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1.
Telecorrelation of the 500 hPa polar circulation and El Nino/SO with the temperature fields in China
By using the monthly data from 1951 through 1984, empirical orthogonal expansion is performed for the 500 hPa geopotential height north of 65oN and the canonical fields are clustered by fuzzy classification. It is noted that both the mean monthly polar vortex fields and the large-scale anomaly fields fall into three regimes, with those of the January mean field and the April anomaly field having characteristic features. In addition, the relationship between the time weigthing coefficients of the canonical fields and El Nino / SO is examined, showing significant anomalies in the large-scale polar anomaly fields during April and October of the year when El Nino occurs. These polar circulation anomalies have considerably influenced the temperature fields in China during April and October. Thus, we may con-clude that this is one of the most important reasons for a relatively cool April and a warm October in China during the El Nino year. 相似文献
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利用典型相关分析(CCA)方法建立统计气候预测模型，对我国冬季气温进行了预测试验，采用历史资料独立样本检验的方法，对预报技巧给出合理的评定。结果表明，使用CCA方法对我国冬季气温进行短期气候预测，有一定的预报技巧，对于特定地区和特定时期优选的因子场组合，可以取得较为满意的预报效果。大部分地区的季平均预报时效在2个季以内时，最佳预报相关系数在0.5以上。季平均的预报水平明显高于月平均的预报。海温场是所有因子场中最好的预报因子，不仅单独海温场的预报效果较好，而且与其他因子场组合后的预报水平还可以得到进一步提高。 相似文献
4.
20世纪全球表面温度场序列的插补试验 总被引：6，自引：0，他引：6
利用基于主分量典型相关分析的典型变量回归 (CVR)插补模式 ,在综合分析Jones等 5°× 5°格点温度资料覆盖率的演变情况、缺测场与基本场温度距平相关结构、稳定性的基础上 ,确定合理的插补方案 ,对其陆面格点温度场进行插补延长试验 ,得到了 1 90 0～ 1 998年连续、均一的全球月平均气温场序列。独立样本检验表明插补效果优良 ,总缺测场误差方差与原序列方差之比低于 0 .40。插补前后全球及纬向平均序列的演变特征基本一致 ,原 Jones序列的线性增温率较重建序列高0 .1 1℃ /(1 0 0年 ) ,可能与原 Jones场序列空间分布的不均一性有关 相似文献
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该文是为应用统计释用预报方法对影响华东地区的热带气旋（ATC）汛频数预报所做的前期研究工作。研究发现:（1）影响华东地区的热带气旋汛频数的局地性异常变化是汛平均环流半球性调整的结果;（2）汛平均环流中的大气长波既反映了月平均环流的特征又和汛频数的变化存在着较好的关系,特别在异常年,其天气系统和相关地区也比较稳定;（3） 利用影响华东地区的热带气旋汛频数和环流变化的关系建立了汛频数的统计预报方程。在短期气候数值形势预报准确的基础上,应用统计释用预报方法所得的准确率为70%左右,若能预报出汛平均环流的异常变化,则可确定ATC汛频数的特多年或特少年。 相似文献
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基于1961～2000年辽宁53个测站40 a逐年的月气温距平和月降水距平百分率资料,根据EOF(经验正交函数)展开的空间特征向量分布特征,将前3个主要特征向量时间系数作为预报量,将500 hPa高度场的高度距平、地转涡度作为预报因子,利用多元统计回归分析,建立了一套定点、定量预测辽宁各月气温与降水量的数学模型。利用该模型对2001~2005年辽宁53个测站的月气温距平和月降水距平百分率进行逐月预报试验。结果表明:对气温和降水量的趋势预报的评分均比较好,有87%以上的月气温距平预测结果的评分超过66.0分,各月的平均Ps评分均高于66.0分,年平均为75.5分或以上,总平均为83.1分;有70%的月降水距平百分率预测结果的Ps评分超过60.0分,各月的平均Ps评分都高于53.0分,年平均为58.0分以上,总平均为66.5分。但对异常气候的预测效果不明显。 相似文献
7.
基于EEMD的黄河中上游夏季降水预报方法的研究 总被引：3，自引：0，他引：3
传统的统计方法难以很好的对气候系统这一集非线性、非平稳性为一身的多层次系统进行处理。因此集层次化处理和平稳化处理的集合正交经验模态分解技术(EEMD)的提出,为解决上述问题提供了有效的途径。本文选取黄河中上游24个气象观测站的逐月降水资料,结合组合预报和集合预报思路,基于EEMD建立了统计预报模型。其中对降水序列中的高频部分进行了二次平稳化处理,实现对2008—2013年6—8月的降水预报,并用预报评分检测预报效果。结果表明:EEMD模型对黄河中上游夏季降水有着较强的预报能力,在该区域与气候模式和传统的统计方法相比具有更高的精度和更好的应用前景。 相似文献
8.
对1952—1980年我国连续的月地面气温用时间序列ARMA（p、q）模型进行随机建模。月温度由60个站组成，用经验正交函数加以展开，取不同的样本长度即348,336和300月，以便考察经验正交展开的稳定性。前四个主成分，即z1,z2,z3,z4取为多维时间序列的变数，因为它们的总方差贡献达99.26%。在这四个主成分序列中的决定性周期用周期图和最大熵方法加以揭露。对一维变量zi,(i=1,2,3,4)的ARMA（p,q）的模型识别用Pandit-Wu方法进行，这样就可求得实验模型。用zi模型的外推值来预报月温度场。距平预报的命中率评分为78.3%，高于目前的业务长期天气预报。 相似文献
9.
一个地方下月的雨量,能不能从当地上月天气演变的结果所记录下来的各种气象要素的数值来推测呢?现在这篇报告的目的就想解答这个问题。关於这方面的研究,以前早有人注意,例如竺可桢教授研究过冬天温度与夏季雨量的关系, 相似文献
10.
将随机过程的交叉理论应用于天气气候极值分析，以长江三角洲地区逐月最高最低气温为例，说明了交叉理论在极值研究中的作用。基于该理论，对上海市近100a一月气温序列，用随机模拟的方法讨论了极端温度出现的频数、持续时间、时间间隔等参数对于气候变化的敏感性，并根据气候变化趋势，预测了未来气候极值统计特征的变化规律。 相似文献
11.
Summary Seven series of monthly pluviometric amounts, sometimes exceeding recording periods of 100 years and compiled by the Instituto Nacional de Meteorología (Spain), are used to study the irregularity of the pluviometric regime along the Spanish Mediterranean coast and nearby Atlantic
coast. First of all, three statistical functions (gamma, log-normal and a combination of Poisson and gamma distributions)
and moment-ratio diagrams are used to model the monthly and annual empirical distributions of precipitation amounts, each
distribution being tested by means of the Kolmogorov-Smirnov test. It is noteworthy that, whereas most of the monthly cases
require the gamma distribution, the pluviometric behaviour of the summer months is well described by the Poisson-gamma distribution.
Moreover, both the log-normal and the gamma distributions satisfactorily model empirical annual amounts. Consequently, rainfall
amounts are not identically distributed along a year for each gauge tested. Second, temporal trends deduced for annual and
seasonal amounts are computed and their statistical significance evaluated. The most notable fact is that, although some linear
trends are close to 1 mm/year, their significance levels exceed the assumed threshold value and, excepting the winter season
for Barcelona, they are considered non-significant from a statistical point of view. Finally, by again using monthly and annual
amounts, three temporal irregularity indexes are computed for each pluviometric series, the temporal disparity of the rainfall
patterns of the Mediterranean region being enhanced as a result. It addition to the temporal irregularity, a change with latitude
is observed both in the parameters of the statistical distributions and the temporal irregularity indexes for the rain gauges
analysed. The two most southerly rain gauges constitute a special case in comparison with the remaining stations, because
they also receive the Atlantic influences due to their proximity to this ocean.
Received February 25, 1999/Revised August 2, 1999 相似文献
12.
基于奇异谱分析的江淮降水场预测模型研究 总被引：4，自引：1，他引：3
中国的降水预报主要是对汛期(夏季)的单站降水量或区域的降水型态进行预报,而主要的预报方法为动力学方法和统计学方法。据此,利用江淮地区的月降水量标准化序列,得到江淮地区降水时空分布型态。并在此基础上,利用奇异谱分析和时间序列的分析方法,设计了统计学的降水预测模型,对江淮地区的月降水量进行了预测试验。结果表明,模型能对江淮降水场的趋势作出较好的预报,且递推时间短时预报效果较好。 相似文献
13.
Mohammad Reza Khazaei Shahin Ahmadi Bahram Saghafian Bagher Zahabiyoun 《Climatic change》2013,119(3-4):631-645
This paper addresses deficiencies of stochastic Weather Generators (WGs) in terms of reproduction of low-frequency variability and extremes, as well as the unanticipated effects of changes to precipitation occurrence under climate change scenarios on secondary variables. A new weather generator (named IWG) is developed in order to resolve such deficiencies and improve WGs performance. The proposed WG is composed of three major components, including a stochastic rainfall model able to reproduce realistic rainfall series containing extremes and inter-annual monthly variability, a multivariate daily temperature model conditioned to the rainfall occurrence, and a suitable multi-variate monthly generator to fit the low-frequency variability of daily maximum and minimum temperature series. The performance of IWG was tested by comparing statistical characteristics of the simulated and observed weather data, and by comparing statistical characteristics of the simulated runoff outputs by a daily rainfall-runoff model fed by the generated and observed weather data. Furthermore, IWG outputs are compared with those of the well-known LARS-WG weather generator. The tested characteristics are a variety of different daily statistics, low-frequency variability, and distribution of extremes. It is concluded that the performance of the IWG is acceptable, better than LARS-WG in the majority of tests, especially in reproduction of extremes and low-frequency variability of weather and runoff series. 相似文献
14.
Summary Rainfall anomaly patterns are obtained for the city of Barcelona from a statistical and a spectral point of view. The time
series consists of monthly rainfall amounts recorded over 128 years without interruption. Monthly positive and negative anomalies,
obtained as the difference between monthly amounts and monthly threshold values, are used for both types of analyses. The
threshold levels are derived form the deciles of theoretical monthly rainfall distributions, which have been previously modelled
by the gamma distribution. Positive and negative anomalies of the monthly rain amounts are investigated for these threshold
levels. The statistical analysis is applied to each decile considered, yielding empirical exponential laws that can be used
to forecast the cumulative number of episodes of consecutive months with either positive or negative anomalies equalling or
exceeding a fixed length. A set of linear laws, relating the expected rainfall amount cumulated during an episode of a fixed
length, is also deduced. It is worthy of mention that, independently of the decile considered, all the exponential and linear
laws have satisfactory regression coefficients. At the same time, it has also been possible to establish the evolution of
the coefficients of these laws with respect to the different deciles considered. The exponential laws for episodes of positive
and negative anomalies are the starting point, together with two hypotheses, to model probabilities of repeated long episodes
over an arbitrary number of years and their return periods in terms of the Poisson distribution model. Moreover, power spectra
are derived for anomalies relative to the 50% decile at monthly and seasonal scale. The spectral estimates obtained are then
compared with theoretical spectra deduced from possible Markovian or random behaviour of the time series of anomalies. Finally,
the significant spectral peaks are discussed and compared with other significant spectral components deduced for some areas
of the Mediterranean domain.
Received November 11, 1999 Revised February 28, 2000 相似文献
15.
P. Hosseinzadeh Talaee Mahdi Kouchakzadeh B. Shifteh Some’e 《Theoretical and Applied Climatology》2014,118(1-2):297-305
Assessment of the reliability and quality of historical precipitation data is required in the modeling of hydrology and water resource processes and for climate change studies. The homogeneity of the annual and monthly precipitation data sets throughout Iran was tested using the Bayesian, Cumulative Deviations, and von Neumann tests at a significance level of 0.05. The precipitation records from 41 meteorological stations covering the years between 1966 and 2005 were considered. The annual series of Iranian precipitation were found to be homogeneous by applying the Bayesian and Cumulative Deviations tests, while the von Neumann test detected inhomogeneities at seven stations. Almost all the monthly precipitation data sets are homogeneous and considered as “useful.” The outputs of the statistical tests for the homogeneity analysis of the precipitation time series had discrepancies in some cases which are related to different sensitivities of the tests to break in the time series. It was found that the von Neumann test is more sensitive than the Bayesian and Cumulative Deviations tests in the determination of inhomogeneity in the precipitation series. 相似文献
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C. D. Papadimas A. Bartzokas C. J. Lolis N. Hatzianastassiou 《Theoretical and Applied Climatology》2012,108(1-2):173-189
The relationship between sea-level pressure (SLP) and 1,000?hPa air temperature (AT) in winter is investigated over the northern hemisphere, and a statistical forecasting of one of the two parameters from the other is attempted on a monthly basis. Mean monthly SLP and 1,000?hPa level AT values at 563 grid points over the northern hemisphere are utilized for January, February and March, for the period 1949–2002. At first, factor analysis is applied to the data sets as a dimensionality reduction tool. Then, canonical correlation analysis is applied to the resultant factor scores time series for the five SLP–AT pairs: SLP(J)–AT(J), SLP(J)–AT(F), SLP(J)–AT(M), AT(J)–SLP(F) and AT(J)–SLP(M), and the synchronous and time-lag connections between the two parameters are investigated. The areas characterized by a satisfactory monthly or/and bi-monthly forecasting ability are detected. The most satisfactory results refer to the areas affected by the Southern Oscillation. It is found that the SLP teleconnection between the areas of the eastern and the western Pacific in January is related to the regime of AT in the central Pacific Ocean, in both February and March. Also, SLP over the Aleutian and Icelandic lows in January is related to AT over their southwestern and southeastern neighbouring areas in February and March. Finally, it appears that there is also ability for monthly/bi-monthly statistical prediction for some areas affected by the well-known oscillations of North Atlantic Oscillation and Pacific/North American Oscillation. A validation of the statistical prediction methodology is carried out, using real-time series of AT and SLP parameters for some characteristic cases. The results show that the statistical prediction presents a remarkable success. The success rate varies from 67% to 83% for the analysis period 1949–2002 and from 71% to 86% for the recent period 2003–2009. 相似文献
17.
我国东南夏季干旱指数的ECC预测方法 总被引：2，自引：0，他引：2
根据中国东南夏季气温和降水显著负相关的特点,构造合适的干旱指数。选取美国NCEP／NCAR再分析月平均海表温度场、北半球500hPa高度场、亚欧大陆表面温度场作为预测因子,取由国家气象中心整理的中国160站月平均降水和温度资料计算出的东南部干旱指数作为预测对象,采用集合典型相关分析方法（ensemble canonical correlation,ECC）预测东南夏季干旱指数。预测与实况之间的空间相关性和时间相关性均表明,该方法优于单因子场典型相关分析（canonical correlation analysis,CCA）预测方法,其中采用超级集合平均法又比等权集合平均法具有更高的预测技巧。 相似文献
18.
Henryk T. Mitosek 《Climatic change》1995,29(1):101-116
The paper contains some results of long-time series analysis of discharges with respect to climate variability and change. The appropriate statistical computations based on data supplied by the Global Runoff Data Center in Koblenz. The computations have been carried out for the case of annual and of monthly (of each month) time series. The verification of the assumed hypotheses has been conducted for 5% significance level.The hypothesis that the mean value and the variance are stationary and ergodic (Kruskal-Wallis test) have to be rejected, respectively: (a) from 10.2% to 21.6% of cases and from 1.7% to 7.4% of cases for monthly discharges; and (b) in 23.3% and 3.4% of cases for annual discharges. Whereas, in case of the Mann-Kendall test trends emerge (a) in the mean value from 25% of cases to 42.6% of cases, and in the variance from 10.2% of cases to 19.3% of cases for monthly discharges; (b) in 42% and 9.1% of cases there occur trends in the mean value and the variance, respectively, for annual discharges. Moreover, results of the tests are presented separately for the time series being independently and dependently distributed in time. 相似文献
19.
The series ofair temperature anomalies inthe free atmosphere from radiosonde and satellite data are compared. Along with the well-known datasets of leading foreign centers, the datasets are considered of monthly temperature anomalies for isobaric surfaces and tropospheric and lower tropospheric layers obtained in the All-Russian Research Institute of Hydrometeoroiogical Information-World Data Center (RIHMI-WDC) from the data of the global network of radiosonde observations. Following numerous literature sources, the study corroborates that it is impossible to detect the so called tropospheric amplification of warming in observational data. The results of the comparison of statistical parameters for different series of air temperature anomalies prove that the RIHMI-WDC dataset is appropriate for solving the problems of climate monitoring on the assessment of air temperature in the free atmosphere. A doubtless advantage of these datasets for the preparation of the data of monitoring and diagnosis of the current climate is that their operational update is possible by processing new monthly portions of radiosonde data for the global network. The other advantage is that they do not depend on the modes of series update in the foreign sources. 相似文献
20.
In this paper a nonlinear method of time series analysis-threshold autoregressive (TAR) model in discrete time is used. The TAR procedure consists of four parts: model building, statistical identification, parameter estimation and forecasting.The object of this study is to estimate monthly total precipitation of Shanghai and Beijing by using open loop TAR model. We can see that the trend of forecasting is in agreement with observations. 相似文献