Present climate and climate change over North America as simulated by the fifth-generation Canadian regional climate model     

Leo Šeparović  Adelina Alexandru  René Laprise  Andrey Martynov  Laxmi Sushama  Katja Winger  Kossivi Tete  Michel Valin 《Climate Dynamics》2013,41(11-12):3167-3201

The fifth-generation Canadian Regional Climate Model (CRCM5) was used to dynamically downscale two Coupled Global Climate Model (CGCM) simulations of the transient climate change for the period 1950–2100, over North America, following the CORDEX protocol. The CRCM5 was driven by data from the CanESM2 and MPI-ESM-LR CGCM simulations, based on the historical (1850–2005) and future (2006–2100) RCP4.5 radiative forcing scenario. The results show that the CRCM5 simulations reproduce relatively well the current-climate North American regional climatic features, such as the temperature and precipitation multiannual means, annual cycles and temporal variability at daily scale. A cold bias was noted during the winter season over western and southern portions of the continent. CRCM5-simulated precipitation accumulations at daily temporal scale are much more realistic when compared with its driving CGCM simulations, especially in summer when small-scale driven convective precipitation has a large contribution over land. The CRCM5 climate projections imply a general warming over the continent in the 21st century, especially over the northern regions in winter. The winter warming is mostly contributed by the lower percentiles of daily temperatures, implying a reduction in the frequency and intensity of cold waves. A precipitation decrease is projected over Central America and an increase over the rest of the continent. For the average precipitation change in summer however there is little consensus between the simulations. Some of these differences can be attributed to the uncertainties in CGCM-projected changes in the position and strength of the Pacific Ocean subtropical high pressure.  相似文献   

The role of closed ecological systems in carbon cycle modelling     

Alexandru Milcu  Martin Lukac  Phil Ineson 《Climatic change》2012,112(3-4):709-716

Acquiring a mechanistic understanding of the role of biotic feedbacks for the links between atmospheric CO₂ concentrations and temperature is essential for trustworthy climate predictions. Currently, computer-based simulations are the only available tool to estimate the global impact of biotic feedbacks on future atmospheric CO₂ and temperatures. Here we propose an alternative and complementary approach by using materially closed, energetically open analogue/physical models of the carbon cycle. We argue that there is unexplored potential in using a materially closed approach to improve our understanding of the magnitude and direction of many biotic carbon feedbacks and that recent technological advances make this feasible. We also suggest how such systems could be designed and discuss the advantages and limitations of establishing physical models of the global carbon cycle.  相似文献   

Structural Properties of Pulsating Star Light Curves Through Fuzzy Divisive Hierarchical Clustering     

Adina Dumitrescu  Alexandru Pop  D. Dumitrescu 《Astrophysics and Space Science》1997,250(2):205-226

The aim of this paper is to explore the possibility of using a fuzzy divisive clustering technique to the classification of pulsating stars according to the shape of their light curves. The considered sample contains Cepheides, RR Lyrae stars, and high amplitude Scuti and SX Phoenicis stars. Our investigations proved the ability of this method to identify morphological groups in a given class of pulsating stars. The method is also useful for establishing the membership of an unknown variable star in a given class.  相似文献   

The intriguing orbital period variability of Y Leonis     

Alexandru Pop  Vlad Turcu  Alexandru Marcu 《Astrophysics and Space Science》2011,333(1):17-28

The orbital period variation of the oEA system Y Leo is revised by taking into account new times of minimum light covering an extended time base of 101.8 yr. A multiperiodic ephemeris was finally established by carefully approaching the problem of periodicity detection for the considered periodic components. A method relying on Monte Carlo simulations was applied. The problem of the long-term behaviour of the O–C curve was taken into account using parabolic, and parabolic + periodic ephemerides. The physical interpretation of the mathematical models describing both long- and short-term behaviour of the O–C curve was performed by considering different mechanisms: the conservative mass transfer, the light-time effect, and the orbital period modulation through the cyclic magnetic activity of the late spectral type secondary component in the system. The consequences of these interpretations are rather intriguing and emphasize the need of new and detailed observational studies on Y Leo.  相似文献   

C. Breitkreuz and N. Petford (eds): Physical geology of high-level magmatic systems and K. Thomson and N. Petford (eds): Structure and emplacement of high-level magmatic systems     

Alexandru Szakács 《Bulletin of Volcanology》2012,74(7):1771-1774

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State-of-the art and future of earthquake early warning in the European region     

John Clinton  Aldo Zollo  Alexandru Marmureanu  Can Zulfikar  Stefano Parolai 《Bulletin of Earthquake Engineering》2016,14(9):2441-2458

European researchers and seismic networks are active in developing new approaches to earthquake early warning (EEW), implementing and operating test EEW systems, and in some cases, offering operational EEW to end users. We present the key recent developments in EEW research in Europe, describe the networks and regions where EEW is currently in testing or development, and highlight the two systems in Turkey and Romania that currently provide operational systems to a limited set of end users.  相似文献   

Using experimental data to reduce the single-building sigma of fragility curves: case study of the BRD tower in Bucharest, Romania   总被引：1，自引：0，他引：1  

Matthieu Perrault  Philippe Gueguen  Alexandru Aldea  Sorin Demetriu 《地震工程与工程振动(英文版)》2013,12(4):643-658

The lack of knowledge concerning modelling existing buildings leads to significant variability in fragility curves for single or grouped existing buildings. This study aims to investigate the uncertainties of fragility curves, with special consideration of the single-building sigma. Experimental data and simplified models are applied to the BRD tower in Bucharest, Romania, a RC building with permanent instrumentation. A three-step methodology is applied： （1） adjustment of a linear MDOF model for experimental modal analysis using a Timoshenko beam model and based on Anderson＇s criteria, （2） computation of the structure＇s response to a large set of accelerograms simulated by SIMQKE software, considering twelve ground motion parameters as intensity measurements （IM）, and （3） construction of the fragility curves by comparing numerical interstory drift with the threshold criteria provided by the Hazus methodology for the slight damage state. By introducing experimental data into the model, uncertainty is reduced to 0.02 considering Sd ） as seismic intensity IM and uncertainty related to the model is assessed at 0.03. These values must be compared with the total uncertainty value of around 0.7 provided by the Hazus methodology.  相似文献   

The dynamics of the snow avalanche affected areas in Piatra Mica mountains (Romania)     

Anca Munteanu  Alexandru Nedelea  Laura Comanescu 《Comptes Rendus Geoscience》2011,343(10):691-700

This article is intended to explain the snow avalanche occurrence, as a natural phenomenon directly influenced by the local natural conditions, for the well-delimited area represented by the Piatra Mica massif, belonging to the Piatra Craiului mountain range (southern Carpathians). In this respect, depending on the factors that may trigger or encourage the avalanches, some vulnerable areas with avalanche occurring conditions have been identified, based on the analysis of the relationships among the factors controlling the avalanche vulnerability in the study area. These factors are mainly represented by the slope aspect, which induces from the very beginning some specific features for each type of slope (north-, east-, south and west-facing slopes), the geological structure, slope gradient and topography. At the same time, the general climatic and biological features have been taken into account, from the point of view of their importance for avalanche occurrence and distribution. Depending on the microrelief exhibited by the avalanche chutes, one can establish distinct dynamical features for each of the four major slopes of the massif. It is worth mentioning that for this study area, this is the first paper dealing with avalanche phenomenon, vulnerable space, control factors and landscape dynamics. In accomplishing this demarche, we used detailed mappings in the field in several stages, the processing of satellite images, analytical (declivities, the exposure of slopes, etc.) and synthetic maps from which the dynamic of sectors with avalanches resulted. The findings of this investigation may further be employed for solving the problems raised by avalanche-prone areas, as well as for devising a better strategy for the effective management of the mountain realm.  相似文献   

The impact of climatic and non-climatic factors on land surface temperature in southwestern Romania     

Cristina?Florina?Ro?caEmail author  Gabriela?Victoria?Harpa  Adina-Eliza?Croitoru  Ioana?Herbel  Alexandru?Mircea?Imbroane  Doina?Cristina?Burada 《Theoretical and Applied Climatology》2017,130(3-4):775-790

Land surface temperature is one of the most important parameters related to global warming. It depends mainly on soil type, discontinuous vegetation cover, or lack of precipitation. The main purpose of this paper is to investigate the relationship between high LST, synoptic conditions and air masses trajectories, vegetation cover, and soil type in one of the driest region in Romania. In order to calculate the land surface temperature and normalized difference vegetation index, five satellite images of LANDSAT missions 5 and 7, covering a period of 26 years (1986–2011), were selected, all of them collected in the month of June. The areas with low vegetation density were derived from normalized difference vegetation index, while soil types have been extracted from Corine Land Cover database. HYSPLIT application was employed to identify the air masses origin based on their backward trajectories for each of the five study cases. Pearson, logarithmic, and quadratic correlations were used to detect the relationships between land surface temperature and observed ground temperatures, as well as between land surface temperature and normalized difference vegetation index. The most important findings are: strong correlation between land surface temperature derived from satellite images and maximum ground temperature recorded in a weather station located in the area, as well as between areas with land surface temperature equal to or higher than 40.0 °C and those with lack of vegetation; the sandy soils are the most prone to high land surface temperature and lack of vegetation, followed by the chernozems and brown soils; extremely severe drought events may occur in the region.  相似文献   

A common methodology for risk assessment and mapping for south-east Europe: an application for heat wave risk in Romania     

Papathoma-Koehle  Maria  Promper  Catrin  Bojariu  Roxana  Cica  Roxana  Sik  Andr&#;s  Perge  Kinga  L&#;szl&#;  Peter  Czikora  Erika Bal&#;zs  Dumitrescu  Alexandru  Turcus  Cosmin  Birsan  Marius-Victor  Velea  Liliana  Glade  Thomas 《Natural Hazards》2016,81(1):89-115

This paper reports on a quantitative estimation of the risk to residents at the toe of Mount Albino, a carbonatic relief covered by shallow deposits of pyroclastic soils, which threatens the municipality of Nocera Inferiore (southern Italy). The quantitative risk analysis (QRA) focuses on one type of mass transport phenomena typical for the context at hand, namely the hyperconcentrated flows. The methodological approach includes three main steps: hazard analysis, consequence analysis and risk estimation. Based on historical incident data, the hazard analysis makes use of a high-resolution digital terrain model and advanced models that incorporate relevant geological and geotechnical input data collected via in situ investigations and laboratory tests. The consequence analysis takes into account information on the exposed persons (age, gender) and their vulnerability. The estimated risk to life is calculated at the individual level (risk to the average and most exposed person). The reported procedure is one of the first QRA’s applications to instabilities which potentially affect natural slopes in Italy, and it was successfully used as technical basis for a public participatory process in Nocera Inferiore, designed and developed to support decisions about risk mitigation measures.  相似文献