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Spain is one of the European countries with most environmental problems related to water scarcity and droughts. Additionally, several studies suggest trends of increasing temperature and decreasing rainfall, mainly for the Iberian Peninsula, due to climate variability and change. While Regional Climate Models (RCM) are a valuable tool for understanding climate processes, the causes and plausible impacts on variables and meteorological extremes present a wide range of associated uncertainties. The multi-model ensemble approach allows the quantification and reduction of uncertainties in the predictions. The combination of models (RCM in this case), generally increases the reliability of the predictions, although there are different weighting methodologies. In this paper, a strategy is presented for the building of non-stationary PDF (probability density functions) ensembles with the aim of evaluating the spatial pattern of future risk of drought for an area. At the same time, the uncertainty associated with the metric used in the construction of the PDF ensembles is assessed. A comparative study of methodologies based on the application of the Reliability Ensemble Averaging (REA), assessing its factors using two performance measures, on the one hand the Perkins Score Methods, on the other hand the Kolmogorov-Smirnov test, is proposed. The evaluation of the sensitivity of the methodologies used in the construction of ensembles, as proposed in this paper, although without completely eliminating uncertainty, allows a better understanding of the sources and magnitude of the uncertainties involved. Despite the differences between the spatial distribution results from each metric (which can be in the order of 40 % in some areas), both approaches concluded about a plausible significant and widespread increase throughout continental Spain of the mean value of annual maximum dry spell lengths (AMDSL) between the years 1990 and 2050. Finally, the more parsimonious approach in the building of ensembles PDF, based on AMDSL in peninsular Spain, is identified. 相似文献
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William Caballero Ramón Giraldo Jorge Mateu 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(7):1553-1563
In a wide range of scientific fields the outputs coming from certain measurements often come in form of curves. In this paper we give a solution to the problem of spatial prediction of non-stationary functional data. We propose a new predictor by extending the classical universal kriging predictor for univariate data to the context of functional data. Using an approach similar to that used in univariate geostatistics we obtain a matrix system for estimating the weights of each functional variable on the prediction. The proposed methodology is validated by analyzing a real dataset corresponding to temperature curves obtained in several weather stations of Canada. 相似文献
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Rosaria Ignaccolo Jorge Mateu Ramon Giraldo 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(5):1171-1186
Functional data featured by a spatial dependence structure occur in many environmental sciences when curves are observed, for example, along time or along depth. Recently, some methods allowing for the prediction of a curve at an unmonitored site have been developed. However, the existing methods do not allow to include in a model exogenous variables that, for example, bring meteorology information in modeling air pollutant concentrations. In order to introduce exogenous variables, potentially observed as curves as well, we propose to extend the so-called kriging with external drift—or regression kriging—to the case of functional data by means of a three-step procedure involving functional modeling for the trend and spatial interpolation of functional residuals. A cross-validation analysis allows to choose smoothing parameters and a preferable kriging predictor for the functional residuals. Our case study considers daily PM10 concentrations measured from October 2005 to March 2006 by the monitoring network of Piemonte region (Italy), with the trend defined by meteorological time-varying covariates and orographical constant-in-time variables. The performance of the proposed methodology is evaluated by predicting PM10 concentration curves on 10 validation sites, even with simulated realistic datasets on a larger number of spatial sites. In this application the proposed methodology represents an alternative to spatio-temporal modeling but it can be applied more generally to spatially dependent functional data whose domain is not a time interval. 相似文献
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Seagrasses of the Great Barrier Reef predominantly occur in coastal regions where terrestrial inputs modify water quality and photosynthetic light is highly variable. Responses to shading were tested for Cymodocea serrulata, Halodule uninervis, Thalassia hemprichii and Zostera muelleri. In aquaria, four light treatments - high (66% surface light), moderate (31%), low (14%) and very low light (1%) treatments - were applied for 102d. Stress responses in the low and very low light treatments occurred in the following sequence: metabolic and physiological changes (reduced growth, increased pigment concentrations and photosynthetic efficiency); shedding (leaf loss, shoot loss) and production of new, altered tissue (leaves with reduced length, width and thickness). Complete shoot loss was projected after 76 (Z. muelleri) to 130d (T. hemprichii). Responses were slower in the low than in the very low treatment, therefore, efforts to minimize water quality degradation will be rewarded with delayed impacts to seagrasses. 相似文献
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Ibtisam Beik Victor Giraldo Gómez Olaf G. Podlaha Jörg Mutterlose 《Arabian Journal of Geosciences》2017,10(15):346
The purpose of this study is to better understand the depositional setting of Late Cretaceous to Early Paleocene oil shales from southeast and central-east Jordan. One core from both the Jafr and the Azraq-Hamza Basins was logged, and their lithology, texture, and ichnofabrics were recorded. A total of 79 thin sections were analyzed petrographically, and eight microfacies types recognized. Both cores show lithologic and petrographic similarities. The oil shales are Maastrichtian to Danian in age and can be described as organic matter and calcite-rich mudrocks. The most abundant granular components are foraminifera and various types of phosphatic bio- and lithoclasts. Macrofossils (bivalves, ostracods, echinoderms) were recorded in some intervals. The current results were compared with data from a previous publication on Maastrichtian oil shales from the Jafr Basin. A new model explaining the deposition of the oil shales of the Jafr and Azraq-Hamza Basins is proposed. The onset of the Maastrichtian oil shale deposition in both basins coincides with the early Maastrichtian transgression in this region. The organic matter-rich sediments were deposited in a mid to outer ramp setting below the storm wave base. Younger oil shales of Late Maastrichtian to Danian age were deposited in a shallower environment, below the fair weather wave base. The Cretaceous/Paleogene boundary is marked by a hiatus in both cores. The Danian oil shales show relatively lower “total organic carbon” content than the Maastrichtian ones. The former are believed to have been deposited in more oxygenated bottom waters of a mid-ramp zone. 相似文献
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Melendez Amanda Caballero-Russi David Gutierrez Soto Mariantonieta Giraldo Luis Felipe 《Natural Hazards》2022,111(2):1121-1152
Natural Hazards - Protecting civil infrastructure from natural and man-made hazards is vital. Understanding the impact of these hazards helps allocate resources efficiently. Researchers have... 相似文献
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Thomas Poulet Juan Felipe Giraldo Erick Ramanaidou Agnieszka Piechocka Victor M. Calo 《Basin Research》2023,35(2):572-591
The Hamersley Basin in Western Australia is one of the world's largest iron ore-producing regions, hosting two types of ore in banded iron formations: the high-grade martite-microplaty haematite and the supergene martite-goethite ores. With the high-grade ores almost entirely mined in the last decade, the supergene ores have more recently become the dominant resource of interest. Consequently, understanding the genesis of these martite-goethite deposits is a critical step for exploration. Yet, although various models exist, there is still no consensus on how these mineral resources formed, complicating the prediction of resource volume and location. Here, we show that the paleo-stratigraphic permeability anisotropy (with higher permeability along strata than across) controls the supergene mimetic enrichment transport process and, subsequently, the mineralisation distribution. We introduce a flow model that implicitly represents strata with a potential function that orients the permeability tensor accurately. The numerical solver uses automatic mesh adaptivity to deliver robust solutions. By accurately reproducing the mineralisation patterns in specific deposits, we identify and quantify the paleo-water table level and permeability anisotropy ratio as the two main controlling parameters for the mineralisation distribution. These insights provide new timing constraints for the mineralisation and the physical process of iron enrichment, suggesting much more potential mineralisation volume in the paleo-reconstructed zones than previously anticipated. These flow models allow us to draw geological conclusions with few a priori assumptions required for the genetic model in which the transport component is dominant. The predictive power of this methodology will allow targeted drilling to narrow down the prospective areas and lower exploration costs. Furthermore, the methodology's generality applies to other commodities in sedimentary basins involving supergene processes and will improve our understanding of various genetic models. 相似文献
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