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Rixen, M.
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- PublicationOpen AccessSurface circulation in the Liguro-Provençal basin as measured by satellite-tracked drifters (2007-2009)(2010-01)
; ; ; ; ; ; ; ; ;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; ; ; ; ; ; ; 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.404 599 - PublicationRestrictedInteraction between currents, meteorological and topographic forcings; the case study of Portofino Promontory (northern Ligurian shelf) in summer 2004(2010-10-18)
; ; ; ; ; ; ; ;Locritani, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Vetrano, A.; National Research Council – ISMAR-SP ;Rixen, M.; NATO Undersea Research Centre ;Gasparini, G.P.; National Research Council – ISMAR-SP ;Povero, P.; University of Genova ;Chiggiato, J.; NATO Undersea Research Centre ;Carmisciano, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ; ; ; ; Hydrological, current-meter and meteorological data were acquired in the northern Ligurian sea in summer 2004. Data have been collected using different kind of instruments and resolutions. This work merges different sources of data to describe the coastal dynamic around the Cape of Portofino and to define its relation with the general cyclonic circulation in the area (represented by Arenzano current), the orography and the meteorological forcing.190 68 - PublicationOpen AccessSueper-Ensemble techniques: application to surface drift prediction during the DART06 and MREA07 campaigns(2009-11)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Vanderbulcke, L.; GeoHydrodynamics and Environmental Research, University of Liege, Belgium ;Beckers, J.-M.; GeoHydrodynamics and Environmental Research, University of Liege, Belgium ;Lenartz, F.; GeoHydrodynamics and Environmental Research, University of Liege, Belgium ;Barth, A.; GeoHydrodynamics and Environmental Research, University of Liege, Belgium ;Poulain, P.-M.; stituto Nazionale di Oceanografia Sperimentale (OGS), Trieste, Italy ;Aidonindis, M.; ServiceIdrographique et Oceanographique de la marine, 13 rue du Chatelier, 29200 Brest, France ;Meyrat, J.; ServiceIdrographique et Oceanographique de la marine, 13 rue du Chatelier, 29200 Brest, France ;Ardhuin, F.; ServiceIdrographique et Oceanographique de la marine, 13 rue du Chatelier, 29200 Brest, France ;Fratianni, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Tonani, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Torrisi, L.; Servizio Meteorologico (Aeronautica Militare), Italy ;Pasquini, S.; Servizio Meteorologico (Aeronautica Militare), Italy ;Chiggiato, J.; ARPA Emilia Romagna, Servizio Idro Meteorologico, Bologna ;Tudor, M.; DHMZ Meteorological and Hydrological Service, Zagreb, Croatia ;Book, J.; US Naval Research Lab., 4555 Overlook Ave, SW, Washington, DC 20375 ;Martin, P.; US Naval Research Lab., 4555 Overlook Ave, SW, Washington, DC 20375 ;Allard, R.; US Naval Research Lab., 4555 Overlook Ave, SW, Washington, DC 20375 ;Peggion, G.; US Naval Research Lab., 4555 Overlook Ave, SW, Washington, DC 20375 ;Rixen, M.; NATO/SACLANT Undersea Research Centre, La Spezia, Italy; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; The prediction of the drift of floating objects is an important task, with applications such as marine transport, pollutant dispersion, and search-and-rescue activities. But forecasting surface drift is also very challenging, because it depends in a complex way on various interacting factors such as the wind, the ocean surface current, and the wave field. Furthermore, although each of the cited factors can be fore- casted by deterministic models, the latter all suffer from limitations, resulting in imperfect predictions. In the present study, we try and predict the drift of buoys launched during the DART06 (Dynamics of the Adriatic sea in Real-Time 2006) and MREA07 (Maritime Rapid Environmental Assessment 2007) sea trials, using the so-called hyper-ensemble technique: different models are combined in order to minimize departure from independent observations during a training period; the ob- tained combination is then used in forecasting mode. We review and try out different hyper-ensemble techniques, going from simple ensemble mean to techniques based on data assimilation, which dynamically update the model’s weights in the combi- nation when new observations become available. We show that the latter methods alleviate the need of fixing the training length a priori, as older information is au- tomatically discarded, and hence they lead to better results. Moreover, they allow to determine a characteristic time during which the model weights are more or less stable, which allows to predict how long the obtained combination will be valid in forecasting mode.282 254 - PublicationRestrictedCOASTAL DYNAMIC FEATURES ALONG THE NORTHERN LIGURIAN SHELF (PORTOFINO CAPE) IN SUMMER 2004: ROLE OF THE METEREOLOGICAL AND THE TOPOGRAPHIC FORCINGS(2010-05-14)
; ; ; ; ; ; ; ;Locritani, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Gasparini, G.P.; Consiglio Nazionale Delle Ricerche – ISMAR-SP ;Vetrano, A.; Consiglio Nazionale Delle Ricerche – ISMAR-SP ;Povero, P.; Università Degli Studi Di Genova ;Rixen, M.; NATO Undersea Research Centre ;Carmisciano, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Castellano, M.; Università Degli Studi Di Genova; ; ; ; ; ; A comprehensive analysis of hydrological, current-meter and meteorological data was performed in the northern Ligurian sea to describe the coastal dynamic near the Portofino cape and its relation with the general cyclonic circulation during summer 2004. Current-meter data was acquired in two coastal sites: the Portofino Cape and the marine area of Arenzano. The hydrological parameters around the cape suggested the presence of two different water masses. The first, located in the lee of the cape, is influenced by local effects, while the second, offshore the cape, is correlated to the general circulation of the Ligurian Sea. The prevalent southern direction of the current in Portofino indicates the presence of a local anticyclonic circulation, associated to the presence of the cape.193 32