中国暴雨的科学与预报：改革开放40年研究成果   总被引：13，自引：4，他引：9  

罗亚丽  孙继松  李英  夏茹娣  杜宇  杨帅  张元春  陈静  代刊  沈学顺  陈昊明  周菲凡  刘屹岷  傅慎明  吴梦雯  肖天贵  陈杨瑞雪  黎慧琦  李明鑫 《气象学报》2020,78(3):419-450

总结了改革开放以来中国学者在暴雨科学与预报领域取得的重要研究进展和主要成果。其中,暴雨机理研究成果从重要天气系统、中国主要区域的暴雨、台风暴雨等3个方面分别进行综述,而暴雨预报技术研发与应用则从中国数值天气预报发展和暴雨预报客观方法两方面进行归纳。   相似文献   

2008年华南前汛期致洪暴雨特征及其对比分析   总被引：10，自引：5，他引：5  

王东海  夏茹娣  刘英 《气象学报》2011,69(1):137-148

着重对2008年华南前汛期持续性致洪暴雨的降水特征及成因进行了天气尺度的研究,并且对比分析了其与20世纪90年代以来华南前汛期洪灾较为严重的几年(1994、1998和2005年)的降水和环流场特征异同,主要得到以下结果:(1)根据影响系统和雨区分布的不同,将2008年华南前汛期降水过程分为4个阶段.第1阶段(5月26-...  相似文献   

Quantification of Aquatic Nano Particles after Different Steps of Bodensee Water Purification with Laser‐induced Breakdown Detection (LIBD)     

Tobias Bundschuh  Roger Knopp  Rudi Winzenbacher  Jae Il Kim  Rainer Kster 《洁净——土壤、空气、水》2001,29(1):7-15

The laser‐induced breakdown detection (LIBD) is a very sensitive method for the direct detection of colloids based on the plasma generation on single particles by a focused, pulsed laser beam and the detection of the produced shock wave or plasma light emission. For the determination of colloid sizes the light emission of single plasmas is detected by a microscope CCD‐camera system. With known mean particle diameter and breakdown probability the particle concentration can be calculated. The application of the LIBD to monitor the change of colloid concentration and size during the purification steps of drinking water at the Bodensee (Lake Constance, Germany) water purification plant is shown. The breakdown probability, correlating to colloid number density, decreases with every purification step. By addition of FeCl₃ as a precipitating agent and with an additional filtration step, not only suspended matter, but also colloids are effectively removed. After this process a remaining particle concentration of 50 ng/L and a mean particle diameter of 27 nm are found.  相似文献   

桶形基础平台负压沉贯遥测遥控技术方案设计   总被引：1，自引：0，他引：1  

朱儒弟  初新杰 《海岸工程》1999,18(1):85-89

桶形基础平台海上安装就位在施工方法与传统的桩基平台截然不同,本文介绍了一种桶形基础平台负夺沉贯施工的遥测遥控系统方案,对现场施工机具的设计参考作用。  相似文献   

Enantioselectivity of polychlorinated biphenyl atropisomers in sediment and biota from the Turtle/Brunswick River estuary, Georgia, USA     

Ross MS  Pulster EL  Ejsmont MB  Chow EA  Hessel CM  Maruya KA  Wong CS 《Marine pollution bulletin》2011,63(5-12):548-555

To investigate the potential for enantioselective transformation and accumulation, the enantiomer distributions of seven polychlorinated biphenyl (PCB) atropisomers were measured in the sediment and biota from a sub-tropical estuary heavily contaminated with Aroclor 1268, a technical mixture of highly chlorinated PCB congeners. Enantiomer fractions (EFs) of PCBs 91, 95, 136, 149, 174, 176, and 183 in marsh sediment, invertebrate, forage and predatory fish species, and bottlenose dolphins were determined. Non-racemic EFs greater than 0.75 were found in sediments for PCBs 136 and 174, likely the result of microbial dechlorination. Although enantiomer fractions in grass shrimp (Palaemonetes spp.) mirrored those of sediment, fish species had EFs that differed significantly from sediment or grass shrimp. Similarly, bottlenose dolphins were also found to contain non-racemic quantities of PCBs 91, 136, 174, 176, and 183. Non-racemic EFs in these biota were likely a result of both uptake of non-racemic proportions of PCBs from the diet and enantioselective biotransformation.  相似文献   

First XMM-Newton observations of strongly magnetic cataclysmic variables – II. Timing studies of DP Leo and WW Hor     

Dirk Pandel  France A. Cordova  Robert E. Shirey  Gavin Ramsay  Mark Cropper  Keith O. Mason  Rudi Much  Dave Kilkenny 《Monthly notices of the Royal Astronomical Society》2002,332(1):116-126

XMM-Newton was used to observe two eclipsing, magnetic cataclysmic variables, DP Leo and WW Hor, continuously for three orbital cycles each. Both systems were in an intermediate state of accretion. For WW Hor we also obtained optical light curves with the XMM-Newton Optical Monitor and from ground-based observations. Our analysis of the X-ray and optical light curves allows us to constrain physical and geometrical parameters of the accretion regions and derive orbital parameters and eclipse ephemerides of the systems. For WW Hor we directly measure horizontal and vertical temperature variations in the accretion column. From comparisons with previous observations we find that changes in the accretion spot longitude are correlated with the accretion rate. For DP Leo the shape of the hard X-ray light curve is not as expected for optically thin emission, showing the importance of optical depth effects in the post-shock region. We find that the spin period of the white dwarf is slightly shorter than the orbital period and that the orbital period is decreasing faster than expected for energy loss by gravitational radiation alone.  相似文献   

A modular graph transformation rule set for IFC‐to‐CityGML conversion     

Helga Tauscher  Joie Lim  Rudi Stouffs 《Transactions in GIS》2021,25(1):261-290

Conversion of Industry Foundation Classes (IFC) building models into CityGML city models is one of the operational scenarios for BIM–GIS integration, with a variety of applications producing and consuming data on either side. Given the in‐depth cross‐domain knowledge required to specify such conversions, the heterogeneity of the IFC input data and the use cases for the resulting CityGML, flexible and configurable solutions are needed that make conversion details accessible to domain specialists. Graph transformation as a conversion method fulfils these requirements. We propose to extend the modularity given by single transformation rules at a more coarse‐grained level and identify four layers with modules of associated rules. We describe a self‐contained set of rules across these modules and demonstrate its application to a range of building models.  相似文献   

Effects of grid cell size and time step length on simulation results of the Limburg soil erosion model (LISEM)     

Rudi Hessel 《水文研究》2005,19(15):3037-3049

With increasing computer power, process‐based models that use grids to discretize space have become increasingly popular. For such models, the simulation results might depend on both grid cell size and, in the case of dynamic models, on the time step length used in the model. In this study, the dynamic Limburg soil erosion model (LISEM) was applied to a small catchment on the Chinese Loess Plateau. To study the effect of grid cell size and time step length, simulations were performed for grid cell sizes ranging from 5 to 100 m for a single time step length, and for time step lengths ranging from 2 to 120 s for a single grid cell size. The results show that the LISEM results vary considerably as a function of both grid cell size and time step length. For both increase in cell size and increasing time step length, the trend was a decrease in predicted discharge and predicted soil loss. For discharge, the most important causes are likely to be a decrease in slope with increasing grid cell size, rainfall averaging for longer time step lengths, and numerical dispersion of the kinematic wave solution. For soil loss, the cause is less clear, reflecting the complexity of soil loss prediction, which depends on available water, transport capacity and sediment redistribution, all of which change in time and space. These results show that a choice for a certain grid cell size and a certain time step length should be made before calibration of the model. Similar erosion models are likely to have similar dependencies on grid size and time step length. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

SOIL CARBON DIOXIDE CONCENTRATIONS AND CLIMATE IN A HUMID SUBTROPICAL ENVIRONMENT     

Rudi H. Kiefer 《The Professional geographer》1990,42(2):182-194

Soil carbon dioxide content, temperature, and moisture were measured biweekly for one year at Pigeon Mountain, GA. Levels of soil CO₂ ranged from 0.04% to 2.4% and were highest during the growing season, lowest during the winter. Soil temperature correlated positively with soil CO₂, accounting for 90% of CO₂ variation. Soil moisture variations decreased CO₂ concentration at times of high soil water content when CO₂ was flushed downward, and also at times of low soil moisture content when CO₂ production was inhibited. A predictive model of logistic form using 14-day means of daily actual evapotranspiration fit the data well (R²= 0.83). The model also tested well against soil CO₂ data acquired in the coastal plain at Rocky Point, NC. If actual evapotranspiration rates are known, the model permits estimation of soil CO₂ without preliminary field work, and can be used for studies of karst denudation, which require soil CO₂ data for seasonal and regional comparison of solution rates.  相似文献   

2009年冬季华北初雪对流层低层风场及 大气层结特征   总被引：2，自引：0，他引：2  

夏茹娣  王东海  张立生 《气候与环境研究》2013,18(1):87-100

对2009年冬季我同华北一次回流初雪天气进行了数值模拟和诊断分析,重点研究了与回流相关的对流层低层风场的动力热力作用以及大气层结特征.结果表明:初雪是存高空低压槽、低空回流切变线以及地面倒槽锋生的共同影响下产生的,降雪区域随着影响系统向东南方向移动而移动;对降雪起到重要动力作用的偏东风回流主要出现在850 hPa及以下层次,其发展一方面与偏西气流形成低空风场辐合线,有利于气流的上升运动,一方面在地形的共同作用下,形成偏南风;偏南风的形成有利于暖空气向降雪区域输送,而暖平流与强冷空气相遇引起了锋生;偏东风回流除了起到重要的动力作用外,热力作用也很明显,其对降雪区域的水汽辐合起到了主要作用;在降雪发生时,对流层低层有明显的降温过程,大气边界层温度降到了0℃以下,850 hPa温度降至-5℃左右,该结果表明冬季关注数值模式模拟的对流层低层温度层结特征,将有助于对降水性质做出更准确的预报.  相似文献