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Despite the general sparseness of water column carbon measurements, the Mediterranean Sea has been identified as an important anthropogenic carbon storage (Álvarez, 2012) where the column inventory is much higher than in the Atlantic or Pacific oceans (Schneider et al., 2010; Lee et al., 2011). The central Mediterranean Sea is even less sampled, although water masses locally formed and spreading are able to affect the deep overturning cell of the Eastern Mediterranean. We refer particularly to the Adriatic Sea, where significant physical biogeochemical processes (dense water formation, river inputs, intense air sea exchanges, phytoplankton blooms, with high primary production, and remineralisation) take place thus affecting air-sea CO2 fluxes and the related carbon seawater chemistry. The spatial and seasonal variability of chemical properties (dissolved oxygen, nutrients), including carbonate system (pHT, AT, DIC, fCO2, saturation states for calcite and aragonite), were determined in the first mesoscale surveys conducted in February and October 2008, under the SESAME project. A latitudinal section along the central Mediterranean Sea and horizontal maps at surface, including the full length of the Adriatic Sea and most of the Ionian Sea, will be presented and discussed with a particular focus on ocean acidification process. All the horizontal maps exhibit latitudinal gradients. pH and total alkalinity (AT) pointed out North-South gradients, depending on the main drivers. The surface AT showed the highest values (>2630 ?m/Kgsw) in the Adriatic basin, particularly on the N. Adriatic shelf (>2675 ?m/Kgsw) due to the effect of many rivers otputs (draining carbonatic basins), while southward the decrease to the lowest values (

Rapporto tecnico della campagna oceanografica PREPARED 2014 nell'ambito del progetto EU-H2020 EuroFleets 2

This paper is the outcome of a workshop held in Rome in November 2011 on the occasion of the 25th anniversary of the POEM (Physical Oceanography of the Eastern Mediterranean) program. In the workshop discussions, a number of unresolved issues were identified for the physical and biogeochemical properties of the Mediterranean Sea as a whole, i.e., comprising the Western and Eastern sub-basins. Over the successive two years, the related ideas were discussed among the group of scientists who participated in the workshop and who have contributed to the writing of this paper. Three major topics were identified, each of them being the object of a section divided into a number of different sub-sections, each addressing a specific physical, chemical or biological issue: 1. Assessment of basin-wide physical/biochemical properties, of their variability and interactions. 2. Relative importance of external forcing functions (wind stress, heat/moisture fluxes, forcing through straits) vs. internal variability. 3. Shelf/deep sea interactions and exchanges of physical/biogeochemical properties and how they affect the sub-basin circulation and property distribution. Furthermore, a number of unresolved scientific/methodological issues were also identified and are reported in each sub-section after a short discussion of the present knowledge. They represent the collegial consensus of the scientists contributing to the paper. Naturally, the unresolved issues presented here constitute the choice of the authors and therefore they may not be exhaustive and/or complete. The overall goal is to stimulate a broader interdisciplinary discussion among the scientists of the Mediterranean oceanographic community, leading to enhanced collaborative efforts and exciting future discoveries. © Author(s) 2014.

We use ambient noise tomography to investigate the crust and uppermost mantle structure beneath the Carpathian-Pannonian region of Central Europe. Over 7500 Rayleigh wave empirical Green's functions are derived from interstation cross-correlations of vertical component ambient seismic noise recordings (2005-2011) using a temporary network of 54 stations deployed during the South Carpathian Project (2009-2011), 56 temporary stations deployed in the Carpathian Basins Project (2005-2007) and 100 permanent and regional broad-band stations. Rayleigh wave group velocity dispersion curves (4-40 s) are determined using the multiple-filter analysis technique. Group velocity maps are computed on a grid of 0.2° × 0.2° from a non-linear 2-D tomographic inversion using the subspace method. We then inverted the group velocity maps for the 3-D shear wave velocity structure of the crust and uppermost mantle beneath the region. Our shear wave velocity model provides a uniquely complete and relatively high-resolution view of the crustal structure in the Carpathian-Pannonian region, which in general is validated by comparison with previous studies using other methods to probe the crustal structure. At shallow depths (30 km are relatively fast, presumably related to shallowing of the Moho consequent on the extensional history of the Pannonian region.

Surface patterns of the low-frequency current in a 20 × 30 km region in front of the Venice Lagoon were analysed from a 13-month-long HF radar data set. Surface circulation was related to prevalent wind regimes in the area and to the tidal flow through the lagoon inlet. Three different categories of wind-forcing were defined: bora (NE wind), sirocco (SE wind), and finally the category containing all other wind directions and calms (winds lower than 3 m/sec). Mean flow and vorticity spatial distributions were discussed for different wind conditions. The coastal area about 5 km wide is characterized by a flow field with maximum vorticity. Outside the coastal boundary layer the interior flow is part of the Adriatic basin-wide cyclonic circulation. Two counter-rotating vortices of the dimension of about 4–5 km were evidenced in the average flow field in front of the lagoon inlet (Malamocco inlet) in all situations except for the bora. The vortex-pair is probably associated with the tidal flow through the inlet. The bora wind induces a strong southward coastal jet detached from the coast by about 5 km homogenizing the flow and eliminating the dipole. The average coastal flow pattern in calm wind conditions was also analysed as a function of the strong inflow/outflow (currents in the inlet > 0.7 m s-1) from the lagoon inlet. In both cases the vorticity pattern is similar, with the negative vorticity to the left of the inlet and positive to the right looking seaward.

The feasibility of monitoring the suspended particle concentration (SPC) and fluxes (PF) with Acoustic Doppler Current Profilers (ADCP) was tested in the Venice Lagoon inlets. The backscatter recorded by boat- and bottom-mounted instruments was converted into SPC estimates with a calibration procedure based on multiple water sample collection and ADCP transects. Time series of PF across the inlets were derived from discharge and SPC data allowing for the calculation of a preliminary budget of the exchanges between the lagoon and the open sea.

The northern Adriatic has been recognized for many years as a region of high marine production at several trophic levels from phytoplankton to fish. The rivers draining into the northern Adriatic are the major sources of external nutrient input, especially during stratified periods. The water mass exchange between the northern region and the remainder of the essentially oligotrophic Adriatic has a great influence on the productivity and standing crops of different sub-areas. A terrigenous supply of nutrients all along the western coast via run-off influences the productivity of a relatively narrow coastal belt, and consequently the biomasses and production rates are spatially very variable. In shallow turbulent environments, like the northern Adriatic, where increased nutrient availability is episodic, the microbial or the grazing food web can alternately dominate in the carbon flow over short time periods. In spring, as a result of episodic nutrient enrichment of the euphotic zone and insufficient grazing, as a controlling factor of their population size, large-sized phytoplankton blooms occur that consequently determine a major export to the bottom via sedimentation. On the opposite, microbial food web is typical of low energy environment, mostly based on regeneration processes. As a consequence, the final fate of photosynthesised carbon can strongly change over time in the same environment as a function of the planktonic food web structures. In the framework of VECTOR project ("VulnErabilità delle Coste e degli ecosistemi marini italiani ai cambiamenti climaTici e loro ruolO nei cicli del caRbonio mediterraneo") a re-analisys of the entire available data set of parameters relevant in driving C fluxes and export rates has been planned to provide conceptual models and appropriate parametrizations to modelers, with the aim to hindcast and forecast ecosystem scenarios at the basin scale.

Lo studio della circolazione costiera e dello scambio di flussi d’acqua tra la laguna di Venezia ed il mare aperto attraverso le sue bocche di porto è stato uno dei temi principali di un progetto di ricerca, finanziato dal CORILA (Consorzio Ricerche Lagunari) negli anni 2001-2004 Un aspetto preso in considerazione in questa ricerca è il ruolo fondamentale che le correnti marine superficiali giocano nell’ambiente costiero per la loro influenza nell’ecosistema, e come il campo di corrente adiacente alle bocche, nella fascia costiera fuori della laguna, interviene nell’efficienza dei flussi attraverso le bocche nel rinnovare le acque della laguna. Lo studio della circolazione superficiale e del suo impatto sulle caratteristiche ambientali richiede l’acquisizione di lunghe serie di dati di corrente di alta qualità, che spesso risultano carenti a causa delle limitazioni nelle tecniche di misura disponibili. Una nuova tecnica di misura basata su una rete di sistemi Radar HF per produrre le mappe della corrente marina superficiale al largo della bocca di porto di Malamocco, è stata utilizzata, permettendo l’analisi della completa serie temporale dal 2001 al 2003. Questa tecnologia, già ampiamente utilizzata negli Stati Uniti e sperimentata per la prima volta in Italia dal gruppo di ricerca del CNR – ISMAR di Venezia, in collaborazione con l’OGS di Trieste ha permesso di superare le difficoltà fino ad ora incontrate nello studio delle correnti in ampie aree di mare. La circolazione costiera é stata studiata con l’utilizzo di radar costieri ad alta frequenza (25-30 MHz). Il radar utilizza due sistemi di antenne ricetrasmittenti posizionate sulle isole di Lido e di Pellestrina, più una terza antenna Rx/Tx installata sulla piattaforma “Acqua Alta”, 8 miglia al largo delle bocche di porto. Con questa configurazione é stata coperta dalle misure una zona larga 20km davanti alla bocca di Malamocco, con una risoluzione spaziale di 1km, ottenendo le serie temporali desiderate.

A network of high frequency (HF) radar systems was used to produce maps of surface velocity offshore of the Malamocco inlet during the 12-month period from November 2001 through October 2002. Inspection of the sub-tidal residual flow fields revealed frequent occurrences of small-scale (~10 km) eddy structures both north and south of the inlet. In addition, several monthly averaged velocity maps indicate the presence of a persistent meander in the mean current patterns. A more objective technique, based on vorticity, was developed to search the data set for the presence of eddies near the inlet and to separate those features from the larger-scale meander pattern. The vorticity at scales of 5-10 km was computed each hour using the low-passfiltered data set and year-long vorticity statistics were investigated at selected locations surrounding the inlet. The vorticity histograms and temporal variability changed significantly as a function of location relative to the Malamocco inlet. Both north and south of the inlet, the mean vorticity was weakly negative reflecting the larger-scale meander pattern whose crest is aligned, approximately, with the inlet. However, the range of vorticity north of the inlet was much greater than it was south of the inlet. A minor peak (or shoulder) in the year-long histogram of vorticity north of the inlet highlighted frequent occurrences of strong (~ 5 × 10-5 s-1) positive vorticity events in that area. A similar statistical behaviour was not seen south of the inlet. This observation was used to define a conditional sampling criteria that lead to a map of the typical flow field associated with strong eddy events. The vorticity time series were also used to investigate the relationship of eddy events to external forcing parameters. Strong winds, for instance, acted to destroy vorticity in the surface current field since they lead to a strong but horizontally uniform response in the surface currents. The roles of sea level variability and offshore current velocity were also investigated.

A series of seasonal cruises and Eulerian current measurements in the Otranto Strait were carried out to study the biogeochemical characteristics of the strait and to estimate the exchange of water, dissolved and particulate matter between the Adriatic and the Ionian Sea. From the biogeochemical distributions obtained, the role for the Adriatic Sea in supporting the N:P ratio anomaly of the Mediterranean is hypothesized. Examining the bottom oxygen distribution, the deep ventilation of the Eastern Mediterranean seems to follow a more complex pathway than previously hypothesized Fluxes computation shows a net outflow through the strait for nitrate, phosphate and silicate, while a slight net inflow was obtained for POC and PN.