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Gabriel Kuhn Shiraj Khan Auroop R. Ganguly Marcia L. Branstetter 《Advances in water resources》2007,30(12):2401-2423
A quantification of the spatio-temporal dependence among precipitation extremes is important for investigating the properties of intense storms as well as flood or flash-flood related hazards. Extreme value theory has been widely applied to the hydrologic sciences and hydraulic engineering. However, rigorous approaches to quantify dependence structures among extreme values in space and time have not been reported in the literature. Previous researchers have quantified the dependence among extreme values through the concept of (pairwise bivariate) tail dependence coefficients. For estimation of the tail dependence coefficients, we apply a recently developed method [Kuhn G. On dependence and extremes. PhD thesis (Advisor: C. Klüppelberg), Munich University of Technology, 2006] which utilized the multivariate tail dependence function of a subclass of elliptical copulas. This study extends the previous approach in the context of space and time by considering pairs of spatial grids in South America and quantifying the dependence among precipitation extremes based on the time series at each spatial grid. In addition, Kendall’s τ is used to estimate the pairwise copula correlation (for an elliptical copula) of precipitation between all grids in South America. The geospatial–temporal dependence measures are applied to precipitation observations from 1940 to 2005 as well as simulations from the Community Climate System Model version 3 (CCSM3) for 1940–2099. New insights are obtained regarding the spatio-temporal dependence structures for precipitation over South America both with regard to correlation as well as tail dependence. 相似文献
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Semantically aligning the heterogeneous geospatial datasets (GDs) produced by different organizations demands efficient similarity matching methods. However, the strategies employed to align the schema (concept and property) and instances are usually not reusable, and the effects of unbalanced information tend to be neglected in GD alignment. To solve this problem, a holistic approach is presented in this paper to integrally align the geospatial entities (concepts, properties and instances) simultaneously. Spatial, lexical, structural and extensional similarity metrics are designed and automatically aggregated by means of approval voting. The presented approach is validated with real geographical semantic webs, Geonames and OpenStreetMap. Compared with the well-known extensional-based aligning system, the presented approach not only considers more information involved in GD alignment, but also avoids the artificial parameter setting in metric aggregation. It reduces the dependency on specific information, and makes the alignment more robust under the unbalanced distribution of various information. 相似文献
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我国数字地理空间框架建设的形势与任务 总被引：1，自引：1，他引：0
数字地理空间框架建设是构建数字中国的重要基础性工作,是测绘部门面临的紧迫任务。本文总结了"十一五"以来数字地理空间框架建设取得的主要进展,分析了存在的主要问题和面临的机遇挑战,研究提出了下一步数字地理空间框架建设的基本思路、主要任务和对策措施。 相似文献
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We reply to Gwilym Eades’s (2010) criticisms by emphasizing the dangers of predestined readings and restating three key points that we made in our previous article (Kingsbury and Jones, 2009): first, that Apollo and Dionysus are mutually affirming rather than oppositional; second, that Walter Benjamin provides valuable theoretical resources to consider the uncertainties and possibilities of technology; and third, that one cannot simply read politics off technology. 相似文献
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An assessment of socioeconomic-environmental vulnerability of the ten major river basins in the Monsoon Asia-Pacific region was performed. The rivers include Indus, Ganges-Brahmaputra-Meghna (GBM), Irrawaddy, Salween, Chao Phraya, Mekong, Red River, Pearl River, Yangtze and Yellow River. The study looked at a combination of various issues, usually investigated in isolation from each other, on a sub-continental scale by using the river basins as the geographical entities for the study. The analysis was conducted by using various geospatial databases including data on nature and environment, demography, governance, water scarcity as well as social and economic development. A vulnerability profile for each of the river basins was produced by using two different approaches. We found that the South Asian basins (Indus and GBM) appeared essentially more vulnerable than the other investigated basins. The other basins are roughly at the same vulnerability level, but their vulnerability profiles differ substantially. The Chinese basins and the Red River are particularly vulnerable to environmental factors. The weak points of Irrawaddy and Salween are in the hazards and economic development, whereas the former is a challenge to Mekong as well. Only Indus and Yellow River suffer from considerable water scarcity. The other basins except GBM are relatively well-off with the social matters. A transparent and pragmatic river basin vulnerability assessment approach was developed, which can be used in any large river basin of the world, producing intercomparable results. The approach allows further decoupling of the used indices in the case of more specific and targeted analyses without losing the comparability of the overall results. 相似文献
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地形图与Geodatabase转换的探讨 总被引：1，自引：1，他引：0
探讨了如何将日常测绘的地形图快速地转入Geodatabase,有效维护基础地理信息系统的现势性;分析了常规转换方法的弊端,结合生产需要,总结出实际工作中可行的解决方案。 相似文献
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《International Journal of Digital Earth》2013,6(9):923-943
ABSTRACTLinked Data is known as one of the best solutions for multisource and heterogeneous web data integration and discovery in this era of Big Data. However, data interlinking, which is the most valuable contribution of Linked Data, remains incomplete and inaccurate. This study proposes a multidimensional and quantitative interlinking approach for Linked Data in the geospatial domain. According to the characteristics and roles of geospatial data in data discovery, eight elementary data characteristics are adopted as data interlinking types. These elementary characteristics are further combined to form compound and overall data interlinking types. Each data interlinking type possesses one specific predicate to indicate the actual relationship of Linked Data and uses data similarity to represent the correlation degree quantitatively. Therefore, geospatial data interlinking can be expressed by a directed edge associated with a relation predicate and a similarity value. The approach transforms existing simple and qualitative geospatial data interlinking into complete and quantitative interlinking and promotes the establishment of high-quality and trusted Linked Geospatial Data. The approach is applied to build data intra-links in the Chinese National Earth System Scientific Data Sharing Network (NSTI-GEO) and data -links in NSTI-GEO with the Chinese Meteorological Data Network and National Population and Health Scientific Data Sharing Platform. 相似文献