Atmospheric and Climatic Hazards: Improved Monitoring and Prediction for Disaster Mitigation   总被引：5，自引：0，他引：5  

Nicholls  Neville 《Natural Hazards》2001,23(2-3):137-155

Natural Hazards - The last few years have seen enormous damage and lossof life from climate and weather phenomena. The mostdamaging events have included the severe 1997/98 ElNiño (with its...  相似文献   

Bayesian analyses of seasonal runoff forecasts     

R. Krzysztofowicz  S. Reese 《Stochastic Environmental Research and Risk Assessment (SERRA)》1991,5(4):295-322

Forecasts of seasonal snowmelt runoff volume provide indispensable information for rational decision making by water project operators, irrigation district managers, and farmers in the western United States. Bayesian statistical models and communication frames have been researched in order to enhance the forecast information disseminated to the users, and to characterize forecast skill from the decision maker's point of view. Four products are presented: (i) a Bayesian Processor of Forecasts, which provides a statistical filter for calibrating the forecasts, and a procedure for estimating the posterior probability distribution of the seasonal runoff; (ii) the Bayesian Correlation Score, a new measure of forecast skill, which is related monotonically to theex ante economic value of forecasts for decision making; (iii) a statistical predictor of monthly cumulative runoffs within the snowmelt season, conditional on the total seasonal runoff forecast; and (iv) a framing of the forecast message that conveys the uncertainty associated with the forecast estimates to the users. All analyses are illustrated with numerical examples of forecasts for six gauging stations from the period 1971–1988.  相似文献   

The Impact of Assimilating Radar-estimated Rain Rates on Simulation of Precipitation in the 17--18 July 1996 Chicago Floods     

Xingbao WANG  M. K. YAU  B. NAGARAJAN  Luc FILLION 《大气科学进展》2010,27(2):195-210

Rainfall prediction remains one of the most challenging problems in weather forecasting. In order to improve high-resolution quantitative precipitation forecasts (QPF), a new procedure for assimilating rainfall rate derived from radar composite reflectivity has been proposed and tested in a numerical simulation of the Chicago floods of 17–18 July 1996. The methodology is based on the one-dimensional variation scheme (1DVAR) assimilation approach introduced by Fillion and Errico but applied here using the Ka...  相似文献   

用一种动力－统计方法提高中国夏季降水的季节预报   总被引：1，自引：0，他引：1       下载免费PDF全文

JIA Xiao-Jing  ZHU Pei-Jun 《大气和海洋科学快报》2010,3(2):100-105

A dynamical-statistical post-processing approach is applied to seasonal precipitation forecasts in China during the summer. The data are ensemble-mean seasonal forecasts in summer (June-August) from four atmospheric general circulation models (GCMs) in the second phase of the Canadian Historical Forecasting Project (HFP2) from 1969 to 2001. This dynamical-statistical approach is designed based on the relationship between the 500 geopotential height (Z500) forecast and the observed sea surface temperature (SST) to calibrate the precipitation forecasts. The results show that the post-processing can improve summer precipitation forecasts for many areas in China. Further examination shows that this post-processing approach is very effective in reducing the model-dependent part of the errors, which are associated with GCMs. The possible mechanisms behind the forecast's improvements are investigated.  相似文献   

A comparison study of the methods of conditional nonlinear optimal perturbations and singular vectors in ensemble prediction     

姜智娜  穆穆 《大气科学进展》2009,26(3):465-470

The authors apply the technique of conditional nonlinear optimal perturbations (CNOPs) as a means of providing initial perturbations for ensemble forecasting by using a barotropic quasi-geostrophic (QG) model in a perfect-model scenario. Ensemble forecasts for the medium range (14 days) are made from the initial states perturbed by CNOPs and singular vectors (SVs). 13 different cases have been chosen when analysis error is a kind of fast growing error. Our experiments show that the introduction of CNOP provides better forecast skill than the SV method. Moreover, the spread-skill relationship reveals that the ensemble samples in which the first SV is replaced by CNOP appear superior to those obtained by SVs from day 6 to day 14. Rank diagrams are adopted to compare the new method with the SV approach. The results illustrate that the introduction of CNOP has higher reliability for medium-range ensemble forecasts.  相似文献   

贵州兴旺煤矿开采地表塌陷预测方法探讨          下载免费PDF全文

隋建红  李超 《山东国土资源》2012,28(6):25-27

以贵州六枝特区兴旺煤矿地表塌陷为例,采用概率积分法作为地表移动及变形预测的模式,选取下沉系数、主要影响角、主要影响半径和水平移动系数为地表移动参数,计算得出井田开采后地表最大下沉值为1 425.3mm,影响面积约1.85km2。并比较说明除移动参数外各类煤柱的留设也是其中需要考虑的因素。  相似文献   

在四维变分同化中运用集合协方差的试验   总被引：1，自引：1，他引：1  

张蕾  邱崇践  张述文 《气象学报》2009,67(6):1124-1132

利用浅水方程模式和模式模拟资料进行数值试验比较3种不同的背景误差协方差矩阵处理方法对四维变分(4DVAR)资料同化的影响.3种背景误差协方差矩阵分别是:(1)对单一变量将背景误差协方差矩阵简化为对角矩阵;(2)将背景误差协方差矩阵的作用简化为高斯过滤;(3)由预报集合生成背景误差协方差矩阵并利用奇异值分解技术解决矩阵的求逆.通过一系列数值试验,比较不同观测密度、不同观测误差下3种背景误差协方差处理方法对4DVAR同化效果的影响.结果表明,背景误差协方差的结构对4DVAR有重大影响.当观测资料的空间密度不够高时,采用对角矩阵得不到满意的结果.高斯过滤方案可以明显改善同化结果,但是对背景误差特征长度比较敏感.第3种方法采用的背景误差协方差矩阵是流型依赖的,而且并不以显式的方式出现在目标函数中.避免了对它求逆的复杂运算.由于做了降维处理,在观测点的密度较低和观测误差较大时可望取得较好的同化结果,同化效果较为稳定.  相似文献   

THE OBJE CTIVE ANALOGUE PREDICTION MODEL FOR TROPICAL CYCLONE TRACK WITH COMPREHENSIVE ASSESSMENT OF THE ENVIRONMENT     

钟元 《热带气象学报(英文版)》2002,8(2):207-217

An objective analogue prediction model for tropical cyclone (TC) track is put forward that comprehensively assesses the environmental field. With the parameters of the tropical cyclone and environmental field at initial and future time, objective analogue criteria are set up in the model. Analogous samples are recognized by comprehensive assessment to historical TC cases for similarity with multivariate criteria,using non-linear analogue indexes especially defined for the purpose. When the historical tracks are coordinateconverted and weighted with reference to analogue indexes,forecast tracks are determined. As shown in model verification and forecast experiments, the model has forecasting skill.  相似文献   

一种基于深度学习的热带气旋路径集成预报方法     

耿逍懿  郝坤  史振威 《海洋科学》2022,46(2):74-86

本文提出了一种基于深度学习的热带气旋(tropical cyclone,TC)路径集成预报方法.该方法以长短期记忆深度网络为模型构架,利用前4个时刻(24 h,间隔6 h)及当前时刻的TC路径记录,以及由不同环境因素所计算的方向预报因子作为输入,分别直接预报和间接(通过预报移动速度)预报路径,集成两者预报结果实现时效为...  相似文献   

Hydrological uncertainty processor based on a copula function   总被引：1，自引：0，他引：1  

Zhangjun Liu  Lihua Xiong  Chong-Yu Xu 《水文科学杂志》2018,63(1):74-86

Quantifying the uncertainty in hydrological forecasting is valuable for water resources management and decision-making processes. The hydrological uncertainty processor (HUP) can quantify hydrological uncertainty and produce probabilistic forecasts under the hypothesis that there is no input uncertainty. This study proposes a HUP based on a copula function, in which the prior density and likelihood function are explicitly expressed, and the posterior density and distribution obtained using Monte Carlo sampling. The copula-based HUP was applied to the Three Gorges Reservoir, and compared with the meta-Gaussian HUP. The Nash-Sutcliffe efficiency and relative error were used as evaluation criteria for deterministic forecasts, while predictive QQ plot, reliability, resolution and continuous rank probability score (CRPS) were used for probabilistic forecasts. The results show that the proposed copula-based HUP is comparable to the meta-Gaussian HUP in terms of the posterior median forecasts, and that its probabilistic forecasts have slightly higher reliability and lower resolution compared to the meta-Gaussian HUP. Based on the CRPS, both HUPs were found superior to deterministic forecasts, highlighting the effectiveness of probabilistic forecasts, with the copula-based HUP marginally better than the meta-Gaussian HUP.  相似文献