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Griffa, A.
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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 - PublicationRestrictedIntegration of Argo trajectories in the Mediterranean Forecasting System and the impact on the regional analysis of the Western Mediterranean circulation(2010)
; ; ; ; ; ; ; ;Taillandier, V. ;Dobricic, S.; CMCC ;Pinardi, N.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Testor, P. ;Griffa, A. ;Mortier, L. ;Gasparini, G. P. ;; ; ; ; ;The impact of Argo float 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 of temperature and salinity (TS) together with satellite altimeter data of sea level anomaly (SLA) are assimilated to produce analyses for short term forecasts. The study period covers 3 months during winter 2005 when four Argo trajectories were present in the northwestern Mediterranean Sea. The scheme is first assessed computing the misfits between observations and model forecast and analysis. The misfit statistics appear improved for float trajectories, while they are not degraded for the other assimilated variables (TS profiles and SLA). This indicates that the trajectory integration is consistent with the other components of the assimilation system and provides new information on horizontal pressure gradients. Comparisons between analyses obtained with and without trajectory assimilation suggest that trajectory assimilation can have an impact on the description of boundary currents and their instabilities, as well as mesoscale activity at regional scales. Changes are depicted by intermediate water mass redistributions, mesoscale eddy relocations, and net transport modulations. These impacts are detailed and assessed considering historical and simultaneous in situ data sets. The results motivate the integration of Argo trajectories in the operational Mediterranean Forecasting System.155 27