江淮梅雨期极端对流微物理特征的双偏振雷达观测研究     

杨忠林  赵坤  徐坤  李凯  陈刚  温龙  刘溯  杨正玮 《气象学报》2019,77(1):58-72

为研究梅雨期极端对流系统的微物理特征,利用2013—2014年江淮梅雨期间南京溧水S波段双偏振雷达探测资料和地面自动站小时降水资料,统计分析了两类极端对流降水系统的微物理特征及差异。这两类极端对流系统的定义基于地面降水强度和雷达回波顶高,分别为所有对流中降水强度最强的1%（R类:小时降水强度>46.2 mm/h）和对流发展高度最高的1%（H类:20 dBz回波顶高>14.5 km）。结果显示这两类极端对流系统仅有30%的样本重合,显示了二者之间的弱相关性。对于相同的反射率因子Z_H,R类极端对流系统的近地面差分反射率因子Z_DR通常较H类极端对流小约0.2 dB,表明R类极端对流具有较小的平均粒径。结合双偏振雷达反演的粒子大小和相态分布显示,虽然两类极端对流都表现出海洋性对流降水特征,但R类极端对流较H类极端对流的总体雨滴粒径更小而数浓度更高,导致R类极端对流系统的地面降水更强。与R类极端对流系统相比,H类极端对流系统的上升运动更强,将更多的水汽和过冷水输送到0℃层以上,有利于形成更大的冰相粒子（如霰粒子等）,并通过融化形成大雨滴。以上研究表明,梅雨期降水强度和对流发展深度并没有必然的联系,极端降水主要是中等高度的对流引起。   相似文献   

Elastoplastic damage modeling of desaturation and resaturation in argillites     

Y. Jia  H. B. Bian  K. Su  D. Kondo  J. F. Shao 《国际地质力学数值与分析法杂志》2010,34(2):187-220

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The environmental impacts of pollutants generated by routine shipping operations on ports     

Adolf K.Y. Ng  Su Song 《Ocean & Coastal Management》2010,53(5-6):301-311

The environmental impacts generated by shipping operations have increasingly become an important research topic, where its pollutants often pose negative externalities to natural habitats and economic losses to coastal areas. While the environmental impact costs generated by shipping disasters, notably large scale accidental oil spills, have been widely studied, hitherto, works dedicated to the assessment of environmental impact costs of pollutants generated by routine shipping operations remain scarce due to their relatively implicit nature and thus delays of consequential risks. Hence, by proposing an economic model and calibrating it to Port of Rotterdam, this paper assesses the environmental impact costs generated by routine shipping operations on ports. By shedding light on this important, but under-researched, issue critical to the well-being of the global shipping industry, this paper provides a decent framework for further research in sustainable shipping and port management for future generations.  相似文献   

Effect of land‐use changes on nonpoint source pollution in the Xizhi River watershed,Guangdong, China     

Kai Xu  Yunpeng Wang  Hua Su  Jingxue Yang  Lili Li  Cang Liu 《水文研究》2013,27(18):2557-2566

The Annualized Agricultural Non‐point Source (AnnAGNPS) pollution model has been widely used to assess and predict runoff, soil erosion, sediment and nutrient loading with a geographic information system. This article presents a case study of the effect of land‐use changes on nonpoint source (NPS) pollution using the AnnAGNPS model in the Xizhi River watershed, eastern Pearl River Delta of Guangdong province, China. The land‐use changes in the Xizhi River watershed between 1998 and 2003 were examined using the multitemporal remote sensing data. The runoff, soil erosion, sediment transport and nutrient loading 1998 and 2003 were assessed using AnnAGNPS. The effects of land‐use changes on NPS were studied by comparing the simulation results of each year. Our results showed that (i) the NPS loadings increased when forest and grass land converted into paddy, orchard and farmland land, and population size and gross domestic product size as well as the usage amounts of fertilizer and pesticide in the entire watershed were firmly correlated with the NPS loadings; (ii) the land‐use change during fast urbanization in particular when other land types were converted into the development land and buildup land led to increasing of NPS pollution; and (iii) urban land expansion showed more important effects on total organic carbon (TOC) loading compared with nitrogen and phosphorus loadings. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Computational homogenization of uncoupled consolidation in micro‐heterogeneous porous media     

Fredrik Larsson  Kenneth Runesson  Fang Su 《国际地质力学数值与分析法杂志》2010,34(14):1431-1458

Variationally consistent homogenization is exploited for the analysis of transient uncoupled consolidation in micro‐heterogeneous porous solids, whereby the classical approach of first‐order homogenization for stationary problems is extended to transient problems. Homogenization is then carried out in the spatial domain on representative volume elements (RVE), which are introduced in quadrature points in standard fashion. Along with the classical averages, a higher‐order conservation quantity is obtained. An iterative FE²‐algorithm is devised for the case of nonlinear permeability and storage coefficients, and it is applied to pore pressure changes in asphalt‐concrete (particle composite). Various parametric studies are carried out, in particular, with respect to the influence of the ‘substructure length scale’ that is represented by the size of the RVE's. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Announcement     

D. A. Novelo-Casanova  Gerardo Suárez 《Natural Hazards》1988,1(1):111-112

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Measurement of rock mass deformation with grouted coaxial antenna cables   总被引：4，自引：0，他引：4  

C. H. Dowding  M. B. Su  K. O'Connor 《Rock Mechanics and Rock Engineering》1989,22(1):1-23

Summary Techniques presented herein show how reflected voltage pulses from coaxial antenna cable grouted in rock masses can be employed to quantify the type and magnitude of rock mass deformation. This measurement is similar to that obtained from a combined full profile extensometer (to measure local extension) and inclinometer (to measure local shearing). Rock mass movements deform the grouted cable, which locally changes cable capacitance and thereby the reflected wave form of the voltage pulse. Thus, by monitoring changes in these reflection signatures, it is possible to monitor rock mass deformation.This paper presents laboratory measurements necessary to quantitatively interpret the reflected voltage signatures. Cables were sheared and extended to correlate measured cable deformation with reflected voltage signals. Laboratory testing included development of grout mixtures with optimum properties for field installation and performance of a TDR (Time Domain Reflectometry) monitoring system. Finally, the interpretive techniques developed through laboratory measurements were applied to previously collected field data to extract hitherto unrealized information.  相似文献   

广东省海岸表层沉积物的重矿物特征及其与沉积环境的关系     

梁百和  朱素琳  吴华新 《岩石矿物学杂志》1989,8(2):180-188

广东省海岸表层沉积物中的重矿物近40种。含量较高的有钛铁矿、赤矿铁、磁铁矿、话石、电气石、黑云母和普通角闪石等。自生矿物主要为硬石膏、自然铜、黄铁矿及菱铁矿。这些矿物来自附近的母岩。根据物源性质不同,可将不同岸段重矿物区分为陆源矿物组合、近源-自生矿物组合和近源矿物组合三种:除物源控制外,重矿物含量、种类、形态特征及其在平面上的分布主要受沉积环境影响。据此,可将重矿物分布类型划分为河口型、海湾型和海岛型三类,且与上述不同矿物组合性质相对应。  相似文献   

Intensity attenuation based on earthquake fault-rupture model     

Xiyuan Zhou  Jingyu Su  Guangjun Wang 《地震科学（英文版）》1988,1(4):85-95

Based on the statistical outcomes relevant to elliptical isoseisms given in ref. [1], the average focal depth and rupture length of fault for earthquakes with different magnitudes or epicentral intensities occurring in East and West China are discussed. A set of intensity attenuation functions appropriated to point source (regarding focal distance as the distance parameter in the attenuation law) and the line source (regarding the shortest distance from the site to rupture line or the average distance from the site to both ends of the rupture line as the distance parameter) are proposed.  相似文献   

河北东坪金矿区水泉沟岩体的地球化学特征   总被引：17，自引：0，他引：17       下载免费PDF全文

魏菊英  苏琪 《地质科学》1994,29(3):256-266

水泉沟岩体主要由二长岩构成。主要矿物是碱性长石和斜长石,它们的含量高达80%以上。石英不多见,暗色矿物含量少。副矿物主要是磁铁矿、石榴石、榍石和锆石。交代结构发育,蚀变现象普遍。主要化学组分和微量元素含量及δ¹⁸O值变化范围大。该二长岩体是由老片麻岩经热液碱交代作用而成。  相似文献