Transport in finite size systems: an exit time approach

In the framework of chaotic scattering we analyze passive tracer transport in finite systems. In particular, we study models with open streamlines and a finite number of recirculation zones. In the non trivial case with a small number of recirculation zones a description by mean of asymptotic quantities (such as the eddy diffusivity) is not appropriate. The non asymptotic properties of dispersion are characterized by means of the exit time statistics, which shows strong sensitivity on initial conditions. This yields a probability distribution function with long tails, making impossible a characterization in terms of a unique typical exit time.Comment: 16 RevTeX pages + 6 eps-figures include

Behaviour-dependent predation risk in swimming zooplankters

Background: The survival of zooplanktonic organisms is determined by their capability of moving in a fluid environment, trading off between the necessities of finding prey and avoiding predators. In previous numerical experiments, we concentrated on the relationship between natatorial modality and encounter success of a virtual copepod swimming in the presence of prey distributed either in patches or uniformly in the environment. Results: In this contribution, we extend this simulation framework to the encounter with chaetognaths, the primary copepod predators, considering different motion rules as a proxy of different swimming strategies and looking at the influence of the concentration of predators and the size of their detection radius in posing a risk on copepod survival. The outcomes of our simulations indicate that more convoluted trajectories are more vulnerable to predator encounter while straighter motions reduce predation risk. Conclusions: Our results are then complemented with those obtained in our previous studies to perform a general cost-benefit analysis of zooplankton motion

Near-surface eddy dynamics in the southern ocean

The Antarctic Circumpolar Current (ACC) is a crucial component of the global ocean conveyor belt, acting as a zonal link among the major ocean basins but, to some extent, limiting meridional exchange and tending to isolate the ocean south of it from momentum and heat income. In this work we investigate one of the most important mechanisms contributing to the poleward transfer of properties in the Southern Ocean, that is the eddy component of the dynamics. For this particular purpose, observations obtained from near-surface drifters have been used: they represent a very useful data set to analyse the eddy field because of their ability to catch a large number of scales of motion while providing a quasi-synoptic coverage of the investigated area. Estimates of the eddy heat and momentum fluxes are carried out using data taken from the Global Drifter Program databank; they refer to Surface Velocity Program drifter trajectories collected in the area south of 35°S between 1995 and 2006. Eddy kinetic energies, variance ellipses, momentum and heat fluxes have been calculated using the pseudo-Eulerian method, showing patterns in good agreement with those present in the literature based on observational and model data, although there are some quantitative differences. The eddy fluxes have been separated into their rotational and divergent portions, the latter being responsible for the meridional transports. The associated zonal and depth-exponentially integrated meridional heat transport exhibits values spanning over a range between -0.4 PW and -1.1 PW in the ACC region, consistent with previous estimates. © 2011 M. Trani et al

Dispersion of passive tracers in model flows: effects of the parametrization of small-scale processes

Abstract. A set of numerical experiments is presented, in which we study the dynamics of passive particles advected by given two-dimensional velocity fields and perturbed by a non-white noise with a characteristic time τ. Data and model results have shown that this kind of random perturbation is able to represent subgridscale processes for upper ocean mesoscale turbulence for regions of the world ocean where turbulence can be assumed to be homogeneous. Extensive computations in different fields characterized by cell-like structure, both stationary and time-dependent, representing very idealized geophysical flow situations, show that the presence of a finite correlation time scale does lead to enhanced or arrested dispersion, depending on the considered flow; however, it does not seem to affect the gross qualitative behaviour of the dispersion processes, which is primarily affected by the large-scale velocity field

Wintertime transport processes in the Gulf of Naples investigated by HF radar measurements of surface currents

Transport processes play a fundamental role in regulating the water renewal in coastal systems. The Gulf of Naples (Southern Tyrrhenian Sea) is a highly urbanised area, receiving pollutant discharges and terrestrial inputs that may reside inside the basin. For this reason, understanding the processes governing coast-offshore transport is of paramount importance for the welfare of the ecosystem and the sustainable exploitation of environmental resources. In this work, we analyse the wind-driven transport over lags of three days in winter reconstructing the basin scale surface circulation by means of High-Frequency radars and evaluating its dependence on wind circulation. Simulations of particle exchange between a coastal and an offshore area have been carried out, outlining the strong relationship between particle fate and circulation structures. Results are interpreted in terms of residence times and possible aggregative areas in the Gulf of Naples

Parenting: awareness about the own educative role and citizen competences / Genitorialità: consapevolezza sul proprio ruolo come educatori e competenze per la cittadinanza.

It is since a long time that the European Community highlights how parents – fundamental resource for the education of the “tomorrow’ citizens” – must be supported in the interpretation of their educative role and in the assumption of their whole responsibility with respect to the related func- tions. This paper presents the results of an ALICE pilot project dedicated to the training of parents with children aged 0-3 and realized as a laboratory of reflection through creative and informal languages. It comes to a formative proposal relative to empowerment interventions, aimed at sustaining par- ent competences and its conscious use from an educational point of view. Each meeting was organised in two phases: (a) self-reflection as parent and then as son/daughter; (b) realization of creative activities to enhance the ed- ucational quality of the relationship with their children. The participation of parents has been constantly active. The feedback obtained through a satis- faction survey and a questionnaire for self-evaluation to compare pre- and post- training has been very satisfactory

L’approccio riflessivo a supporto della genitorialità / Reflexive approach as a measure of parenting support.

Questo articolo descrive la componente operativa di uno studio sviluppato nell’ambito di una tesi di dottorato, il cui principale obiettivo è quello di analizzare, nel contesto genitoriale, le caratterizzazioni più significative del- la relazione educativa. E’ anche parte delle attività promosse dal Progetto Europeo ALICE, che ha tra i suoi obiettivi la formazione attraverso linguag- gi creativi e informali utilizzati dagli adulti per interagire con i bambini. Lo scopo dell’articolo è quello di mostrare come misure efficaci a supporto della genitorialità siano anche quelle che includono l’uso di metodologie informali e linguaggi creativi; inoltre, si mostra come tali misure possano avvenire nella direzione dell’educazione, del buon trattamento e della cu- ra, allo scopo di guidare i genitori verso una riflessione critica delle abilità educative che già possiedono e delle quali non sono pienamente con- sapevoli

Parenting: awareness about the own educative role and citizen competences

It is since a long time that the European Community highlights how parents – fundamental resource for the education of the “tomorrow’ citizens” – must be supported in the interpretation of their educative role and in the assumption of their whole responsibility with respect to the related functions. This paper presents the results of an ALICE pilot project dedicated to the training of parents with children aged 0-3 and realized as a laboratory of reflection through creative and informal languages. It comes to a formative proposal relative to empowerment interventions, aimed at sustaining parent competences and its conscious use from an educational point of view. Each meeting was organised in two phases: (a) self-reflection as parent and then as son/daughter; (b) realization of creative activities to enhance the educational quality of the relationship with their children. The participation of parents has been constantly active. The feedback obtained through a satisfaction survey and a questionnaire for self-evaluation to compare pre- and post- training has been very satisfactory

An integrated reconstruction of the multiannual wave pattern in the gulf of naples (South-Eastern Tyrrhenian Sea, Western Mediterranean Sea)

Surface gravity waves retrieved by a network of HF (High Frequency) radars and measured in situ by an ADCP (Acoustic Doppler Current Profiler) current meter connected to an elastic beacon were used to carry out a multiple-year characterization of the wave field of the Gulf of Naples (south-eastern Tyrrhenian Sea, western Mediterranean). The aim of the work was to create a climatology of the study area and to demonstrate the potential of an integrated platform for coastal studies. The patterns recorded by the different instruments were in agreement with the wave climatology of the southern Tyrrhenian Sea as well as with previous scores for the same area. The results presented in this work also highlight seasonal and interannual consistency in the wave patterns for each site. In a wider context, this study demonstrates the potential of HF radars as long-term monitoring tools of the wave field in coastal basins, and supports the development of integrated observatories to address large-scale scientific challenges such as coastal ocean dynamics and the impact of global change on the local dynamics

Evaluation of HF-radar wave measures in the Gulf of Naples

HF-radar systems are commonly employed for detecting the upper sea currents. Nevertheless, the signal of such systems can be further post-processed for characterizing as well the wave characteristics, though this is a recent application whose reliability has not been yet exhaustively investigated. In this work, we evaluate HF-radar measures of significant wave height, wave mean period and incident direction against the outcomes of two numerical models previously validated. The comparison is developed in the Gulf of Naples (hereinafter GoN), taking advantage of three antennas placed in the locations of Castellamare di Stabia, Portici and Sorrento. First, a wave hindcast defined on a regional scale is employed; then, wave data are down-scaled through a local model defined over a finer resolution (local scale). The agreement between the systems is evaluated through statistical error indexes. Results show good consistency, leaving room for deepening the use of radars for wave data collection