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基于ERA-Interim再分析资料的中国极端气温分析   总被引:1,自引:0,他引:1       下载免费PDF全文
采用中国陆域1989年-2009年3小时0.71°格点的ERA-Interim地表2 m气温预报数据,运用累积分布函数与分位数对研究区的极端低温和极端高温进行分析。结果表明:东北、青藏高原及西北地区为极端低温的集聚区,极端低温逐步沿西北-东南方向递增;青藏高原为全国极端高温中的唯一冷中心,西北盆地为最热中心;ERA-Interim再分析资料能够较好地反映中国极端低温和极端高温空间分布规律,整体上具有较好的可信度。结合分位数方法定量分析了极端气温的持续时间,为极端气候事件的定量研究提供了方法借鉴。  相似文献
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应用区域化流量历时曲线模拟无资料地区径流过程时,模拟精度常受到有资料地区径流资料长短、回归因素及推求的流量历时曲线片段长短等因素的影响。采用中周期连续时段径流资料,通过流量历时分位数回归法推求无资料地区流量历时曲线,并以此率定水文模型参数,进而实现洣水流域无资料地区降雨径流过程模拟。模拟结果表明:综合考虑多种回归因素有利于提高流量历时曲线精度;采用流量历时曲线片段也可实现模型参数率定,且随着片段延长,率定精度也相应增加;在流量历时曲线高、中、低水三类片段中,采用中水片段率定的精度相对高于仅用高水或低水片段,因此率定过程中应尽可能保留流量历时曲线中水部分片段。  相似文献
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研究了基于分位数回归的大坝变形监测预测模型,并结合实例进行分析和预报,通过与多项式模型及指数平滑法的拟合精度和预测结果的比较,证明分位数回归法有很好的拟合效果和预测精度,可以很好地应用于大坝变形监测的数据处理中.  相似文献
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摘要:水价是市场的方向标,其价格受多方因素影响。本文探讨了生活水价的影响因素,建立分位数回9-J模型,并从弹性的角度分析各个因素对生活水价的影响程度,比较了条件均值所反映的“平均水平”和不同分位数上的条件分布。结果表明:水资源费、固定资产折旧和大修理费用的变化对水价影响程度最大,水价中应适当增加人力成本,同时,需要提升人们的节水意识,提高固定资产的使用效率。  相似文献
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L-moments based regional flood frequency analysis has been carried out on the seven sites of Punjab, Pakistan. Discordancy measure in terms of L-moments has been used to screen the data on each of the seven sites. Homogeneity of the region has been tested using the L-moments based heterogeneity measure (H). H has been calculated using four parameter Kappa distribution with 500 simulations. In order to find the most suitable distribution for quantile estimates, a number of L-moments based frequency distributions, such as, generalized logistic (GLO), generalized extreme-value (GEV), generalized normal (GNO), Pearson type III (PE3), generalized Pareto (GPA) and five parameter Wakeby (WAK) distribution, have been used. Based on the L-moment ratio diagram and Z DIST statistic, three distributions; GNO, GPA and GEV have been identified as the suitable candidates for regional distribution. Accuracy measures for the estimated regional growth curves and quantiles have been calculated for the three candidate distributions, using Monte Carlo simulations. Simulations study showed that GNO distribution is the robust distribution with GPA as suitable alternative but GEV is not an appropriate distribution for the study area.  相似文献
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Global demand for freshwater has led to unprecedented levels of water abstraction from riverine systems. This has resulted in large alterations in natural river flows. The deleterious impacts of reduced flows on fish and macroinvertebrate abundances have been thoroughly investigated; in contrast, there is a limited understanding of the potential for changes in the abundance of nuisance benthic algal/cyanobacterial blooms. In New Zealand, Phormidium sp. blooms are common in numerous rivers during summer low flows. In this study, an in‐stream habitat assessment is used to examine the relationship between Phormidium habitat availability and reducing flows. Over 650 observations of Phormidium mats, from seven sites (Hutt River, lower North Island, New Zealand), were used to construct habitat suitability curves for depth, velocity and substrate. Preference curves were fitted using both the ‘forage ratio’ and ‘quantile regression’ methods. Phormidium growth, observed at all seven sites, increased significantly from upstream (uppermost site, 5.2% mat cover) to downstream (63.5%). The habitat suitability curves revealed Phormidium had a large tolerance to velocity, depth and substrate type. Consequently, decreases in flow had only negligible effects on available Phormidium habitat. During periods of stable flow, Phormidium abundance positively correlated with increased nitrogen concentrations, potentially explaining the large variation in Phormidium cover from upstream to downstream. Quantile regression generated habitat suitability criteria were a more accurate predictor of available Phormidium habitat than the forage ratio criteria. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献
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