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751.
引发湖南特大暴雨山洪的MCS回波发展和演变 总被引:1,自引:0,他引:1
由MCS引发的暴雨是造成湖南山洪地质灾害的主要因素之一.新一代天气雷达对此类天气系统有强的监测和预警能力,在对较大范围的降水估测、获取降水和降水云体的风场结构等方面有很好的应用前景.本文以2005年5月31日~6月1日湖南特大暴雨山洪过程为例,介绍了引发这次山洪地质灾害的MCS雷达回波的发展和演变,分析了回波特征与地面雨量的关系,总结了强对流发生、发展的径向速度变化,讨论了风廓线在预测强对流天气中的应用,为雷达监测、分析和预测同类灾害提供参考. 相似文献
752.
A 10-yr regional climate simulation was performed using the fifth-generation PSU/NCAR Mesoscale Model Version 3 (MM5V3) driven by large-scale NCEP/NCAR reanalyses. Simulations of winter and summer mean regional climate features were examined against observations. The results showed that the model could well simulate the 10-yr winter and summer mean circulation, temperature, and moisture transport at middle and low levels. The simulated winter and summer mean sea level pressure agreed with the NCAR/NCEP reanalysis data. The model could well simulate the distribution and intensity of winter mean precipitation rates as well as the distribution of summer mean precipitation rates, but it overestimated the summer mean precipitation over North China. The model's ability to simulate the regional climate change in winter was superior to that in summer. In addition, the model could simulate the inter-annual variation of seasonal precipitation and surface air temperature. Geopotential heights and temperature at middle and high levels between simulations and observations exhibited high anomaly correlation coefficients. The model also showed large variability to simulate the regional climate change associated with the El Nino events. The MM5V3 well simulated the anomalies of summer mean precipitation in 1992 and 1995, while it demonstrated much less ability to simulate that in 1998. Generally speaking, the MM5V3 is capable of simulating the regional climate change, and could be used for long-term regional climate simulation. 相似文献
753.
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 下载免费PDF全文
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
754.
北京市部分地区土壤和植物中多环芳烃的分布 总被引:3,自引:1,他引:3
研究了北京市区东部、东南部和西南部不同功能区土壤和绿化植物中多环芳烃(PAHs)的分布特征,讨论了土壤和植物叶片中多环芳烃质量分数的相关性。结果表明:车流量较多的路边土壤PAHs质量分数很高,西城区北京杨叶片中PAHs质量分数较高;相同采样点的土壤与植物叶片中多环芳烃的质量分数相关显著。 相似文献
755.
多源遥感影像数据融合是提高海量遥感影像数据利用率,获取更多决策辅助信息的有效手段之一。目前一些商业遥感图像处理软件在进行多源遥感影像融合时,存在效率低、精度难以达到实用要求等问题。本文提卅了基于图像线特征的遥感影像精确配准、纠正、融合新方法,该方法运用线特征算法提取图像边缘特征点作为控制点,然后通过全自动图像匹配获取密集同名点对,由这些同名点对构成密集三角网(小面元)实现影像精确配准;最后进行影像纠正融合处理。大量实践表明,该方法是一种高效实用、高精度的遥感影像配准、纠正、融合方法,能大大改善山区等特殊地区的配准精度。 相似文献
756.
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758.
Limo TANG Shanghong ZHANG Mingzhong YU Xingkui WANG 《国际泥沙研究》2006,21(4):272-280
1 INTRODUCTION The mechanism of particle movement in the flow is one of basic problems of sediment transport research. The conventional measurement approaches usually disturb the structure of the flow, consequently inducing errors. With the development of… 相似文献
759.
Distribution and fractionation mechanism of stable carbon isotope of coalbed methane 总被引:1,自引:0,他引:1
The stable carbon isotope values of coalbed methane range widely, and also are gener- ally lighter than that of gases in normal coal-formed gas fields with similar coal rank. There exists strong carbon isotope fractionation in coalbed methane and it makes the carbon isotope value lighter. The correlation between the carbon isotope value and Ro in coalbed methane is less obvious. The coaly source rock maturity cannot be judged by coalbed methane carbon isotope value. The carbon isotopes of coalbed methane become lighter in much different degree due to the hydrodynamics. The stronger the hydrodynamics is, the lighter the CBM carbon isotopic value becomes. Many previous investigations indicated that the desorption-diffusion effects make the carbon isotope value of coalbed methane lighter. However, the explanation has encountered many problems. The authors of this arti- cle suggest that the flowing groundwater dissolution to free methane in coal seams and the free methane exchange with absorbed one is the carbon isotope fractionation mechanism in coalbed methane. The flowing groundwater in coal can easily take more 13CH4 away from free gas and com- paratively leave more 12CH4. This will make 12CH4 density in free gas comparatively higher than that in absorbed gas. The remaining 12CH4 in free gas then exchanges with the adsorbed methane in coal matrix. Some absorbed 13CH4 can be replaced and become free gas. Some free 12CH4 can be ab- sorbed again into coal matrix and become absorbed gas. Part of the newly replaced 13CH4 in free gas will also be taken away by water, leaving preferentially more 12CH4. The remaining 12CH4 in free gas will exchange again with adsorbed methane in the coal matrix. These processes occur all the time. Through accumulative effect, the 12CH4 will be greatly concentrated in coal. Thus, the stable carbon isotope of coalbed methane becomes dramatically lighter. Through simulation experiment on wa- ter-dissolved methane, it had been proved that the flowing water could fractionate the carbon isotope of methane, and easily take heavy carbon isotope away through dissolution. 相似文献
760.
海安地震台新场地的地电阻率观测于2004年12月初步建成,在试观测期间发现地电阻率东西测向观测数据严重受农村广播干扰,这种干扰国内未见报道,本文初步分析和总结了这种干扰的特征、产生机理及干扰排除措施,对其他台站建设地电阻率观测台站有一定的指导意义。 相似文献