Stochastic approach to convective motions driven by a localized buoyancy flux in the sea

A model for the dynamics of intermittent dense water plumes in a sea initially at rest, suddenly perturbed on the air-sea surface by a series of random buoyancy inputs localized on small space and time scales is presented. It is shown that plume evolution and scaling laws are ruled by random external forcing leading to a higher time power behaviour, depending on the probability of the event 1/T; this time power hides slower internal randomness if 1/T <<1, so that plume evolution depends on the air-sea interaction statistics and its frequency. The perturbative slowing down effect of a constant stratification and the dissipative mixing effect of the viscosity are also shown

Problematiche legate all'effetto serra ed ai cambiamenti climatici (Storia,fenomenologia fisica,problemi aperti

Analisi di alcune problematiche legate all'effetto serra

A 3D model for a stochastic set of small scale plumes in open sea

A stochastic model for the Lagrangian dynamics of se4a dense water plumes,generated by a surface sochastic forcing due to wind bursts is here presented. The entrainment and mixing effect, the dependence of scaling laws on the statistics of the external events, and the enhancing perturbative effect of rotation are discussed

Study of the environmental effects of underwater natural CO2 emissions by means of scientific diving techniques (Panarea Island – Italy)

To study the effects of anomalous concentrations of CO2 in the sea a volcanic area was identified in the southern Tyrrhenian Sea, where submarine CO2-rich discharges occur in shallow water producing underwater gas plumes. Specific fluid sampling and water-chemistry measuring techniques were developed to be used by scientific divers in order to identify the chemical composition of the gas emissions and their effect on the marine surroundings. Laboratory experiments were conducted to identify the main features of the physical interaction of a gas plume with the surrounding liquid environment

Field study and laboratory experiments of bubble plumes in shallow seas as analogues of sub-seabed CO2 leakages

To understand the effects of increased levels of CO2 on the marine realm, it is possible to study areas where, for natural reasons, there are emissions of CO2 from the seabed. One of these areas is located east of Panarea Island (Aeolian Islands - Southern Tyrrhenian Sea - Italy). Here, the volcanic activity that characterizes the Aeolian archipelago causes a continuous release of CO2 (up to 98% of the total gas) from several vents on the seafloor in shallow water. This area was studied by means of surface techniques and direct SCUBA diving surveys; the data presented refers to a field campaign performed in 2008. To collect the necessary data, some dedicated sampling and measuring techniques were developed for use in an underwater environment. The chemistry of the fluids and their influence on the water body was determined via logs and transects in the field and by gas-chromatographic and liquid-chromatographic laboratory analysis. The flux from some of the main gas vents was also measured directly underwater. Furthermore, some laboratory experiments in a two-layer stratified fluid were conducted to understand the main features of the physical interaction of a gas plume with the surrounding environment. Both field and laboratory experiments show that there is a development of a pseudo-convective cell around the rising plume with the formation of vortices that act as a physical barrier thus reducing the interaction between the plume and the surrounding water. (C) 2010 Elsevier Ltd. All rights reserved

Coherent abyssal eddies observed over the KM4 site from a single mooring in the Ionian Sea (Central Mediterranean Sea)

No abstract availabl

Slow abyssal clockwise rotating eddies in the Ionian sea

The dynamical characteristics of the deep currents flowing over the KM4 site (36◦ 30’N; 15◦50’E) measured, from July 2001 to March 2003, through two Aanderaa RCM 7-8 current meters set at 2700 m and 3050 m depth (230 m from the bottom) are here investigated. The presence of 8 large scale slow barotropic vortices, clockwise rotating, is discussed

Abyssal undular vortices in the Eastern Mediterranean basin

Abyssal temperature and velocity observations performed within the framework of the Neutrino Mediterranean Observatory, a project devoted to constructing a km3-scale underwater telescope for the detection of high-energy cosmic neutrinos, demonstrate cross-fertilization between subnuclear physics and experimental oceanography. Here we use data collected south of Sicily in the Ionian abyssal plain of the Eastern Mediterranean (EM) basin to show for the first time that abyssal vortices exist in the EM, at depths exceeding 2,500 m. The eddies consist of chains of near-inertially pulsating mesoscale cyclones/anticyclones. They are embedded in an abyssal current flowing towards North-Northwest. The paucity of existing data does not allow for an unambiguous determination of the vortex origin. A local generation mechanism seems probable, but a remote genesis cannot be excluded a priori. The presence of such eddies adds further complexity to the discussion of structure and evolution of water masses in the EM