Stratosphere key for wintertime atmospheric response to warm Atlantic decadal conditions   总被引：1，自引：1，他引：0  

N.-E. Omrani  N. S. Keenlyside  Jürgen Bader  Elisa Manzini 《Climate Dynamics》2014,42(3-4):649-663

There is evidence that the observed changes in winter North Atlantic Oscillation (NAO) drive a significant portion of Atlantic Multi Decadal Variability (AMV). However, whether the observed decadal NAO changes can be forced by the ocean is controversial. There is also evidence that artificially imposed multi-decadal stratospheric changes can impact the troposphere in winter. But the origins of such stratospheric changes are still unclear, especially in early to mid winter, where the radiative ozone-impact is negligible. Here we show, through observational analysis and atmospheric model experiments, that large-scale Atlantic warming associated with AMV drives high-latitude precursory stratospheric warming in early to mid winter that propagates downward resulting in a negative tropospheric NAO in late winter. The mechanism involves stratosphere/troposphere dynamical coupling, and can be simulated to a large extent, but only with a stratosphere resolving model (i.e., high-top). Further analysis shows that this precursory stratospheric response can be explained by the shift of the daily extremes toward more major stratospheric warming events. This shift cannot be simulated with the atmospheric (low-top) model configuration that poorly resolves the stratosphere and implements a sponge layer in upper model levels. While the potential role of the stratosphere in multi-decadal NAO and Atlantic meridional overturning circulation changes has been recognised, our results show that the stratosphere is an essential element of extra-tropical atmospheric response to ocean variability. Our findings suggest that the use of stratosphere resolving models should improve the simulation, prediction, and projection of extra-tropical climate, and lead to a better understanding of natural and anthropogenic climate change.  相似文献   

The Italian strong motion network   总被引：2，自引：2，他引：0  

Antonella Gorini  Mario Nicoletti  Paolo Marsan  Riccardo Bianconi  Rita De Nardis  Luisa Filippi  Sandro Marcucci  Franco Palma  Elisa Zambonelli 《Bulletin of Earthquake Engineering》2010,8(5):1075-1090

The Italian Strong Motion Network is a permanent monitoring system run by the Italian national emergency management department (Dipartimento della Protezione Civile, DPC). The network is known as RAN (Rete Accelerometrica Nazionale). An extensive project for updating and improving the technology of RAN instruments as well as the number of recording points was performed in the last 10 years. A wide site selection survey was carried out from eastern Sicily along the Italian peninsula, covering high seismic risk areas. The recording station density and the choice of high-quality digital strong motion instruments ensure reliability of the RAN network in the long-term. At the end of 2008, the free field sites selection and instruments installation, planned in the project, were quite completed. In planning and drawing the new RAN, special attention has been devoted to the robustness of the transmission systems, and to the distribution of new stations in order to ensure plenty of data during a seismic emergency. We spent special care both in the estimation of the RAN site responses and in the diffusion of the strong motion data. In order to better identify damaged earthquake areas, improved ground motion parameters need to be set. Such parameters will also assist future progress for engineering seismic design techniques as well as disaster mitigation.  相似文献   

A new approach to define surface/sub-surface transition in gravel beds   总被引：1，自引：1，他引：0  

Heather Haynes  Anne-Marie Ockelford  Elisa Vignaga  William M. Holmes 《Acta Geophysica》2012,60(6):1589-1606

The vertical structure of river beds varies temporally and spatially in response to hydraulic regime, sediment mobility, grain size distribution and faunal interaction. Implicit are changes to the active layer depth and bed porosity, both critical in describing processes such as armour layer development, surface-subsurface exchange processes and siltation/ sealing. Whilst measurements of the bed surface are increasingly informed by quantitative and spatial measurement techniques (e.g., laser displacement scanning), material opacity has precluded the full 3D bed structure analysis required to accurately define the surface-subsurface transition. To overcome this problem, this paper provides magnetic resonance imaging (MRI) data of vertical bed porosity profiles. Uniform and bimodal (?? _g = 2.1) sand-gravel beds are considered following restructuring under sub-threshold flow durations of 60 and 960 minutes. MRI data are compared to traditional 2.5D laser displacement scans and six robust definitions of the surface-subsurface transition are provided; these form the focus of discussion.  相似文献   

A 4D-variational ocean data assimilation application for Santos Basin,Brazil     

Mauricio da Rocha Fragoso  Gabriel Vieira de Carvalho  Felipe Lobo Mendes Soares  Daiane Gracieli Faller  Luiz Paulo de Freitas Assad  Raquel Toste  Lívia Maria Barbosa Sancho  Elisa Nóbrega Passos  Carina Stefoni Böck  Bruna Reis  Luiz Landau  Hernan G. Arango  Andrew M. Moore 《Ocean Dynamics》2016,66(3):419-434

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An interactive biplot implementation in R for modeling genotype-by-environment interaction     

Elisa Frutos  M. Purificación Galindo  Víctor Leiva 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(7):1629-1641

Classical and GGE biplot methods are graphical procedures that allow multivariate data to be analyzed. In particular, the GGE biplot displays the genotype main effect (G) and the genotype by environment interaction (GE) in two-way data. The GGE biplot originates from data graphical analysis of multi-environment trials (MET). Thus, agronomists, crop scientists and geneticists are potential users of this method. However, it can also be used to visualize and analyze other types of data. In this paper, we propose a new interactive computational implementation in R language to perform the main functions of the classical and GGE biplot methods, so it is also useful for MET data visual analysis. This implementation is organized in an R package named GGEBiplotGUI . This package is the only interactive, noncommercial and open source software that currently exists, offering a free alternative to available commercial software. In addition, it can be used without to practically have knowledge of the R programming language. Here, we present and discuss the capabilities and features of the GGEBiplotGUI package and illustrate them by using real data. The GGEBiplotGUI package graphically addresses the questions that a researcher likely asks. This R package is not only a tool for visual data analysis of multi-environment trials, useful for plant breeders and geneticists, in order to study yields from genotypes and interactions between genotype and environment, but also data from other areas can be analyzed by the GGEBiplotGUI package.  相似文献   

Modeling of Landslide‐Generated Tsunamis with GRASS     

Massimiliano Cannata  Roberto Marzocchi  Monia Elisa Molinari 《Transactions in GIS》2012,16(2):191-214

The following research aims to enhance and spread the capacity of assessing risk due to landslide‐generated tsunamis by fostering the use of a GIS (Geographic Information System), and in this particular instance, an Open Source GIS (where “Open Source” can be loosely defined as freely available source code). For this purpose, we tested a procedure to be spatially implemented in the Open Source GRASS GIS through developing a module named r.impact.tsunami that simulates landslide‐generated tsunami. In this article we present its application in a case study performed on Como Lake (Lago di Como) in northern Italy. The review of the results identified sources of uncertainties while the model sensitivity outlined the influence of the parameters governing the model. Moreover, in order to verify the model validity, we implemented a new module (r.swe), that simulates the tsunami propagation and run‐up with the shallow water equations, and compared the results. Notwithstanding non‐negligible differences, the two models produced results of the same magnitude; this confirmed the validity of both models, although a rigorous validation of the models could not be performed due to the lack of observed data.  相似文献   

Redox Potential and Seasonal Porewater Biogeochemistry of Three Mountain Wetlands in Southeastern Kentucky, USA     

Yvonne Thompson  Brian C. Sandefur  A. D. Karathanasis  Elisa D’Angelo 《Aquatic Geochemistry》2009,15(3):349-370

Redox potentials (Eh) were monitored bimonthly and porewater chemistry was analyzed seasonally at three slightly-acidic, high-elevation Kentucky wetlands that differed in hydrology, parent materials, and vegetation. At all sites, Eh values were below 300 mV, which indicated that reducing conditions persisted within the upper 90 cm and fluctuated mainly within the range of iron and sulfate reduction. Significant relationships of Eh values with depth were observed only at the Martins Fork wetland, where precipitation was the primary water source. The strongest and most stable reducing conditions, observed at the Kentenia site, reflected consistently high water levels, which were sustained by ground water. The third wetland (Four Level) was distinguished by irregular Eh fluctuations coinciding with strong seasonal ground-water upwelling. Although Fe³⁺ and SO₄ ²⁻ were the primary terminal electron acceptors in all wetlands, porewater chemistry also varied significantly by season and soil depth in response to piezometric water level fluctuations. Additional factors that influenced porewater chemistry included: (1) the presence of limestone parent materials that affected porewater pH, Ca²⁺, and Mg²⁺; and (2) the prevalence of sphagnum moss or graminoid species that influenced dissolved organic carbon, CO₂, and CH₄. Results from this study indicated the diverse range and importance of multiple factors in controlling biogeochemical processes and properties in small, high-elevation Appalachian wetlands.  相似文献   

Changes in eruptive style during the A.D. 1538 Monte Nuovo eruption (Phlegrean Fields, Italy): the role of syn-eruptive crystallization     

Claudia D’Oriano  Elisa Poggianti  Antonella Bertagnini  Raffaello Cioni  Patrizia Landi  Margherita Polacci  Mauro Rosi 《Bulletin of Volcanology》2005,67(7):601-621

The Monte Nuovo eruption is the most recent event that occurred at Phlegrean Fields (Italy) and lasted from 29 September to 6 October 1538. It was characterized by 2 days of quasi-sustained phreatomagmatic activity generating pumice-bearing pyroclastic density currents and forming a 130-m-high tuff cone (Lower Member deposits). The activity resumed after a pause of 2 days with two discrete Vulcanian explosions that emplaced radially distributed, scoria-bearing pyroclastic flows (Upper Member deposits). The juvenile products of Lower and Upper Members are, respectively, phenocryst-poor, light-coloured pumice and dark scoria fragments with K-phonolitic bulk compositions, identical in terms of both major and trace elements. Groundmass is formed by variable proportions of K-feldspar and glass, along with minor sodalite and Fe-Ti oxide present in the most crystallized samples. Investigations of groundmass compositions and textures were performed to assess the mechanisms of magma ascent, degassing and fragmentation along the conduit and implications for the eruptive dynamics. In pumice of the Lower Member groundmass crystal content increases from 13 to 28 vol% from the base to the top of the sequence. Products of the Upper Member consist of clasts with a groundmass crystal content between 30 and 40 vol% and of totally crystallized fragments. Crystal size distributions of groundmass feldspars shift from a single population at the base of the Lower Member to a double population in the remaining part of the sequence. The average size of both populations regularly increases from the Lower to the Upper Member. Crystal number density increases by two orders of magnitude from the Lower to the Upper Member, suggesting that nucleation dominated during the second phase of the eruption. The overall morphological, compositional and textural data suggest that the juvenile components of the Monte Nuovo eruption are likely to record variations of the magma properties within the conduit. The different textures of pumice clasts from the Lower Member possibly reflect horizontal gradients of the physical properties (P, T) of the ascending magma column, while scoriae from the second phase are thought to result from the disruption of a slowly rising plug crystallizing in response to degassing. In particular, crystal size distribution data point to syn-eruptive degassing-induced crystallization as responsible for the transition in eruptive style from the first to the second phase of the eruption. This mechanism not only has been proved to profoundly affect the dynamics of dome-forming calc-alkaline eruptions, but may also have a strong influence in driving the eruption dynamics of alkaline magmas of intermediate to evolved compositions.Editorial responsibility: J. Donnelly-Nolan  相似文献   

Kinematic and geochronological constraints on shear deformation in the Ferriere-Mollières shear zone (Argentera-Mercantour Massif,Western Alps): implications for the evolution of the Southern European Variscan Belt     

Simonetti  Matteo  Carosi  Rodolfo  Montomoli  Chiara  Langone  Antonio  D’Addario  Enrico  Mammoliti  Elisa 《International Journal of Earth Sciences》2018,107(6):2163-2189

International Journal of Earth Sciences - In the Western Alps, a steeply dipping km-scale shear zone (the Ferriere-Mollières shear zone) cross-cuts Variscan migmatites in the...  相似文献   

Temporal trends in extreme rainfall intensity and erosivity in the Mediterranean region: a case study in southern Tuscany,Italy   总被引：2，自引：0，他引：2  

Chiara Vallebona  Elisa Pellegrino  Paolo Frumento  Enrico Bonari 《Climatic change》2015,128(1-2):139-151

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