Wet deposition due to fog in the Po Valley,Italy     

Sandro Fuzzi  Giordano Orsi  Mauro Mariotti 《Journal of Atmospheric Chemistry》1985,3(2):289-296

Wet deposition due to radiation fog is examined in this paper. The area where the reported measurements were performed, the Po Valley, northern Italy, is characterized by both a high fog occurrence during the fall-winter months and fog water solutions of high ionic concentration and acidity.Estimated wet deposition for NH ₄ ⁺ , NO _inf3 ^sup- and SO _inf4 ^sup2- ions due to fog droplet settling to the ground accounts for 13.2, 12.1 and 5.3 percent with respect to bulk precipitations over the same period: January–March and October–December (fog season).Fog deposition rates show that this process can be an important pathway of trace gases and particles loss from the air. First indicative results of fog removal efficiency with respect to air particulate matter are presented.Dry deposition parameters should be taken into account in evaluating the potential effect of fog droplet deposition on vegetation.  相似文献   

Sediment delivery processes and the spatial distribution of caesium-137 in a small Sicilian basin     

Vito Ferro  Costanza Di Stefano  Giuseppe Giordano  Salvatore Rizzo 《水文研究》1998,12(5):701-711

The sediment delivery processes occurring in a small Sicilian basin are modelled using the spatially distributed SEDD model recently proposed by Ferro and Minacapilli. The model is applied by using soil data (grain-size distribution, organic matter content, etc.) of 129 samples uniformly distributed over the study area and compiling the available information (topographic map, soil data, etc.) into a Geographical Information System. Finally, the predictive capability of the distributed sediment delivery approach is tested experimentally using the caesium-137 measurement technique. The comparison between calculated sediment yield and the corresponding measured caesium-137 loss is used to validate the SEDD model at the scale of both the single morphological unit and the entire basin. © 1998 John Wiley & Sons, Ltd.  相似文献   

Isotopic evidence for open system processes within the Campanian Ignimbrite (Campi Flegrei–Italy) magma chamber     

I. Arienzo  L. Civetta  A. Heumann  G. Wörner  G. Orsi 《Bulletin of Volcanology》2009,71(3):285-300

New Sr and Nd isotope data for whole rocks, glasses and minerals are combined to reconstruct the nature and origin of mixing end-members of the 200 km³ trachytic to phonolitic Campanian Ignimbrite (Campi Flegrei, Italy) magmatic system. The least-evolved magmatic end-member shows equilibrium between host glass and the majority of the phenocrysts and is less radiogenic in Sr and Nd than the most-evolved magma. On the contrary, only the Fe-rich pyroxene from the most-evolved erupted magma is in equilibrium with the matrix glass, while all other minerals are in isotopic disequilibrium. These magmas mixed prior to and during the Campanian Ignimbrite eruption and minerals were freely exchanged between the magma batches. Combining the results of the geochemical investigations on magma end-members with geophysical and geological data, we develop the following scenario. In stage 1, a parental, less differentiated magma rose into the middle crust, and evolved through combined crustal assimilation and crystal fractionation. In stage 2, the differentiated magma rose to shallower depth, fed the pre-Campanian Ignimbrite activity and evolved by further open-system processes into the most-evolved and most-radiogenic Campanian Ignimbrite end-member magma. In stage 3, new trachytic magma, isotopically distinct from the pre-Campanian Ignimbrite magmas, rose from ca. 6 km to shallower depth, recharged the most-evolved pre-Campanian Ignimbrite magma chamber, and formed the large and stratified Campanian Ignimbrite magmatic system. During the course of the Campanian Ignimbrite eruption, the two layers were tapped separately and/or simultaneously, and gave rise to the range of chemical and isotopic values displayed by the Campanian Ignimbrite pumices, glasses and minerals.  相似文献   

Tephra fallout hazard assessment at the Campi Flegrei caldera (Italy)   总被引：4，自引：2，他引：2  

A. Costa  F. Dell’Erba  M. A. Di Vito  R. Isaia  G. Macedonio  G. Orsi  T. Pfeiffer 《Bulletin of Volcanology》2009,71(3):259-273

Tephra fallout associated with renewal of volcanism at the Campi Flegrei caldera is a serious threat to the Neapolitan area. In order to assess the hazards related with tephra loading, we have considered three different eruption scenarios representative of past activity: a high-magnitude event similar to the 4.1 ka Agnano-Monte Spina eruption, a medium-magnitude event, similar to the ∼3.8 ka Astroni 6 eruption, and a low-magnitude event similar to the Averno 2 eruption. The fallout deposits were reconstructed using the HAZMAP computational model, which is based on a semi-analytical solution of the two-dimensional advection–diffusion–sedimentation equation for volcanic tephra. The input parameters into the model, such as total erupted mass, eruption column height, and bulk grain-size and components distribution, were obtained by best-fitting field data. We carried out tens of thousands simulations using a statistical set of wind profiles, obtained from NOAA re-analysis. Probability maps, relative to the considered scenarios, were constructed for several tephra loads, such as 200, 300 and 400 kg/m². These provide a hazard assessment for roof collapses due to tephra loading that can be used for risk mitigation plans in the area.  相似文献   

On the chaotic diffusion in multidimensional Hamiltonian systems     

P. M. Cincotta  C. M. Giordano  J. G. Martí  C. Beaugé 《Celestial Mechanics and Dynamical Astronomy》2018,130(1):7

We present numerical evidence that diffusion in the herein studied multidimensional near-integrable Hamiltonian systems departs from a normal process, at least for realistic timescales. Therefore, the derivation of a diffusion coefficient from a linear fit on the variance evolution of the unperturbed integrals fails. We review some topics on diffusion in the Arnold Hamiltonian and yield numerical and theoretical arguments to show that in the examples we considered, a standard coefficient would not provide a good estimation of the speed of diffusion. However, numerical experiments concerning diffusion would provide reliable information about the stability of the motion within chaotic regions of the phase space. In this direction, we present an extension of previous results concerning the dynamical structure of the Laplace resonance in Gliese-876 planetary system considering variations of the orbital parameters accordingly to the error introduced by the radial velocity determination. We found that a slight variation of the eccentricity of planet c would destabilize the inner region of the resonance that, though chaotic, shows stable when adopting the best fit values for the parameters.  相似文献   

Improving strain rate estimation from velocity data of non-permanent GPS stations: the Central Apennine study case (Italy)     

Arianna Pesci  Giordano Teza  Giuseppe Casula 《GPS Solutions》2009,13(4):249-261

An efficient procedure is proposed to define realistic lower limits of velocity errors of a non-permanent GPS station (NPS), i.e., a station where the antenna is installed and operates for short time periods, typically 10–20 days per year. Moreover, the proposed method is aimed at being independent of standard GPS data processing. The key is to subsample appropriately the coordinate time series of several continuous GPS stations situated nearby or inside the considered NPS network, in order to simulate the NPS behavior and to estimate the velocity errors associated with the subsampling procedure. The obtained data are used as lower limits to accept or correct the error estimates provided by standard data processing. The proposed approach is applied to data from the dense, non-permanent network in the Central Apennine of Italy based on a sequence of solutions for the overlapping time spans 1999–2003, 1999–2004, 1999–2005 and 1999–2007. Both the original and error-corrected velocity patterns are used to compute the strain rate fields. The comparison between the corresponding results reveals large differences that could lead to divergent interpretations about the kinematics of the study area.  相似文献   

Analysis of testing methods of pipelines for limit state design     

F. Guarracino  M. Fraldi  A. Giordano 《Applied Ocean Research》2008,30(4):297-304

It is well known that the design of submarine pipelines relies on accurate test results for the local buckling collapse of pipes subjected to bending loading. The present paper analyses apparently anomalous values of axial tensile and compressive strains from recent test results in comparison to the values that would be expected on the basis of simple bending theory. This could have important consequences for the efficacy of the design factors derived using these results. The cause of the differences between the strain values obtained in the tests and those expected on the basis of simple bending theory are explained using finite element modelling. The differences result from the type of collars and supports commonly used in bending tests, the effects of which persist for a greater length along the test pipe than has hitherto been assumed. In general, it is pointed out that the application of the simplified engineering theory of bending can be erroneous when ovalisation is imposed or, on the contrary, the boundary conditions of the section are restrained from ovalising deformations. The influence of the D/t ratio is also analysed.The results contribute to the understanding of a crucial limit state for the design of onshore and offshore pipelines.  相似文献   

Morphology, dynamics and plasma parameters of plumes and inter-plume regions in solar coronal holes     

K. Wilhelm  L. Abbo  F. Auch��re  N. Barbey  L. Feng  A. H. Gabriel  S. Giordano  S. Imada  A. Llebaria  W. H. Matthaeus  G. Poletto  N.-E. Raouafi  S. T. Suess  L. Teriaca  Y.-M. Wang 《Astronomy and Astrophysics Review》2011,19(1):1-70

Coronal plumes, which extend from solar coronal holes (CH) into the high corona and??possibly??into the solar wind (SW), can now continuously be studied with modern telescopes and spectrometers on spacecraft, in addition to investigations from the ground, in particular, during total eclipses. Despite the large amount of data available on these prominent features and related phenomena, many questions remained unanswered as to their generation and relative contributions to the high-speed streams emanating from CHs. An understanding of the processes of plume formation and evolution requires a better knowledge of the physical conditions at the base of CHs, in plumes and in the surrounding inter-plume regions. More specifically, information is needed on the magnetic field configuration, the electron densities and temperatures, effective ion temperatures, non-thermal motions, plume cross sections relative to the size of a CH, the plasma bulk speeds, as well as any plume signatures in the SW. In spring 2007, the authors proposed a study on ??Structure and dynamics of coronal plumes and inter-plume regions in solar coronal holes?? to the International Space Science Institute (ISSI) in Bern to clarify some of these aspects by considering relevant observations and the extensive literature. This review summarizes the results and conclusions of the study. Stereoscopic observations allowed us to include three-dimensional reconstructions of plumes. Multi-instrument investigations carried out during several campaigns led to progress in some areas, such as plasma densities, temperatures, plume structure and the relation to other solar phenomena, but not all questions could be answered concerning the details of plume generation process(es) and interaction with the SW.  相似文献   

Updating knowledge on growth,population dynamics,and ecology of the blue and red shrimp,Aristeus antennatus (Risso, 1816), on the basis of the study of its instars     

Lidia Orsi Relini  Alessandro Mannini  Giulio Relini 《Marine Ecology》2013,34(1):90-102

Both national (GRUND) and international (MEDITS) trawl surveys carried out in the Italian seas since 1994 have produced consistent and rather homogeneous samples of red shrimps (per season, gear, and methods to ascertain abundance). Study and discussion of data regarding Aristeus antennatus (Risso, 1816) from Ligurian fishing grounds during the REDs project (FISH/2004/03‐32) made it possible to verify how key instars of the life of the female shrimp can be recognized from length frequency distributions derived from trawl surveys, allowing the age distributions to be split up. The segment of life that can be studied spans ages 1 and 10 and includes 20 instars, but larger sizes have been found which may extend the life span another 3 years. After age 5, only one growth instar per year occurs. Based on our study of the instars, we developed a size/age key for A. antennatus and used it to derive a von Bertalanffy growth function, total mortality rates and exploitation rates. Our results are related to basic biological and ecological characteristics of this species. Large individuals (females ≥50 mm CL at age 5 onward) present in a considerable percentage in the Ligurian Sea, are very important because (i) their fecundity is very high and therefore greatly influences the reproductive potential and (ii) they represent commercially the most valuable part of the catch. In addition, substantial relationships between the life history of A. antennatus and local oceanographic processes exist because the long life span of the species enlarges the area to which eggs and larvae are transported in surface currents, as well as the active return movements in deep waters where adult life mainly takes place. In the study area, the Northern Current provides the possibility of great horizontal displacement of A. antennatus eggs, larvae and early juveniles and, in general, attention to surface circulation may help to identify affinities in distant Mediterranean populations. This study presents A. antennatus in terms of a resource on the move at a Western Mediterranean scale.  相似文献   

The role of uncertainties in the design of international water treaties: an historical perspective   总被引：1，自引：1，他引：0  

Alena Drieschova  Itay Fischhendler  Mark Giordano 《Climatic change》2011,105(3-4):387-408

Water is one natural resource whose management is especially susceptible to uncertainties, many of which are being exasperated by climate change. Some of these uncertainties originate from knowledge deficits in physical conditions while others relate to behavioral and social variability related to water supply and use. However, to our knowledge no quantitative analysis of how uncertainties have been translated into transboundary water treaty structures exists. The present paper partially fills this gap through an examination of how uncertainty has been reflected in basin specific transboundary treaties and how that reflection has changed over the last century. While we could identify only minor trends in the frequency with which uncertainties are mentioned in treaties, we did find two clear patterns in the strategies adopted to deal with them. First, treaties seem to adopt a portfolio approach that spreads the dangers of uncertainty by concurrently including several management strategies simultaneously. Second, there is a trend towards more open-ended strategies in recent decades, rather than hard codification of rules as had earlier been more common.  相似文献