A new air-sea physics parametrization is developed along with a correction of the ECMWF Era-40 re... more A new air-sea physics parametrization is developed along with a correction of the ECMWF Era-40 reanalysis in order to close the heat and fresh water budgets for the Mediterranean basin during the period that ranges from 1958 to 2001. The empirical bulk formulas for the evaluation of the radiative part of the total heat flux has been replaced by the use of the ECMWF ERA-40 reanalysis radiative fields. The latter and the basic forcing fields used to compute the surface fluxes on a standard OGCM have been corrected by comparison with different reliable data sets and in-situ data. The correction method is based on the preliminary evaluation of the best estimate of heat and fresh water budgets for the period 1985-2001 using the benchmark fields in order to validate them, and the computation of bias reduction terms applicable to the ECMWF fields for those 17 years. The obtained space-dependent factors are subsequently extended to the entire ERA-40 reanalysis time window. This method provides a surface total heat flux QT of -7 W/m2 and a deficit E-P of -0.64 m/yr. Interannual and climatological values of QT and FT are presented and related to the North Atlantic Oscillation (NAO) index.
A coupled Adriatic Sea General Circulation and sediment transport model was used to study the dyn... more A coupled Adriatic Sea General Circulation and sediment transport model was used to study the dynamics of coarse and fine sediment transport and resuspension in the Northern Adriatic Sea. The sediment sizes of coarse (>50 μm) and fine (<50 μm) materials were sorted by their settling velocities. The bottom boundary layer (BBL) was discretized by a vertical sigma coordinate system with high resolution, and the wave-current interaction mechanism was considered. The sediment distributions and fluxes under various forcing conditions such as the Po River plume, the Bora and Scirocco wind stress and the surface waves were studied by process oriented numerical simulations. The conclusions are that maximum northward sediment transport occurs under the forcing by the Po River plume with the Scirocco wave resuspension. The largest southward sediment transport was due to the combined effect of the Po River plume and the Bora wind forcing under the Bora wave conditions. A realistic forcing numerical experiment was also conducted for November 1994 when the full range of forcing functions were experienced by the region. In this presentation, we show the existing complexity of the sediment distribution and flux features in the Northern Adriatic Sea. The significant roles that wave driven sediment resuspension played in determining this complexity in the shallow coastal areas of the region will also be highlighted.
The Mediterranean ocean Forecasting System (MFS) has started operational activi- tiesin January 2... more The Mediterranean ocean Forecasting System (MFS) has started operational activi- tiesin January 2000. Presently it produces daily analyses and weekly 10-days forecasts of currents and temperature and salinity fields for the entire Mediterranean at approxi- mately 10 km resolution.The main elements of the MFS - simultaneously operating in near real time observationaldata network, general circulation model and data assimila- tion scheme- were implemented as part of an EU funded project called Mediterranean Forecasting System Pilot Project (MFSPP). MFSPP developed also a system of re- gional and shelf circulation models and ecological models, which are planned to be major elements of the future forecasting system in the coastal areas. The second phase will be undretaken by another EU fundedn project, called the Mediterranean ocean Forecasting System: Toward Environmental Predictions (MF- STEP), which is seeking further consilidation and expansion of the MFS.The main goal of the MFTSEP is to advance monitoring technology to achieve maximum reli- ability of the Near Real Time observing system, to demostrate practical feasibility of the regional and shelf forecasting in several Mediterranean sub-regions (3 and 1.5 km) and to start the development of end-users interfaces for exploitation of project results. MFSTEP will introduce in MFS new elements of multidisciplinary and multiparame- ter observing system components, together with modelling components that will allow in the succesive phase to carry out marine biochemical fluxes predictions. The specific objectives of the MFSTEP are to improve and expand existing large scalemonitoring system; to add new observing system components in terms of biochemical measure- ments and new automated technology; to improve 10 days basin scale forecast and to demonstrate feasibility of near real time five days forecasts in different shelf areas; to develop asinhronous ocean-atmosphere coupling over regional and shelf areas; to develop three-dimensional biochemical models coupled to the forecasting system for future prediction of ecosystem variability; to consilidate and disseminate forecasts in a wide users community and develop applications for end users.
Journal of Geophysical Research Oceans, Dec 1, 2002
A coupled Adriatic Sea General Circulation and sediment transport model was used to study the dyn... more A coupled Adriatic Sea General Circulation and sediment transport model was used to study the dynamics of coarse and fine sediment transport and resuspension in the Northern Adriatic Sea. The sediment sizes of coarse (>50 μm) and fine (<50 μm) materials were sorted by their settling velocities. The bottom boundary layer (BBL) was discretized by a vertical sigma coordinate system with high resolution, and the wave-current interaction mechanism was considered. The sediment distributions and fluxes under various forcing conditions such as the Po River plume, the Bora and Scirocco wind stress and the surface waves were studied by process oriented numerical simulations. The conclusions are that maximum northward sediment transport occurs under the forcing by the Po River plume with the Scirocco wave resuspension. The largest southward sediment transport was due to the combined effect of the Po River plume and the Bora wind-forcing under the Bora wave conditions. A realistic forcing numerical experiment was also conducted for November 1994 when the full range of forcing functions were experienced by the region. This study shows that wave-driven sediment resuspension is an important resuspension mechanism in the shallow coastal areas of the Northern Adriatic Sea, and contributes significantly to the complexity of the sediment distribution and flux features in the region.
The Adriatic Sea general circulation model coupled to a third generation wave model SWAN and a se... more The Adriatic Sea general circulation model coupled to a third generation wave model SWAN and a sediment transport model was implemented in the Adriatic Sea to study the dynamics of the sediment transport and resuspension in the northern Adriatic Sea (NAS) during the Bora event in January 2001. The bottom boundary layer (BBL) was resolved by the coupled model with high vertical resolution, and the mechanism of the wave-current interaction in the BBL was also represented in the model. The study found that, during the Bora event of 13-17 January 2001, large waves with significant wave height 2 m and period of 5 s were generated by strong winds in the northwestern shelf of the Adriatic where the direction of wave propagation was orthogonal to the current. The combined motion of the wave and current in the BBL increased the bottom stress over the western Adriatic shelf, resulting in stronger sediment resuspension there. Combining stronger bottom resuspension and strong upward vertical flux of resuspended sediments due to turbulent mixing, the model predicted that sediment concentration near the Po River was much higher than that predicted by the model run without wave forcing. The study also shows that wave-current interaction in the BBL reduced the western Adriatic Coastal Currents (WACCs) in the shallower north. It is concluded that wave forcing significantly changed the sediment distributions and increased the total horizontal fluxes over the western shelf. These results signified wave effect on sediment flux and distribution in the NAS, and suggested that waves cannot be neglected in the study of dynamics of sediment transport and resuspension in the shallow coastal seas. By including the tidal forcing in the coupled model, we also examined the effect of tides on the sediment transport dynamics in the NAS.
The Mediterranean Forecasting System (MFS) has been in operations for nearly a decade, and it is ... more The Mediterranean Forecasting System (MFS) has been in operations for nearly a decade, and it is continuously providing analyses on a weekly basis for the region. These forecasts are of great importance as they provide local and basin-scale information of the environmental state of the sea, and are also highly useful for tracking oil spill and search-and-rescue missions. The circulation in the interior Mediterranean Sea is to a large extent characterized by meso-scale eddies, which often have proved somewhat difficult to simulate in an adequate manner due to their high temporal and spatial variability. 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 to constrain and ameliorate the numerical output primarily in terms of the subsurface velocity fields. The method of implementing the float positions into the cost function is highly unique, since it uses a tangent-linear trajectory model as the observational operator. The modeled float trajectories are obtained by integration of the linearized particle advection equation during 5-day periods, corresponding to the time when the Argo floats are drifting at parking depth (350m). For the first time, basin-wide numerical experiments have been undertaken for a 3-year period (2005-2007), and it was concluded that the trajectory assimilation significately improves the simulation of Argo float trajectories based upon analyses. Indeed, statistical studies of the root-mean-square differences between the observed and analysed float positions showed that the new OceanVar scheme yields ~20% better estimates of the predicted ocean currents. It was furthermore established that the extended OceanVAR scheme does not compromise the forecast/analysis quality of the other state variables (e.g. SLAs, temperature, salinity). A notable decrease in availability of Argo-float data was noted during the period, with the maximum amount and spread of floats in 2005. The impact of the fall-off in float abundance was studied in terms of analyses, and implications on the operational activities will be pointed out.
Multi-model Super-Ensembles (SE) aim at combining optimally different models. A dynamic Kalman Fi... more Multi-model Super-Ensembles (SE) aim at combining optimally different models. A dynamic Kalman Filter version of this technique was applied to a unique set of in-situ data and operational ocean models during the Dynamics of the Adriatic in Real-Time (DART) field experiment. The technique was shown to significantly improve forecasting skills.
Long term, high resolution re-analyses of the Mediterranean Sea circulation and thermohaline stru... more Long term, high resolution re-analyses of the Mediterranean Sea circulation and thermohaline structure are now available from the NextData and MyOcean projects. The first is a 60 years re-analysis (1953-2012) done with atmospheric AMIP forcing and the second is 25 years re-analysis (1987-2012) done with ECMWF atmospheric forcing re-analysis. Both concur to have a representation of the longest time series of salinity anomalies in the Mediterranean Sea, the highest space-time reconstruction ever done for the whole basin. The salinity anomalies of the Mediterranean Sea below seven hundred meters of the past 60 years are examined in comparison with the Eastern Mediterranean Transient, a phenomenon Dr. A.Hecht contributed to discover during POEM. Deep water salinity changes and Gibraltar Strait anomalies are also examined in the light of possible feedback mechanisms, as well as the structure and correlation of such salinity anomalies with atmospheric forcing.
The Southern Adriatic Northern Ionian coastal Forecasting System (SANIFS) is a short-term forecas... more The Southern Adriatic Northern Ionian coastal Forecasting System (SANIFS) is a short-term forecasting system based on unstructured grid approach. The model component is built on SHYFEM finite element three-dimensional hydrodynamic model (e.g. [Umgiesser et al., 2004], [Ferrarin et al., 2013]). The operational chain exploits a downscaling approach starting from the Mediterranean oceanographic-scale model MFS (Mediterranean Forecasting System, operated by INGV, e.g. [Tonani et al., 2008], [Oddo et al., 2014]). The implementation set-up has been designed to provide accurate hydrodynamics and active tracer processes in the coastal waters of Southern Eastern Italy (Apulia, Basilicata and Calabria regions), where the model is characterized by a variable resolution in range of 50-500 m. The horizontal resolution is also high in open-sea areas, where the elements size is approximately 3 km. The model is forced: (i) at the lateral open boundaries through a full nesting strategy directly with...
A new air-sea physics parametrization is developed along with a correction of the ECMWF Era-40 re... more A new air-sea physics parametrization is developed along with a correction of the ECMWF Era-40 reanalysis in order to close the heat and fresh water budgets for the Mediterranean basin during the period that ranges from 1958 to 2001. The empirical bulk formulas for the evaluation of the radiative part of the total heat flux has been replaced by the use of the ECMWF ERA-40 reanalysis radiative fields. The latter and the basic forcing fields used to compute the surface fluxes on a standard OGCM have been corrected by comparison with different reliable data sets and in-situ data. The correction method is based on the preliminary evaluation of the best estimate of heat and fresh water budgets for the period 1985-2001 using the benchmark fields in order to validate them, and the computation of bias reduction terms applicable to the ECMWF fields for those 17 years. The obtained space-dependent factors are subsequently extended to the entire ERA-40 reanalysis time window. This method provides a surface total heat flux QT of -7 W/m2 and a deficit E-P of -0.64 m/yr. Interannual and climatological values of QT and FT are presented and related to the North Atlantic Oscillation (NAO) index.
A coupled Adriatic Sea General Circulation and sediment transport model was used to study the dyn... more A coupled Adriatic Sea General Circulation and sediment transport model was used to study the dynamics of coarse and fine sediment transport and resuspension in the Northern Adriatic Sea. The sediment sizes of coarse (>50 μm) and fine (<50 μm) materials were sorted by their settling velocities. The bottom boundary layer (BBL) was discretized by a vertical sigma coordinate system with high resolution, and the wave-current interaction mechanism was considered. The sediment distributions and fluxes under various forcing conditions such as the Po River plume, the Bora and Scirocco wind stress and the surface waves were studied by process oriented numerical simulations. The conclusions are that maximum northward sediment transport occurs under the forcing by the Po River plume with the Scirocco wave resuspension. The largest southward sediment transport was due to the combined effect of the Po River plume and the Bora wind forcing under the Bora wave conditions. A realistic forcing numerical experiment was also conducted for November 1994 when the full range of forcing functions were experienced by the region. In this presentation, we show the existing complexity of the sediment distribution and flux features in the Northern Adriatic Sea. The significant roles that wave driven sediment resuspension played in determining this complexity in the shallow coastal areas of the region will also be highlighted.
The Mediterranean ocean Forecasting System (MFS) has started operational activi- tiesin January 2... more The Mediterranean ocean Forecasting System (MFS) has started operational activi- tiesin January 2000. Presently it produces daily analyses and weekly 10-days forecasts of currents and temperature and salinity fields for the entire Mediterranean at approxi- mately 10 km resolution.The main elements of the MFS - simultaneously operating in near real time observationaldata network, general circulation model and data assimila- tion scheme- were implemented as part of an EU funded project called Mediterranean Forecasting System Pilot Project (MFSPP). MFSPP developed also a system of re- gional and shelf circulation models and ecological models, which are planned to be major elements of the future forecasting system in the coastal areas. The second phase will be undretaken by another EU fundedn project, called the Mediterranean ocean Forecasting System: Toward Environmental Predictions (MF- STEP), which is seeking further consilidation and expansion of the MFS.The main goal of the MFTSEP is to advance monitoring technology to achieve maximum reli- ability of the Near Real Time observing system, to demostrate practical feasibility of the regional and shelf forecasting in several Mediterranean sub-regions (3 and 1.5 km) and to start the development of end-users interfaces for exploitation of project results. MFSTEP will introduce in MFS new elements of multidisciplinary and multiparame- ter observing system components, together with modelling components that will allow in the succesive phase to carry out marine biochemical fluxes predictions. The specific objectives of the MFSTEP are to improve and expand existing large scalemonitoring system; to add new observing system components in terms of biochemical measure- ments and new automated technology; to improve 10 days basin scale forecast and to demonstrate feasibility of near real time five days forecasts in different shelf areas; to develop asinhronous ocean-atmosphere coupling over regional and shelf areas; to develop three-dimensional biochemical models coupled to the forecasting system for future prediction of ecosystem variability; to consilidate and disseminate forecasts in a wide users community and develop applications for end users.
Journal of Geophysical Research Oceans, Dec 1, 2002
A coupled Adriatic Sea General Circulation and sediment transport model was used to study the dyn... more A coupled Adriatic Sea General Circulation and sediment transport model was used to study the dynamics of coarse and fine sediment transport and resuspension in the Northern Adriatic Sea. The sediment sizes of coarse (>50 μm) and fine (<50 μm) materials were sorted by their settling velocities. The bottom boundary layer (BBL) was discretized by a vertical sigma coordinate system with high resolution, and the wave-current interaction mechanism was considered. The sediment distributions and fluxes under various forcing conditions such as the Po River plume, the Bora and Scirocco wind stress and the surface waves were studied by process oriented numerical simulations. The conclusions are that maximum northward sediment transport occurs under the forcing by the Po River plume with the Scirocco wave resuspension. The largest southward sediment transport was due to the combined effect of the Po River plume and the Bora wind-forcing under the Bora wave conditions. A realistic forcing numerical experiment was also conducted for November 1994 when the full range of forcing functions were experienced by the region. This study shows that wave-driven sediment resuspension is an important resuspension mechanism in the shallow coastal areas of the Northern Adriatic Sea, and contributes significantly to the complexity of the sediment distribution and flux features in the region.
The Adriatic Sea general circulation model coupled to a third generation wave model SWAN and a se... more The Adriatic Sea general circulation model coupled to a third generation wave model SWAN and a sediment transport model was implemented in the Adriatic Sea to study the dynamics of the sediment transport and resuspension in the northern Adriatic Sea (NAS) during the Bora event in January 2001. The bottom boundary layer (BBL) was resolved by the coupled model with high vertical resolution, and the mechanism of the wave-current interaction in the BBL was also represented in the model. The study found that, during the Bora event of 13-17 January 2001, large waves with significant wave height 2 m and period of 5 s were generated by strong winds in the northwestern shelf of the Adriatic where the direction of wave propagation was orthogonal to the current. The combined motion of the wave and current in the BBL increased the bottom stress over the western Adriatic shelf, resulting in stronger sediment resuspension there. Combining stronger bottom resuspension and strong upward vertical flux of resuspended sediments due to turbulent mixing, the model predicted that sediment concentration near the Po River was much higher than that predicted by the model run without wave forcing. The study also shows that wave-current interaction in the BBL reduced the western Adriatic Coastal Currents (WACCs) in the shallower north. It is concluded that wave forcing significantly changed the sediment distributions and increased the total horizontal fluxes over the western shelf. These results signified wave effect on sediment flux and distribution in the NAS, and suggested that waves cannot be neglected in the study of dynamics of sediment transport and resuspension in the shallow coastal seas. By including the tidal forcing in the coupled model, we also examined the effect of tides on the sediment transport dynamics in the NAS.
The Mediterranean Forecasting System (MFS) has been in operations for nearly a decade, and it is ... more The Mediterranean Forecasting System (MFS) has been in operations for nearly a decade, and it is continuously providing analyses on a weekly basis for the region. These forecasts are of great importance as they provide local and basin-scale information of the environmental state of the sea, and are also highly useful for tracking oil spill and search-and-rescue missions. The circulation in the interior Mediterranean Sea is to a large extent characterized by meso-scale eddies, which often have proved somewhat difficult to simulate in an adequate manner due to their high temporal and spatial variability. 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 to constrain and ameliorate the numerical output primarily in terms of the subsurface velocity fields. The method of implementing the float positions into the cost function is highly unique, since it uses a tangent-linear trajectory model as the observational operator. The modeled float trajectories are obtained by integration of the linearized particle advection equation during 5-day periods, corresponding to the time when the Argo floats are drifting at parking depth (350m). For the first time, basin-wide numerical experiments have been undertaken for a 3-year period (2005-2007), and it was concluded that the trajectory assimilation significately improves the simulation of Argo float trajectories based upon analyses. Indeed, statistical studies of the root-mean-square differences between the observed and analysed float positions showed that the new OceanVar scheme yields ~20% better estimates of the predicted ocean currents. It was furthermore established that the extended OceanVAR scheme does not compromise the forecast/analysis quality of the other state variables (e.g. SLAs, temperature, salinity). A notable decrease in availability of Argo-float data was noted during the period, with the maximum amount and spread of floats in 2005. The impact of the fall-off in float abundance was studied in terms of analyses, and implications on the operational activities will be pointed out.
Multi-model Super-Ensembles (SE) aim at combining optimally different models. A dynamic Kalman Fi... more Multi-model Super-Ensembles (SE) aim at combining optimally different models. A dynamic Kalman Filter version of this technique was applied to a unique set of in-situ data and operational ocean models during the Dynamics of the Adriatic in Real-Time (DART) field experiment. The technique was shown to significantly improve forecasting skills.
Long term, high resolution re-analyses of the Mediterranean Sea circulation and thermohaline stru... more Long term, high resolution re-analyses of the Mediterranean Sea circulation and thermohaline structure are now available from the NextData and MyOcean projects. The first is a 60 years re-analysis (1953-2012) done with atmospheric AMIP forcing and the second is 25 years re-analysis (1987-2012) done with ECMWF atmospheric forcing re-analysis. Both concur to have a representation of the longest time series of salinity anomalies in the Mediterranean Sea, the highest space-time reconstruction ever done for the whole basin. The salinity anomalies of the Mediterranean Sea below seven hundred meters of the past 60 years are examined in comparison with the Eastern Mediterranean Transient, a phenomenon Dr. A.Hecht contributed to discover during POEM. Deep water salinity changes and Gibraltar Strait anomalies are also examined in the light of possible feedback mechanisms, as well as the structure and correlation of such salinity anomalies with atmospheric forcing.
The Southern Adriatic Northern Ionian coastal Forecasting System (SANIFS) is a short-term forecas... more The Southern Adriatic Northern Ionian coastal Forecasting System (SANIFS) is a short-term forecasting system based on unstructured grid approach. The model component is built on SHYFEM finite element three-dimensional hydrodynamic model (e.g. [Umgiesser et al., 2004], [Ferrarin et al., 2013]). The operational chain exploits a downscaling approach starting from the Mediterranean oceanographic-scale model MFS (Mediterranean Forecasting System, operated by INGV, e.g. [Tonani et al., 2008], [Oddo et al., 2014]). The implementation set-up has been designed to provide accurate hydrodynamics and active tracer processes in the coastal waters of Southern Eastern Italy (Apulia, Basilicata and Calabria regions), where the model is characterized by a variable resolution in range of 50-500 m. The horizontal resolution is also high in open-sea areas, where the elements size is approximately 3 km. The model is forced: (i) at the lateral open boundaries through a full nesting strategy directly with...
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