Local Circulation Diurnal Patterns and Their Relationship with Large-Scale Flows in a Coastal Area of the Tyrrhenian Sea   总被引：1，自引：0，他引：1  

Igor Petenko  Giangiuseppe Mastrantonio  Angelo Viola  Stefania Argentini  Lucia Coniglio  Paolo Monti  Giovanni Leuzzi 《Boundary-Layer Meteorology》2011,139(2):353-366

In order to characterise the local low-level circulation in the Tyrrhenian Sea coastal area near Rome, the wind field observed by conventional anemometers, Doppler sodar, and rawinsonde has been analysed. The prevailing diurnal behaviour of wind speed and direction as a function of season was highlighted, and the existence of two different patterns of the local circulation, mainly due to land and sea breezes and to the drainage flow from the mouth of the Tiber valley, revealed. The comparison between the low-level circulation and synoptic flow allowed us to determine the influence of the large-scale flow on nocturnal currents that are observed at the Pratica di Mare site and the way that wind direction evolves during the day. Numerical simulations are consistent with experimental data and depict the main features of the low-level wind field in the area.  相似文献   

A research program to map the Galactic Emission at low frequencies     

G. De Amici  S. Torres  M. Bensadoun  M. Bersanelli  G. Dall'Oglio  M. Limon  G. Smoot  G. Sironi  T. Villela  C. Witebsky 《Astrophysics and Space Science》1994,214(1-2):151-160

The need for accurate and complete maps of the galaxy at radio frequencies is made evident not only by the importance of the data in the study of galactic dynamics and structure formation but also in the analysis of cosmic background radiation data. A summary of the existing radio surveys of our galaxy is presented along with their limitations. A new program, the Galactic Emission Mapping (GEM) project, to obtain calibrated and complete maps of the galaxy in the 400 to 1400 MHz range, is outlined.Presented at the 2nd UN/ESA Workshop, held in Bogotá, Colombia, 9-13 November, 1992.  相似文献   

Ground motion amplification due to shallow cavities in nonlinear soils   总被引：2，自引：0，他引：2  

Stefania Sica  Angelo Dello Russo  Federica Rotili  Armando Lucio Simonelli 《Natural Hazards》2014,71(3):1913-1935

Subsurface cavities or stiff inclusions represent mechanical discontinuities for seismic waves propagating in soils. They modify the propagation pattern of seismic waves and alter soil response in correspondence to the ground level or building foundations. In the literature, different analytical and numerical solutions have been proposed to account for the effect of underground cavities or inclusions on the motion generated by P, S or R waves. In these former studies, the subsoil was assimilated to a homogeneous, isotropic and linear elastic halfspace containing one or more cavities. In the present study, the effect of subsurface cavities on ground motion amplification has been analysed accounting for soil stiffness degradation and associated damping increase with increasing levels of shear strains, a fundamental aspect of soil behaviour under earthquakes. The analysed model was inspired to a real case represented by the village of Castelnuovo (Italy), which during the 2009 Abruzzo earthquake suffered huge damage. The main shock (6 April 2009) caused the collapse of 50 % of the whole built environment. The historical centre of Castelnuovo rises on a hill. In its subsoil, there are many cavities with roofs 2–3 m below the ground level. The longitudinal NW–SE section of the hill has been investigated by 2D nonlinear site response analyses. A preliminary site response analysis was performed without modelling cavities, to identify ground motion amplification due to mere stratigraphic and topographic factors. The numerical model was later refined inserting: (1) a single cavity below the hilltop, (2) multiple cavities placed below the ground surface of the hill and (3) multiple cavities filled with concrete (inclusions). The performed study highlights the important role exerted by underground cavities on the ground motion computed at the hill surface. This effect should be properly considered for both microzonation studies and the correct determination of the seismic actions on specific buildings.  相似文献   

HASSET: a probability event tree tool to evaluate future volcanic scenarios using Bayesian inference     

Rosa Sobradelo  Stefania Bartolini  Joan Martí 《Bulletin of Volcanology》2014,76(1):1-15

Event tree structures constitute one of the most useful and necessary tools in modern volcanology for assessment of hazards from future volcanic scenarios (those that culminate in an eruptive event as well as those that do not). They are particularly relevant for evaluation of long- and short-term probabilities of occurrence of possible volcanic scenarios and their potential impacts on urbanized areas. In this paper, we introduce Hazard Assessment Event Tree (HASSET), a probability tool, built on an event tree structure that uses Bayesian inference to estimate the probability of occurrence of a future volcanic scenario and to evaluate the most relevant sources of uncertainty from the corresponding volcanic system. HASSET includes hazard assessment of noneruptive and nonmagmatic volcanic scenarios, that is, episodes of unrest that do not evolve into volcanic eruption but have an associated volcanic hazard (e.g., sector collapse and phreatic explosion), as well as unrest episodes triggered by external triggers rather than the magmatic system alone. Additionally, HASSET introduces the Delta method to assess precision of the probability estimates, by reporting a 1 standard deviation variability interval around the expected value for each scenario. HASSET is presented as a free software package in the form of a plug-in for the open source geographic information system Quantum Gis (QGIS), providing a graphically supported computation of the event tree structure in an interactive and user-friendly way. We also include further in-depth explanations for each node together with an application of HASSET to Teide-Pico Viejo volcanic complex (Spain).  相似文献   

The lentic–lotic character of Mediterranean rivers and its importance to aquatic invertebrate communities     

Andrea Buffagni  Stefania Erba  David G. Armanini 《Aquatic Sciences - Research Across Boundaries》2010,72(1):45-60

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Long‐term changes in hydroid (Cnidaria,Hydrozoa) assemblages: effect of Mediterranean warming?     

Stefania Puce  Giorgio Bavestrello  Cristina Gioia Di Camillo  & Ferdinando Boero 《Marine Ecology》2009,30(3):313-326

Marine hydroids are markedly seasonal in temperate seas, being extremely sensitive to climatic changes disrupting seasonal patterns. Modifications in the composition, seasonality, bathymetric distribution and reproductive period of hydroid assemblages are useful to evaluate the influence of global warming on the marine ecosystem. The hydroids on the rocky cliff of the Portofino Promontory (Ligurian Sea, Italy) were carefully studied between 1976 and 1983; in particular, in 1980 the study was carried out along a vertical transect. The hydroids were sampled again throughout 2004, with the same techniques and along the same transect. Species diversity decreased slightly in the 2004 survey. Some species present in 1980 had disappeared in 2004, but other species with southern affinity, never recorded from the area, became abundant in 2004. Species that were present in summer in the first period were also present in winter in the second one. Furthermore, shallow summer species widened their bathymetric distribution, reaching deeper levels. These data strongly suggest that the Portofino hydroid assemblage reacted to the water temperature increase found in the Mediterranean Sea.  相似文献   

Transient kinematic pile bending in two-layer soil     

Stefania Sica  George Mylonakis  Armando Lucio Simonelli 《Soil Dynamics and Earthquake Engineering》2011

The dynamic response of piles to seismic loading is explored by means of an extensive parametric study based on a properly calibrated Beam-on-Dynamic-Winkler-Foundation (BDWF) model. The investigated problem consists of a single vertical cylindrical pile, modelled as an Euler–Bernoulli beam, embedded in a subsoil consisting of two homogeneous viscoelastic layers of sharply different stiffness resting on a rigid stratum. The system is subjected to vertically propagating seismic S waves, in the form of a transient motion imposed on rock outcrop. Several accelerograms recorded in Italy are employed as input motions in the numerical analyses. The paper highlights the severity of kinematic pile bending in the vicinity of the interface separating the two soil layers. In addition to factors already investigated such as layer stiffness contrast, relative soil–pile stiffness, interface depth and intensity of ground excitation, the paper focuses on additional important factors, notably soil material damping, stiffness of Winkler springs and frequency content of earthquake excitation. Existing predictive equations for assessing kinematic pile bending at soil layer interfaces are revisited and new regression analyses are performed. A synthesis of findings in terms of a set of simple equations is provided. The use of these equations is discussed through examples.  相似文献   

Earthquake early warning for earth dams: concepts and objectives     

Luca Pagano  Stefania Sica 《Natural Hazards》2013,66(2):303-318

In the geotechnical field, the risk related to slope instabilities or collapse of geotechnical structures are increasingly being faced by early warning systems, capable of: (1) predicting the incipient collapse based on the interpretation of a continuous monitoring of the structure and (2) spreading alarm promptly to reduce people exposure. Compared with structural approaches, early warning systems have two important advantages: a faster, simpler and less expensive implementation and environmental compatibility. Past experience indicates that vulnerability of earth dams is generally low under both static and seismic loading conditions. In spite of this, earth dams are characterized by a high-risk level, due to the high exposure factor. Nowadays, the application of early warning systems to dams is fully supported by the technological progress achieved in the telecommunication field, since it is possible to install and automate recordings and transmission of all physical variables significant to check dam safety: accelerations, displacements, pore-water pressures, total stresses, seepage flows. A considerable lack still arises in the predictive models for interpreting monitoring data and providing indicators on dam safety soon after a strong earthquake. The present work illustrates the basic concepts of an earthquake early warning (EEW) system for earth dams and the main features that should characterize a predictive model to such a scope. An application to a real case is finally provided, enhancing the role played by each monitored physical variable for the aims of EEW.  相似文献   

Dioxin Like Compounds Bulk Deposition on Corn (Zea mais) and Alfa Alfa (Medicago sativa): Modelled Levels on Derived Silage and Hay and Their Relevance for Dairy Production     

Gianfranco Brambilla  Stefania Paola De Filippis  Vittorio Esposito  Gaetano Settimo 《洁净——土壤、空气、水》2013,41(2):113-118

Dioxin‐like compounds from regular, occasional or fugitive airborne sources of emission may fall out on fodders close to be harvested for silage and hay production. In this way, a prolonged long‐term intake of contaminated forages in dairy animals may be envisaged, able to determine a rise of the background contamination in milk. We simulated different risk scenarios taking into account the inventoried bulk dry depositions in rural areas of the aforesaid contaminants, silage and hay biomass production per hectare, forages regimen in dairy animals, and the congeners carry‐over rate (COR) from forages to milk. Considering atmospheric depositions >10 pg I‐TE m^?2 day^?1 and accounting for a 30% COR, dairy milk could rise up to the PCDD/F level of 3 pg WHO₁₉₉₈‐TE g^?1 fat. The modelling indicates that in rural areas bulk emissions should be selectively minimised, accounting for the calendar of the different agricultural practices, because of their potential impact on the fodders. Since environmental factors play a non‐negligible role in food production, a stronger harmonisation between I‐TE and WHO_1998–2005‐TE scales with respect to dioxin‐like polychlorobiphenyl congeners inclusion is envisaged. This will allow the prevention of the human indirect exposure to such contaminants when released in the air.  相似文献   

Perfluorinated compounds in blood of Caretta caretta from the Mediterranean Sea     

Cristiana Guerranti  Stefania Ancora  Nicola Bianchi  Guido Perra  Emiliano Leonida Fanello  Simonetta Corsolini  Maria Cristina Fossi  Silvano Ettore Focardi 《Marine pollution bulletin》2013

Perfluorinated compounds (PFCs), widely used for their hydro-oil repellent properties, are almost non-degradable in the environment; there is scientific evidence that indicate bioaccumulation. They represent a threat to many organisms, because they are toxic and are endocrine disruptors. Scientific studies have demonstrated the presence of PFCs in blood and liver samples of fish, turtles, birds and mammals of marine ecosystems in different geographical areas. The aim of this study was to determine the distribution of PFOS and PFOA in blood samples of the marine turtle Caretta caretta, using a minimally invasive sampling procedure. 49 blood samples of marine turtle, taken from several Italian marine turtle rescue centers, were analyzed. While PFOA was never detected, measurable concentrations of PFOS were found in 15 blood samples; the values show a range from 1.14 ng/g to 28.51 ng/g (wet wt.). No differences between groups of samples taken from different areas were found.  相似文献