用非参数估计技术预报风的研究

该文介绍了使用非参数估计技术制作风的预报试验。为了有一个较完整的历史样本集,试验中使用了1981—2003年共23年的逐日资料。在采用的K近邻非参数估计技术中,由于风的特殊性,其不是标量而是矢量,试验中根据天气学原理,设计和试用了一种根据过程相似性从历史样本集中搜索出近邻子集和新的从近邻子集中挑选最佳样本的方法。试验结果显示,所试用的预报方法不仅使得风的预报Ts评分有一定的提高,同时使得3 d降水量的预报Ts评分也有一定的提高,这表明该方法具有一定的实际参考使用价值。     

基于RegCM4模式的中国区域日尺度降水模拟误差订正

气候模式模拟得到的各气候变量与观测相比,总会存在一定的偏差,所得到的气候变化预估结果难以在影响评估模型中直接应用。本文尝试对一个区域气候模式（RegCM4.4）所模拟的中国区域逐日降水,基于概率分布（分位数映射）方法进行统计误差订正。在订正过程中,以模拟时段1991~2010年中的前半段（1991~2000年）作为参照时段,建立传递函数,对后一时段（2001~2010年）进行订正并检验其效果。首先对使用参数和非参数所建立的6种不同传递函数方法进行对比,发现6种方法均可明显减少降水模拟的误差,其中利用非参数转换建立传递函数的RQUANT方法效果更好。随后进一步分析了采用该方法对模式模拟降水所做订正的效果,结果表明,该方法可以明显改善对平均降水,以及降水年际变率和极端事件的模拟结果。     

Bulgarian mountains air temperatures and precipitation—statistical downscaling of global climate models and some projections

Measured air temperature and precipitation data from three high mountainous Bulgarian stations were used along with data from 18 global climate models (GCMs). Air temperature and precipitation outputs of preindustrial control experiment were compared with actually observed values. GCM with the best overall performance is BCCR BCM 2.0 for air temperatures (period 1941?C2009) and CGCM 3.1/T47 for precipitation (period 1947?C2009). Statistical methods were used in this research??nonparametric Spearman correlation, Mann?CWhitney test, multiple linear regression, etc. Projections were made for the following future decades: 2015?C2024, 2045?C2054 and 2075?C2084. The best months, described by multiple linear regression (MLR) model of air temperatures, are November, January, March, and May. The worst described are summer months. There is not any pattern in the relationship between constructed MLR models and measured precipitation. Models that perform the best in different months at the three investigated stations are MIUB ECHO-G, GISS AOM, CGCM 3.1/T63, and CNRM CM3 for air temperatures and GFDL CM 2.1, GISS AOM, and MIUB ECHO-G for precipitation. The fit between statistical models' outputs and values observed at stations is different, better in cold part of the year. There will be mixed future changes of air temperatures at all the three high mountainous stations. An increase of temperatures is expected in April, November, and December. A decrease will happen in February, July, and October. Mean annual temperatures are expected to rise by 0.1?°C (Botev) to 0.2?°C (Musala and Cherni vrah) in the decade 2075?C2084, but mean annual temperatures at the end of the period with measurements (2009) has already exceeded by far projected values. Trends in precipitation are mixed both in spatial and in temporal directions. Observed decrease of precipitation, especially in the warm half of the year, is not described well in MLR models. The same is valid for annual amounts, which are projected to be higher than those measured in the end of instrumental period (2009). This is opposite to observed trends in recent decades, especially at stations Cherni vrah and Botev, where a significant decrease of precipitation amounts has happened.     

Coverage probability of bootstrap confidence intervals in heavy-tailed frequency models, with application to precipitation data

Bootstrap, a technique for determining the accuracy of statistics, is a tool widely used in climatological and hydrological applications. The paper compares coverage probabilities of confidence intervals of high quantiles (5- to 200-year return values) constructed by the nonparametric and parametric bootstrap in frequency analysis of heavy-tailed data, typical for maxima of precipitation amounts. The simulation experiments are based on a wide range of models used for precipitation extremes (generalized extreme value, generalized Pareto, generalized logistic, and mixed distributions). The coverage probability of the confidence intervals is quantified for several sample sizes (n?=?20, 40, 60, and 100) and tail behaviors. We show that both bootstrap methods underestimate the width of the confidence intervals but that the parametric bootstrap is clearly superior to the nonparametric one. Even a misspecification of the parametric model—often unavoidable in practice—does not prevent the parametric bootstrap from performing better in most cases. A tendency to narrower confidence intervals from the nonparametric than parametric bootstrap is demonstrated in the application to high quantiles of distributions of observed maxima of 1- and 5-day precipitation amounts; the differences increase with the return level. The results show that estimation of uncertainty based on nonparametric bootstrap is highly unreliable, especially for small and moderate sample sizes and for very heavy-tailed data.     

45年来塔里木河流域气候变化对径流量的影响研究

根据塔里木河流域40个气象站1961-2005年的降水、 气温资料及源区内7个水文站1957-2005年年径流量资料, 利用Mann-Kendall检验, 分析了近45年来塔里木河流域的气候变化的特征, 探讨了气候变化对塔里木河流域水资源的影响。结果表明： 整个流域除个别站点外, 塔里木河流域气温整体呈显著上升趋势, 且以秋季最显著, 降水增加以夏季最明显。特别是中天山南坡, 而流域西南部、 和田地区和巴州南部的降水量几乎没有增加。根据Mann-Kendall检验结果, 除阿克苏河年径流量呈显著增加趋势外, 其它3条源流（和田河、 叶尔羌河、 开都河）径流量近45年变化趋势均不显著。     

兰州地区降水量正态分布特征

在对降水资料的分析过程中,要求资料的时间序列呈正态分布。利用兰州地区的兰州、皋兰、榆中和永登4个站点1960~2009年的降水量资料,采用"偏度—峰度系数+W检验"方法,基于SPSS软件,对兰州地区的年、季和月降水量正态特征进行分析。结果表明,兰州地区4个气象站的年降水量均呈正态性分布;兰州、皋兰和永登3站的夏、秋2季降水量为正态性分布,而榆中站只有秋季降水量为正态性分布,且秋季降水量的正态性最好,冬季最差;大多数月降水量不服从正态分布,但对降水序列进行平方根处理后,其正态性得到明显的改善。     

浙江省1901—2017年降水序列构建及变化特征分析

基于通过均一性检验的历史观测资料和GPCC格点降水数据,采用逐步回归方法,构建了可以代表浙江省的1901—2017年年降水序列,并通过Morlet小波分析、MK检验、气候趋势等分析了浙江百年降水变化特征。结果表明：浙江68个台站1951—2017年月降水序列数据质量较好,均通过RHtest均一性检验。交叉检验表明,采用逐步回归方法区别台站资料长度建立的最优拟合方程组,能很好地反演浙江68个台站1901—2013年年降水情况。1901—2017年浙江省年降水量无明显线性变化趋势,但存在56 a和35 a两个变化主周期,在1960年前后全省降水由多雨期向少雨期突变。1901—2017年浙江降水气候倾向率呈东北高西南低的分布特征,各地数值分布在-15.6~19.1 mm/10a之间;平均相对变率呈北低南高的分布特征,各地数值分布在11.1%~20.2%之间。     

Long-term trend and variability of precipitation in Chhattisgarh State,India

Spatial and temporal precipitation variability in Chhattisgarh State in India was examined by using monthly precipitation data for 102 years (1901–2002) from 16 stations. The homogeneity of precipitation data was evaluated by the double-mass curve approach and the presence of serial correlation by lag-1 autocorrelation coefficient. Linear regression analysis, the conventional Mann–Kendall (MK) test, and Spearman’s rho were employed to identify trends and Sen’s slope to estimate the slope of trend line. The coefficient of variation (CV) was used to analyze precipitation variability. Spatial interpolation was done by a Kriging process using ArcGIS 9.3. Results of both parametric and non-parametric tests and trend tests showed that at 5 % significance level, annual precipitation exhibited a decreasing trend at all stations except Bilaspur and Dantewada. For both annual and monsoon precipitation, Sen’s test showed a decreasing trend for all stations, except Bilaspur and Dantewada. The highest percentage of variability was observed in winter precipitation (88.75 %) and minimum percentage variability in annual series (14.01 %) over the 102-year periods.     

宁波市年降水量时空变化特征

应用主分量分析、气候突变检验、“墨西哥帽”小波分析及谱分析等多种方法对宁波市1953~2003年的年降水量进行了时空特征分析。结果表明:宁波市所辖7个气象站年降水量呈现出从西南往北—东北方向递减的趋势,与全市地形走向基本一致,年降水量最大、最小值相差400 mm左右;全市各地年降水量的年际变化趋势是一致的;宁波市区年降水量在20世纪60年代末到70年代初接近突变临界值,近年也有发生转折的趋势;进入21世纪以来,宁波市年降水量处于偏少的气候背景中,2003年变化最为剧烈;宁波市区年降水量有准4年的振荡周期。     

Study of homogeneity of precipitation in a region in the province of Buenos Aires,Argentina

Summary Monthly and annual climatic variabilities of precipitation were analyzed from a 60 years record of rainfall data at 10 measuring stations in the humid region of Argentina.Different statistical techniques were used to analyze the regional homogeneity of precipitation fields. Special structures and monthly trends were studied. Simple correlations of yearly precipitation at different locations were computed. Exponential functions relating cross-correlations and distances were determined through regression analysis.Monthly and annual rainfall show no evident signs of trends; aleatory processes are predominant in the whole region; and, correlation functions are independent of the direction of the vector connecting the stations.With 3 Figures     

我国东部夏季降水量长年代资料的插补、订正及效果检验

使用均值生成函数、标准正态均一性检验方法和相关分析等方法对我国东部地区96个观测站1931—2020年夏季降水量长年代资料进行了一系列插补、检验、订正及效果分析等工作。结果表明：(1)均值生成函数拟合的1931—2020年各站夏季降水量资料的整体趋势和极值与观测值均有较好的一致性,其中无缺测资料的6个站点观测值和拟合值在距平符号一致率上达到了86.1%,可以满足插补工作的需要。(2)对1931—1950年和1951—2020年2个时段的夏季降水量资料,用平均值和方差2个统计量对插补后的资料进行差异性检验,共有8站具有显著性差异。(3)对插补后的1931—2020年夏季降水量资料进行了均一性检验和均一化订正,其中13站存在非均一性。(4)将订正后的站点资料与CRU＿TS4.05(University of East Anglia Climatic Research Unit Global 0.5°Monthly Time Series)数据库的格点资料进行空间分布相似度分析,2套资料在1931—1950、1951—2020和1931—2020年这3个时段的空间相关系数分别达到了0.90,...     

Parametric versus non-parametric estimates of climatic trends

Summary Two methods of estimation of the trend magnitude are compared: the parametric one (least-squares regression) with the non-parametric one (median of pairwise slopes). The comparison is carried out for seasonal and annual trends of ten climatic variables at a network of stations in the Czech Republic. We show that the difference between the two trend estimates is very small, falling well within the 95% confidence limits of the parametric estimate. The magnitude of the difference does not depend on the degree of normality of the distributions, with the exception of two variables, maximum temperature and precipitation, for which a slight dependence is observed. As a by-product, the normality of seasonal and annual means of the climatic variables is evaluated by the Kolmogorov-Smirnov one-sample test.     

昆山市暴雨时空分布特征及设计暴雨强度公式推求

基于江苏省昆山市2008—2015年12个自动气象站逐分钟降雨数据和常规气象站小时降雨量数据,并选取5个代表站分别代表不同的生态系统,先对昆山市降雨和暴雨的时空特征进行分析,然后采用年多个样法进行暴雨选样,利用指数分布、皮尔逊Ⅲ型分布和耿贝尔分布分析暴雨发生频率,最后使用高斯-牛顿法推求不同生态系统代表站的暴雨强度公式参数,结果表明:(1)昆山市各站点2008—2015年期间年降雨量都呈增长趋势,夏季降雨量最多、冬季最少,一天中01时(北京时间,下同)左右为降雨谷值,18时左右为降雨峰值,白天降雨多于夜晚; 在空间分布上,农田和城市生态系统的年降雨量、年降雨日数最多,湿地和湖泊生态系统较少。(2)暴雨日数年际差异大,年内暴雨主要集中在夏季,暴雨发生频次日变化呈“双峰型”分布,暴雨发生频次在02时和18时最多,09时和24时最少; 市区的暴雨日数空间变异系数大于郊区,且从市中心向外递减。(3)城市生态系统适宜采用皮尔逊Ⅲ型分布推求暴雨强度公式,其他类型生态系统适宜采用指数分布推求暴雨强度公式。      

Evaluation of various root transformations of daily precipitation amounts fitted with a normal distribution for Australia

This paper evaluates the various root transformations (2/3, 7/12, 1/2, 5/12, 1/3, and 1/4) of daily precipitation amounts fitted with a truncated normal distribution model for 189 stations across Australia. The results indicate that all stations used in this study can be identified to have a specific root transformation resulting in a “good” fit with a normal distribution and the minimum correlation coefficients (r) fitted with a normal distribution is 0.9925. The 5/12 power transformation leads to the “best” fit with a normal distribution in 47% of stations across Australia. This conclusion could extend the applications of many statistical testing techniques and methods on daily precipitation studies.     

中国降水年内分配的时空演变特征之新法研究

利用中国160站50a月降水资料，分别用降水量序列法、降水量方差法及降水量离差法定量计算了全年降水的聚集程度（聚集度）和最大降水对应的聚集时间（聚集期），并利用计算出的聚集度和聚集期分析了中国降水年内时空变化的气候特征，验证并比较了3种新方法的合理性；挑选长江中下游作为关键区，对该区的聚集度进行了区域平均的趋势分析和小波分析，结果发现，该区的降水聚集度具有明显的年际变化，而年代际变化则表现得比较稳定。     

浙江省分钟降水自记纸信息化数据与人工读取数据的对比及适用性分析

为了探讨信息化分钟降水自记纸数据在短历时时段下的适应能力,对比评估了1980-2000年浙江省19个国家基本（准）站信息化后的分钟降水自记纸数据和同期人工读取降水数据。利用滑动求和的方法提取信息化分钟降水不同历时下每年最大降水量,并使用偏差百分率、方差比、偏差概率、相关分析等统计方法,对比分析了信息化后的分钟降水自记数据与人工读取数据的时空特征差异及信息化数据的适用性。研究结果表明：信息化后的分钟降水数据与人工观测数据的结果在整体及单次降水过程中的表现较为一致,数值上整体略偏小,相关系数达到0.99。30min以上历时信息化后分钟数据与人工校核数据非常接近,且稳定性很高。信息化后分钟数据计算结果比人工读取结果更为客观,可以较好地代替人工读取结果的同时,有效地弥补了自动气象站建站之前逐分钟降水资料记录的空缺,为计算暴雨强度公式、设计暴雨雨型等需要长时间序列分钟降水的研究工作奠定了基础。     

宁夏六盘山区多年降水的时空变化分析

选用宁夏六盘山区4个代表测站自建站以来至2007年的各月降水资料,用回归、周期和突变分析等统计方法进行分析,揭示了其多年时空变化规律.通过分析,得出了其季、年线性变化趋势和年变化周期及突变点,发现各区域降水存在着不同的变化规律,年降水均呈减少趋势,存在准14 a、11 a等变化周期,并发生了多次突变.     

A Comparison of Four Precipitation Distribution Models Used in Daily Stochastic Models

Stochastic weather generators are statistical models that produce random numbers that resemble the observed weather data on which they have been fitted; they are widely used in meteorological and hydrologi- cal simulations. For modeling daily precipitation in weather generators, first-order Markov chain-dependent exponential, gamma, mixed-exponential, and lognormal distributions can be used. To examine the perfor- mance of these four distributions for precipitation simulation, they were fitted to observed data collected at 10 stations in the watershed of Yishu River. The parameters of these models were estimated using a maximum-likelihood technique performed using genetic algorithms. Parameters for each calendar month and the Fourier series describing parameters for the whole year were estimated separately. Bayesian infor- mation criterion, simulated monthly mean, maximum daily value, and variance were tested and compared to evaluate the fitness and performance of these models. The results indicate that the lognormal and mixed-exponential distributions give smaller BICs, but their stochastic simulations have overestimation and underestimation respectively, while the gamma and exponential distributions give larger BICs, but their stochastic simulations produced monthly mean precipitation very well. When these distributions were fitted using Fourier series, they all underestimated the above statistics for the months of June, July and August.     

长江三角洲地区降水资料的均一性检验与订正试验

该文对1961—2002年我国长江三角洲地区36个地面观测站的年、月降水资料序列作均一性检验和订正试验, 以探讨我国年、月降水气候观测序列的均一化方法和思路。该文首先从与待检台站序列相关性较好、台站距离较近的台站中选取了若干站点作为待检台站的参考台站建立参考序列, 采用传统的标准正态检验 (SNHT) 方法, 对所研究的地区年降水的均一性进行了检验。检验结果显示, 该地区降水序列中存在非均一性现象。考虑到所选地区站点密度仍然不够, 文中还采用了一种不依赖于参考台站的思路, 对上述检验结果进行了进一步确认后, 最后对不连续序列进行了逐月订正调整。对比分析表明, 对序列的订正较为合理。在已有的研究基础上, 结合我国台站网络实际特点, 提出结合不同思路来研究我国降水量数据均一性是必要的和可行的, 应用该思路对于我国降水序列进行均一性研究具有一定的合理性和应用前景。     

基于DEM的新疆克州气候要素空间分布模拟

摘要: 根据新疆克州及其周边13个气象台站1961-2010年的历史气候资料,采用基于DEM的空间插值技术对该地区年平均气温、降水量和日照时数等气候要素的空间分布进行了模拟分析。结果表明：（1）经验证,该方法对克州年平均气温等主要气候要素的空间分布模拟效果较好,精度较高;（2）新疆克州年平均气温的空间分布总体呈现“平原高,山区低”的特点;年降水量呈现“北部多,南部少;山区多,平原少”的空间分布格局;年日照时数的空间分布总体呈现“高山带多,中、低山带和山前倾斜平原少”的特征。