CPLat: first operational experimental processing center for SIRGAS in Argentina     

María Paula Natali  M. Müller  L. Fernández  C. Brunini 《Journal of Geodesy》2009,83(3-4):219-226

The SIRGAS permanent GPS network which is in fact the IGS network densification for the American continent, consists today of more than 200 stations covering the continent and islands. It is currently processed by the IGS RNAAC SIR centre at Deutsches Geodätisches Forschungsinstitut producing weekly free solutions relying on IGS final orbits and EOP that contribute to the ITRF through IGS. By August 2006, the SIRGAS Working Group I had accepted five proposals for experimental processing centers within the region that would collaborate with IGS RNAAC SIR. One of them, Centro de Procesamiento La Plata (CPLat) in Argentina, began processing 60 stations on October 2006. By January 2007 CPLat reached operational capability, delivering weekly free solution SINEX files, with an internal consistency of 1.5 mm average for the horizontal components, and 3 mm in the vertical. Comparisons with IGS global and IGS RNAAC SIR weekly solutions were taken as external consistency indications, showing average RMS residuals of 1.8, 2.4 and 5 mm for the north, east, and vertical component, respectively. Analysis and comparison of adjusted solution time series from CPLat and other processing centers has proved to be highly valuable for solution QC, namely detection and identification of station anomalous behavior or modelling problems. These procedures will ensure the maintenance of the performance specifications for CPLat solutions. Action is being taken in order to guarantee the continuity of this effort beyond the experimental phase.  相似文献   

Spatial variability of prodeltaic undulations on the Guadalfeo River prodelta: support to the genetic interpretation as hyperpycnal flow deposits     

F. J. Lobo  J. A. Goff  I. Mendes  P. Bárcenas  L. M. Fernández-Salas  W. Martín-Rosales  J. Macías  V. Díaz del Río 《Marine Geophysical Researches》2015,36(4):309-333

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The climate in Zafra from 1750 to 1840: precipitation     

M. I. Fernández-Fernández  M. C. Gallego  F. Domínguez-Castro  R. M. Trigo  J. M. Vaquero 《Climatic change》2015,129(1-2):267-280

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A cyclical period variation detected in the updated orbital period analysis of TV Columbae     

Zhibin Dai  Shengbang Qian  Eduardo Fernández Lajús  G. L. Baume 《Astrophysics and Space Science》2010,330(2):243-248

Two CCD photometries of the intermediate polar TV Columbae are made for obtaining two updated eclipse timings with high precision. There is an interval time ～17 yr since the last mid-eclipse time observed in 1991. Thus, the new mid-eclipse times might offer an opportunity to check the previous orbital ephemerides. A calculation indicates that the orbital ephemeris derived by Augusteijn et al. (Astron. Astrophys. Suppl. Ser. 107:219, 1994) should be corrected. Based on the proper linear ephemeris (Hellier in Mon. Not. R. Astron. Soc. 264:132, 1993), the new orbital period analysis suggests a cyclical period variation in the O–C diagram of TV Columbae. Using Applegate’s mechanism to explain the periodic oscillation in the O–C diagram, the required energy is larger than the energy that a M0-type star can afford over a complete variation period of ～31.0(±3.0) yr. Thus, the light travel-time effect indicates that the tertiary component in TV Columbae may be a dwarf with a low mass, which is near the lower mass limit of ～0.08M _⊙ as long as the inclination of the third body is high enough.  相似文献   

Occurrence and fate of polycyclic aromatic hydrocarbons in the coastal surface microlayer   总被引：2，自引：0，他引：2  

Guitart C  García-Flor N  Bayona JM  Albaigés J 《Marine pollution bulletin》2007,54(2):186-194

Polycyclic aromatic hydrocarbons (PAHs) were measured in the coastal sea surface microlayer (SML), the sub-surface waters (SSW) and the overlying atmosphere in order to investigate the influence of the SML on contaminant enrichment and air-sea exchange. Samples were collected at two contrasting locations of the NW Mediterranean, one urban influenced (off Barcelona, Spain) and another comparatively clean (off Banyuls-sur-Mer, France). Statistical data analysis confirmed the accumulation of PAHs in the SML with respect to the SSW (20.3+/-9.1 vs. 13.1+/-10.0 ng L(-1) in the dissolved phase; 709+/-207 vs. 158+/-111 ng g(-1) in the particulate phase). This accumulation was higher at the contaminated location (Barcelona station) compared with the more pristine one, with PAH enrichments 1.5 and 4.5 times higher for the dissolved and particulate phases, respectively, indicating that the enrichment of PAHs in the SML is dominated by particle transport processes.  相似文献   

Analysis of the correlations between freeze–thaw and salt crystallization tests     

V. Cárdenes  F. J. Mateos  S. Fernández-Lorenzo 《Environmental Earth Sciences》2014,71(3):1123-1134

Two of the most popular weathering tests used for dimension stone are EN 12371 freeze–thaw (FT) and EN 12370 Salt Crystallization (SC). These tests are used to assign a durability value to the rocks. Both tests are based on the cyclical growth of crystals in the porous system of the rock, which causes structural stress on the rock matrix that may affect its integrity. The weathering mechanism is the same in both tests although the rate of volume increase is higher for the salt crystals. Due to this similarity, the two tests provide complementary information. The EN (European Norms) recommend evaluating the results together, but do not establish correlations between the results of these two tests for different types of rocks. Knowing these relationships would improve the understanding of the results and the response to weathering of the rock once placed in a building. In this work, several ornamental rocks (sandstones, limestones, dolostones, and a travertine) from the Iberian Peninsula were submitted to FT and SC tests. Rocks were mineralogically and petrographically characterized, and their porous systems were defined by a combination of techniques (scanning electronic microscopy, digital images analysis, and mercury porosimetry). The results of the tests were quantified numerically to compare them. The velocity of propagation of ultrasonic waves was measured before and after the tests. After the statistical analysis, significant correlations were found between the FT and SC tests, and between the connected porosity and the durability index of the rocks.  相似文献   

Building a 3D geomodel for water resources management: case study in the Regional Park of the lower courses of Manzanares and Jarama Rivers (Madrid, Spain)     

Francisco Carreño Conde  Sandra García Martínez  Javier Lillo Ramos  Raquel Fernández Martínez  Ariana Mabeth-Montoya Colonia 《Environmental Earth Sciences》2014,71(1):61-66

Water resources management of protected sites requires a powerful tool to analyze the process and changes that are occurring in the environment. This paper describes a 3D geomodel design of the Jarama River Detrital Aquifer located in Madrid (Spain). That hydrogeological unit is included in the “Parque Regional de los Cursos Bajos de los Ríos Manzanares y Jarama” (Regional Park of the Lower Courses of Manzanares and Jarama Rivers). The goal of this work is to define a method by which a three-dimensional (3D) model can be created with hydrogeologic geometry real of main aquifer, to accomplish an adequate management of the groundwater resources. All data used in this study were integrated in a geographic database: geological and hydrogeological information, geological map (1:25,000), eleven cross-sections, piezometric maps and a digital elevation model. The constructed 3D model of the Jarama Aquifer shows geometric features and spatial distribution and variations of geologic units. Thus, the 3D model allows the assessment of volumes of each unit, the depth and thickness variations of the main aquifer, and the spatial and temporal variations of water tables. From the 3D model, the most suitable areas (in terms of groundwater protection) for managed recharge and mining works have been identified.  相似文献   

3D alluvial aquifer reconstruction in polluted areas by means of GPR (Sabiñánigo,N Spain)     

Ó. Pueyo Anchuela  J. F. Ipas-Lloréns  H. Gil Garbí  A. M. Casas-Sainz  A. Pocoví Juan  M. L. Garijo  J. G. Fernández-Martos  J. Fernández-Cascán 《Environmental Earth Sciences》2014,72(11):4291-4302

Assumptions of simple geometries for alluvial deposits (related to main rivers) can preclude determination of complexities that are revealed as fundamental controls in underground flow. Although subhorizontal contacts between alluvial and substratum materials are expected, previous sedimentary or erosional processes can result in irregular geometries, only accessible through detailed analysis. The studied case presents the 3D reconstruction of a Quaternary terrace in the proximities of Sabiñánigo (Southern Pyrenees, Northeastern Spain), lying on homogeneous Eocene marls. The studied area is located in an industrialized area supporting strongly pollutant chemical industry (chlorinated pesticides) for the past 50 years. The objective of the study was to constrain the groundwater pathway along the area to subsequently analyze leakage of chemicals to the water table. In order to reveal preferred flow paths, a detailed characterization of the internal structure of the alluvial deposits (0.5–13 m thick) and their relations with the Tertiary substratum was carried out by means of ground penetrating radar (GPR, 50 and 100 MHz antennas). The obtained models permit identifying several topographic highs in the alluvial/substratum contact, determining preferred pathways in water flow, favoring particular conditions associated with low levels of the water table. The presented results support the interest of application of GPR surveys in order to characterize the groundwater pathways in expected homogeneous areas and their importance in order to establish the contaminant surveillance network.  相似文献   

Alleviating drought and water scarcity in the Mediterranean region through managed aquifer recharge     

Henao Casas  J. D.  Fernández Escalante  E.  Ayuga  F. 《Hydrogeology Journal》2022,30(6):1685-1699

Drought and water scarcity can significantly impair the sustainable development of groundwater resources, a scenario commonly found in aquifers in the Mediterranean region. Water management measures to address these drivers of groundwater depletion are highly relevant, especially considering the increasing severity of droughts under climate change. This study evaluates the potential of managed aquifer recharge (MAR) to offset the adverse effects of drought and water scarcity on groundwater storage. Los Arenales aquifer (central Spain), which was unsustainably exploited for irrigation in the second half of the twentieth century, is employed as a case study. Two neighbouring zones within this aquifer are contrasted, namely, Los Arenales (LA) and Medina del Campo (MC). The primary difference between them in terms of water resources management is the wide-scale implementation of MAR systems in LA since the early 2000s. Several groundwater statistical methods are used. Groundwater-level trend analysis and average piezometric levels show in LA a faster recovery of aquifer storage and less susceptibility to drought compared to MC. On the other hand, standardised precipitation indexes and standardised groundwater level indexes of detrended groundwater-level time series, which do not include the effects of MAR, show that LA can be more negatively affected by drought and groundwater abstraction. The sharper recovery of piezometric levels in LA when considering MAR, and bigger drought impacts observed when the effects of this measure are removed, demonstrate that MAR can effectively alleviate the impacts of water scarcity and drought, providing an adaptation solution to climate change worldwide.

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Landslide detection and inventory by integrating LiDAR data in a GIS environment     

J. A. Palenzuela  M. Marsella  C. Nardinocchi  J. L. Pérez  T. Fernández  J. Chacón  C. Irigaray 《Landslides》2015,12(6):1035-1050

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