A modified global model for predicting the tritium distribution in precipitation, 1960–2005     

Yanhong Zhang  Shujun Ye  Jichun Wu 《水文研究》2011,25(15):2379-2392

A modified global model for predicting the tritium concentration in precipitation has been developed using the dataset of International Atomic Energy Agency/the World Meteorological Organization (IAEA/WMO) over the period from 1960 to 2005. The tritium concentration in precipitation and its history can be estimated at any location using the model. The modified global model of tritium in precipitation (MGMTP) here presented has higher accuracy than the global model of tritium in precipitation (GMTP) developed by Doney et al. ( 1992 ). The new model is not only more appropriate for a particular station but also applicable for the un‐normalized observations directly. Another advantage of MGMTP is that it can estimate a longer history (from 1960 to 2005) of tritium content in precipitation than GMTP (from 1960 to 1986). The seasonal cycle of tritium in precipitation has also been modelled in the form of a simple cosine function with five parameters. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Evolution of scouring process downstream of grade‐control structures under steady and unsteady flows     

Jau‐Yau Lu  Jian‐Hao Hong  Kai‐Po Chang  Tai‐Fang Lu 《水文研究》2013,27(19):2699-2709

For many incised channels, one of the most common strategies is to install some hard structures, such as grade‐control structures (GCSs), in the riverbed to resist further incision. In this study, a series of experiments, including both steady and unsteady flow conditions, were conducted to investigate the scouring process downstream of a GCS. Three distinct phases, including the initial, developing and equilibrium phases, during the evolution of scour holes were identified. In addition, a semi‐empirical method was proposed to predict the equilibrium scour‐hole profile for the scour countermeasure design. In general, the comparisons between the experimental and simulated results are reasonably consistent. As the studies on temporal variation of the scour depth at GCSs caused by floods are limited, the effect of flood hydrograph shapes on the scour downstream of GCSs without upstream sediment supply was also investigated experimentally in this study. Based on the dimensional analysis and the concept of superposition, a methodology is proposed to simulate the time evolution of the maximum scour depth downstream of a GCS for steady flows. Moreover, the proposed scheme predicts reasonably well the temporal variations of the maximum scour depth for unsteady flows with both single and multiple peak. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

北黄海潮流、余流垂直结构及其季节变化   总被引：1，自引：0，他引：1  

鲍献文  宋军  姚志刚  乔璐璐  鲍敏  万凯 《中国海洋大学学报(自然科学版)》2010,40(11)

基于对2006年夏季与2007年冬季在123.51°E,38.00°N的各1个月潮流和水位观测数据的分析,发现夏季余流呈现两层结构,上层流向为西北,下层流向东南,并且当大潮日期附近,在跃层附近深度存在若干流速较强的水层;冬季余流除了个别层以外基本上均为西北向流入北黄海,从中可以看到风场改变所引发的异常增减水和强流出现。对潮流椭圆的分析表明,半日潮族分潮流的最大流向自夏季至冬季存在着顺时针的旋转,旋转角大约为16(°)～18(°),并且夏季半日潮族随深度顺时针,全日潮族逆时针旋转,而冬季基本上上下一致。  相似文献   

Managing coastal area resources by stated choice experiments     

Xin Liu  Kai W. Wirtz 《Estuarine, Coastal and Shelf Science》2010,86(3):512-517

In many coastal regions, oil spills can be considered as one of the most important and certainly the most noticeable forms of marine pollution. Efficient contingency management responding to oil spills on waters, which aims at minimizing pollution effects on coastal resources, turns out to be critically important. Such a decision making highly depends on the importance attributed to different coastal economic and ecological resources. Economic uses can, in principal, be addressed by standard measures such as value added. However, there is a missing of market in the real world for natural goods. Coastal resources such as waters and beach cannot be directly measured in money terms, which increases the risk of being neglected in a decision making process. This paper evaluates these natural goods of coastal environment in a hypothetical market by employing stated choice experiments. Oil spill management practice in German North Sea is used as an example. Results from a pilot survey show that during a combat process, beach and eider ducks are of key concerns for households. An environmental friendly combat option has to be a minor cost for households. Moreover, households with less children, higher monthly income and a membership of environmental organization are more likely to state that they are willing to pay for combat option to prevent coastal resources from an oil pollution. Despite that choice experiments require knowledge of designing questionnaire and statistical skills to deal with discrete choices and conducting a survey is time consumed, the results have important implications for oil spill contingency management. Overall, such a stated preference method can offer useful information for decision makers to consider coastal resources into a decision making process and can further contribute to finding a cost-effective oil preventive measure, also has a wide application potential in the field of Integrated Coastal Zone Management (ICZM).  相似文献   

本溪县汤池沟热田热储特征及资源量评价     

李凯  佘岩  金尚荣  何屹  陈越 《国土资源》2000,(4)

汤池沟热田大地构造位置处于辽阳－本溪凹陷与凤城凸起的交接部位，属浅埋藏水热对流型热田。热储由中生代燕山期花岗斑岩、凝灰岩组成。热源为岩浆活动的余热。热流体主要靠侧向基岩裂隙水及断裂充水带的水补给，自北东向南西方向以脉状裂隙水运动为主，热流体直接受北东、北北东及北西向断裂控制。该热田储存有较丰富的地热资源，热能总量计算为 58.05 TJ，目前的热水开采量每年为 414 000 t,相当于消耗燃烧值为 29.3 MJ的标准煤每年 1 833.43 t，如果按此潜力开发，其开采年限预计可持续 80年以上。  相似文献   

Astronomical series of the Earth rotation parameters     

B. Kolaczek  Ye Shu hua 《Astrophysics and Space Science》1991,177(1-2):121-138

An outline of the astrometric series of the ERP of their accuracy and of the results obtained from analyses of these data are given in the paper. Presently known systematic differences between the astrometric ERP series and those determined by VLBI and Lageos ranging techniques are discussed. Some geophysical applications of latitude and longitude variations determined by astrometric techniques are mentioned.  相似文献   

Approach to modeling and virtual-reality-based simulation for plant canopy lighting     

Haopeng Wang  Kai Zhao  Fengbin Song 《中国地理科学(英文版)》2008,18(4):374-381

Over the past 20 years, significant progress has been made in virtual plant modeling corresponding to the rapid advances in information technology. Virtual plant research has broad applications in agronomy, forestry, ecology and remote sensing. As many biological processes are driven by light, it is the key for virtual plant to estimate the light absorbed by each organ. This paper presents the radiance equation suitable for calculating sun and sky light intercepted by plant organs based on the principles of the interaction between light and plant canopy firstly; analyzes the process principles of plant canopy primary lighting based on ray casting and projection secondly; describes the multiple scattering of plant lighting based on Monte Carlo ray tracing method and on the radiosity method thirdly; and confirms the research with 3D visualization based on Virtual Reality Modeling Language （VRML） finally. The research is the primary work of digital agriculture, and important for monitoring and estimating corn growth in Northeast China.  相似文献   

用地基GPS资料分析大气可降水汽总量   总被引：16，自引：5，他引：11  

杜瑞林  乔学军  王琪  万蓉  王伟  杨少敏  谭凯 《大地测量与地球动力学》2005,25(3):121-124

利用“中国地壳运动监测网络”和三峡监测网的地基GPS资料，通过Bernese软件以及根据Bevis等和Rocken等水汽解算原理编制的水汽解算软件。获得了武汉、巴东、兴山、泸州等长江流域测站大气可降水汽总量分布和时间间隔为2小时的GPS遥感大气可降水汽序列，并与站点雨量及区域面雨量进行对比分析，结果表明：地基GPS遥感水汽量变化与地面降水有很好的相关性。而且GPS遥感水汽变化序列峰值对应于强降水提前了8～22小时。有助于强降水特别是突发性强降水的预测；多个站点的GPS遥感水汽总量联合分析，对于区域水汽总量变化研究有一定意义。  相似文献   

回转椭球电场问题一种新解法     

董豹  叶明建 《成都信息工程学院学报》1996,(Z1)

讨论关于回转椭球静态场求解的一般方法，借助回转椭圆坐标系，静态场问题的一般解可以用实宗量和虚宗量勒让德函数以及余弦函数形式表出，使得结果更为简明和系统化。所得结果可以直接应用到椭球导体电场、尖端效应、介质椭球极化以至双极化雷达测量降水问题等，具有相当具体的实用价值。  相似文献   

ESR DATING OF FLUVIAL SEDIMENTS USING GE CENTER IN QUARTZ   总被引：3，自引：0，他引：3  

业渝光  和杰  刁少波  高钧成 《中国地理科学(英文版)》1993,3(3):284-289

Using the Ge centers of quartz sediments, the buried ages of fluvial sediments were determined by ESR technique. The ESR ages obtained from Ge centers are consistent with the TL ages, correspond with their horizons, accord with the geological background, and every ESR age is available. In this paper, determination of total dose of natural radiation (TD) and the reliability of ESR age using Ge center are also discussed.  相似文献