528 research outputs found
Late hercynian dike sets in Central Iberia as a result of progressive deformation within a megacontinental dextral shear zone
[Resumen] En este trabajo se analiza el contexto geotectónico global de los sistemas filonianos
intruidos en el centro peninsular durante tiempos tardihercínicos. Estos sistemas forman tres familias diferenciadas, con el siguiente orden de intrusión: 1) Diques EW de pórfido y aplita; 2) Filones de baritina, de direcciones N65 °E a N120oE; y 3) Diques NS de cuarzo, diabasa y lamprófido. La intrusión de estas tres familias de diques puede asociarse con los tres episodios
tectónicos tardihercínicos: Uno primer extensional, uno segundo transcurrente dúctil, y un último transcurrente frágil. Tanto estos episodios tectónicos, como los sistemas filonianos, pueden explicarse dentro de un esquema de deformación progresiva en una zona de cizalla transcurrente dextral de escala megacontinental (paniendo del clásico esquema para la provincia tardihercínica europea de ARTHAUD, F. YMATIE, Ph., 1977).[Abstract] In this work we analize the global geotectonic context characterizing the intrusion
of different dike sets in central Iberia during late Hercynian times. Three main dike sets might be distinguished, with the following order of intrusion: 1) EW porphyry and aplitic dikes; 2) N65°E to N1200E barite veins; and, 3) NS dikes of quartz, diabase, and lamprophyre. The intrusion of these three dike sets might be associated with the three late Hercynian tectonic events: A first one extensional, a second one ductile-transcurrent, and a last one brittle-transcurrent. Both these dike sets, and the tectonic events which triggered them, might be understand within a scheme involving progressive deformation within a megaconúnental dextral shear zone (fol1owing theclassical scenario for the late Hercynian european province of ARTHAUD, F. and MArrE, Ph., 1977)
Geoteetonie models of the E-W trending dikes in the Spanish Central System
[Resumen] En este trabajo se efectúa una revisión de los modelos geotectónicos actualmente
existentes para explicar el emplazamiento de los haces de diques ácidos, que con dirección E-W afloran en el Sistema Central Español. Clásicamente, se han propuesto dos tipos de modelos distintos: uno de origen ligado a la intrusión de los batolitos graníticos que los contienen, y otro de origen ligado a procesos tectónicos posteriores a la intrusión de dichos batolitos. Sin embargo, recientemente ha sido sugerido un modelo mixto (DOBLAS, M., 1987) que invoca a la vez la participación de procesos tectónicos y magmáticos, dentro de un esquema de «detachments» extensionales tardi-hercínicos. En nuestra opinión, este último modelo parece ser el que mejor explica el conjunto de las características de estos haces de diques, y por tanto es el que desarrollamos, más ampliamente, en este trabajo.[Abstract] In this paper we revise different geotectonic models which have been proposed till now, to explain the emplacement of the EW trending acid dike swarrns in the Spanish Central System. Two types of models have been suggested: one of them invokes an origin related to the emplacement of the granitic batholiths, and the other proposes an origin related to tectonic processes happening after the emplacement of these batholiths. However, recently, a combined model has been suggested (DOBLAS, M., 1987), in which both magmatic and tectonic processes playa role, within a latehercynian extensional detachment scheme. We think that this hypothesis is the most adequate to explain the different characteristics of the dike swarms, and in this paper we will develop further this idea
ENSEMBLES: a new multi-model ensemble for seasonal-to-annual predictions: Skill and progress beyond DEMETER in forecasting tropical Pacific SSTs
A new 46-year hindcast dataset for seasonal-to-annual ensemble predictions has been created using a multi-model ensemble of 5 state-of-the-art coupled atmosphere-ocean circulation models. The multi-model outperforms any of the single-models in forecasting tropical Pacific SSTs because of reduced RMS errors and enhanced ensemble dispersion at all lead-times. Systematic errors are considerably reduced over the previous generation (DEMETER). Probabilistic skill scores show higher skill for the new multi-model ensemble than for DEMETER in the 4–6 month forecast range. However, substantially improved models would be required to achieve strongly statistical significant skill increases. The combination of ENSEMBLES and DEMETER into a grand multi-model ensemble does not improve the forecast skill further. Annual-range hindcasts show anomaly correlation skill of ∼0.5 up to 14 months ahead. A wide range of output from the multi-model simulations is becoming publicly available and the international community is invited to explore the full scientific potential of these data
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Full-field and anomaly initialization using a low-order climate model: a comparison and proposals for advanced formulations
Initialization techniques for seasonal-to-decadal climate predictions fall into two main categories; namely full-field initialization (FFI) and anomaly initialization (AI). In the FFI case the initial model state is replaced by the best possible available estimate of the real state. By doing so the initial error is efficiently reduced but, due to the unavoidable presence of model deficiencies, once the model is let free to run a prediction, its trajectory drifts away from the observations no matter how small the initial error is. This problem is partly overcome with AI where the aim is to forecast future anomalies by assimilating observed anomalies on an estimate of the model climate.
The large variety of experimental setups, models and observational networks adopted worldwide make it difficult to draw firm conclusions on the respective advantages and drawbacks of FFI and AI, or to identify distinctive lines for improvement. The lack of a unified mathematical framework adds an additional difficulty toward the design of adequate initialization strategies that fit the desired forecast horizon, observational network and model at hand.
Here we compare FFI and AI using a low-order climate model of nine ordinary differential equations and use the notation and concepts of data assimilation theory to highlight their error scaling properties. This analysis suggests better performances using FFI when a good observational network is available and reveals the direct relation of its skill with the observational accuracy. The skill of AI appears, however, mostly related to the model quality and clear increases of skill can only be expected in coincidence with model upgrades.
We have compared FFI and AI in experiments in which either the full system or the atmosphere and ocean were independently initialized. In the former case FFI shows better and longer-lasting improvements, with skillful predictions until month 30. In the initialization of single compartments, the best performance is obtained when the stabler component of the model (the ocean) is initialized, but with FFI it is possible to have some predictive skill even when the most unstable compartment (the extratropical atmosphere) is observed.
Two advanced formulations, least-square initialization (LSI) and exploring parameter uncertainty (EPU), are introduced. Using LSI the initialization makes use of model statistics to propagate information from observation locations to the entire model domain. Numerical results show that LSI improves the performance of FFI in all the situations when only a portion of the system's state is observed. EPU is an online drift correction method in which the drift caused by the parametric error is estimated using a short-time evolution law and is then removed during the forecast run. Its implementation in conjunction with FFI allows us to improve the prediction skill within the first forecast year.
Finally, the application of these results in the context of realistic climate models is discussed
Indicators of the sense of intrusion in dikes
[Resumen] En este trabajo se establecen una serie de criterios que permite deducir el sentido
de la inyección en los diques. Estos criterios son de dos tipos: A) Criterios basados en indicadores cinemáticos de la deformación, que se observan a meso y microescala en los contactos dique-roca de caja, y B) Criterios basados en la observaci6n cartográfica de ciertas variaciones geométricas, texturales, composicionales y de la deformación a lo largo de la dirección de flujo dentro del dique.
A su vez, los primeros se subdividen en:
1) EStructuras de flujo magmático.
2) EStructuras miloníticas dúctiles a dúctiles-frágiles.
3) EStructuras frágiles.
La deducci6n del sentido de la intrusi6n en los diques tiene gran importancia, tanto para los los esquemas tectónicos regionales, como para el estudio de los flujos magmáticos.[Abstract] In this paper we study sorne criteria that are useful as indicators of the sense of intrusion in dikes. There are two types of criteria: A) Criteria based on kinematic indicators, which are observable on the meso and microscale, on the dike/host-rock interfaces; B) Criteria based on the cartographical observation of certain geometrical, textural, compositional, and deformational variations along the direction of intrusion of the dikes. The meso and microscale indicators might be subdivided into three main types of structures:
1) Structures of magmatic flow;
2) Ductile to ductile-brittle mylonitic structures);
3) Brittle structures.
The deduction of the sense of intrusion in dikes is very important, both for the establishment of regional tectonic schemes, and for the study of magmatic flow patterns
RALF/LRX monitor cell wall integrity during tomato fruit formation
Plant developmental processes depend largely on a correct communication between cells, together with the ability to respond to such communication. Traditionally cell to cell communication has been studied through the action of phytohormones such as auxin, ethylene, etc. However, in the past decade, Small Signaling Peptides (SSPs) have been identified as key regulators coordinating an extensive range of developmental and stress processes. Plant cells perceive SSPs at the cell wall by Receptor-Like Kinases (RLKs), activating a huge range of biochemical and physiological processes. SSPs from Rapid Alkalinization Factor (RALFs) family are ubiquitous in dicot plants and they have been associated to cell wall integrity during cell wall remodeling. RALFs peptides can bind two types of receptors: Leucine-Rich Repeat Extensin proteins (LRXs), and Catharanthus roseus RLK1-Like (CrRLK1L). All recent discoveries remark the importance of RALF/LRX/CrRLK1L module regulating cell wall status. A tomato fruit formation is a perfect model to further understand the role of this mechanism, since requires a tightly regulation during the cell wall softening phase. It has already been reported that some members of CrRLK1Ls regulate fruit ripening in few species like tomato, strawberry or apple, remarking the importance of these receptors and their ligands sensing changes produced in the cell wall during the ripening process. Here, we initiate a biochemical and phenotypical characterization of RALF/LRX proteins in order to elucidate their role during tomato ripening process
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The Japanese Electricity System 15 months After March 11th 2011
The Great East Japan earthquake and tsunami on March 11th 2011 caused mass destruction, significant loss-of-life and a large displacement of people. It also placed significant strain of Japan's electricity-generating infrastructure. There was a significant reduction in capacity due to the damage in thermal generation and gradual closure of Japan's nuclear power plants; the ability for load-balancing across the Japanese grid was compromised due to limited interconnections between the different utilities that comprise the Japanese electricity system. This paper looks at the first fifteen months following the earthquake and tsunami: outlining the supply reduction and consequent attempts to manage the demand. In turn it highlights the foibles of Japan's vertically-integrated monopolistic structures and the evolution of governmental and utilities response that went from decisions made 'on-the-fly' to a more developed policy for peak-demand electricity savings. The findings from this paper should serve as a useful set of examples to aid decision makers in contingency planning for disruptive large-scale reduction in electricity-generating capacity
Changing Seasonal Rainfall Distribution With Climate Directs Contrasting Impacts at Evapotranspiration and Water Yield in the Western Mediterranean Region
Over the past century, climate change has been reflected in altered precipitation regimes worldwide. Because evapotranspiration is sensitive to both water availability and atmospheric demand for water vapor, it is essential to assess the likely consequences of future changes of these climate variables to evapotranspiration and, thus, runoff. We propose a simplified approach for annual evapotranspiration predictions, based on seasonal evapotranspiration estimates, accounting for the strong seasonality of meteorological conditions typical of Mediterranean climate, still holding the steady state assumption of basin water balance at mean annual scale. Sardinian runoff decreased over the 1975-2010 period by more than 40% compared to the preceding 1922-1974 period. Most of annual runoff in Sardinian basins is produced by winter precipitation, a wet season with relatively high evaporation rates. We derived linear seasonal evapotranspiration responses to seasonal precipitation, and, in turn, a relationship between the parameters of the linear functions and the seasonal vapor pressure deficit (D), accounting for residuals with basin properties. We then used these relationships to predict evapotranspiration and runoff using future Intergovernmental Panel on Climate Change climate scenarios, considering changing precipitation and D seasonality. We show that evapotranspiration is insensitive to D scenario changes. Although both evapotranspiration and runoff are sensitive to precipitation seasonality, future changes in runoff are related only to changes of winter precipitation, while evapotranspiration changes are related to those of spring and summer precipitation. Future scenario predicting further runoff decline is particularly alarming for the Sardinian water resources system, requiring new strategies and designs in water resources planning and management.Peer reviewe
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