1,720,985 research outputs found
Dinamica di una corrente costiera interagente con un promontorio: uno studio numerico per un fluido stratificato
No full textA 3-D numerical study of pollutant dispersion in a coastal current interacting with a headland
No full textThe effect of a promontory on the passive tracer advected by a coastal current: a full three-dimensional study
Full text linkThe coupling of a community three-dimensional primitive equation model with a three-dimensional Lagrangian dispersion model is used to describe with sufficient accuracy the temporal and spatial evolution of passive tracers released along a coast characterized by the presence of a cape. The simulations show how different initial conditions influence dispersion properties in a stratified sea, also to provide some insight on the valuation of the environmental impact of pollutants released along the coast. Finally, the power spectra content in a well-defined frequency range of the internal gravity waves is interpreted on the basis of vortex shedding in the lee of the promontory
The dispersion of passive tracers in marine environment: a case study of the Tyrrhenian Sea
No full textThe Tyrrhenian Sea is one of the most anthropized sub-basin of the Mediterranean Sea and this fact poses a challenge to authorities in charge of managing the marine environment. To cope with this question, the coupling of the ocean model POM (Princeton Ocean Model) with the Lagrangian dispersion model LASEMOD (LAgrangian SEa MODel) is addressed to investigate the temporal and spatial evolution of a passive pollutant released in the vicinity of the Latial coast. It is worth to note that the above LASEMOD has been developed by the authors.
The POM is a three-dimensional, free surface, sigma coordinate, primitive equation ocean model which includes a turbulence sub-model. The LASEMOD is a first-order autoregressive model for the particle velocities. Such a model is based on the so called “well-mixed” condition (Thomson, 1987) and takes into account the integral time scale of the turbulence. This implies that dispersion is correctly resolved in the vicinity of the release and that, coherently with the theory, a full mixing is achieved at long travel times. The simulation shows with reasonably accuracy the time evolution of both the hydrodynamic and the concentration fields and provides a useful insight into the evaluation of the environmental impact of pollutant releases along the coast
L'uso di un modello ad area limitata (UB/NMC) nella simulazione della ciclogenesi alpina: risultati preliminari
No full textViene utilizzato un modello ad area limitata (UB/NMC) per simulare lo sviluppo di un ciclone, considerato di moderata intensità, sul Mediterraneo occidentale nel marzo 1982.La risoluzione del modello è di 0.5° di latitudine e di longitudine e la rappresentazione orografica è di tipo "silhouette". Al fine della "validazione" del modello sono state effettuate prove in assenza di montagne e con modifiche delle altezze "silhouette", che hanno mostrato come il modello riproduca l'importante ruolo dell'orografia nell'innesco della ciclogenesi alpina. Montagne molto "smussate" non riescono a riprodurre le caratteristiche essenziali del fenomeno, mentre montagne molto più pronunciate rispetto ai profili reali le modificano in modo sensibile, causando un anticipo temporale ed uno spostamento verso nord dello sviluppo, ciò in accordo con precedenti risultati
New Results of Multidimensional Analysis of TAO/NOAA Data on “El Niño” Phenomenon
No full textIn order to study the “El Niño” phenomenon on the basis of the available data, we started an exploratory analysis of the set of surface temperature time-series produced from the USA's National Oceanic and Atmospheric Administration (NOAA). Some results of Principal Component Analysis and Hierarchical Factor Classification applied on The data set relative to the period 1991-2008 are reported. Together with the regular seasonal fluctuation and the subdivision in 14 classes of the time-series, all spatially connected, the occurrence of El Niño in 2007 results from the data as a very strong perturbation of an otherwise very regular pattern
Mixing Processes in a Weakly Stratified Ocean: a Case Study for The Terra Nova Bay (Antarctica) Polynya
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