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Climate extremes, such as extreme hot temperatures and heat waves, can have dramatic societal, economic, and ecological consequences. China has experienced remarkable interannual and decadal changes in hot extremes during the last several decades. However, the underlying mechanisms responsible for changes in the hot extremes over China have not been clearly identified. In this study, we investigate the role of land-atmosphere coupling for hot days and heat waves during summer over China using two long-term ... 相似文献
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程细玉 《华侨大学学报(自然科学版)》1998,(2):115-117
利用随机变量变换,分别在完全样本和第Ⅱ型截尾样本的情形下,得到一个求极值Ⅰ型变异系数的置信限的一个简便而有效的办法. 相似文献
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程士宏 《北京大学学报(自然科学版)》2000,36(1):8-19
设{(Xn,Yn)}是i.i.d.随机向量序列,共同d.f.为F。本文在更弱的条件下证明了An-1(Y(n, n)-Bn)→I对某准d.f.I成立,从而推广了Nagaraja和David的结果。此外还指出:对于(an-1(Xn, n-bn),An-1(Y(n, n)-Bn))的联合分布的弱收敛,本文的条件不仅充分,而且必要。最后,揭露了二元极值弱收敛与(an-1 (Xn, n-bn), An-1 (Y(n, n)-Bn))的联合分布弱收敛之间的紧密联系。 相似文献
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利用广东省各主要河流的20个水文站的年最高水位资料,采用皮尔逊—Ⅲ型分布理论和适线法进行重现期的极值计算分析。结果表明,采用这种方法拟合效果较好,大多数站点的绝对误差小于0.4m,相对误差小于5%;不管从现有资料分析,还是从多年一遇的极值分析,北江、东江、西江的极值距平值均较大,重现期T=100a时半数站点的极值距平值在6.0m以上,其中西江流域的梧州站极值距平值最大达8.04m。因此,北江、西江、东江是广东省防洪的重点流域。 相似文献
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水资源是维持内陆河流域复合生态系统的重要纽带.大气降水作为流域水资源的重要来源,其时空分布及强度变化会对流域生态水文过程有着重要影响.本文以河西走廊内陆河流域19个气象站1960—2012年逐日降水资料为基础,构建了最大1d降水量、最大连续5d降水量和非常湿天降水总量等极端降水指标,通过采用多种极值概率分布模型探讨研究区极端降水指标在频次、强度和贡献率方面的变化,从而为分析极端降水对流域生态水文过程的影响提供科学依据.结果表明,基于GEV最优概率分布模型,得出研究区超过5年一遇的最大1d降水量、最大连续5d降水量、非常湿天降水总量近年来发生次数有所增加,尤其是2000年以后增加更为明显;研究区极端降水强度在2000年以后也明显增强;在极端降水量对年降水总量的贡献率方面,近年来石羊河流域总体呈现增加趋势,黑河流域上游呈现增加趋势、中游和下游以下降趋势为主,疏勒河流域上游和下游呈现增加趋势,中游则以下降趋势为主. 相似文献
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Land-atmosphere coupling amplifies hot extremes over China 总被引:3,自引:0,他引:3
Climate extremes, such as extreme hot temperatures and heat waves, can have dramatic societal, economic, and ecological consequences. China has experienced remarkable interannual and decadal changes in hot extremes during the last several decades. However, the underlying mechanisms responsible for changes in the hot extremes over China have not been clearly identified. In this study, we investigate the role of land-atmosphere coupling for hot days and heat waves during summer over China using two long-term Weather Research and Forecasting model simulations with and without interactive soil moisture. Results indicate that land-atmosphere coupling mainly amplifies hot extremes over China. In particular, significant amplifying effects appear over most of eastern and southwestern China. Over these areas, land-atmosphere coupling generally accounts for 30%-70% of the numbers of hot days and heat waves. This study highlights the critical importance of land-atmosphere interactions for the occurrence of hot extremes over China. 相似文献
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基于已经积累的大量数据,结合生产科研实际,应用数据库技术与极值统计法,设计开发了辽阳石油化纤公司关键设备腐蚀信息管理系统,该系统实现了对关键设备腐蚀图文信息的综合管理,并提供了一个内嵌的数据库管理系统,以完成对实验数据的管理,此外,系统引入极值统计法,用于进行设备腐蚀寿命的预测,为设备的维修,更换提供科学依据。 相似文献
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Climate extremes and changes in eastern China are closely related to variations of the East Asian summer monsoon and corresponding atmospheric circulations.The relationship between frequencies of temperature and precipitation extremes in China during the last half century is investigated using Singular Value Decomposition analysis.During 1980-1996,there was a typical pattern with fewer hot days and more precipitation extremes in the northern part of eastern China,and more hot days and fewer precipitation extremes in the southern part.This geographic pattern tended to reverse after 1997,with fewer hot days and more extreme precipitation days south of the Yangtze River and vice versa to the north.Differences in atmospheric circulation between the former and latter periods are presented.We conclude that a mid-level anomalous high/low,upper-level anomalous easterlies/westerlies over the north/south of eastern China,a weakened East Asian summer monsoon and associated upper-tropospheric center of cooling(30°N,110°E) are all favorable for the changes in frequencies of temperature and precipitation extremes. 相似文献