http://hdl.handle.net/2122/388 2013-05-22T05:15:35Z http://hdl.handle.net/2122/7990 Title: Earthquakes, volcanic eruptions and geodynamics: a 'box for thinking and working' Authors: Fregonese, R.; RSE spa milano ITALY Abstract: After reviewing the main results present in the literature on geodynamic toward seismic and volcanic activity and risks, the paper present a causative global model of these phenomena and delineates a model of calculus for earthquakes and volcanic eruptions prediction. The model involves a mechanical schematization of the entire globe, make use of Somigliana’s identity and gives results in terms of probabilities given the PDF of mechanical parameters like Lamè’m on fault planes and viscosity of the magmas. The results then can be updated with short and long term precursors. 2012-06-21T22:00:00Z http://hdl.handle.net/2122/6575 Title: Self-sustained oscillations at Volcan de Colima (Mexico) inferred by Independent Component Analysis Authors: De Lauro, E.; Univ. of Salerno; De Martino, S.; Univ. of Salerno; Palo, M.; Univ. of Salerno; Ibanez, M. J.; Univ. of Granada Abstract: We have analyzed Long-Period (LP) seismic events of Volcan de Colima (Mexico) recorded by four three-component broad-band seismometers during January 2006. Frequency-domain analysis shows broad-band spectra mainly in the range 0.3-2 Hz characterized by a monotonic decreasing envelope, as those observed in a cylindrically-symmetric self-oscillating cavity interacting with a confined jet. Independent Component Analysis, a time decomposition method extracts two or three nonlinear oscillation modes depending on the station, with the fundamental one peaked at [0.4-0.5]Hz. These decomposed waves are self-sustained oscillations with low dimensionality and a well defined spectral content. Moreover, they show radial polarization in near field and transverse polarization in far field in North-West South-East direction. Finally, we depict a branched plumbing system with two principal conduits directed along orthogonal directions. 2011-01-11T23:00:00Z http://hdl.handle.net/2122/6150 Title: Statistical analysis of the volcano seismicity during the 2007 crisis of Stromboli, Italy: a 3-day oscillatory signal as onset of the activity Authors: De Martino, Salvatore; University of Salerno; Falanga, Mariarosaria; University of Salerno; Palo, Mauro; University of Salerno; Montalto, Placido; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Patanè, Domenico; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia Abstract: We analyze the volcano seismicity recorded during the 2007 eruption of Stromboli. Data-set is composed of the continuous recordings of a three-component broad-band seismometer and of a strainmeter. Starting from the characterization of the standard activity as a stationary phase of equilibrium, we investigate the non-equilibrium phase of the effusive process. A statistical analysis of the explosions reveals that the occurrence is always driven by a Poisson process as for the standard activity, even approaching the effusion phase, with the only difference in shortening the inter-times just during the effusion. A slightly different process can be advocated for the swarms of the explosions, because a maximum in the distribution of inter-times can be evidenced. Regarding the amplitudes of the explosion-quakes, they have a log-normal distribution until the effusion onset as in the standard Strombolian activity. The actual departure from that stationarity seems to be traced by an early deformative response at very long period. It appears as a transient oscillating signal characterized by a period of about three days that modulates the explosion amplitudes. In a conceptual organ pipe-like model it is related to the chocking of the pipe. The successive activity can be interpreted as the response of volcano to restore the equilibrium condition. 2010-10-14T12:52:31Z http://hdl.handle.net/2122/5846 Title: Surface circulation in the Liguro-Provençal basin as measured by satellite-tracked drifters (2007-2009) Authors: Poulain, P-M.; Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, OGS, Trieste, Italy; Gerin, R.; Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, OGS, Trieste, Italy; Rixen, M.; NATO Undersea Research Centre, La Spezia, Italy; Zanasca, P.; NATO Undersea Research Centre, La Spezia, Italy; Teixeira, J.; NATO Undersea Research Centre, La Spezia, Italy; Griffa, A.; Consiglio Nazionale delle Ricerche, CNR-ISMAR, La Spezia, Italy; De Marte, M.; Istituto Idrografico della Marina, Genova, Italy; Pinardi, N.; University of Bologna, Ravenna, Italy Abstract: The surface circulation in the Liguro-Provençal basin (Northwestern Mediterranean) is studied using satellite-tracked drifters in 2007-2009. Complex circulation patterns prevailed in the eastern Ligurian Sea, before the drifters eventually joined the Northern Current (NC) in the coastal area off Genoa. Between 5°E and 7°E30’, most drifters were advected offshore before heading to the east and eventually closing a basin-wide cyclonic circulation. This offshore turning is related to the wind and wind stress curl during Mistral events. Although the Western Corsican Current was well delineated by the drifters, no signature of the Eastern Corsican Current was shown, indicating limited connectivity between the Tyrrhenian and Ligurian seas in summer 2007. Pseudo-Eulerian velocity statistics were calculated in the coastal region extending between Genoa and the Gulf of Lyons. Fast currents are evident on the shelf break, especially off Imperia (maximum of 90 cm/s) where the bathymetric slope is larger and the NC is closer to shore and narrower. In contrast, a stagnation area inshore of the NC near Fréjus is characterized by little mean flow and low velocity fluctuations. Mean currents are also reduced off Menton-Nice where the variability is maximum. More to the west, the NC broadens and slightly reduces in strength. 2009-12-31T23:00:00Z http://hdl.handle.net/2122/5730 Title: Ocean Ensemble Forecasting, Part II: Mediterranean Forecast System Response Authors: Bonazzi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Pinardi, N.; CIRSA, University of Bologna, Ravenna, ITALY; Dobricic, S.; Centro EuroMediterraneo per i Cambiamenti Climatici, Bologna, ITALY; Milliff, R. F.; NWRA, Colorado Research Associates Div.; Boulder, CO, USA; Wikle, C. K.; Statistics Department, University of Missouri; Columbia, MO, USA; Berliner, L. M.; Statistics Department, Ohio State University; Columbus, OH, USA Abstract: This paper analyzes the ocean forecast response to surface vector wind (SVW) distributions generated by a Bayesian Hierarchical Model (BHM) developed in Part I (Milliff et al., 2009). A new method for Ocean Ensemble Forecasting (OEF), so-called BHM-SVW-OEF, is described. BHM-SVW realizations are used to produce and force perturbations in the ocean state during 14-day analysis and 10-day forecast cycles of the Mediterranean Forecast System (MFS). The BHM-SVW-OEF ocean response spread is amplified at the mesoscales and pycnocline of the eddy field. The new method is compared to an ensemble response forced by ECMWF Ensemble Prediction System (EEPS) surface winds, and to an ensemble forecast started from perturbed initial conditions derived from an ad hoc Thermocline Intensified Random Perturbation (TIRP) method. The EEPS-OEF shows spread at the basin scales while the TIRP-OEF response is mesoscale intensified as in the BHM-SVW-OEF response. TIRP-OEF perturbations fill more of the MFS domain while the BHM-SVW-OEF perturbations are more location-specific, concentrating ensemble spread at the sites where the ocean model response to uncertainty in the surface wind forcing is largest. The BHM-SVW-OEF method offers a practical and objective means for producing short-term forecast spread by modeling surface atmospheric forcing uncertainties that have maximum impact at the ocean mesoscales. 2008-12-31T23:00:00Z http://hdl.handle.net/2122/5721 Title: Ocean Ensemble Forecasting, Part I: Ensemble Mediterranean Winds from a Bayesian Hierarchical Model Authors: Milliff, R. F.; NWRA, Colorado Research Associates Div.; Boulder, CO, USA; Bonazzi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Wikle, C. K.; Statistics Department, University of Missouri; Columbia, MO, USA; Pinardi, N.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Berliner, L. M.; Statistics Department, Ohio State University; Columbus, OH, USA Abstract: A Bayesian Hierarchical Model (BHM) is developed to estimate surface vector wind fields (SVW), and associated uncertainties, over the Mediterranean Sea. The BHM-SVW incorporates data-stage inputs from analyses and forecasts of the European Centre for Medium-Range Weather Forecasts (ECMWF) and from the QuikSCAT data record. The process model stage of the BHM-SVW is based on a Rayleigh Friction Equation model for surface winds. Dynamical interpretations of posterior distributions of the BHM-SVW parameters are discussed. Ten realizations from the posterior distribution the BHM-SVW are used to force the data assimilation step of an experimental ensemble ocean forecast system for the Mediterranean Sea in order to create a set of ensemble initial conditions. Ensemble initial condition spread is quantified by computing standard deviations of ocean state variable fields over the 10 ensemble members, driven by 10 realizations from the BHM-SVW posterior distribution over a 14-day sequential data assimilation period. Ensemble spread occurs on mesoscale time and space scales, in close association with strong synoptic scale wind forcing events. A companion paper compares the performance of the MFS ensemble forecasts given initial condition generation and forecast forcing from the BHM-SVW, with forecasts based on more traditional methods of ensemble generation 2008-12-31T23:00:00Z http://hdl.handle.net/2122/5708 Title: Impact of Multi-altimeter Sea Level Assimilation in the Mediterranean Forecasting Model Authors: Pujol, M. I; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Dobricic, S.; Centro Euro-Mediterraneo per i Cambiamenti Climatici, via A. Moro 44, 40128 Bologna, Italy; Pinardi, N.; Alma Mater Studiorum Università di Bologna, Centro Interdipartimentale per la Ricerca sulle Scienze Ambientali, Via S. Alberto 163, 48100 Ravenna, Italy; Adani, M.; Centro Euro-Mediterraneo per i Cambiamenti Climatici, via A. Moro 44, 40128 Bologna, Italy Abstract: In this paper we analyze the impact of multi-satellite altimeter observations assimilation in a high-resolution Mediterranean model. Four different altimeter missions (Jason-1, Envisat, Topex/Poseidon interleaved and Geosat Follow-On) are used over a 7-month period [September 2004, March 2005] to study the impact of the assimilation of one to four satellites on the analyses quality. The study highlights three important results. First, it shows the positive impact of the altimeter data on the analyses. The corrected fields capture missing structures of the circulation and eddies are modified in shape, position and intensity with respect to the model simulation. Secondly, the study demonstrates the improvement in the analyses induced by each satellite. The impact of the addition of a second satellite is almost equivalent to the improvement given by the introduction of the first satellite: the second satellite data brings a 12% reduction of the root mean square of the differences between analyses and observations for the Sea Level Anomaly (SLA). The third and fourth satellite also significantly improve the rms, with more than 3% reduction for each of them. Finally, it is shown that Envisat and Geosat Follow-On additions to J1 impact the analyses more than the addition of Topex/Poseidon suggesting that the across track spatial resolution is still one of the important aspects of a multi-mission satellite observing system. This result could support the concept of multi-mission altimetric monitoring done by complementary horizontal resolution satellite orbits. 2008-12-31T23:00:00Z http://hdl.handle.net/2122/5701 Title: On the corrections of ERA-40 surface flux products consistent with the Mediterranean heat and water budgets and the connection between basin surface total heat flux and NAO Authors: Pettenuzzo, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Large, W.G.; National Center for Atmospheric Research, Boulder, Colorado; Pinardi, N.; Bologna University, Corso di Scienze Ambientali, Ravenna, Italy Abstract: This is a study of heat fluxes and heat budget of the Mediterranean Sea using the European Centre for Medium-Range Weather Forecasts (ECMWF) 45 year reanalysis data set ERA-40. The simple use of the ERA-40 surface flux components fails to close the budget and, in particular, the shortwave radiation flux is found to be underestimated with respect to observed data by about 10%. The heat flux terms are recomputed and corrected in order to close the heat and freshwater budgets of the Mediterranean basin over the period 1958 to 2001, thus producing a corrected ERA-40 surface flux data set. Various satellite and in situ observational data are used to construct spatially varying corrections to the ERA-40 products needed to compute the air-sea fluxes. The corrected interannual and climatological net surface heat and freshwater fluxes are and , respectively, which are regarded as satisfactorily closing the Mediterranean heat and water budgets. It is also argued that there is an important contribution from large heat losses associated with a few severe winters over the Mediterranean Sea. This is shown to be related to wind regime anomalies, which strongly affect the latent heat of evaporation that is the main responsible for the interannual modulation of the total heat flux. Furthermore, the surface total heat flux anomaly time series is compared with the North Atlantic Oscillation (NAO) index, and the result is a positive correlation with ocean warming for positive NAO index and cooling associated to negative index periods. 2008-12-31T23:00:00Z http://hdl.handle.net/2122/5699 Title: Is the southeastern Adriatic Sea coastal strip 1 an eutrophic area? Authors: Marini, M.; Institute of Marine Science, National Research Council, Ancona, Italy; Grilli, F.; 1Institute of Marine Science, National Research Council, Ancona, Italy; Guarnieri, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Jones, B.; University of Southern California, Los Angeles, USA; Klajic, Z.; Institute of Marine Biology Kotor, Montenegro; Pinardi, N.; CIRSA, University of Bologna, Ravenna, Italy; Sanxhaku, M.; Institute of Hydrometeorology, Tirana, Albania Abstract: The aim of the present study is to understand and assess the eutrophic state of the Buna-Bojana river delta coastal strip, in the southeastern Adriatic Sea, and contrast it with the northern Po river dominated shelf area. We present and compare observations of chemical and physical state variables from the two areas of the Adriatic Sea and we also use a numerical model output to depict the circulation structures of the two areas. The area affected by the Po River discharge extends at least one hundred kilometres southward of the delta and approximately twenty kilometres offshore. Maximum chlorophyll concentrations follow closely the river waters. Similarly to the northern Adriatic Sea, the Buna/Bojana river discharge extends northward along the coasts for one hundred kilometres and shows large maxima in chlorophyll. The two coastal areas have opposite dominant dynamical processes: while the Po river affected area is a downwelling region, the Buna/Bojana is characterized by upwelling favourable winds. However, during the period of study, upwelling is not a dominant feature of the circulation and both the shelf slope current and the along shore currents in the southeastern Adriatic Sea are northward, the along shore current probably dominated by the river runoff. Under these conditions, primary productivity is high in both areas which allows us to conclude that river plume dynamics with the associated nutrient inputs control the eutrophication state of the coastal strip, regardless of the general hydrodynamics regime of the southeastern Adriatic Sea area 2008-12-31T23:00:00Z http://hdl.handle.net/2122/4872 Title: Integration of ARGO trajectories in the Mediterranean Forecasting System and impact on the regional analysis of the Western Mediterranean circulation Authors: Taillandier, V.; LOV, Villefranche-sur-Mer, France; Dobricic, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Testor, P.; LOCEAN-IPSL, Paris, France; Pinardi, N.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Griffa, A.; CNR-ISMAR, La Spezia, Italy; Mortier, L.; LOCEAN-IPSL, Paris, France; Gasparini, G. P.; CNR-ISMAR, La Spezia, Italy Abstract: The impact of ARGO trajectory assimilation on the quality of ocean analyses is studied by means of an operational oceanographic model implemented in the Mediterranean Sea and a 3D-var assimilation scheme. For the first time, both ARGO trajectories and vertical profiles together with satellite data are assimilated to produce analyses for short term forecasts. The study period covers three months during winter 2005 when four ARGO trajectories were present in the northwestern Mediterranean Sea. It is shown that their integration is consistent with the other components of the assimilation system, and it contributes to refine the model error structure with new information on horizontal pressure gradients. So the analysis benefits of a more accurate description of the boundary currents and their instabilities that drive the mesoscale activity of regional circulations. As a consequence, the trajectory assimilation remotely and significantly influences the basin scale circulation. Changes can be depicted by intermediate water mass redistributions, mesoscale eddy relocations or net transports modulations. These impacts are detailed and assessed considering historical and contemporary datasets. The obtained qualitative and quantitative agreements motivate the integration of ARGO trajectories in the operational Mediterranean Forecasting System. 2008-12-18T23:00:00Z