MIS 5/4 transition in a mountain environment: herpetofaunal assemblages from Cueva del Camino,central Spain     

Hugues‐Alexandre Blain  César Laplana  Paloma Sevilla  Juan Luis Arsuaga  Enrique Baquedano  Alfredo Pérez‐González 《Boreas: An International Journal of Quaternary Research》2014,43(1):107-120

The Cueva del Camino site (Pinilla del Valle, Madrid, Spain) is located in the upper valley of the Lozoya River in the Sierra de Guadarrama, a mountain range extending NE?SW within the Central Range System. Due to its location within a mountain range on the central Iberian Peninsula at an altitude of 1114 m a.s.l. and the numerical dating of its sediments, the palaeontological site of Cueva del Camino has proved a highly relevant location for studying the ecological changes linked to the climatic fluctuations at the end of Marine Isotope Stage (MIS) 5 and the beginning of MIS 4. Environmental reconstructions suggest a rather open, patchy landscape throughout the succession, with abundant evidence of dry meadows, scrublands and rocky habitats. The climate can be considered as generally warm, reaching mean annual temperatures (MATs) of up to 13.8°C (i.e. higher than today's by up to 2.9°C). Three cooler events can be seen throughout the succession as reflected by the presence of Rana iberica, Anguis fragilis and Coronella austriaca. The first of these events may correlate with MIS 5b; the second in the Central sector may correlate with the Stadial I pollen event occurring at the end of MIS 5a; and the third event, corresponding to the coldest MAT of the entire succession with MATs 0.9°C lower than today's, may correspond to the transition from MIS 5a to MIS 4. The evolution of mean annual precipitation (MAP) is characterized by warm periods, drier and cold periods, as well as wetter periods (up to +356 mm compared to today's MAP values), similar to what occurs today in the high‐elevation areas of the neighbouring mountains. Our study gives new quantitative estimations for the climatic fluctuations in mountain environments of central Spain at the MIS 5/4 transition and their associated ecological changes.  相似文献   

Reply to the Comment by Bergmann on “The Høvsøre Tall Wind-Profile Experiment: A Description of Wind Profile Observations in the Atmospheric Boundary Layer”     

Alfredo Peña  Rogier Floors  Sven-Erik Gryning 《Boundary-Layer Meteorology》2015,157(3):547-551

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Global climate models as forcing for regional ocean modeling: a sensitivity study in the Iberian Basin (Eastern North Atlantic)     

Ana Cordeiro Pires  Rita Nolasco  Alfredo Rocha  Alexandre M. Ramos  Jesus Dubert 《Climate Dynamics》2014,43(3-4):1083-1102

This work evaluates the performance of several global climate models (GCMs) as forcing of a regional ocean model configuration centered in the Iberian Basin. The study is divided in two parts. First, the output of nine GCMs is analyzed based on the fields needed to force the ocean model (Regional Ocean Modelling System—ROMS). GCMs differ greatly between them and their performance depends on the field. In the second part, the two GCMs with the worst performances in both extremes of the ensemble are used as forcing for two ROMS simulations, with the purpose of assessing the range of uncertainty comprised in this set of GCMs. Two other ROMS runs are setup: one climatologically forced control run, and one forced with the average of all the nine GCMs—the ensemble mean. Results show that the tendency of overestimation/underestimation of the forcings is reflected in the modeled hydrography, both at the surface and deeper layers down to 500 m. Nevertheless, in terms of circulation, all four runs reproduce the Azores Current, as well as the coastal transition zone seasonality (winter poleward flow and summer upwelling-associated equatorward flow). The CGCMs output performance as forcing depends on the forcing variable: one performs well for one or more variables, but badly for others, and which field is well or badly reproduced varies for each CGCM. Therefore, there is not a single CGCM having the best forcing for all variables. Hence, our results indicate that the most adequate approach consists of using the ensemble mean as forcing rather than using an individual model. This is supported by the general low overall (i.e. for all forcing variables) errors of the ensemble mean regarding the control climatological dataset, and the good comparison of the ensemble-forced ROMS run with the control run.  相似文献   

Reply to ��Comment on Sousa, M.L. and Costa, A.C., ��ground-motion scenarios consistent with probabilistic seismic hazard disaggregation analysis. Application to Mainland Portugal��?�� by Jo?o F. B. D. Fonseca and Susana P. Vilanova     

Maria Lu��sa Sousa  Alfredo Campos Costa 《Bulletin of Earthquake Engineering》2011,9(4):1297-1307

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AMO’s structure and climate footprint in observations and IPCC AR5 climate simulations   总被引：1，自引：1，他引：0  

Argyro Kavvada  Alfredo Ruiz-Barradas  Sumant Nigam 《Climate Dynamics》2013,41(5-6):1345-1364

This study aims to characterize the spatiotemporal features of the low frequency Atlantic Multidecadal Oscillation (AMO), its oceanic and atmospheric footprint and its associated hydroclimate impact. To accomplish this, we compare and evaluate the representation of AMO-related features both in observations and in historical simulations of the twentieth century climate from models participating in the IPCC’s CMIP5 project. Climate models from international leading research institutions are chosen: CCSM4, GFDL-CM3, UKMO-HadCM3 and ECHAM6/MPI-ESM-LR. Each model employed includes at least three and as many as nine ensemble members. Our analysis suggests that the four models underestimate the characteristic period of the AMO, as well as its temporal variability; this is associated with an underestimation/overestimation of spectral peaks in the 70–80 year/10–20 year range. The four models manifest the mid-latitude focus of the AMO-related SST anomalies, as well as certain features of its subsurface heat content signal. However, they are limited when it comes to simulating some of the key oceanic and atmospheric footprints of the phenomenon, such as its signature on subsurface salinity, oceanic heat content and geopotential height anomalies. Thus, it is not surprising that the models are unable to capture the majority of the associated hydroclimate impact on the neighboring continents, including underestimation of the surface warming that is linked to the positive phase of the AMO and is critical for the models to be trusted on projections of future climate and decadal predictions.  相似文献   

A late Holocene record of arid events from the Cuzco region,Peru     

Alex Chepstow‐Lusty  Michael R. Frogley  Brian S. Bauer  Mark. B. Bush  Alfredo Tupayachi Herrera 《第四纪科学杂志》2003,18(6):491-502

The small recently infilled lake basin of Marcacocha (13°13′S, 72°12′W, 3355 m) in the Cuzco region of Peru has a morphology and location that renders it extremely sensitive to environmental change. A record of vegetation, human impact and climatic change during the past 4200 yr has been obtained from a highly organic core taken from the centre of the basin. Sustained arid episodes that affected the Peruvian Andes may be detectable using the proxy indicator of sedge (Cyperaceae) pollen abundances. As the lake‐level was lowered during sustained drier conditions, the local catchment was colonised by Cyperaceae, whereas during lake floods, they retreated or were submerged and pollen production was correspondingly reduced. Drier episodes during prehistoric times occurred around 900 bc , 500 bc , ad 100 and ad 550, with a longer dry episode occurring from ad 900 to 1800. Evidence from the independently derived Quelccaya ice‐core record and the archaeological chronology for the Cuzco region appears to support the climatic inferences derived from the sedge data. Many of these aridity episodes appear to correspond with important cultural changes in the Cuzco region and elsewhere in the Central Andes. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Galactic Globular Cluster Relative Ages: Clues on the Milky Way Formation and Evolution     

Alfred Rosenberg  Antonio Aparicio  Giampaolo Piotto  Ivo Saviane 《Astrophysics and Space Science》2002,281(1-2):125-126

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Decrease of keV electron and ion fluxes in the dayside magnetosphere during the early phase of magnetospheric disturbances     

B. Hultqvist  B. Aparicio  H. Borg  R. Arnoldy  T.E. Moore 《Planetary and Space Science》1981,29(1):107-126

We demonstrate that a decrease of the keV particle fluxes in the dayside magnetosphere near the geosynchronous orbit is characteristic of the first several hours of magnetospheric disturbances. After some hours newly injected plasma from the nightside reaches the ‘evacuated’ regions of the dayside magnetosphere and strong flux increases are observed. The high altitude observational results reported here agree well with earlier results of measurements near the ionosphere. The ‘evacuation’ of the dayside magnetosphere is interpreted in terms of a change in the convection pattern associated with an increase of the large scale electric field at the onset of the disturbance. The model presented is capable of accommodating all characteristics of the observational data, such as the temporal and spatial distributions, energy and pitch angle characteristics, and differences between electrons and protons.  相似文献   

NGC 3109: Halo/Disk Structures in Faint Galaxies     

Sebastian L. Hidalgo  Antonio Aparicio 《Astrophysics and Space Science》2002,281(1-2):123-124

We present here preliminary results of our wide-field study of NGC 3109: a low luminosity galaxy in the outskirts of the Local Group. Its edge-on orientation (which simplifies the study of a possible halo) and the possibility that it could, in fact, be a small spiral (the smallest in the Local Group) makes its deep analysis of major relevance to understand the properties of dwarf galaxies and the transition from dwarf irregulars to spirals. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

Structural behaviour and design criteria of under‐deck cable‐stayed bridges subjected to seismic action     

Alfredo Camara  Ana M. Ruiz‐Teran  Peter J. Stafford 《地震工程与结构动力学》2013,42(6):891-912

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