正确认识和对待天气气候预报的不确定性   总被引：3，自引：2，他引：1  

王东海  杜钧  柳崇健 《气象》2011,37(4):385-391

美国国家科学发展的指导机构同家研究顾问委员会(NRC)不久前发表了一份关于天气、气候和水文预报的不确定性的凋研报告.报告强调了预报不确定性信息在终端用户应用气象预报作决策中的重要性,同时指出一个预报如果没有定量地估计它的不确定性,那么该预报是不完全的.该报告中文版的出版工作正在进行中,现藉此机会向读者综合地介绍一下预报不确定性的问题.文中首先讨论了预报不确定性的缘由以及应该如何来科学地对待它.然后介绍了要应对这一问题所要进行的一些具体措施和策略.最后,简要地介绍了美国气象界为此所做的一些努力和计划以供参考.通过上述讨论和介绍,希望引起更多的人对预报不确定性问题的重视并科学应对以更好地服务社会.  相似文献   

Uncertainty analysis for the integration of seismic and controlled source electro‐magnetic data     

Myoung Jae Kwon  Roel Snieder 《Geophysical Prospecting》2011,59(4):609-626

We study the appraisal problem for the joint inversion of seismic and controlled source electro‐magnetic (CSEM) data and utilize rock‐physics models to integrate these two disparate data sets. The appraisal problem is solved by adopting a Bayesian model and we incorporate four representative sources of uncertainty. These are uncertainties in 1) seismic wave velocity, 2) electric conductivity, 3) seismic data and 4) CSEM data. The uncertainties in porosity and water saturation are quantified by a posterior random sampling in the model space of porosity and water saturation in a marine one‐dimensional structure. We study the relative contributions from the four individual sources of uncertainty by performing several statistical experiments. The uncertainties in the seismic wave velocity and electric conductivity play a more significant role on the variation of posterior uncertainty than do the seismic and CSEM data noise. The numerical simulations also show that the uncertainty in porosity is most affected by the uncertainty in the seismic wave velocity and that the uncertainty in water saturation is most influenced by the uncertainty in electric conductivity. The framework of the uncertainty analysis presented in this study can be utilized to effectively reduce the uncertainty of the porosity and water saturation derived from the integration of seismic and CSEM data.  相似文献   

An approach to handling non-Gaussianity of parameters and state variables in ensemble Kalman filtering   总被引：4，自引：0，他引：4  

Haiyan Zhou  J. Jaime Gómez-Hernández 《Advances in water resources》2011,34(7):844-864

The ensemble Kalman filter (EnKF) is a commonly used real-time data assimilation algorithm in various disciplines. Here, the EnKF is applied, in a hydrogeological context, to condition log-conductivity realizations on log-conductivity and transient piezometric head data. In this case, the state vector is made up of log-conductivities and piezometric heads over a discretized aquifer domain, the forecast model is a groundwater flow numerical model, and the transient piezometric head data are sequentially assimilated to update the state vector. It is well known that all Kalman filters perform optimally for linear forecast models and a multiGaussian-distributed state vector. Of the different Kalman filters, the EnKF provides a robust solution to address non-linearities; however, it does not handle well non-Gaussian state-vector distributions. In the standard EnKF, as time passes and more state observations are assimilated, the distributions become closer to Gaussian, even if the initial ones are clearly non-Gaussian. A new method is proposed that transforms the original state vector into a new vector that is univariate Gaussian at all times. Back transforming the vector after the filtering ensures that the initial non-Gaussian univariate distributions of the state-vector components are preserved throughout. The proposed method is based in normal-score transforming each variable for all locations and all time steps. This new method, termed the normal-score ensemble Kalman filter (NS-EnKF), is demonstrated in a synthetic bimodal aquifer resembling a fluvial deposit, and it is compared to the standard EnKF. The proposed method performs better than the standard EnKF in all aspects analyzed (log-conductivity characterization and flow and transport predictions).  相似文献   

Effect of surge uncertainty on probabilistically computed dune erosion     

K.L. Roscoe  F. Diermanse 《Coastal Engineering》2011

To assess the flood protection capacity of dunes in The Netherlands, a semi-probabilistic dune-erosion prediction method is currently in use in which uncertainties in input parameters of an empirical dune erosion model were taken into account, with the exception of the uncertainty in the extreme surge distribution. Previous research has shown that the surge is by far the most influential parameter affecting erosion in the currently used erosion model, which is due both to the influence of the surge level itself and to the conditional dependence of the wave height and period on the surge level in the probabilistic model used for the assessment. Furthermore, the distribution of extreme surge levels has been shown to contain large statistical uncertainty. The inclusion of uncertainty in input variables into probabilistic models results in more extreme events (in this case erosion) for the same exceedance probability, largely due to the incorporation of higher values of the input variables. The goal of the research described in this paper was to determine the impact of the inclusion of uncertainty in the extreme surge distribution on the estimate of critical erosion (erosion associated with an exceedance frequency of 10^− 5 per year). The uncertainty in the surge distributions was estimated and parameterized, and was incorporated into the probabilistic model. A reduction in uncertainty was subsequently imposed to estimate what value a reduction in uncertainty can offer, in terms of the impact on critical erosion. The probabilistic technique first-order reliability method (FORM) was applied to determine the relative contribution of the uncertainty in the surge distribution (as well as the remaining stochastic variables) to the critical erosion. The impact of the inclusion of uncertainty in the surge distribution on the critical retreat distance was found to be substantial with increases ranging from 34% to 93% of the original estimate at five locations along the Dutch coast. The reduced uncertainty showed a more subtle impact, with increases in critical retreat distance ranging from 10% to 26% of the original estimate. The relative importance analysis showed that the uncertainty in the surge distribution has a strong influence, with the relative importance ranging from 10% to 23% for an exceedance frequency of 10^− 5 per year.  相似文献   

Exploratory modeling for analyzing coupled human-natural systems under uncertainty     

《Global Environmental Change》2020

Modeling is a crucial approach for understanding the past and exploring the future of coupled human-natural systems. However, uncertainty in various forms challenges inferences from modeling results. Model-based support for decision-making has increasingly adopted an emerging exploratory approach. This approach addresses uncertainty explicitly through systematically exploring the implications of modeling assumptions, aiming to enhance the robustness of inferences from models. Despite a variety of applications, the extent and the way(s) that exploratory modeling can deal with the challenges that arise from the uncertainty and complexity of decision-making with stakeholders has not yet been systematically framed. We address this gap in two ways. First, we present a taxonomy of the ways that exploratory modeling can be used to inform robust inferences in coupled human-natural systems by mapping the technical capabilities of this approach in relation to the diversity of past applications. This subsequently guides an investigation of the practical benefits and challenges of these capabilities in handling uncertainty and complexity. Second, we discuss different ways for integrating genuine stakeholder engagement into exploratory modeling through transdisciplinary research. Finally we outline some priorities for future expansion of this research area.  相似文献   

Drought and the future of rural communities: Opportunities and challenges for climate change adaptation in regional Victoria,Australia     

Anthony S. Kiem  Emma K. Austin 《Global Environmental Change》2013,23(5):1307-1316

Australia's vulnerability to climate variability and change has been highlighted by the recent drought (i.e. the Big Dry or Millennium Drought), and also recent flooding across much of eastern Australia during 2011 and 2012. There is also the possibility that the frequency, intensity and duration of droughts may increase due to anthropogenic climate change, stressing the need for robust drought adaptation strategies. This study investigates the socio-economic impacts of drought, past and present drought adaptation measures, and the future adaptation strategies required to deal with projected impacts of climate change. The qualitative analysis presented records the actual experiences of drought and other climatic extremes and helps advance knowledge of how best to respond and adapt to such conditions, and how this might vary between different locations, sectors and communities. It was found that more effort is needed to address the changing environment and climate, by shifting from notions of ‘drought-as-crisis’ towards acknowledging the variable availability of water and that multi-year droughts should not be unexpected, and may even become more frequent. Action should also be taken to revalue the farming enterprise as critical to our environmental, economic and cultural well-being and there was also strong consensus that the value of water should be recognised in a more meaningful way (i.e. not just in economic terms). Finally, across the diverse stakeholders involved in the research, one point was consistently reiterated: that ‘it's not just drought’. Exacerbating the issues of climate impacts on water security and supply is the complexity of the agriculture industry, global economics (in particular global markets and the recent/ongoing global financial crisis), and demographic changes (decreasing and ageing populations) which are currently occurring across most rural communities. The social and economic issues facing rural communities are not just a product of drought or climate change – to understand them as such would underestimate the extent of the problems and inhibit the ability to coordinate the holistic, cross-agency approach needed for successful climate change adaptation in rural communities.  相似文献   

Agricultural risk management policies under climate uncertainty   总被引：1，自引：0，他引：1  

Jesús Antón  Andrea Cattaneo  Shingo Kimura  Jussi Lankoski 《Global Environmental Change》2013,23(6):1726-1736

Climate change is forecasted to increase the variability of weather conditions and the frequency of extreme events. Due to potential adverse impacts on crop yields it will have implications for demand of agricultural risk management instruments and farmers’ adaptation strategies. Evidence on climate change impacts on crop yield variability and estimates of production risk from farm surveys in Australia, Canada and Spain, are used to analyse the policy choice between three different types of insurance (individual, area-yield and weather index) and ex post payments. The results are found to be subject to strong uncertainties and depend on the risk profile of different farmers and locations; the paper provides several insights on how to analyse these complexities. In general, area yield performs best more often across our countries and scenarios, in particular for the baseline and marginal climate change (without increases in extreme events). However, area yield can be very expensive if farmers have limited information on how climate change affects yields (misalignment in expectations), and particularly so under extreme climate change scenarios. In these more challenging cases, ex post payments perform well to increase low incomes when the risk is systemic like in Australia; Weather index performs well to reduce the welfare costs of risks when the correlation between yields and index is increased by the extreme events. The paper also analyses the robustness of different instruments in the face of limited knowledge of the probabilities of different climate change scenarios; highlighting that this added layer of uncertainty could be overcome to provide sound policy advice under uncertainties introduced by climate change. The role of providing information to farmers on impacts of climate change emerges as a crucial result of this paper as indicated by the significantly higher budgetary expenditures occurring across all instruments when farmers’ expectations are misaligned relative to actual impacts of climate change.  相似文献   

非均质含水层中渗流与溶质运移研究进展简   总被引：1，自引：0，他引：1  

Qin Ronggao  Cao Guangzhu  Wu Yanqing 《地球科学进展》2014,29(1):30-41

Natural aquifer heterogeneity controls the groundwater flow and solute transport, and how to accurately quantify the flow and solute transport in heterogeneous aquifers has received wide attention by many scholars, and has become a hot research topic in earth science. Theoretically, a systematic review is given by the following aspect: flow and solute transport model, moment analysis, multi scale analysis. The resolved and remained issues for scale conversion in hydrogeology research are pointed out. Secondly, recent advances of heterogeneous field test, uncertainty and velocity connectivity are analyzed. Finally, the geophysical inversion of aquifer heterogeneity, stochastic theory and development of stochastic simulation software, scale conversion and uncertainty of velocity connectivity, and the relationship between heterogeneity and hydrogeological condition on the major four aspects of the future research direction is pointed out.  相似文献   

ICP-MS测定矿泉水中锂和锶含量的不确定度分析     

廖丽荣  杜白  刘玉 《云南地质》2014,33(3):413-416

采用电感耦合等离子体质谱法（ICP-MS）对饮用天然矿泉水中的锂和锶进行测定,分析了测定过程中不确定度的主要来源,按JJF 1059-1999《测量不确定度评定与表示》对各个不确定度来源进行分析评定,给出了此法测定过程中的扩展不确定度,使得测定结果的表达更加客观和真实.  相似文献   

Coupled hydro-mechanical fault reactivation analysis incorporating evidence theory for uncertainty quantification     

《Computers and Geotechnics》2014

The injection of water (or CO₂) at high pressure is a common practice to enhance oil production. A crucial component of this activity is the estimation of the maximum pressure at which the fluids can be injected without inducing the reactivation of pre-existing faults that may exist in the formation. The damage zones typically formed around the geological faults are highly heterogeneous. The materials involved in the damage zones are characterized by the huge variation of their properties and high uncertainties associated with them. To estimate the maximum allowable injection pressure this paper presents a novel approach based on: a coupled hydro-mechanical formulation (for the numerical analyses); a criterion based on the total plastic work (for the fault reactivation); and the evidence theory (for uncertainty quantification). A case study based on information gathered from an actual field is presented to illustrate the capabilities of the proposed framework.  相似文献