http://hdl.handle.net/2122/157 2013-05-22T22:20:49Z http://hdl.handle.net/2122/8644 Title: Eddy diffusivity derived from drifter data for dispersion model applications Authors: De Dominicis, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Leuzzi, G.; DICEA,“La Sapienza” University of Rome, Rome, Italy; Monti, P.; DICEA,“La Sapienza” University of Rome, Rome, Italy; Pinardi, N.; Corso di Scienze Ambientali, University of Bologna, Ravenna, Italy; Poulain, P.; OGS, Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Trieste, Italy Abstract: Ocean transport and dispersion processes are at the present time simulated using Lagrangian stochastic models coupled with Eulerian circulation models that are supplying analyses and forecasts of the ocean currents at unprecedented time and space resolution. Using the Lagrangian approach, each particle displacement is described by an average motion and a fluctuating part. The first one represents the advection associated with the Eulerian current field of the circulation models while the second one describes the sub-grid scale diffusion. The focus of this study is to quantify the sub-grid scale diffusion of the Lagrangian models written in terms of a horizontal eddy diffusivity. Using a large database of drifters released in different regions of the Mediterranean Sea, the Lagrangian sub-grid scale diffusion has been computed, by considering different regimes when averaging statistical quantities. In addition, the real drifters have been simulated using a trajectory model forced by OGCM currents, focusing on how the Lagrangian properties are reproduced by the simulated trajectories. 2012-08-17T22:00:00Z http://hdl.handle.net/2122/8643 Title: Predictions for oil slicks detected from satellite images using MyOcean forecasting data Authors: Zodiatis, G.; Oceanography Centre, University of Cyprus, Nicosia, Cyprus; Lardner, R.; Oceanography Centre, University of Cyprus, Nicosia, Cyprus; Solovyov, D.; Oceanography Centre, University of Cyprus, Nicosia, Cyprus; Panayidou, X.; Oceanography Centre, University of Cyprus, Nicosia, Cyprus; De Dominicis, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia Abstract: The pan-European capacity for the Ocean Monitoring and Forecasting (MyOcean) Marine Core Service, implementing the Global Monitoring for Environment and Security (GMES) objectives, targets the provision of ocean state observations from various platforms and analysis and forecasting products to assist, among other downscaling activities, the needs of the operational response to marine safety, particularly concerning oil spills. The MEDSLIK oil spill and trajectory prediction system makes use of the MyOcean regional and Cyprus Coastal Ocean Forecasting and Observing System (CYCOFOS) downscaled forecasting products for operational application in the Mediterranean and pre-operational use in the Black Sea. Advanced Synthetic Aperture Radar (ASAR) satellite remote sensing images from the European Space Agency (ESA) and European Maritime Safety Agency CleanSeaNet (EMSA-CSN) provide the means for routine monitoring of the southern European seas for the detection of illegal oil discharges. MEDSLIK offers various ways, to be described in this paper, of coupling the MyOcean forecasting data with ASAR images to provide both forecasts and hindcasts for such remotely observed oil slicks. The main concern will be the drift of the oil slick and also, in the case of the forecast mode, its diffusive spreading, although some attempt is also made to estimate the changes in the state of the oil. The successful link of the satellite-detected oil slicks with their operational predictions using the MyOcean products contributes to the operational response chain and the strengthening of maritime safety for accidental or illegal spills, in implementation of the Mediterranean Decision Support System for Marine Safety (MEDESS-4MS) regarding oil spills. 2012-12-17T23:00:00Z http://hdl.handle.net/2122/7856 Title: Study of the hydrodynamical processes in the Boka Kotorska Bay with a finite element model Authors: Bellafiore, D.; Guarnieri, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Grilli, F.; Penna, P.; Bortoluzzi, G.; Giglio, F.; Pinardi, N. Abstract: Boka Kotorska Bay, located in the southeastern Adriatic Sea along the Montenegro coastline, is a complex morphological structure, consisting of three embayments. They are connected and interact with the sea through narrow straits and the bay can be consid- ered one of the main freshwater inputs into the southern Adriatic Sea. In the framework of the ADRICOSM-STAR project, a hydrody- namical model of this region provided results that are compared with CTD data and hydrodynamic scenarios are discussed for the bay. A finite element coastal model nested in a finite difference model that runs on the Adriatic Sea has been used to reproduce the complex morphology of the bay. Hydrodynamic modeling allows studying the main characteristics of this bay, identifying it as a Region of Freshwater Influence (ROFI). The freshwater input com- ing from the numerous sources present in the bays can strongly modify temperature, salinity and current patterns. The computa- tion of the buoyancy ratio of the thermal and haline buoyancy flux showed that the Kotor and Morinj Bays experience a major effect of surface heating in summer, while the rest of the bay seems to be mostly affected by freshwater influence from precipitation and river discharge. An average estuarine situation is seen, presenting a surface outflow and a bottom inflow of water. Specific hydrody- namic processes can be detected in the channels that connect the different sub-basins of the Boka Kotorska Bay. Moreover, the com- putation of the Kelvin number in correspondence of the internal straits suggests classifying the Kotor and Morinj Bays differently from the outermost areas. The innermost Kotor and Morinj Bays, generally exchange little water with the sea and they have high values of residence times. However, their fresh water springs and rivers have the highest discharges that can change abruptly the pic- ture with increase of the total water exchange between the bay and the sea. 2010-12-31T23:00:00Z http://hdl.handle.net/2122/7824 Title: Quality Assessment of a 1985–2007 Mediterranean Sea Reanalysis Authors: Adani, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Dobricic, S.; Pinardi, N. Abstract: A simulation and two reanalyses from 1985 to 2007 have been produced for the Mediterranean Sea using different assimilation schemes: a reduced-order optimal interpolation [System for Ocean Forecast and Analysis (SOFA)] and a three-dimensional variational scheme (OceanVar). The observational dataset consists of vertical temperature and salinity in situ profiles and along-track satellite sea level anomalies; daily mean fields of satellite sea surface temperature are used for correcting the air–sea fluxes. This paper assesses the quality of the reanalyses with respect to observations and the simulation. Both the SOFA and OceanVar schemes give very similar root-mean-square errors and biases for temperature and salinity fields compared with the assimilated observations. The largest errors are at the thermocline level and in regions of large eddy field variability. However, OceanVar gives 20% better results for sea level anomaly root-mean-square error. 2010-12-31T23:00:00Z http://hdl.handle.net/2122/7817 Title: On the assessment of Argo float trajectory assimilation in the Mediterranean Forecasting System Authors: Nilsson, J. A. U.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Dobricic, S.; CMCC, Bologna; Pinardi, N.; Università di Bologna; Taillandier, V.; Laboratoire d’Oceanographie de Villefranche, France; Poulain, P.-M.; The National Institute of Oceanography and Applied Geophysics (OGS), Trieste, Italy Abstract: The Mediterranean Forecasting System (MFS) has been operational for a decade, and is continuously providing forecasts and analyses for the region. These forecasts comprise local- and basin-scale information of the environmental state of the sea and can be useful for tracking oil spills and supporting search-and-rescue missions. Data assimilation is a widely used method to improve the forecast skill of operational models and, in this study, the three-dimensional variational (OceanVar) scheme has been extended to include Argo float trajectories, with the objective of constraining and ameliorating the numerical output primarily in terms of the intermediate velocity fields at 350 m depth. When adding new datasets, it is furthermore crucial to ensure that the extended OceanVar scheme does not decrease the performance of the assimilation of other observations, e.g., sea-level anomalies, temperature, and salinity. Numerical experiments were undertaken for a 3-year period (2005–2007), and it was concluded that the Argo float trajectory assimilation improves the quality of the forecasted trajectories with ~15%, thus, increasing the realism of the model. Furthermore, the MFS proved to maintain the forecast quality of the sea-surface height and mass fields after the extended assimilation scheme had been introduced. A comparison between the modeled velocity fields and independent surface drifter observations suggested that assimilating trajectories at intermediate depth could yield improved forecasts of the upper ocean currents. 2010-12-31T23:00:00Z http://hdl.handle.net/2122/7808 Title: Ocean ensemble forecasting. Part I: Ensemble Mediterranean winds from a Bayesian hierarchical model Authors: Milliff, R. F.; Bonazzi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Wikle, C. K.; Pinardi, N.; Berliner, L. M. Abstract: A Bayesian hierarchical model (BHM) is developed to estimate surface vector wind (SVW) fields 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 SVW retrievals 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 of 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. The sequential data-assimilation method of the Mediterranean forecast system (MFS) is adapted to the ensemble implementation. Analyses of sample ensemble initial conditions for a single data-assimilation period in MFS are presented to demonstrate the multivariate impact of the BHM–SVW ensemble generation methodology. Ensemble initial-condition spread is quantified by computing standard deviations of ocean state variable fields over the ten ensemble members. The methodological findings in this article are of two kinds. From the perspective of statistical modelling, the process-model development is more closely related tophysicalbalances than inpreviousworkwithmodels for the SVW.Fromthe ocean forecast perspective, the generation of ocean ensemble initial conditions via BHM is shown to be practical for operational implementation in an ensemble ocean forecast system. Phenomenologically, ensemble spread generated via BHM–SVW occurs on ocean mesoscale time- and space-scales, in close association with strong synoptic-scale wind-forcing events. A companion article describes the impacts of the BHM–SVW ensemble method on the ocean forecast in comparisons with more traditional ensemble methods. 2010-12-31T23:00:00Z http://hdl.handle.net/2122/7760 Title: MyOcean Specification Requirements Document for WP9-Med-MFC Authors: Tonani, Marina; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Drudi, Massimiliano; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Teruzzi, Anna; OGS, Trieste; Korres, Gerasimos; HCMR,Athens; Fratianni, Claudia; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Grandi, Alessandro; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Marino, Stefano; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia 2010-11-30T23:00:00Z http://hdl.handle.net/2122/7759 Title: MyOcean Service Interface Operations Process Manual for WP9SubSystem Authors: Tonani, Marina; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Fratianni, Claudia; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Drudi, Massimiliano; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Teruzzi, Anna; OGS, Trieste; Korres, Gerasimos; HCMR, Athens 2011-02-01T23:00:00Z http://hdl.handle.net/2122/7758 Title: Product User Manual Authors: Grandi, Alessandro; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Teruzzi, Anna; OGS, Trieste; Fratianni, Claudia; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Drudi, Massimiliano; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Korres, Gerasimos; HCMR, Athens; Tonani, Marina; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia 2011-06-28T22:00:00Z http://hdl.handle.net/2122/7757 Title: MyOcean Scietific Calibration Report for WP9-Med-MFC Authors: Nilsson, Jenny; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Fratianni, Claudia; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Vladyslav, Lyubartsev; CMCC,Italy; Teruzzi, Anna; OGS, Trieste; Grandi, Alessandro; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Adani, Mario; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Korres, Gerasimos; HCMR, Athens; Pinardi, Nadia; Universita' degli Studi di Bologna, Italia; Tonani, Marina; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia 2011-11-22T23:00:00Z