基于贝叶斯理论的水文不确定性分析研究进展

水文过程受众多自然和人为因素影响,决定了其变化的极端复杂性,表现为确定性的动态规律与不确定性的统计规律共存。水文不确定性分析的理论和方法在认识水文规律中发挥着重要作用,其中贝叶斯作为一种主要理论方法在水文水资源相关问题的研究中得到了较广泛的应用。本文评述了贝叶斯理论在水文频率分析、水文预报、确定性和不确定性方法耦合等研究中的进展,对基于贝叶斯理论的水文不确定性重点研究内容进行了展望。     

青藏高原冬春季积雪异常与西南地区夏季降水的关系

选取1961-2007年青藏高原冬、春季积雪日数资料和西南地区夏季降水资料,对高原积雪和降水作奇异值分解(SVD)分析.结果表明:冬春季高原积雪对西南地区夏季旱涝有重要的影响.冬、春季高原积雪的不同分布将造成后期西南地区夏季降水分布出现差异.西南地区夏季降水对冬季高原积雪异常最敏感的区域主要是四川东北部、重庆、西藏中西部,对春季积雪异常最敏感的区域主要位于四川东部、重庆、贵州东北部,以及西藏中东部.与降水敏感区相对应的冬季高原积雪分布的关键区是西藏中西部和青海中南部至四川西北部地区,春季则转变为西藏西部和青海部分地区.总的来说,冬季高原积雪的异常变化比春季对西南地区夏季降水的影响更为明显.因此,前期青藏高原积雪是西南地区夏季降水预测中的一个重要信号,对夏季西南地区降水有一定的指示和预测意义;冬季高原积雪日数尤其具有预报指示意义,可作为一个重要的预测指标.     

Simulating the value of El Niño forecasts for the Panama Canal

The Panama Canal relies on rain-fed streamflow into Gatun Lake, the canal’s primary storage facility, for operations—principally ship passage and hydropower generation. Precipitation in much of Panama has a strong negative relationship with eastern tropical Pacific sea surface temperature (SST) and this relationship is reflected in Gatun Lake inflows. For example, the correlation coefficient between wet season (July–December) inflow and NINO3 SST is −0.53 over the period 1914–1997. Operational capabilities to predict tropical Pacific SSTs have been demonstrated by several forecast systems during the past decade, and (as we show) such SST forecasts can be used to reduce the uncertainty of estimates of future inflows (compared with climatological expectations). Because substantial reductions in lake inflow negatively impact canal operations, we wondered whether these forecasts of future inflows, coupled with a method for translating that information into effective operational policy, might result in more efficient canal management. A combined simulation/optimization/assessment “virtual” canal system was implemented and exercised using operational El Niño forecasts over the period 1981–1998. The results show the following main points:

(i)

At current demand levels, the canal system is relatively robust (insensitive to flow forecasts) unless flows are substantially reduced (i.e., during El Niño episodes) or forecasts are extremely accurate.     

点云数据直接缩减方法及缩减效果研究

分析了国外点云数据处理中数据缩减方法的研究现状,针对实际工程中三维激光扫描数据采集的过密情况,提出利用扫描间隔进行点云数据直接缩减的方法,并编程实现所提出的算法。通过对真实的三维激光扫描点云数据的缩减处理,建立点云数据直接缩减的预测模型。     

中国"代"尺度气候预测

将子波分析技术与随机动力学相结合,提出了突变点数建模代尺度气候预测新技术—突变点数建模技术,并将该技术应用于中国不同地区代尺度的干湿驰豫时间的预报。研究结果表明,在代尺度上,我国北方、西南和东南气候灾害频繁,南方多涝,西北和北方(不包括东北)则多旱。由于该技术是关于时间序列建模的,故可以应用到水文、地震、生态等领域有关的建模和预测。     

Application of wavelet‐based multi‐model Kalman filters to real‐time flood forecasting

This paper presents the application of a multimodel method using a wavelet‐based Kalman filter (WKF) bank to simultaneously estimate decomposed state variables and unknown parameters for real‐time flood forecasting. Applying the Haar wavelet transform alters the state vector and input vector of the state space. In this way, an overall detail plus approximation describes each new state vector and input vector, which allows the WKF to simultaneously estimate and decompose state variables. The wavelet‐based multimodel Kalman filter (WMKF) is a multimodel Kalman filter (MKF), in which the Kalman filter has been substituted for a WKF. The WMKF then obtains M estimated state vectors. Next, the M state‐estimates, each of which is weighted by its possibility that is also determined on‐line, are combined to form an optimal estimate. Validations conducted for the Wu‐Tu watershed, a small watershed in Taiwan, have demonstrated that the method is effective because of the decomposition of wavelet transform, the adaptation of the time‐varying Kalman filter and the characteristics of the multimodel method. Validation results also reveal that the resulting method enhances the accuracy of the runoff prediction of the rainfall–runoff process in the Wu‐Tu watershed. Copyright © 2004 John Wiley & Sons, Ltd.     

累加阶层线性模型的长三角地区年降雨量预测

将灰色系统模型与阶层线性模型的思想和方法结合起来,拓展了模型的适用范围,给出了累加阶层线性AMM(1,1)模型,并在结合长三角年降雨量的具体实例时进行了模型改进.对原模型与改进后的AMM(1,1)进行比较,验证了模型的实用性,为降雨量的预测提供了一种新途径.     

基于环流分型的逐时气温预报技术探讨

论文利用2009年1-2月T213模式产品、30年来的常规观测报文以及场区逐时气温记录,综合运用环流分型和Kalman滤波方法,基于逐月环流型的气温增率建立了场区72h逐时气温释用预报模型,并针对场区2009年3-7月各天72h逐时气温进行了具体的预报。结果表明:Kalman滤波算法能够得到较为精确的温度最值预报,通过环流分型得到的逐时气温预报准确率能够达到73.2%,可以作为逐时气温预报一种较好的方法。     

Detailed insights into the influence of flood-coping appraisals on mitigation behaviour

Insights into flood mitigation behaviour are important because of the ongoing shift to risk-based flood management approaches in Europe and worldwide, which envisage a contribution from flood-prone households to risk reduction. The recent literature on factors that influence flood mitigation behaviour indicates that flood-coping appraisal is an important variable to understand and explain flood mitigation behaviour. Coping appraisal originates from Protection Motivation Theory (PMT), and refers to the cognitive process that people undergo when evaluating their own ability to avoid a certain risk. However, the empirical literature on the importance of coping appraisal is still scarce, and, in particular, little is known about the independent influence of the three single components of coping appraisal on precautionary behaviour: namely, response efficacy, self-efficacy, and response cost. This study presents the results of a recent survey among 752 flood-prone households along the river Rhine in order to provide detailed insights into the influence of the components of flood-coping appraisal on four different types of flood mitigation behaviour: structural building measures, adapted building use, the deployment of flood barriers, and the purchase of flood insurance. The results confirm that flood-coping appraisal is an important variable in terms of precautionary behaviour. In particular, both response efficacy and self-efficacy contribute to the models which explain the four different types of flood-mitigation behaviour. Based on these findings, it is concluded that risk communication should focus more strongly on the potential of flood-mitigation measures to effectively reduce or avoid flood damage, as well as on information about how to implement such measures in practice.     

准地转理论基本问题回顾与讨论

准地转理论是大气动力学的中心问题之一,它提供了从大气动力学基本原理入手分析大尺度天气系统演变的方法。准地转理论有助于预报员理解中高纬度大尺度天气系统的三维结构,分析、预报天气系统的发展和移动,因此被称为短期天气预报的理论基础。准地转理论具有完整的理论体系,它包含了较多的基本假定,故容易导致对其中的一些基本问题的理解有混淆。本文从基础的动力学知识出发,对准地转理论的基本概念、基本近似、核心理论及其在实际天气预报过程中的应用作了回顾和讨论。内容包括:准地转运动与准地转近似定义、准地转运动理论的范畴、天气图上的大尺度运动、准地转运动理论与短期天气预报的关系、由斜压二层模式下的准地转理论对高空槽脊和地面气旋发展与移动的判断等。