monthly surface and mid-tropospheric circulation patterns suggest that surface pressure variations over Missouri and Illinois are most strongly correlated to discharge. The mid-tropospheric patterns most directly related to discharge place the Great Lakes in a trough-to-ridge flow pattern. The analysis confirms that at this scale, lee shore advection resulting in ‘lake-effect’ precipitation is not very important to regional discharge, and neither are variations in the Pacific–North American teleconnection.  相似文献   

自动搜索最小多边形算法的研究   总被引：2，自引：1，他引：2  

周秋生 《测绘工程》1996,5(2):33-38

多边形的自动搜索是ＧＩＳ空间分析的基本算法之一，同时也在地籍拆宗、导线网闭合环的闭合差计算等领域有着重要的作用。本文依据一般的图形数据结构，提出了一种结点标记的搜索算法，利用该算法可自动搜索出所有独立的最小多边形。  相似文献   

单波高精度测距系统的研究   总被引：12，自引：0，他引：12  

张学庄  王爱公 《测绘学报》1996,25(3):186-189

本文介绍了测距精度优于１０＾－６的自动高精度测距系统的构成、原理及春应用。  相似文献   

极地海冰异常对我国夏季大气环流和降水影响的数值研究   总被引：5，自引：3，他引：5  

吴尚森  梁建茵  纪忠萍 《热带气象学报》1996,12(2):105-112

利用全球大气环流谱模式分别进行了南极和北极海冰面积异常偏大和偏小的数值试验，对６－８月的结果进行了对比分析，讨论了极地海冰异常对我国夏季大气环流和降水的可能影响。结果表明，南极或北极海冰面积异常偏大，则我国夏季风变弱，特别蝇使得南亚高压、西北太平洋副热带高压等减弱。南极海冰面积偏大使得我国黄河－长江－带地区降水减少，北极海冰面积偏大，造成我国东部地区的降水量有所减少，模拟结果与统计分析相一致。可同  相似文献   

Description of A Nine-Level Grid Point Atmospheric General Circulation Model   总被引：31，自引：0，他引：31  

Liang Xinzhong 《大气科学进展》1996,13(3):269-298

  相似文献