共查询到16条相似文献，搜索用时 140 毫秒
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定量反演降水及其在青藏高原东北边缘地区面雨量估算中的应用 总被引：1，自引：0，他引：1
雷达-雨量计联合校准降水结合了雷达区域覆盖和雨量计单点精度高的优势, 利用雷达进行区域降水量估计是提高雷达应用能力的重要方向之一. 通过利用在青藏高原东北边坡地区的雷达回波-降水反演关系式, 对2012年5月10日的这一地区的一次区域性强降水过程进行反演比较, 并利用平均校准法、 最优插值法和用卡尔曼滤波确定变分系数的变分-卡尔曼滤波进行空间校准. 结果表明:利用最优化法得到的本地降水反演关系式效果要明显优于其他波段或地域的固有关系式, 可以有效改变过低估计的状况; 变分-卡尔曼滤波由于考虑了雷达区域扫描的优势, 校准效果最好, 可以细致反映空间降水分布, 对降水预报、 地质灾害预警等都有重要意义.通过建立多仰角多变量的降水关系式, 并进一步对反演结果采用有效的数学校正法可能会对空间面雨量估测取得更好的效果. 相似文献
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P-III型分布已被众多学者广泛应用于降水量的拟合,且效果良好,而降雨Z指数恰好假设某一时段的降水量服从这一分布,并且计算简便,结果比较符合实际,是反应旱涝分布及程度的一种常见的方法。在实际应用中,由于各区域降水的特征,导致结果不符合实际情况,需对其进行修正。从此角度出发,从我国七个区(华北、华中、华东、华南、东北、西北和西南地区)选取各区代表站的年降水量资料,分析了代表性站点降水频率特性,并对Z指数等级界限值进行修正。结果表明:由于各区域降水特性的差异,Z指数界限值有所不同,尤其华东、华南两区与其他区域差异较明显,由此推测我国降水在空间上存在差异。 相似文献
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青藏高原由于降水观测点分布等原因一直是水文和气候研究的薄弱环节。2005年5~10月在青藏高原唐古拉山中部冬克玛底河流域进行连续的人工气象观测。观测期间根据不同降水类型和气温之间的相关关系,采用气温2.7℃为临界值对降水类型进行了划分,利用已有的T-200B型自动雨雪量计和普通雨量计的修正公式,并在日尺度基础上对降水进行了修正对比。经过修正,中游T-200B型雨量站全年降水量662.1 mm;普通雨量计全年降水量为657.2 mm;2005年修正后的降水量相比1993年观测到的降水量472 mm增加了近200 mm。结果表明在高寒山区降水观测,依据同步观测的气温划分降水类型,可以根据相关修正公式修正T-200B型自动雨雪量计和普通雨量计降水观测值。从而能够在高寒山区恶劣的自然环境自动连续准确的观测高寒区域的降水。 相似文献
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基于气象站观测数据,利用探测率(POD)、报错率(FAR)、临界成功系数(CSI)和相关系数(R)、平均绝对误差(MAE)对TRMM 3B42V7、CMORPH、PERSIANN、PERSIANN-CDR遥感降水资料在青海湖流域及周边区域探测降水事件的准确度和记录降水量的精度进行了评价。结果表明,CMORPH数据探测的降水事件最为准确,PERSIANN-CDR和TRMM 3B42次之,PERSIANN探测降水事件的准确度最差。从遥感数据记录降水量精度来看,年尺度上表现为TRMMCMORPHPERSIANN-CDRPERSIANN,月尺度上表现为TRMMPERSIANN-CDRCMORPHPERSIANN,日尺度上表现为TRMM CMORPHPERSIANN-CDRPERSIANN。海拔是影响遥感降水资料精度的重要因素,PERSIANN和PERSIANN-CDR两种数据误差受海拔影响更为明显。通过综合评估4种遥感资料的适用性,认为TRMM是较适合于青海湖流域及周边区域的降水资料。 相似文献
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四川盆地降水日变化特征分析和个例模拟 总被引：2，自引：0，他引：2
利用台站观测降水资料,分析四川盆地及周边地区降水分布和日变化特征,得到以下结论:四川地区降水存在2个高值中心,均位于盆地周围的山地;盆地降水"夜雨"特征明显;川西高原降水峰值以午夜前降水量的贡献为主;盆中与盆地西南边缘山地的降水峰值由夜间降水量与降水频率共同作用;盆地东北边缘的山地是午前降水频率与后半夜的降水量均有贡献。其次,结合WRF模式的数值试验,对2008年9月23～24日发生在盆地的夜间暴雨过程进行模拟研究和综合分析。结果表明WRF模式较好地模拟了此次天气过程降水的空间分布和日变化规律,通过分析模拟的环流场与温湿场发现,夜雨的形成与大尺度环流场的影响和地形强迫关系密切。 相似文献
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高精度降雨监测雷达设备为获取精细化的流域面雨量信息提供了高新技术设备解决方案。其方法是利用物体对电磁波的散射作用来对面降雨量进行监测。对其组成和应用效果做出初步探讨,给出一个用常规雨量计所得到的累积降水量与测雨雷达收集得到的降水量比较,对雨量计算中各类方法的优缺点进行应用分析,总结技术应用成果并辅以案例说明。高精度降雨雷达设备以较高的时空分辨率,获取较大面积的测量数据,并能迅速更新降水的三维结构,将逐步成为广泛应用的高新技术设备。 相似文献
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开展降雨型黄土滑坡预警对于区域性防治滑坡具有重要意义。本研究在收集1985~2015年兰州市降雨型黄土滑坡历史数据的基础上,运用反距离权重插值(IDW)和核密度估算(KDE)方法揭示了降雨引发黄土滑坡的时空分布规律。该文基于统计学的基本原理,运用相关性和偏相关性等方法建立适合兰州市的有效降雨量模型。通过拟合有效降雨量与滑坡因子的线性回归关系,确定引发黄土滑坡的临界降雨量阈值,设定兰州市黄土滑坡的降雨量危险性预警等级。研究表明:(1)兰州市黄土滑坡灾害点沿着黄河及其支流沿岸分布,城关区滑坡点最多且呈环形分布,西固区次之,其他地区分布较少;(2)降雨是兰州市及其周边地区黄土滑坡的关键诱因,10d有效降雨量与滑坡因子均呈现显著正相关特性,其相关系数达到0.698;(3)依据10mm、20mm和40mm临界降雨量阈值将预警等级划分为低、中、高3个危险性等级。 相似文献
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《Atmósfera》2014,27(1):47-60
Lack of data in maximum daily rainfall frequency analysis can generate ineffcient estimates for design purposes. An approach to diminish these errors is to apply regional estimation techniques, which require that all stations be located at the same homogeneous region. In this paper, a delineation of homogeneous precipitation regions was made based on the multivariate methods of principal component analysis and hierarchical ascending clustering. A region in northwestern Mexico was selected to apply this methodology. It was concluded that only the coeffcients of variation of the L-moments, along with latitude, longitude and altitude at each climatological station are sufficient to define the homogeneous rainfall regions, and that either the inclusion or exclusion of information in the regional techniques has a direct impact on the estimation of events associated to different return periods. 相似文献
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Precipitation is a key input variable for hydrological and climate studies. Rain gauges can provide reliable precipitation measurements at a point of observations. However, the uncertainty of rain measurements increases when a rain gauge network is sparse. Satellite-based precipitation estimations SPEs appear to be an alternative source of measurements for regions with limited rain gauges. However, the systematic bias from satellite precipitation estimation should be estimated and adjusted. In this study, a method of removing the bias from the precipitation estimation from remotely sensed information using artificial neural networks-cloud classification system (PERSIANN-CCS) over a region where the rain gauge is sparse is investigated. The method consists of monthly empirical quantile mapping of gauge and satellite measurements over several climate zones as well as inverse-weighted distance for the interpolation of gauge measurements. Seven years (2010–2016) of daily precipitation estimation from PERSIANN-CCS was used to test and adjust the bias of estimation over Saudi Arabia. The first 6 years (2010–2015) are used for calibration, while 1 year (2016) is used for validation. The results show that the mean yearly bias is reduced by 90%, and the yearly root mean square error is reduced by 68% during the validation year. The experimental results confirm that the proposed method can effectively adjust the bias of satellite-based precipitation estimations. 相似文献
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《Atmósfera》2014,27(4):411-427
Daily extreme precipitation values are among environmental events with the most disastrous consequences for human society. Information on the magnitudes and frequencies of extreme precipitations is essential for sustainable water resources management, planning for weather-related emergencies, and design of hydraulic structures. In the present study, regional frequency analysis of maximum daily rainfalls was investigated for Golestan province located in the northeastern Iran. This study aimed to find appropriate regional frequency distributions for maximum daily rainfalls and predict the return values of extreme rainfall events (design rainfall depths) for the future. L-moment regionalization procedures coupled with an index rainfall method were applied to maximum rainfall records of 47 stations across the study area. Due to complex geographic and hydro-climatological characteristics of the region, an important research issue focused on breaking down the large area into homogeneous and coherent sub-regions. The study area was divided into five homogeneous regions, based on the cluster analysis of site characteristics and tests for the regional homogeneity. The goodness-of-fit results indicated that the best fitting distribution is different for individual homogeneous regions. The difference may be a result of the distinctive climatic and geographic conditions. The estimated regional quantiles and their accuracy measures produced by Monte Carlo simulations demonstrate that the estimation uncertainty as measured by the RMSE values and 90% error bounds is relatively low when return periods are less than 100 years. But, for higher return periods, rainfall estimates should be treated with caution. More station years, either from longer records or more stations in the regions, would be required for rainfall estimates above T=100 years. It was found from the analyses that, the index rainfall (at-site average maximum rainfall) can be estimated reasonably well as a function of mean annual precipitation in Golestan province. Index rainfalls combined with the regional growth curves, can be used to estimate design rainfalls at ungauged sites. Overall, it was found that cluster analysis together with the L-moments based regional frequency analysis technique could be applied successfully in deriving design rainfall estimates for northeastern Iran. The approach utilized in this study and the findings are of great scientific and practical merit, particularly for the purpose of planning for weather-related emergencies and design of hydraulic engineering structures. 相似文献
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Regional frequency analysis of extreme precipitation and its spatio-temporal characteristics in the Huai River Basin, China 总被引：1，自引：1，他引：0
With the increasing exposure of populations and economy to natural hazards, the spatio-temporal characteristics of extreme rainfall remain a key subject of study. Based on annual maximum rainfall (AM) and peaks over threshold rainfall series at 30 meteorological stations during 1960–2011 in the Huai River Basin (HRB), spatio-temporal characteristics of extreme rainfall are analyzed through regional frequency analysis method using L-moments. The accuracy and uncertainty analysis of quantile estimations are also carried out, and the regional and at-site frequency analyses are compared. Results indicate the following: (1) During 1960–2011, AM precipitation at 20 stations in the HRB shows an increasing trend, while at the other 10 stations, it shows a decreasing trend. And both the increased and decreased trends are not significant. (2) The HRB can be categorized into three homogeneous regions via cluster analysis. For both at-site and regional frequency analyses, the root mean square error values increase with the increase in return periods. The estimations are reliable enough for the return periods of less than 100 years. The quantile estimates of large return period from regional frequency analysis are more accurate and have smaller uncertainty than those from at-site frequency analysis. (3) Extreme precipitation in the HRB concentrates in the upstream of the Huai River and YiShuSi water system in the east of the HRB. Generally, the area with extreme precipitation, especially the upper reaches of the Huai River and Yimeng Mountain areas, also has large standard variations of extreme precipitation, which will increase the risk of natural hazards. 相似文献
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Spatio-temporal variations in precipitation are affecting agricultural production in China in the context of climate change. Based on daily precipitation data from 63 national meteorological stations on the Huang-Huai-Hai Plain from 1963 to 2012, this paper analysed the spatio-temporal variations in precipitation in terms of precipitation days and intensity, using spatial interpolation, linear trend estimation and wavelet analysis. The results indicated that: (i) from 1963 to 2012, the number of annual precipitation days and intensity decreased gradually from the southeast to the northwest. Additionally, the distribution of the extreme precipitation index was similar to that of the annual precipitation index; (ii) the number of annual precipitation days and heavy precipitation days gradually decreased, while precipitation intensity and extreme precipitation days and extreme rainfall intensity remained relatively stable or decreased. The spatial patterns of annual variation trends were considerably different. The annual precipitation days and intensity trends are consistent with the overall trend, while that of the extreme rainfall index in some regions differs from the overall trend; (iii) the precipitation index displayed different periodic oscillations during the period, and the precipitation index values differed at different time scales. However, all the precipitation index values exhibited a 28-yr oscillation. 相似文献