共查询到19条相似文献,搜索用时 718 毫秒
1.
相空间EOF方法及其在气候诊断中的应用 总被引:21,自引:3,他引:21
提出了相空间EOF新方法,由此研究了四川测站降水和温度和气候变化。结果表明:突变性是气候变化最重要的特征,周期性是第二位的;突变在气候变化的高层次上有显著反映,低层次对突变具有反馈作用,正(负)反馈作用突出(掩盖)气候变化的突变性;并且在气候诊断分析中,这是一种有特色的方法。 相似文献
2.
3.
中国旱涝史料的层次分析 总被引:23,自引:2,他引:21
文中用子波变换的方法对中国近500年旱涝等级资料进行了分析,发现在不同气候层次上,旱涝变化的特征有所差异,高层次上的旱(涝)期常由若干个低层次的偏旱(涝)期组成;各层次上气候系统的动力行为也表现出不同的特征,要对气候的变化趋势作预测必须在具体层次上而言才有意义。不同层次间突变点的变化往往表现为层次升高时部分奇异点(突变点)退化为平常点,而层次降低时,又会发生平常点进化为奇异点的现象。此外,还发现中国总体上说偏涝期长于偏旱期,但不同地区又有所不同;中国南北方的旱涝演替存在一定的位相差。 相似文献
4.
气候变化对经济和社会发展造成的影响已成为当前各国政府和科学家十分关注的问题,如持续多年的非洲干旱使得许多国家出现严重的粮食危机,上百万人处于饥荒之中;即使在经济最发达的美国,干旱(1988年)、严寒(1977年)也给粮食和能源造成了严峻的形势。因此,对气候的异常变化作出正确预测已成为一个需要解决的重大科学问题。气候一般是指某地区的平均天气状况及其变化特征,常指气象要素(如温度、降水、风等)的统计特征值。气候变化就是相对于气候平均值的偏差。气候和气候变化有明显的动态特征,表现为各种不同时间尺度的变化特征。… 相似文献
5.
第三讲 气候状态变化趋势与突变分析 总被引:52,自引:7,他引:52
第三讲气候状态变化趋势与突变分析黄嘉佑(北京大学地球物理系,100871)本讲着重介绍怎样对气象要素时间演变序列作趋势与突变分析。1气侯状态变化的趋势天气过程长期演变趋势是气候变化或变迁研究的重要内容。所谓趋势是指气候要素大体的变化情况,即描述很长时... 相似文献
6.
PAGES计划与CLIVAR计划中的交叉科学问题 总被引:5,自引:1,他引:5
过去全球变化(PAGES)是国际地圈、生物圈计划(IGBP)的一个核心计划,从1991年开始预计施行到2010年。气候变率与可预报性研究(CLIVAR)是世界气候研究计划(WCRP)新设的一个子计划,从1996年开始也是施行到2010年。两个计划有不少交叉的科学问题:(1)低纬气候变化动力学,(2)全球海洋温盐环流,(3)区域到全球尺度水的变率,(4)气候突变动力学,(5)气候模式发展及改进,(6)气候变化的检测,本文对以上问题作了扼要介绍。 相似文献
7.
扎龙湿地周边区域极端气温不对称变化分析 总被引:8,自引:1,他引:8
为了了解扎龙湿地对小区域气候的调节作用及其变化趋势。利用MANN—KENDALL检验等4种气候变化趋势分析方法,分析了扎龙湿地周边区域的富裕、林甸、社蒙、泰来气象站1957--2002年最高、最低气温的变化特征。结果表明,最高、最低气温存在明显的不对称变化,在部分时段还存在着反向变化趋势;最低气温的变化还明显地存在着气候突变的特征;这种极端气温的不对称变化,使该区域气温的日较差有明显的递减趋势。R/S分析(改变尺度范围分析法)表明最高、最低气温的变化存在明显的Hurst现象,该区域气候变暖有趋于减缓的趋势。 相似文献
8.
9.
冬季NPO突变前后大气环流和我国天气气候的变化 总被引:2,自引:2,他引:2
用Mann-Kendall突变检验方法对北太平洋涛动10a际气候突变进行的研究指出,在1976年左右存在着一次明显的气候突变,而突变前后大气环流场及遥相关型均发生了显著的变化。进而研究了北太平洋涛动突变前后我国冬季天气气候的变化特征。结果表明,突变前(后),我国冬季气温一致性偏低(高),且北方地区的变化明显大于南方;而降水则呈现出长江中下游地区偏多(少)和华南偏少(多)的反相特征。此外,冬季NPO突变前,北太平洋涛动以3a和6~7a的周期为主;突变后,3a周期仍然存在,但5a和10a左右的周期开始占主导地位。 相似文献
10.
11.
12.
Huang Jiayou 《大气科学进展》2000,17(2):184-192
To reveal climatic variation over North China, the climatic jumps in summer in Beijing are analyzed using the data of precipitation of summer (June, July, August) during the period of 1841-1993, in which those missed before 1950 were reconstructed by the stepwise regression method with minimum forecast error. The climatic jumps at different scales are analyzed using different diagnostic methods with different decade (10-100 years) windows. Some new methods and ideas are proposed. The variance difference, the linear tendency difference, and the difference of power spectral distribution between the samples before and after the period at the moving point in the center of the series are compared with other methods (for example, Mann-Kendall test, t-test, and accumulative anomaly etc.). Considering the differences among the statistics above, a synthetic jump index is also proposed in order to get the definite jump points in the moving series. The results show that the climatic jumps in the area occurred in the 1890’s, the 1910s and the 1920s, and mostly in the 1920s, which suggests that the local climatic jumps in North China have a simultaneous response to the global warming in the hundred-year scales. 相似文献
13.
B. G. Hunt 《Climate Dynamics》2008,30(5):467-483
Outputs from a 10,000-year simulation with a coupled global climatic model for present climatic conditions have been used
to investigate the behaviour of the Pacific Decadal Oscillation (PDO), the North Pacific Oscillation (NPO) and related phenomena.
The analysis reveals a wide range of temporal variability for these Oscillations, suggesting that observations to date provide
only a limited sample of possible outcomes. In addition, the simulation suggests that the current observed phase relation
between the PDO and NPO may not be typical of longer-term variability. Climatic jumps appear to be a ubiquitous feature of
climatic variability, and while, as observed, the most common interval between such jumps is about 20 years, intervals of
up to 100 years occur in the simulation. The probability density functions of the PDO and NPO are very close to Gaussian,
with the PDO being represented by an auto-regressive function of order one, while the NPO consisted of white noise. An FFT
analysis of PC1 of the PDO revealed periodicities concentrated near 10 years, while for the NPO the principal periodicities
were decadal to bidecadal. Global distributions of the distributions of the correlations between PC1 or the NPO and selected
climatic variables were similar, and in agreement with observations. These correlations highlight the inter-relationships
between these two Oscillations. The above correlations were not necessarily stable in time for a given geographical point,
with transitions occurring between positive and negative extremes. Climatic jumps were identified with transitions of both
the PDO and NPO, with magnitudes of importance as regards climatic perturbations. Spatial patterns of the changes associated
with such jumps have global scales, and the need to consider the implications of these jumps in regard to greenhouse induced
climatic change is noted. 相似文献
14.
15.
1INTRODUCTIONTropicalwesternPacificOceanisanareathathasthehighestoceantemperatureacrosstheglobe.Asmostofthewarmwaterconcentratesintheregion,itisknownasthe搘esternPacificwarmpool?Asshowninsomestudies[1-5],thegeneralcirculationandshort-termclimaticchangeswillbeseriouslyaffectedifthermodynamicconditionchangesinthewaters,whichthenhaveanimportantroletoplayintheonsetofanyENSOepisodes.Therehasnotbeenanyunifieddefinitionoftheindexforthewarmpool.FollowingthecriterionofWyrtki[4],however,theareae… 相似文献
16.
Statistical series of flood/drought (F/D) grades and F/D variabilities were derived for the flood and drought chronology (2700 bc-1980 AD) of central China. Two types of climatic jumps were analyzed. The moving sign-test, T-test and F-test were applied to detect jump signals. A few wet-to-dry jumps for time-scales from decades to thousand years were compared with relevant climatic changes in other regions of the world. Changes in the annual rainfall due to jumps were estimated. Some F/D-deficient-to-F/D-frequent jumps were also found and their significance is discussed.Contribution to Clima Locarno — Past and Present Climate Dynamics; Conference September 1990, Swiss Academy of Sciences — National Climate Program 相似文献
17.
Streamflows have a direct dependence on precipitation and these are directly linked to the climate. Then, in this paper the temporal climatic variability in the Río de la Plata Basin is analysed through the changes in the river's discharges. These are the reflection of the climatic inputs areally integrated, and in consequence, contain more information on climate variability than that provided by the scarce punctual records of precipitation and temperature. The time series of streamflows correspond to monthly and annual means in stations selected in the basin for the period 1931–1992. However, in the present paper, the period 1901–1992 was considered in all cases whenever possible. The following changes and tendencies in the flow series were detected: 1. An important change of tendency between 1970 and 1972, and another not so significant before that date were detected in 1917–1918 and 1943–1944. 2. The jumps in the means in several sub-periods were detected using different methods. They showed jumps mainly in the period 1970–1972 in the annual streamflows series. The jumps in the annual streamflow series consist of an abrupt change in climatic variables affecting temporarily the averages of such variables during a certain period of time (years). The results are consistent with the conclusions obtained by other authors for the same region, both in precipitation and in the general circulation of the atmosphere. Keeping in mind this analysis of the series of streamflows, indicators of normal variability of tendencies relative to natural regional causes were detected, although the local causes were not anthropogenically analysed, and so no other manifestations of randomless in the zone of the Basin under study because of the lacking of data. 相似文献
18.
Gesa A. Weyhenmeyer 《Climatic change》2008,88(2):199-208
Evaluating trends over time (nonparametric Mann–Kendall test) for 18 water chemical variables from 79 reference lakes, distributed
all over Sweden, during spring since 1984 showed most significant trends for atmospheric deposition driven sulfate (SO4) concentrations. The decrease in SO4 concentrations was on average 2.7 times higher at lower (56°N to 59°N) than at higher latitudes (60°N to 68°N). This large
difference in the rate of change between lower and higher latitudes could not solely be explained by atmospheric deposition
as the rates of change in SO4 wet deposition differed by a factor of only 1.5 between lower and higher latitudes. Significantly higher rates of change
at lower than at higher latitudes are known from the timing of lake ice breakup, a typical climate change indicator. The rates
of change in the timing of lake ice breakup differed by a factor of 2.3 between lower and higher latitudes. Other water chemical
variables showing significantly higher rates of change at lower than at higher latitudes were water color (a factor of 3.5),
calcium (a factor of 2.9), magnesium (a factor of 5.5) and conductivity (a factor of 5.9). The rates of change of all these
variables were strongly related to the rates of change in the timing of lake ice breakup along a latitudinal gradient (R
2 = 0.41–0.78, p < 0.05), suggesting that climatic changes can accelerate atmospheric driven changes at especially lower latitudes. This acceleration
will result in more heterogeneous lake ecosystems along a latitudinal gradient. 相似文献