Facies analysis of the Middle and Late Quaternary sediment infill of the northern Weihe Basin,Central China          下载免费PDF全文

Daniël S. Rits  Maarten A. Prins  Simon R. Troelstra  Ronald T. van Balen  Yan Zheng  Christiaan J. Beets  Bin Wang  Xiaoqiang Li  Jie Zhou  Hongbo Zheng 《第四纪科学杂志》2016,31(2):152-165

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Challenges of tracking extratropical cyclones in regional climate models     

Hélène Côté  Kevin M. Grise  Seok-Woo Son  Ramón de Elía  Anne Frigon 《Climate Dynamics》2015,44(11-12):3101-3109

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Intensification of Southern Hemisphere westerly winds 2000–1000 years ago: evidence from the subantarctic Campbell and Auckland Islands (52–50°S)          下载免费PDF全文

Chris S. M. Turney  Matt McGlone  Jonathan Palmer  Christopher Fogwill  Alan Hogg  Zoë A. Thomas  Mathew Lipson  Janet M. Wilmshurst  Pavla Fenwick  Richard T. Jones  Ben Hines  Graeme F. Clark 《第四纪科学杂志》2016,31(1):12-19

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Dynamics of the January 2013–June 2014 explosive-effusive episode in the eruption of Volcán de Colima,México: insights from seismic and video monitoring     

Vyacheslav M. Zobin  Raúl Arámbula  Mauricio Bretón  Gabriel Reyes  Imelda Plascencia  Carlos Navarro  Armando Téllez  Arnoldo Campos  Miguel González  Zoraida León  Alejandro Martínez  Carlos Ramírez 《Bulletin of Volcanology》2015,77(4):1-13

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Rain on snow induced urban floods in cold maritime climate: Risk,indicators and trends     

Hrund Ólöf Andradóttir  Anna Rut Arnardóttir  Tarek Zaqout 《水文研究》2021,35(9):e14298

Urban floods pose a societal and economical risk. This study evaluated the risk and hydro-meteorological conditions that cause pluvial flooding in coastal cities in a cold climate. Twenty years of insurance claims data and up to 97 years of meteorological data were analysed for Reykjavík, Iceland (64.15°N; <100 m above sea level). One third of the city's wastewater collection system is combined, and pipe grades vary from 0.5% to 10%. Results highlight semi-intensive rain (<7 mm/h; ≤3 year return period) in conjunction with snow and frozen ground as the main cause for urban flood risk in a climate which undergoes frequent snow and frost cycles (avg. 13 and 19 per season, respectively). Floods in winter were more common, more severe and affected a greater number of neighbourhoods than during summer. High runoff volumes together with debris remobilized with high winds challenged the capacity of wastewater systems regardless of their age or type (combined vs. separate). The two key determinants for the number of insurance claims were antecedent frost depth and total precipitation volume per event. Two pluvial regimes were particularly problematic: long duration (13–25 h), late peaking rain on snow (RoS), where snowmelt enhanced the runoff intensity, elongated and connected independent rainfall into a singular, more voluminous (20–76 mm) event; shorter duration (7–9 h), more intensive precipitation that evolved from snow to rain. Closely timed RoS and cooling were believed to trigger frost formation. A positive trend was detected in the average seasonal snow depth and volume of rain and snowmelt during RoS events. More emphasis, therefore, needs to be placed on designing and operating urban drainage infrastructure with regard to RoS co-acting with frozen ground. Furthermore, more detailed, routine monitoring of snow and soil conditions is important to predict RoS flood events.  相似文献   

Analysis of the interannual variability of annual daily extreme water levels in the St Lawrence River and Lake Ontario from 1918 to 2010          下载免费PDF全文

Ali A. Assani  Raphaëlle Landry  Stacey Biron  Jean‐Jacques Frenette 《水文研究》2014,28(13):4011-4022

We compared the interannual variability of annual daily maximum and minimum extreme water levels in Lake Ontario and the St Lawrence River (Sorel station) from 1918 to 2010, using several statistical tests. The interannual variability of annual daily maximum extreme water levels in Lake Ontario is characterized by a positive long‐term trend showing two shifts in mean (1929–1930 and 1942–1943) and a single shift in variance (in 1958–1959). In contrast, for the St Lawrence River, this interannual variability is characterized by a negative long‐term trend with a single shift in mean, which occurred in 1955–1956. As for annual daily minimum extreme water levels, their interannual variability shows no significant long‐term change in trend. However, for Lake Ontario, the interannual variability of these water levels shows two shifts in mean, which are synchronous with those for maximum water levels, and a single shift in variance, which occurred in 1965–1966. These changes in trend and stationarity (mean and variance) are thought to be due to factors both climatic (the Great Drought of the 1930s) and human (digging of the Seaway and construction of several dams and locks during the 1950s). Despite this change in means and variance, the four series are clearly described by the generalized extreme value distribution. Finally, annual daily maximum and minimum extreme water levels in the St Lawrence and Lake Ontario are negatively correlated with Atlantic multidecadal oscillation over the period from 1918 to 2010. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

External controls on the distribution,fabrics and mineralization of modern microbial mats in a coastal hypersaline lagoon,Cayo Coco (Cuba)   总被引：1，自引：0，他引：1       下载免费PDF全文

Anthony Bouton  Emmanuelle Vennin  Aurélie Pace  Raphaël Bourillot  Christophe Dupraz  Christophe Thomazo  Arnaud Brayard  Guy Désaubliaux  Pieter T. Visscher 《Sedimentology》2016,63(4):972-1016

Active, carbonate‐mineralizing microbial mats flourish in a tropical, highly evaporative, marine‐fed lagoonal network to the south of Cayo Coco Island (Cuba). Hypersaline conditions support the development of a complex sedimentary microbial ecosystem with diverse morphologies, a variable intensity of mineralization and a potential for preservation. In this study, the role of intrinsic (i.e. microbial) and extrinsic (i.e. physicochemical) controls on microbial mat development, mineralization and preservation was investigated. The network consists of lagoons, forming in the interdune depressions of a Pleistocene aeolian substratum; they developed due to a progressive increase in sea‐level since the Holocene. The hydrological budget in the Cayo Coco lagoonal network changes from west to east, increasing the salinity. This change progressively excludes grazers and increases the saturation index of carbonate minerals, favouring the development and mineralization of microbial mats in the easternmost lagoons. Detailed mapping of the easternmost lagoon shows four zones with different flooding regimes. The microbial activity in the mats was recorded using light–dark shifts in conjunction with microelectrode O₂ and HS^? profiles. High rates of O₂ production and consumption, in addition to substantial amounts of exopolymeric substances, are indicative of a potentially strong intrinsic control on mineralization. Seasonal, climate‐driven water fluctuations are key for mat development, mineralization, morphology and distribution. Microbial mats show no mineralization in the permanently submersed zone, and moderate mineralization in zones with alternating immersion and exposure. It is suggested that mineralization is also driven by water‐level fluctuations and evaporation. Mineralized mats are laminated and consist of alternating trapping and binding of grains and microbially induced magnesium calcite and dolomite precipitation. The macrofabrics of the mats evolve from early colonizing Flat mats to complex Cerebroid or Terrace structures. The macrofabrics are influenced by the hydrodynamic regime: wind‐driven waves inducing relief terraces in windward areas and flat morphologies on the leeward side of the lagoon. Other external drivers include: (i) storm events that either promote (for example, by bioclasts covering) or prevent (for example, by causing erosion) microbial mat preservation; and (ii) subsurface degassing, through mangrove roots and desiccation cracks covered by Flat mats (i.e. forming Hemispheroids and Cerebroidal structures). These findings provide in‐depth insights into understanding fossil microbialite morphologies that formed in lagoonal settings.  相似文献   

Analysis of extreme rainfall in the Ebre Observatory (Spain)     

Núria Pérez-Zanón  M. Carmen Casas-Castillo  Raúl Rodríguez-Solà  Juan Carlos Peña  Anna Rius  J. Germán Solé  Ángel Redaño 《Theoretical and Applied Climatology》2016,124(3-4):935-944

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An Alternative Protocol for Single Zircon Dissolution with Application to (U‐Th‐Sm)/He Thermochronometry          下载免费PDF全文

Bouchaïb Tibari  Arnaud Vacherat  Martin Stab  Raphaël Pik  Delphine Yeghicheyan  Pascal Hild 《Geostandards and Geoanalytical Research》2016,40(3):365-375

Zircon (U‐Th‐Sm)/He (ZHe) thermochronometry is a powerful tool that has been widely used in geology to constrain the exhumation histories of orogens. In this study, we present an alternative protocol for dissolving zircon grains for determination of parent nuclides. This new alkali fusion procedure developed at the SARM (Service d'Analyse des Roches et des Minéraux) in Nancy, France, is fast (requiring only 2 d, including cleaning steps) and offers several advantages over conventional methods by avoiding: (i) use of HF pressure dissolution and (ii) complete removing of grains from the metal microvials. After dissolution, U, Th and Sm were measured using an ICP‐MS. We tested the new procedure on two different ZHe reference materials, the Fish Canyon Tuff and Buluk Tuff; these provided precision values for ZHe‐age estimations of 9 and 6% (1s), respectively. In addition, using this method, zircons from the Buluk Tuff are shown to be chemically more homogenous and more suitable for assessing the uncertainty of the entire integrated procedure.  相似文献   

Identifying influence areas with connectivity analysis – application to the local perturbation of heterogeneity distribution for history matching     

Véronique Gervais  Mickaële Le Ravalec 《Computational Geosciences》2018,22(1):3-28

Numerical representations of a target reservoir can help to assess the potential of different development plans. To be as predictive as possible, these representations or models must reproduce the data (static, dynamic) collected on the field. However, constraining reservoir models to dynamic data – the history-matching process – can be very time consuming. Many uncertain parameters need to be taken into account, such as the spatial distribution of petrophysical properties. This distribution is mostly unknown and usually represented by millions of values populating the reservoir grid. Dedicated parameterization techniques make it possible to investigate many spatial distributions from a small number of parameters. The efficiency of the matching process can be improved from the perturbation of specific regions of the reservoir. Distinct approaches can be considered to define such regions. For instance, one can refer to streamlines. The leading idea is to identify areas that influence the production behavior where the data are poorly reproduced. Here, we propose alternative methods based on connectivity analysis to easily provide approximate influence areas for any fluid-flow simulation. The reservoir is viewed as a set of nodes connected by weighted links that characterize the distance between two nodes. The path between nodes (or grid blocks) with the lowest cumulative weight yields an approximate flow path used to define influence areas. The potential of the approach is demonstrated on the basis of 2D synthetic cases for the joint integration of production and 4D saturation data, considering several formulations for the weights attributed to the links.  相似文献