Improved initial ensemble generation coupled with ensemble square root filters and inflation to estimate uncertainty     

Laura Dovera  Ernesto Della Rossa 《Computational Geosciences》2012,16(2):437-453

The performance of the Ensemble Kalman Filter method (EnKF) depends on the sample size compared to the dimension of the parameters space. In real applications insufficient sampling may result in spurious correlations which reduce the accuracy of the filter with a strong underestimation of the uncertainty. Covariance localization and inflation are common solutions to these problems. The Ensemble Square Root Filters (ESRF) is also better to estimate uncertainty with respect to the EnKF. In this work we propose a method that limits the consequences of sampling errors by means of a convenient generation of the initial ensemble. This regeneration is based on a Stationary Orthogonal-Base Representation (SOBR) obtained via a singular value decomposition of a stationary covariance matrix estimated from the ensemble. The technique is tested on a 2D single phase reservoir and compared with the other common techniques. The evaluation is based on a reference solution obtained with a very large ensemble (one million members) which remove the spurious correlations. The example gives evidence that the SOBR technique is a valid alternative to reduce the effect of sampling error. In addition, when the SOBR method is applied in combination with the ESRF and inflation, it gives the best performance in terms of uncertainty estimation and oil production forecast.  相似文献   

Potential loading damage to industrial storage tanks due to volcanic ash fallout     

Maria Francesca Milazzo  Giuseppa Ancione  Anna Basco  David George Lister  Ernesto Salzano  Giuseppe Maschio 《Natural Hazards》2013,66(2):939-953

The phenomenon of volcanic fallout ash from Mt. Etna in Sicily (Italy) is well known and frequent in recent years, as in the period 2001–2004. As a consequence, significant problems for the population, road, rail and air traffic and production activities have occurred. The industrial areas of Catania and Augusta-Priolo, located in south eastern Sicily, might be involved during particular weather conditions. This paper aims at determining the potential scenarios of damage to industrial facilities caused by volcanic ash fallout. The work has been focused on the study of both fixed and floating roof storage tanks, containing flammable liquids, and examines extreme failures damage causing the greatest loss of containment for these facilities. To include scenarios arising from natural phenomena (Na-Tech events) in the standard risk assessment procedure, the estimation of the vulnerability of these facilities is necessary. The study has been applied to the area surrounding Mt. Etna, and the procedure can also be extended to other case studies.  相似文献   

A relocatable ocean model in support of environmental emergencies     

Michela De Dominicis  Silvia Falchetti  Francesco Trotta  Nadia Pinardi  Luca Giacomelli  Ernesto Napolitano  Leopoldo Fazioli  Roberto Sorgente  Patrick J. Haley Jr.  Pierre F. J. Lermusiaux  Flavio Martins  Michele Cocco 《Ocean Dynamics》2014,64(5):667-688

During the Costa Concordia emergency case, regional, subregional, and relocatable ocean models have been used together with the oil spill model, MEDSLIK-II, to provide ocean currents forecasts, possible oil spill scenarios, and drifters trajectories simulations. The models results together with the evaluation of their performances are presented in this paper. In particular, we focused this work on the implementation of the Interactive Relocatable Nested Ocean Model (IRENOM), based on the Harvard Ocean Prediction System (HOPS), for the Costa Concordia emergency and on its validation using drifters released in the area of the accident. It is shown that thanks to the capability of improving easily and quickly its configuration, the IRENOM results are of greater accuracy than the results achieved using regional or subregional model products. The model topography, and to the initialization procedures, and the horizontal resolution are the key model settings to be configured. Furthermore, the IRENOM currents and the MEDSLIK-II simulated trajectories showed to be sensitive to the spatial resolution of the meteorological fields used, providing higher prediction skills with higher resolution wind forcing.  相似文献   

Structure and position of the bottom salinity front in the Amazon Estuary     

Ernesto Molinas  Susana Beatriz Vinzon  Carla de Paula Xavier Vilela  Marcos Nicolas Gallo 《Ocean Dynamics》2014,64(11):1583-1599

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Experimental analysis of infragravity waves in two eroded microtidal beaches   总被引：1，自引：0，他引：1  

MARIO Conde-Frias  LUIS Otero  JUAN Camilo Restrepo  JUAN Carlos Ort&#;z 《海洋学报(英文版)》2017,36(5):31-43

This work aims to contribute to the characterization and understanding of infragravity waves on two beaches with erosion problems. For this reason, we have used an array of ADCP and a pressure sensor to measure wave parameters and pressure inside and outside of the surf zone during the dry and rainy period in the beaches of Galerazamba and Manzanillo del Mar (both dissipative and eroded beaches) located in the Colombian Caribbean coast. Based on these measurements, we have carried out a spectral analysis in order to identify the frequency components that characterize the wave and its energy; thus, we identified the characteristic frequencies of infragravity waves to finally filter the infragravity signal on each beach in different seasonal periods. Among the results of the Welch spectrum applied to surface elevation time series, we found that, the frequencies'' energy of the sea-swell band decreases due to bottom friction and wave breaking as the wave approaches the shore, while the frequencies'' energy of the infragravity band increases significantly. In addition, for the wavelet analysis, we could observe how the energy of the infragravity band, especially the lowest frequencies gain energy as the waves approaches the coast. Furthermore, based on the infragravity wave obtained from the extreme wave event registered during the field campaign we can conclude that the contribution of this signal is important in the erosion problems presented in the beaches of Galerazamba and Manzanillo del Mar. Finally, these results show the need to realize other studies that allow us to understand deeply, the role of infragravity waves on the morphological changes that occurs in these beaches.  相似文献   

Hydrogeological and hydrochemical characterization of two karstic discharge areas in San Luis Potosí, Mexico   总被引：1，自引：0，他引：1  

Lisa Krienen  Michel Heuser  Nicole Höbig  Manuel Ernesto Mares Ochoa  Thomas R. Rüde  Antonio Cardona Benavides 《Environmental Earth Sciences》2017,76(24):825

Two karstic discharge areas, Río Verde (RV) and Ciénega de Cabezas (CC), located in a distance of 80 km to each other are chosen to determine the influence of local variations in geology and climatic condition on water chemistry and to examine if the groundwater, supplying the discharge areas, undergoes the same evolution and has a common source. Both study areas are situated on the carbonate platform Valles-San Luis Potosí and comprise a similar geological setting, but despite of their spatial vicinity the climate is semiarid in RV and humid in CC presenting an important factor on the amount of discharge and the concentrations of ions in the discharge. The investigation encompasses discharge, hydrochemical and physico-chemical parameter evaluations as well as the determination of saturation indices, hydrochemical modelling and water type characterization of surface water samples to derive knowledge of the groundwater systems. Scatterplots and saturation indices were used to proof the influence of lithological variability. Both study areas represent normal alkaline water, marked by high concentrations of calcium and magnesium with varying concentrations of bicarbonate and sulphate. In RV, the water interacts with dolomite rocks and gypsum layers, whereas in CC the dolomite content is depleted and the influence of limestone rocks increases. The climatic impact on the groundwater in RV is noticeable by the increase in ionic concentrations due to higher evaporation. In CC the higher amount of precipitation dilutes the groundwater and causes decreasing ionic concentrations.  相似文献   

Historical analysis (2000-2005) of the coastal water quality in San Andrés Island, SeaFlower Biosphere Reserve, Caribbean Colombia     

Brigitte Gavio  Shelly Palmer-Cantillo  J. Ernesto Mancera 《Marine pollution bulletin》2010,60(7):1018-1030

To understand the coastal water quality of San Andrès Island, and provide tools for the management of its marine resources, we present the historical analysis of the island monitoring, which includes ammonia, nitrites, nitrate, phosphates, fecal and total coliforms. The anthropogenic pressure on the coastal system is heavy, with water nutrification, posing at risk seagrass and coral ecosystems. During dry season, biologically available nitrogen is 3-9 times higher than the maximum recommended for coral reefs, while during wet season values are 2-6.4 times the maximum. Biologically available phosphorous is also high, 1-8 times the maximum during dry season, 2-13 times during wet season. In some sites the concentration of pathogenic bacteria is above the limits set by law for primary and secondary contact. It is urgent to improve the management of sewage discharge, the main polluting source of San Andres coastal waters.  相似文献   

Modal response analysis of multi‐support structures using a random vibration approach          下载免费PDF全文

Ernesto Heredia‐Zavoni  Sandra Santa‐Cruz  Francisco L. Silva‐González 《地震工程与结构动力学》2015,44(13):2241-2260

A formulation is developed for modal response analysis of multi‐support structures using a random vibration approach. The spectral moments of the structural response are rigorously decomposed into contributions from spectral moments of uncoupled modal responses. An advantage of the proposed formulation is that the total dynamic response can be obtained on the basis of mode by mode uncoupled analyses. The contributions to the total response from modal responses under individual support ground motions and under cross‐correlated pairs of support ground motions can be recognized explicitly. The application and performance of the formulation is illustrated by means of an example using a well‐established coherency spectrum model and widely known power spectra models, such as white noise and Kanai–Tajimi. The first three spectral moments of displacement, shear, and bending moment responses are computed, showing that the formulation produces the same results as the exact solution. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Effects of reclamation and regeneration processes on organic matter from estuarine soils and sediments   总被引：1，自引：0，他引：1  

C. Santín  J.M. de la Rosa  H. Knicker  X.L. Otero  M.Á. Álvarez  F.J. González-Vila 《Organic Geochemistry》2009,40(9):931-941

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Paleomagnetism, geochemistry and Ar/Ar dating of the North-eastern Paraná Magmatic Province: tectonic implications     

M. Ernesto  M. I. B. Raposo  L. S. Marques  P. R. Renne  L. A. Diogo  A. de Min   《Journal of Geodynamics》1999,28(4-5)

Seventy sites of sills, flows and dikes from Northeastern Paraná Magmatic Province (PMP), were submitted to paleomagnetic, chemical and radiometric analyses. The rocks are high in TiO₂ content, and similar in composition to the rocks from the northern region of PMP. The sills intrude mainly Paleozoic sediments, and can be subdivided into two domains; the northern being characterized by sills showing reversed polarities, and the southern essentially by sills of normal polarities. ⁴⁰Ar/³⁹Ar dating of three distinct sills gave plateau ages (129.9 ± 0.1, 130.3 ± 0.1 and 131.9 ± 0.4 Ma) that are similar to surface-outcropping flows of the Northern Paraná Basin, and the Ponta Grossa dikes. The new paleomagnetic data combined with existing data from the northern PMP allowed the calculation of a paleomagnetic pole at 71.4° E and 83.0° S (N = 92; α₉₅=2.4°; k = 39). This pole is in good agreement with poles for central and southern PMP, which are slightly older than the northern PMP, as well as for the contemporaneous Central Alkaline Province (Paraguay) on the western side of PMP. In contrast, the coeval pole for the Ponta Grossa dikes (eastern border of PMP), however, is slightly displaced from that group of poles, suggesting that dikes in that area may have undergone some tectonic tilting.  相似文献