Quantitative precipitation forecasts: a statistical adaptation of model outputs through an analogues sorting approach   总被引：2，自引：0，他引：2  

Charles Obled  Guillaume Bontron  Rmy Garon 《Atmospheric Research》2002,63(3-4)

Medium-term quantitative precipitation forecasts (QPFs) up to several days ahead are required to issue early flood warnings and to allow optimum operation of hydraulic structures or reservoirs. This paper describes an approach which can be seen as an adaptation of deterministic meteorological model outputs. It involves searching for a sample of past situations similar to the current one from a long meteorological archive. The analogy is considered in terms of general circulation patterns over a window covering western Europe. For this restricted sample of days similar to the day at hand, the corresponding sample of observed daily precipitation is extracted for each catchment. The rainfall to be observed during the current day is assumed to follow the same distribution, known from this empirical sample. This provides a probabilistic forecast expressed, for example, by a central quantile and a confidence range. This paper describes the many choices underlying the optimisation of this approach: choice of predictor variables to characterise a meteorological situation, choice of similarity criterion between two situations, criterion for performance evaluation between two versions of the algorithm, etc. This method was calibrated over about 50 catchments located in France, Italy and Spain, using a meteorological and hydrological archive running from 1953 to 1996. Comparisons carried out over a validation sample (1995–1996) with three poor-man methods prove the interest of this approach, in a perfect prognosis context. In real-time operation, the use of forecast instead of observed predictor variables, essentially geopotential fields, produces only a minor decrease in performance. The use of the single-valued central quantile supplemented by the confidence interval provided a QPF that has proved effective and informative on the potential for extreme values.  相似文献   

T63数值预报产品图形处理系统          下载免费PDF全文

庄建敏 《气象》1995,21(8):39-43

用于Ｔ６３数值预报产品输出的图形系统是一个具有资料获取，数据建筑，数值内插，等值线求算，平滑，图形显示和人工干预等多种功能的实时业务系统，该系统用户界面友好，操作简便，产品内容丰富，图形分析质量高，速度快，实时性强，是进行天气预报和数值预报分析的有力工具。  相似文献   

基于小波分析的粮食产量对气候变化的响应研究——以西藏自治区为例   总被引：1，自引：0，他引：1  

汤小橹  金晓斌  盛莉  周寅康  孙涛 《地理与地理信息科学》2008,24(6)

提取1960-2005年西藏自治区粮食单产数据,选取4个典型气象台站,以粮食耕作面积作为加权因子获取综合气象因子数据,采用小波分析方法分析粮食产量对气候变化的响应关系,并预测后期西藏自治区粮食产量的总体趋势。研究发现,西藏粮食单产、气温、光照、降水均具有明显的25 a特征时间尺度的周期性波动,粮食产量对气候变化响应密切,气温偏暖、光照偏长、降水偏多对粮食生产较为有利。趋势预测表明西藏自治区的粮食生产正由相对丰年向相对贫年转化,需引起重视。  相似文献   

高分辨率非线性三维整体反演研究(英文)     

李勇  王绪本  李志荣  李琼  李正文 《应用地球物理》2009,6(2):159-165

高分辨率非线性三维整体反演方法是基于非线性理论,在层位控制下,将工区多井(或全部井)的测井数据与井旁地震道数据输入具有多输入多输出的网络,同时进行整体训练,可获得整个工区的自适应权函数,并建立综合非线性映射关系,并根据储层在纵横方向上的地质变化特征更新这种非线性映射关系,这样,就能对反演过程及其反演结果起到约束和控制的作用,从而获得稳定且分辨率高的地震反演剖面(速度反演剖面/波阻抗反演剖面/密度反演剖面),实现整体反演,该方法通过模型试算和实际资料处理,获得较好的地质效果,证明该方法精度高、实用性强,可用于储层的定量分析。  相似文献   

结构控制的前馈-反馈算法对比与分析     

李智  谈忠坤  谭平  周福霖 《华南地震》2008,28(1):1-10

基于瞬时最优控制算法和经典的线性二次型高斯（Gauss）控制算法．推导了三种前馈-反馈算法．其控制器的设计包含两个部分：基于传统控制算法的反馈部分和在采样时间内对地震动信息的前馈部分。以在建的某电视塔（610m）为例。通过跟常用的线性二次型高斯（Gauss）闭环反馈控制算法相比较,对比分析了这三种前馈-反馈算法在地震作用下．对结构反应的控制效果;针对规范中对层间位移角和舒适度的要求．深入研究了在三种不同的控制目标下,基于LQG前馈-反馈算法（FFLQG）对结构反应控制的有效性：最后。通过一种新的权系数选择方法,研究了不同的输出反馈对基于LQG前馈-反馈算法控制效果的影响。  相似文献   

Electrochemical Properties of Electrodes with Different Shapes and Diffusion Kinetic Analysis of Microbial Fuel Cells on Ocean Floor     

FU Yubin  LIU Jia  SU Jia  ZHAO Zhongkai  LIU Yang  XU Qian 《青岛海洋大学学报(英文版)》2012,(1):25-31

  相似文献   

天津市地震前兆台网运行、产出与管理     

王建国  王宝锁  马义山  王云泉  李悦 《东北地震研究》2012,28(4)

对天津市地震前兆台网系统运行、产出与应用、技术管理工作进行了综述,畅谈了几点工作体会,以及面临的困难。在以后的工作中,天津市地震前兆台网还需不断加强责任意识、服务意识和创新意识,在汇集存储、质量监控、技术保障、异常核实、科学研究中发挥重要的作用,为将来解决地震预报难题夯实基础。  相似文献   

安徽测震台网监测效能综合分析     

张佑龙  金艳  夏仕安  李发 《华南地震》2012,32(1):99-106

安徽测震台网＂十五＂期间通过升级、改造、新建24个子台并汇集周边6省19个测震台站的数据,建成安徽省省级测震台网,极大提高了测震台网的监测能力、速报能力、数据产出能力。综合分析了安徽测震台网＂十五＂项目建设后的监测效能,并对进一步提高测震台网效能进行了探讨。  相似文献   

Estimation of base motion in instrumented steel buildings using output‐only system identification          下载免费PDF全文

Dimitrios G. Lignos  Eduardo Miranda 《地震工程与结构动力学》2014,43(4):547-563

A procedure to estimate the seismic motion at the base of a building from measured acceleration response at two or more floors is presented. The proposed method is comprised of two steps. In the first step, the dynamic characteristics of the building are inferred by using an output‐only system identification procedure. In the second step, the motion of the base of the building is estimated by using the transfer function of a simplified building model consisting of a shear and flexural continuous beam together with dynamic properties obtained in the first step. The proposed method is validated first with an analytical model subjected to the 1940 El Centro ground motion and then with an instrumented building in California that experienced the 1994 Northridge earthquake, and the ground motions at the base of the building are available. It is shown that the proposed method is capable of providing very good estimates of the motion at the base. The use of the proposed method is finally illustrated on an instrumented building, where the sensor at the base of the building did not function during the 1994 Northridge earthquake. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Water resource utilization efficiency and spatial spillover effects in China   总被引：2，自引：2，他引：0  

Caizhi Sun  Liangshi Zhao  Wei Zou  Defeng Zheng 《地理学报(英文版)》2014,24(5):771-788

Based on provincial panel data of water footprint and grey water footprint, and with the help of data envelopment analysis model considering and without considering the unde- sirable output, this paper estimates the water resources utilization efficiency in China from 1997 to 2011. The spatial weighting matrix based on economy-spatial distance function is established to discuss spatial autocorrelation of water resources utilization efficiency. With the help of absolute/3-convergence model, this paper concludes that there exists/%convergence in the water resources utilization efficiency. Under the conditions of considering and without considering the undesirable output, it takes about 52.6 and 5.6 years respectively to achieve the extent of half of convergence. By mean of the spatial Durbin econometric model, this paper studies spatial spillover effects of the provincial water resources utilization efficiency in China. The results are as follows. 1） With considering and without considering the undesir- able output, there is significant spatial correlation in provincial water resource efficiency in China. 2） Under the two cases, the spatial autoregressive coefficients （p） are 0.278 and 0.507 respectively, at 1% significance level. There exist the spatial spillover effects of provin- cial water resources utilization efficiency. 3） With considering the undesirable output, these factors of the education funds, the transportation infrastructure, and the industrial and agri- cultural water consumption proportion have positive impacts. These factors of foreign direct investment, the industry value-added water consumption per ten thousand yuan, per capita water consumption, and the total precipitation have negative impacts. 4） Without considering the undesirable output, the factor of GDP per laborer has a greater positive significant influ- ence on the water resources utilization efficiency. However the facts of industry value-added water consumption in ten thousand yuan and the transportation infrastructure have no sig- nificant influence. 5） Regardless of undesirable output of water resources utilization efficiency the assessment of the present real water resources utilization in China will be distorted and policy-making will be misled. The water efficiency measure considering environmental factors （such as gray water footprint） is more reasonable.  相似文献