Large biases and inconsistent climate change signals in ENSEMBLES regional projections   总被引：1，自引：1，他引：0  

Marco Turco  Antonella Sanna  Sixto Herrera  Maria-Carmen Llasat  José Manuel Gutiérrez 《Climatic change》2013,120(4):859-869

In this paper we analyze some caveats found in the state-of-the-art ENSEMBLES regional projections dataset focusing on precipitation over Spain, and highlight the need of a task-oriented validation of the GCM-driven control runs. In particular, we compare the performance of the GCM-driven control runs (20C3M scenario) with the ERA40-driven ones (“perfect” boundary conditions) in a common period (1961–2000). Large deviations between the results indicate a large uncertainty/bias for the particular RCM-GCM combinations and, hence, a small confidence for the corresponding transient simulations due to the potential nonlinear amplification of biases. Specifically, we found large biases for some RCM-GCM combinations attributable to RCM in-house problems with the particular GCM coupling. These biases are shown to distort the corresponding climate change signal, or “delta”, in the last decades of the 21st century, considering the A1B scenario. Moreover, we analyze how to best combine the available RCMs to obtain more reliable projections.  相似文献   

The ecological fallacy in a time series context: evidence from Spanish regional unemployment rates     

Juan Carlos Duque  Manuel Artís  Raúl Ramos 《Journal of Geographical Systems》2006,8(4):391-410

The ecological fallacy (EF) is a common problem regional scientists have to deal with when using aggregated data in their analyses. Although there is a wide number of studies considering different aspects of this problem, little attention has been paid to the potential negative effects of the EF in a time series context. Using Spanish regional unemployment data, this paper shows that EF effects are not only observed at the cross-section level, but also in a time series framework. The empirical evidence obtained shows that analytical regional configurations are the least susceptible to time effects relative to both normative and random regional configurations, while normative configurations are an improvement over random ones.

Raúl RamosEmail:

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The Prestige crisis: operational oceanography applied to oil recovery, by the Basque fishing fleet     

González M  Uriarte A  Pozo R  Collins M 《Marine pollution bulletin》2006,53(5-7):369-374

On 19th November 2002, the oil tanker Prestige (containing 77,000 tonnes of heavy fuel no. 2 (M100)) sank in 3500 m of water, off the coast of northwestern Spain. Intermittent discharge of oil from the stricken tanker, combined with large-scale sea surface dispersion, created a tracking and recovery problem. Initially, conventional oil recovery approaches were adopted, close to the wreck. With time and distance from the source, the oil dispersed dramatically and became less viscous. Consequently, a unique monitoring, prediction and data dissemination system was established, based upon the principles of 'operational oceanography'; this utilised in situ tracked buoys and numerical (spill trajectory) modelling outputs, in combination with remote sensing (satellite sensors and visual observation). Overall, wind effects on the surface waters were found to be the most important mechanism controlling the smaller oil slick movements. The recovery operation involved up to 180 fishing boats, 9-30 m in length. Such labour-intensive recovery of the oil (21,000 tonnes, representing an unprecedented ratio of 6.6 tonnes at sea, per tonne recovered on land) continued over a 10 month period. The overall recovery at sea, by the fishing vessels, represented 63% of the total oil recovered at sea; this compares to only 37% recovered by specialised 'counter- pollution' vessels.  相似文献   

Mechanisms of fine extinction band development in vein quartz: new insights from correlative light and electron microscopy     

Tine?Derez  Tom?Van Der?Donck  Oliver?Plümper  Philippe?Muchez  Gill?Pennock  Martyn?R.?Drury  Manuel?SintubinEmail author 《Contributions to Mineralogy and Petrology》2017,172(7):56

Fine extinction bands (FEBs) (also known as deformation lamellae) visible with polarized light microscopy in quartz consist of a range of nanostructures, inferring different formation processes. Previous transmission electron microscopy studies have shown that most FEB nanostructures in naturally deformed quartz are elongated subgrains formed by recovery of dislocation slip bands. Here we show that three types of FEB nanostructure occur in naturally deformed vein quartz from the low-grade metamorphic High-Ardenne slate belt (Belgium). Prismatic oriented FEBs are defined by bands of dislocation walls. Dauphiné twin boundaries present along the FEB boundaries probably formed after FEB formation. In an example of two sub-rhombohedral oriented FEBs, developed as two sets in one grain, the finer FEB set consists of elongated subgrains, similar to FEBs described in previous transmission electron microscopy studies. The second wider FEB set consists of bands with different dislocation density and fluid-inclusion content. The wider FEB set is interpreted as bands with different plastic strain associated with the primary growth banding of the vein quartz grain. The nanometre-scale fluid inclusions are interpreted to have formed from structurally bounded hydroxyl groups that moreover facilitated formation of the elongate subgrains. Larger fluid inclusions aligned along FEBs are explained by fluid-inclusion redistribution along dislocation cores. The prismatic FEB nanostructure and the relation between FEBs and growth bands have not been recognized before, although related structures have been reported in experimentally deformed quartz.  相似文献   

Overview of the Geology of Cuba     

Manuel A. ITURRALDE-VINENT 《《地质学报》英文版》2017,91(Z1):22-22

Cuba is the largest island in the Greater Antilles(GA) and has been part of the North American Plate(NOAM) since Upper Eocene time. It is separated from other GA islands by the North Caribbean Transform Fault System which defines the present boundary between the NOAM and the Caribbean Plate(CARIB). The GA began to form ~135 Ma ago, after the breakup of Pangea, in the leading edge of CARIB, due to subduction of Proto-Caribbean lithosphere(NOAM) beneath CARIB until collision with the Bahamian platform in the Middle to Late Eocene time(~48 to 40 Ma). Between the Maastrichtian and the Late Eocene the Cayman spreading ridge and the Oriente transform formed and western CARIB was transferred to NOAM. The geology of Cuba is dominated by three lithotectonic units, which reflects its evolution as a Cretaceous-Paleogene convergent margin:(1) deformed(para)autochthonous NOAM Jurassic and Cretaceous continental margin and basin sections and PaleoceneEocene synorogenic foredeep;(2) ophiolite complexes and serpentinite mèlanges and ~135 to 47 Ma magmatic arc suite interbedded with or overlain by Latest CretaceousPaleogene synorogenic strata; and(3)(neo)autochthonous late Upper Eocene to Recent deposits which unconformably overlie the two older units.  相似文献   

The External Tanger Unit (Intrarif sub-Domain,External Rifian Zones,Morocco): an interdisciplinary study   总被引：1，自引：0，他引：1  

Soufian Maaté  Francisco Javier Alcalá  Francesco Guerrera  Rachid Hlila  Alí Maaté  Manuel Martín-Martín  Giuliana Raffaelli  Francisco Serrano  Mario Tramontana 《Arabian Journal of Geosciences》2017,10(24):556

The External Tanger Unit represents one of the most complete Cretaceous-Miocene successions in the central areas of the Internal Intrarif sub-Domain (External Rif Zones, Morocco). An interdisciplinary study has been carried out to propose a new characterization of this unit which would allow a better comprehension of the confused and complex relationships among different units of the same sub-domain. The results achieved can be summarized as follows: (1) redefinition of the stratigraphic (litho-, bio-, and chrono-) record and introduction of a new, informal lithostratigraphic terminology; (2) recognition of two main depositional sequences (lower-middle Eocene p.p. and lower Oligocene p.p.-lower Miocene p.p.) separated by extended gaps (latest Cretaceous-early Eocene p.p. and middle Eocene p.p.-early Oligocene p.p.); (3) reconstruction of the evolution of the sedimentary realm, and of the relationships between tectonics and sedimentation; and (4) comparison between the upper Cretaceous-Miocene stratigraphic record and tectonic events of the Intrarif, which is located in the western external portion of the Maghrebian Flysch Basin, and the equivalent sedimentary record of the eastern portion of this basin in the Tunisian Tell. More in general, our results allowed (i) a first reconstruction of the Cretaceous-Miocene main tectono-sedimentary events; (ii) a more detailed location of the sedimentary suite in the external African Margin in the context of a wider palaeogeographic framework; and (iii) the definition of the main stages of the geological evolution of the area.  相似文献   

Plankton carbon metabolism and air–water CO2 fluxes at a hypereutrophic tropical estuary          下载免费PDF全文

Mariana Guenther  Moacyr Araújo  Carlos Noriega  Manuel Flores‐Montes  Eliane Gonzalez‐Rodriguez  Sigrid Neumann‐Leitão 《Marine Ecology》2017,38(2)

Multiple biotic and abiotic drivers regulate the balance between CO₂ assimilation and release in surface waters. In the present study, we compared in situ measurements of plankton carbon metabolism (primary production and respiration) to calculated air–water CO₂ fluxes (based on abiotic parameters) during 1 year (2008) in a hypereutrophic tropical estuary (Recife Harbor, NE Brazil – 08°03′S, 34°52′W) to test the hypothesis that high productivity leads to a net CO₂ flux from the atmosphere. The calculated CO₂ fluxes through the air–water interface (FCO₂) were negative throughout the year (FCO₂: –2 to –9 mmol C·m^?2·day^?1), indicating that Recife Harbor is an atmospheric CO₂ sink. Respiration rates of the plankton community ranged from 2 to 45 mmol C·m^?2·hr^?1. Gross primary production ranged from 0.2 to 281 mmol C·m^?2·hr^?1, exceeding respiration during most of the year (net autotrophy), except for the end of the wet season, when the water column was net heterotrophic. The present results highlight the importance of including eutrophic tropical shallow estuaries in global air–water CO₂ flux studies, in order to better understand their role as a sink of atmospheric CO₂.  相似文献   

The interaction of tectonics,climate and eustasy in controlling dolomitization: A case study of Cenomanian–Turonian,shallow marine carbonates of the Iberian Basin     

Richard Newport  Manuel Segura  Jonathan Redfern  Cathy Hollis 《Sedimentology》2020,67(5):2223-2247

During the Cretaceous, high global sea-level and low latitudinal temperature variations led to the growth of epeiric carbonate platforms. Platform-scale dolomitization of these platforms is not common, reflecting the low Mg/Ca ratio of seawater and a humid climate. This study describes the processes governing pervasive dolomitization of a land-attached carbonate platform within the Iberian Basin. Dolomite is planar to sub-planar with a geochemical signature consistent with dolomitization from penesaline seawater. Dolomitization was most pervasive during a 1 Myr period in the middle Cenomanian, by repeated reflux of seawater from brine pools formed on the top of a southward-prograding carbonate platform. Tilting and structural reorganization in the Upper Cenomanian led to a reversal in polarity of the platform, and dolomitization was restarted by the northward reflux of seawater. Rising relative sea-level and oceanic acidification led to back-stepping of the platform such that the supply of dolomitizing fluids was cut off. In the Lower Turonian, pervasively dolomitized rudist rudstone facies in the south of the study area indicate that dolomitization restarted, either penecontemporaneously or later, from highly evaporated Campanian–Maastrichtian seawater. A systematic increase in dolomite crystal size up-section ties broadly, but not entirely, to stratigraphy. It is possible that these textural differences reflect changes in fluid chemistry, limestone permeability or precursor rock texture. However, the lack of stratigraphic conformance, and the preservation of the earliest-formed dolomite only in the oldest sediments, could indicate a progressive recrystallization of early-formed dolomite through repeated reflux of brines. As such, the succession appears to preserve a fossilized record of dolomite recrystallization through time during the Cenomanian–Turonian. The results of this study therefore provide a record of the progressive dolomitization of a carbonate platform and demonstrate the important interplay of climate and basin-scale tectonics on dolomite distribution and crystallinity.  相似文献   

Evaluation of liquefaction potential in an intermountain Quaternary lacustrine basin (Fucino basin,central Italy)     

Paolo Boncio  Sara Amoroso  Giovanna Vessia  Marco Francescone  Mauro Nardone  Paola Monaco  Daniela Famiani  Deborah Di Naccio  Alessia Mercuri  Maria Rosaria Manuel  Fabrizio Galadini  Giuliano Milana 《Bulletin of Earthquake Engineering》2018,16(1):91-111

In this study, we analyse the susceptibility to liquefaction of the Pozzone site, which is located on the northern side of the Fucino lacustrine basin in central Italy. In 1915, this region was struck by a M 7.0 earthquake, which produced widespread coseismic surface effects that were interpreted to be liquefaction-related. However, the interpretation of these phenomena at the Pozzone site is not straightforward. Furthermore, the site is characterized by an abundance of fine-grained sediments, which are not typically found in liquefiable soils. Therefore, in this study, we perform a number of detailed stratigraphic and geotechnical investigations (including continuous-coring borehole, CPTu, SDMT, SPT, and geotechnical laboratory tests) to better interpret these 1915 phenomena and to evaluate the liquefaction potential of a lacustrine environment dominated by fine-grained sedimentation. The upper 18.5 m of the stratigraphic succession comprises fine-grained sediments, including four strata of coarser sediments formed by interbedded layers of sand, silty sand and sandy silt. These strata, which are interpreted to represent the frontal lobes of an alluvial fan system within a lacustrine succession, are highly susceptible to liquefaction. We also find evidence of paleo-liquefaction, dated between 12.1–10.8 and 9.43–9.13 kyrs ago, occurring at depths of 2.1–2.3 m. These data, along with the aforementioned geotechnical analyses, indicate that this site would indeed be liquefiable in a 1915-like earthquake. Although we found a broad agreement among CPTu, DMT and shear wave velocity “simplified procedures” in detecting the liquefaction potential of the Pozzone soil, our results suggest that the use and comparison of different in situ techniques are highly recommended for reliable estimates of the cyclic liquefaction resistance in lacustrine sites characterized by high content of fine-grained soils. In geologic environments similar to the one analysed in this work, where it is difficult to detect liquefiable layers, one can identify sites that are susceptible to liquefaction only by using detailed stratigraphic reconstructions, in situ characterization, and laboratory analyses. This has implications for basic (Level 1) seismic microzonation mapping, which typically relies on the use of empirical evaluations based on geologic maps and pre-existing sub-surface data (i.e., age and type of deposits, prevailing grain size, with particular attention paid to clean sands, and depth of the water table).  相似文献   

Sibsonian and non-Sibsonian natural neighbour interpolation of the total electron content value     

Kacper Kotulak  Adam Froń  Andrzej Krankowski  German Olivares Pulido  Manuel Henrandez-Pajares 《Acta Geophysica》2017,65(1):13-28

In radioastronomy the interferometric measurement between radiotelescopes located relatively close to each other helps removing ionospheric effects. Unfortunately, in case of networks such as LOw Frequency ARray (LOFAR), due to long baselines (currently up to 1500 km), interferometric methods fail to provide sufficiently accurate ionosphere delay corrections. Practically it means that systems such as LOFAR need external ionosphere information, coming from Global or Regional Ionospheric Maps (GIMs or RIMs, respectively). Thanks to the technology based on Global Navigation Satellite Systems (GNSS), the scientific community is provided with ionosphere sounding virtually worldwide. In this paper we compare several interpolation methods for RIMs computation based on scattered Vertical Total Electron Content measurements located on one thin ionospheric layer (Ionospheric Pierce Points—IPPs). The results of this work show that methods that take into account the topology of the data distribution (e.g., natural neighbour interpolation) perform better than those based on geometric computation only (e.g., distance-weighted methods).  相似文献