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941.
DEVEX-disdrometer evaluation experiment: Basic results and implications for hydrologic studies 总被引:1,自引:0,他引:1
Witold F. Krajewski Anton Kruger Clelia Caracciolo Peter Golé Laurent Barthes Jean-Dominique Creutin Jean-Yves Delahaye Efthymios I. Nikolopoulos Fred Ogden Jean-Paul Vinson 《Advances in water resources》2006
Increasing our understanding of the small scale variability of drop size distributions (DSD), and therefore of several bulk characteristics of rainfall processes, has major implications for our interpretation of the remote sensing based estimates of precipitation and its uncertainty. During the spring and summer of 2002 the authors conducted the DEVEX experiment (disdrometer evaluation experiment) to compare measurements of natural rain made with three different types of disdrometers collocated at the Iowa City Municipal Airport in Iowa City, Iowa in the Midwestern United States. This paper focuses on the evaluation of the instruments rather than analysis of the hydrometeorological aspects of the observed events. The comparison demonstrates discrepancies between instruments. The authors discuss the systematic and random effects in terms of rainfall quantities, drop size distribution properties, and the observed drop size vs. velocity relationships. Since the instruments were collocated, the effects of the natural variability of rain are reduced some with time integration, isolating the instrumental differences. The authors discuss the status of DSD measurement technologies and the implications for a range of hydrologic applications from remote sensing of rainfall to atmospheric deposition to soil erosion and sediment transport in the environment. The data set collected during the DEVEX experiment is made available to the research community. 相似文献
942.
荒漠戈壁区地表疏松层中元素的分布规律 总被引:2,自引:0,他引:2
通过对荒漠戈壁区不同矿区地表疏松层中元素的分布规律研究发现:主要成矿元素和指示元素均在近地表疏松层中富集,同时,在粒级分布上又倾向于细粒级(-160目)富集,可见,在对荒漠戈壁区进行区域地球化学调查中,采集弱胶结层(10~40 cm)细粒级样品(-160目)为最佳采样介质,这样能有效地捕捉深部含矿信息。 相似文献
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946.
黔东南暴雨气候特征及其地形影响 总被引:2,自引:2,他引:2
利用1960~2000年贵州省黔东南地区降水观测资料,统计分析黔东南地区暴雨时空分布特征,进一步揭示其活动规律及主要影响因素。结果表明:黔东南地区暴雨有显著年代际变化特征,存在准15年的周期变化,并与贵州降水和长江中下游降水呈同位相;存在两个暴雨多发中心,夜间暴雨较多。黔东南暴雨地域分布极为复杂,局地性暴雨较多,这与黔东南特殊地形有着密切关系,地形因素是影响黔东南地区暴雨的重要原因,对形成上述特征的气候学成因做了初步讨论。 相似文献
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948.
Characteristics of Aerosol Ionic Compositions in Summer 2003 at Lin''''an of Yangtze Delta Region 总被引:1,自引:0,他引:1
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YAN Peng ZHANG Yangmei YANG Dongzhen TANG Jie ZHOU Xiuji 《Acta Meteorologica Sinica》2006,20(3):374-382
With the size-resolved aerosol mass and ion composition data obtained at Lin'an regional atmospheric pollution monitoring station in July 2003, the size distributions of aerosol mass and ionic components, and the correlations between major ion pairs were analyzed. The primary results indicate that in the period of in-situ measurement, the aerosols are mainly composed of fine particles. The mass of aerosols with size less than 2.1μm accounts for 66% of the total mass of all size ranges, in which about 50% of the mass is contributed by the particles with size less than 0.65μm. Similar to the size distributions of aerosol mass, the water-soluble ions are mainly concentrated in the size range of <0.65μm, accounting for about 77% of the sum of analyzed ions, and the ions within the range of <2.1μm reach 88%. The sulfate, ammonium, and potassium are the dominant ionic components in fine particles (particle size less than 2.1μm). Ion correlation analysis suggests that the sulfates in fine particles are mostly in the compounds of (NH4)2SO4, Na2SO4, and K2SO4, but for submicron particles the sulfates are mainly in the form of (NH4)2SO4. 相似文献
949.
考虑在可数背景状态下,时间离散的拟生灭过程(QBD过程)平稳分布的尾概率的渐近态。通过对QBD过程某些条件的限定,应用马尔可夫更新定理,得出在一定合理的条件下,当水平趋于无穷时的尾概率的几何衰变。通过初等方法,将该结论应用于时间离散的加入最短队模型。 相似文献
950.
Introduction Earthquake often brings large catastrophe to the mankind, especially in recent years when a large number of destructive earthquakes occur in the whole globe, which have caused tremendous casualties and losses to the people. Obviously, it is not very reasonable to make up financial losses and carry out post-seismic reconstruction by the government only for such kind of huge earth- quake losses. Therefore, as an effective measure to raise fund and make up financial losses, earth- qu… 相似文献