Using Statistical Downscaling to Quantify the GCM-Related Uncertainty in Regional Climate Change Scenarios： A Case Study of Swedish Precipitation   总被引：2，自引：0，他引：2  

Deliang CHEN  Christine ACHBERGER  Jouni R¨AIS¨ANEN  Cecilia HELLSTR¨OM 《大气科学进展》2006,23(1):54-60

There are a number of sources of uncertainty in regional climate change scenarios. When statistical downscaling is used to obtain regional climate change scenarios, the uncertainty may originate from the uncertainties in the global climate models used, the skill of the statistical model, and the forcing scenarios applied to the global climate model. The uncertainty associated with global climate models can be evaluated by examining the differences in the predictors and in the downscaled climate change scenarios based on a set of different global climate models. When standardized global climate model simulations such as the second phase of the Coupled Model Intercomparison Project （CMIP2） are used, the difference in the downscaled variables mainly reflects differences in the climate models and the natural variability in the simulated climates. It is proposed that the spread of the estimates can be taken as a measure of the uncertainty associated with global climate models. The proposed method is applied to the estimation of global-climate-model-related uncertainty in regional precipitation change scenarios in Sweden. Results from statistical downscaling based on 17 global climate models show that there is an overall increase in annual precipitation all over Sweden although a considerable spread of the changes in the precipitation exists. The general increase can be attributed to the increased large-scale precipitation and the enhanced westerly wind. The estimated uncertainty is nearly independent of region. However, there is a seasonal dependence. The estimates for winter show the highest level of confidence, while the estimates for summer show the least.  相似文献   

Earthquake catalogues and modelling strategies. A new testing procedure for the comparison between competing models     

G. Grandori  E. Guagenti  L. Petrini 《Journal of Seismology》2006,10(3):259-269

In this paper we consider the procedures that, on the basis of an earthquake catalogue, yield the magnitude distribution function F _M (F _M generators). In particular, our attention is focused on the F _M generators that are currently used in the frame of the probabilistic seismic hazard analysis at a site. From an engineering point of view, the behaviour of F _M in the range of strong earthquakes is of crucial importance. On the other hand, in general, the statistical validation of F _M in that range is not feasible because of an insufficient number of strong earthquakes in available catalogues.Our investigation is limited to the problem of the comparison between competing F _M generators. We show that a simple empirical F _M generator (called the CFP generator) can be more reliable than generators based on mathematical models. The numerical experiments that support this statement regards two test-sites and two mathematical models of magnitude distribution, namely the truncated-exponential and the characteristic-type models.The main conclusion is the suggestion of a test (called the CFP-test) that can be summarized as follows. Let X be a site for which, with current criteria, a specific F _M ^X generator based on a mathematical model has been selected. At this point, following the comparison approach described in the paper, the F _M ^X generator is compared with the empirical CFP generator. It can happen (actually it happens in many of our numerical experiments) that this test indicates the CFP generator as more reliable than the selected F _M ^X generator.  相似文献   

快速精密星历替代精密星历定位的初步研究   总被引：3，自引：1，他引：3       下载免费PDF全文

尹继尧  徐平  吴培稚 《地震工程学报》2006,28(1):36-41

由于GPS精密定位所需的IGS精密星历要在两周以后才能得到,因而利用两天后即可得到的快速精密星历、12小时后得到的超快速精密星历代替精密星历是GPS应用于地震短临预测的一个重要条件。本文利用北京市全球定位综合应用服务系统中五个GPS连续观测站一年半的数据,分别用三种星历进行精密定位计算,得到了小规模网中快速精密星历一般可以代替精密星历进行精密定位计算的结果。  相似文献   

Study on Statistical Features About Weak Earthquake Activity Before Moderately Strong Earthquakes in the Middle Northern Part of the Qinghai-Xizang （Tibet） Block     

Ma Heqing 《中国地震研究》2006,20(2):148-158

In regards to the earthquakes recording M ≥ 5.0 that occurred in middle northern part of the Qinghai-Xizang （Tibet） Block from 1970 - 2003, in this study we describe the temporal and spatial centralization features of the weak earthquakes and the enhancement and anomalous quiescence of their seismic activity before main shocks through 4 parameters, which are basically not correlated： earthquake time centralization degree parameter Ct, earthquake space centralization degree parameter Cd, η value and weak earthquake frequency and so on. On the basis of calculation results, it has been seen that before earthquakes with M ≥ 5.0 took place in the middle northern part of the Qinghal-Xizang （Tibet） Block, the frequency of weak earthquakes often shows ascent and drop, their strength shows an obvious enhancement and the centralization distribution with time and space is evident.  相似文献   

自由网平差方法及统计特性新探     

王仲锋 《测绘与空间地理信息》1998,(2)

本文结合参数平差和主成分估计理论,导出了误差方程中含多重共线性时未知参数的求解公式,并以定理的形式,证明了主成分估计的解是极小范数解。由此,将主成分估计推广到秩亏网平差中,同时导出了未知参数估值之协因数阵的计算公式,同时,证明了自由网平差的传统特性。  相似文献   

江苏-南黄海地区未来地震形势的统计分析     

门可佩  曾卫 《高原地震》1998,(3)

根据１５００年以来的地震资料,应用数理统计、灰色预测、干支６０周期分析等多种方法,对江苏—南黄海地区未来３～５年地震形势进行分析和预测,结果表明：该区目前处于本世纪第２活跃幕中后期,未来几年内依然存在５～６级地震的危险性,至２０００年７月,累积发震概率将达到０．７～０．８,１９９９—２０００年、２００２—２００３年均有可能发生５级以上中强地震。  相似文献   

某些测震学指标与地震相关性研究   总被引：3，自引：0，他引：3  

张军  黄显良 《地震》1998,18(2):171-176

通过对１０项测震学指示宾１０ａ的大范围时空扫描得出的有震和无震“预报”进行了与５．０级以上的地震的相关性研究,结果证明这１０项指标当显性水平较低时,均可通过统计检验,表明是有效的提取异常指标。作还依统计检验结果对１０项测震学指标与地震相关性好坏进行了排序,并通过分析得到各指标今后优化方向．  相似文献   

Retrieval single-doppler radar wind with variational assimilation method-part i: objective selection of functional weighting factors   总被引：1，自引：0，他引：1  

Wei Ming  Dang Renqing  Ge Wenzhong  Takao Takeda 《大气科学进展》1998,15(4):553-568

In variational problem, the selection of functional weighting factors (FWF) is one of the key points for discussing many relevant studies. To overcome arbitrariness and subjectivity of the empirical selecting methods used widely at present, this paper tries to put forward in optimal objective selecting method of FWF. The focus of the study is on the weighting factors optimal selection in the variation retrieval single-Doppler radar wind field with the simple adjoint models. Weighting factors in the meaning of minimal variance are calculated out with the matrix theory and the finite difference method of partial differential equation. Experiments show that the result is more objective comparing with the factors obtained with the empirical method.  相似文献   

Seasonality and duration in extreme value distributions of significant wave height     

Fernando J. Mndez  Melisa Menndez  Alberto Luceo  Raúl Medina  Nicholas E. Graham 《Ocean Engineering》2008,35(1):131-138

This paper presents a statistical model to characterize the long-term extreme value distribution of significant wave height, conditioning to the duration of the storm and accounting for seasonality. A time-dependent version of the peak over threshold (POT) approach is used to build the model, which is then applied to specific reanalysis time series and NOAA buoy records. The model considers the annual and semiannual cycles which are parameterized in terms of harmonic functions. The inclusion of seasonal variabilities substantially reduces the residuals of the fitted model. The information obtained in this study can be useful to design maritime works, because (a) the model improves the understanding of the variability of extreme wave climate along a year and (b) the model accounts for the duration of the storm, which is a key parameter in several formulations for rubble mound breakwater design.  相似文献   

华东地区月平均气温统计降尺度方法比较   总被引：1，自引：0，他引：1  

高红霞  汤剑平 《气象科学》2015,35(6):760-768

用中国地面气象观测站的逐日气温观测资料和NCEP/NCAR再分析资料,分别使用基于多元线性回归(MLR)和3种主成分分析(PCA)的统计降尺度方法,对1959-2008年的华东地区的月平均气温分两个时段进行统计降尺度分析并加以检验,比较了不同降尺度方法的结果。结果表明:对于华东地区气温的统计降尺度预报,基于MLR的统计降尺度方法相对于3种PCA方法而言,对单站年际变化模拟方面有一定优势。PCA方法应用于统计降尺度时,预报因子的区域选择是影响统计降尺度结果的重要因素之一。对于温度进行统计降尺度分析时,预报因子中包含温度因子是非常必要的;所试验的4种降尺度方法,对各站点多年平均情况的模拟要好于对区域平均的年际变化的模拟。  相似文献