Alpine paleostress reconstruction and active faulting in Western Iberia     

Loreto Antón  Alfonso Muñoz-Martin  Gerardo De Vicente 《Central European Journal of Geosciences》2010,2(2):152-164

The study of intraplate tectonics is crucial for understanding the deformation within plates, far from active plate boundaries and associated stress transmission to the plate interiors. This paper examines the tectonic evolution of the Variscan basement at the western margin of the Cenozoic Duero basin. Located east of the Vilariça Fault System in NW Iberia, this intraplate zone is a relatively flat but elevated area with an intense NNE-SSW trending fault system and associated moderate seismicity. Although the area has played an important role in the Duero basin configuration, its Alpine to present-day tectonic evolution has not been well constrained. In order to characterize the successive paleostress fields, 1428 pairs of fault-striae were measured at 56 sites and two focal mechanisms were used. Stress inversion methods have been applied to analyze paleostress regimes. Results show the existence of three dominant maximum horizontal stress (Shmax) trends: N-S, NE-SW and E-W. Relative and absolute dating of the activated faults for each Shmax shows that the clearly predominant N-S paleostress field in the zone has been active since the Oligocene up to the present day; while a NE-SW stress field is found to have been active during the Cretaceous and an older E-W paleostress field was active in the earlier Alpine cycle (Late Triassic).  相似文献   

Geo-environmental mapping using physiographic analysis: constraints on the evaluation of land instability and groundwater pollution hazards in the Metropolitan District of Campinas,Brazil     

Paulo Cesar Fernandes-da-Silva  Ricardo Vedovello  Claudio Jose Ferreira  John Canning Cripps  Maria Jose Brollo  Amelia Joao Fernandes 《Environmental Earth Sciences》2010,61(8):1657-1675

Geo-environmental terrain assessments and territorial zoning are useful tools for the formulation and implementation of environmental management instruments (including policy-making, planning, and enforcement of statutory regulations). They usually involve a set of procedures and techniques for delimitation, characterisation and classification of terrain units. However, terrain assessments and zoning exercises are often costly and time-consuming, particularly when encompassing large areas, which in many cases prevent local agencies in developing countries from properly benefiting from such assessments. In the present paper, a low-cost technique based on the analysis of texture of satellite imagery was used for delimitation of terrain units. The delimited units were further analysed in two test areas situated in Southeast Brazil to provide estimates of land instability and the vulnerability of groundwater to pollution hazards. The implementation incorporated procedures for inferring the influences and potential implications of tectonic fractures and other discontinuities on ground behaviour and local groundwater flow. Terrain attributes such as degree of fracturing, bedrock lithology and weathered materials were explored as indicators of ground properties. The paper also discusses constraints on- and limitations of- the approaches taken.  相似文献   

European temperature records of the past five centuries based on documentary/instrumental information compared to climate simulations     

Eduardo Zorita  Anders Moberg  Lotta Leijonhufvud  Rob Wilson  Rudolf Brázdil  Petr Dobrovolný  Jürg Luterbacher  Reinhard Böhm  Christian Pfister  Dirk Riemann  Rüdiger Glaser  Johan Söderberg  Fidel González-Rouco 《Climatic change》2010,101(1-2):143-168

Two European temperature reconstructions for the past half-millennium, January-to-April air temperature for Stockholm (Sweden) and seasonal temperature for a Central European region, both derived from the analysis of documentary sources and long instrumental records, are compared with the output of climate simulations with the model ECHO-G. The analysis is complemented by comparisons with the long (early)-instrumental record of Central England Temperature (CET). Both approaches to study past climates (simulations and reconstructions) are burdened with uncertainties. The main objective of this comparative analysis is to identify robust features and weaknesses in each method which may help to improve models and reconstruction methods. The results indicate a general agreement between simulations obtained with temporally changing external forcings and the reconstructed Stockholm and CET records for the multi-centennial temperature trend over the recent centuries, which is not reproduced in a control simulation. This trend is likely due to the long-term change in external forcing. Additionally, the Stockholm reconstruction and the CET record also show a clear multi-decadal warm episode peaking around AD 1730, which is absent in the simulations. Neither the reconstruction uncertainties nor the model internal climate variability can easily explain this difference. Regarding the interannual variability, the Stockholm series displays, in some periods, higher amplitudes than the simulations but these differences are within the statistical uncertainty and further decrease if output from a regional model driven by the global model is used. The long-term trend of the CET series agrees less well with the simulations. The reconstructed temperature displays, for all seasons, a smaller difference between the present climate and past centuries than is seen in the simulations. Possible reasons for these differences may be related to a limitation of the traditional ‘indexing’ technique for converting documentary evidence to temperature values to capture long-term climate changes, because the documents often reflect temperatures relative to the contemporary authors’ own perception of what constituted ‘normal’ conditions. By contrast, the amplitude of the simulated and reconstructed inter-annual variability agrees rather well.  相似文献   

Intercomparison and analyses of the climatology of the West African Monsoon in the West African Monsoon Modeling and Evaluation project (WAMME) first model intercomparison experiment   总被引：3，自引：3，他引：0  

Yongkang Xue  Fernando De Sales  W. K.-M. Lau  Aaron Boone  Jinming Feng  Paul Dirmeyer  Zhichang Guo  Kyu-Myong Kim  Akio Kitoh  Vadlamani Kumar  Isabelle Poccard-Leclercq  Natalie Mahowald  Wilfran Moufouma-Okia  Phillip Pegion  David P. Rowell  Jae Schemm  Siegfried D. Schubert  Andrea Sealy  Wassila M. Thiaw  Augustin Vintzileos  Steven F. Williams  Man-Li C. Wu 《Climate Dynamics》2010,35(1):3-27

This paper briefly presents the West African Monsoon (WAM) Modeling and Evaluation Project (WAMME) and evaluates WAMME general circulation models’ (GCM) performances in simulating variability of WAM precipitation, surface temperature, and major circulation features at seasonal and intraseasonal scales in the first WAMME experiment. The analyses indicate that models with specified sea surface temperature generally have reasonable simulations of the pattern of spatial distribution of WAM seasonal mean precipitation and surface temperature as well as the averaged zonal wind in latitude-height cross-section and low level circulation. But there are large differences among models in simulating spatial correlation, intensity, and variance of precipitation compared with observations. Furthermore, the majority of models fail to produce proper intensities of the African Easterly Jet (AEJ) and the tropical easterly jet. AMMA Land Surface Model Intercomparison Project (ALMIP) data are used to analyze the association between simulated surface processes and the WAM and to investigate the WAM mechanism. It has been identified that the spatial distributions of surface sensible heat flux, surface temperature, and moisture convergence are closely associated with the simulated spatial distribution of precipitation; while surface latent heat flux is closely associated with the AEJ and contributes to divergence in AEJ simulation. Common empirical orthogonal functions (CEOF) analysis is applied to characterize the WAM precipitation evolution and has identified a major WAM precipitation mode and two temperature modes (Sahara mode and Sahel mode). Results indicate that the WAMME models produce reasonable temporal evolutions of major CEOF modes but have deficiencies/uncertainties in producing variances explained by major modes. Furthermore, the CEOF analysis shows that WAM precipitation evolution is closely related to the enhanced Sahara mode and the weakened Sahel mode, supporting the evidence revealed in the analysis using ALMIP data. An analysis of variability of CEOF modes suggests that the Sahara mode leads the WAM evolution, and divergence in simulating this mode contributes to discrepancies in the precipitation simulation.  相似文献   

Modelling soil heat flux     

Claudia M. Núñez  Eduardo A. Varas  Francisco J. Meza 《Theoretical and Applied Climatology》2010,100(3-4):251-260

A mathematical model to calculate soil heat flux in three steps is presented. In the first, an hourly air temperature based on the average daily temperature, using Fourier series coefficients is estimated. The estimated hourly air temperature constitutes an input variable for the second step of the model. In the second step, heat transfer principles, using the thermal properties of the soil in order to obtain a soil temperature profile in a 1-m-depth soil stratum, is applied. Finally, the results of the second stage are used to numerically calculate hourly heat flux in the soil. Correlation coefficients between observed and calculated hourly temperature values over the three summer months were 0.98, 0.97 and 0.96. Correlation coefficient for the entire study period between observed and estimated soil heat-flux values was 0.92 with a mean square error of 19.8 W m^–2.  相似文献   

Modelling and interpreting the dependence of clustering on the spectral energy distributions of galaxies     

Lan Wang  Cheng Li  Guinevere Kauffmann  Gabriella De Lucia 《Monthly notices of the Royal Astronomical Society》2007,377(4):1419-1430

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Comparison of spectral and time domain calibration methods for precipitation‐discharge processes     

Jan J. Quets  Gabriëlle J. M. De Lannoy  Valentijn R. N. Pauwels 《水文研究》2010,24(8):1048-1062

Hydrological model parameter estimation is an important aspect in hydrologic modelling. Usually, parameters are estimated through an objective function minimization, quantifying the mismatch between the model results and the observations. The objective function choice has a large impact on the sensitivity analysis and calibration outcomes. In this study, it is assessed whether spectral objective functions can compete with an objective function in the time domain for optimization of the Soil and Water Assessment Tool (SWAT). Three empirical spectral objective functions were applied, based on matching (i) Fourier amplitude spectra, (ii) periodograms and (iii) Fourier series of simulated and observed discharge time series. It is shown that most sensitive parameters and their optimal values are distinct for different objective functions. The best results were found through calibration with an objective function based on the square difference between the simulated and observed discharge Fourier series coefficients. The potential strengths and weaknesses of using a spectral objective function as compared to utilising a time domain objective function are discussed. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

WMAP 3-yr data with Correlated Component Analysis: anomalous emission and impact of component separation on the CMB power spectrum     

A. Bonaldi  S. Ricciardi  S. Leach  F. Stivoli  C. Baccigalupi  G. De Zotti 《Monthly notices of the Royal Astronomical Society》2007,382(4):1791-1803

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Granites and their enclaves,developments in petrology, 3: J. Didier. Elsevier,Amsterdam-London-New York, 1973, 393 pp., Dfl. 100.00     

C.A.R. De Albuquerque 《Chemical Geology》1974,13(3):234-236

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Late Holocene effective precipitation variations in the maritime regions of south-west Scandinavia     

R. De Jong  D. Hammarlund  A. Nesje 《Quaternary Science Reviews》2009,28(1-2):54-64

At present, the climate in south-west Scandinavia is predominantly controlled by westerlies carrying moist Atlantic air, which forms a main source of precipitation in all seasons. Past variations in the ratio between precipitation and evaporation (effective precipitation) from terrestrial sites, however, may indicate changes in the degree of maritime influence. Palaeoclimatic archives in this region are thus ideally situated to study past changes in atmospheric circulation patterns. In this study, multi-proxy comparisons of records from three peat bogs and two lakes are used to reconstruct regional-scale variations of effective precipitation in south-west Sweden during the Late Holocene. The total aeolian sediment influx into two peat bogs is used as a proxy for storm activity. The frequency of storm phases increases strongly after ca 2500 cal yrs BP. Dry conditions occur on a regional scale around 4800–4400, 2000–1700, 1300–1000, 700–500 and 300–100 cal yrs BP. In addition, a comparison to winter precipitation reconstructed from four Norwegian glaciers shows similar variations during the past ca 2000 years. This indicates that the climate in both regions was controlled by large-scale atmospheric circulation dynamics of the North Atlantic region. The strong variability of effective precipitation and storm activity after ca 2500 cal yrs BP indicates a highly variable climate.  相似文献