After recent impulses on the subject of seismic oceanography, widely described on selected literature [Holbrook et al.(20003)], seismic profiles usually acquired to map and describe the ocean sea floors, adequately treated and integrated by hydrological data along the water column, are now considered useful to provide information on the thermohaline structure of the water masses. Indeed, it is now possible to observe the oceanic dynamic and some structures (such as eddies, double-diffusion, thermohaline intrusions, internal waves) at a very high detail.
In the field of the Seismic Oceanography or Geophysical Oceanography there exist still several problems to be solved, such as the definition of protocols to allow a better confrontation of acquired data, the development of techniques to obtain optimal acquisition, especially in shallow waters, the need of development appropriate processing algorithms, etc. This will hopefully allow to obtain useful information on the ocean vertical microstructure as well.
The necessity of testing and developing these methodologies, as well as the need of improving the knowledge of the processes at the interface sediment-sea, are at the basis of this Cruise carried out using the Italian CNR R/V Urania. Indeed, the difficulty of acquiring synoptic data (e.g. classical hydrology, currentometry, meteorology, turbulence, etc.) has until now limited the optimal use of modeling potentialities and an adequate synthesis of results. The availability of synoptic observations as those provided by the seismic oceanography approach would allow then to monitor much larger regions in a shorter time and, with the help of more classical measurements such XBTs and vertical or towed CTDs, together with the support of turbulence measurements obtained via free falling probes, to depict and outline the vertical stratification in frontal regions at a very high resolution.
The interest at the origin of this proposal was also shared by several international research groups, including two represented on this cruise, the Naval Research Laboratory (NRL) an the University of Durham that have oriented their activity in the direction of the seismic oceanography (e.g. [Nakamura et al.(2006)]). The activity of the EU funded (NEST, FP6) Consortium GO, Geophysical Oceanography, coordinated by Dr. R.W. Hobbs is here acknowledged as the first dedicated European effort on the topic, and the program at NRL coordinated by Dr. W.T. Wood and Dr. J.W. Book is one of the first, if not the first American seismic oceanography effort driven by oceanographic objectives.
In order to show the feasibility and the current state of the art in the field of the seismic oceanography, we have proposed to explore the southern Adriatic Sea region for two weeks at the end of winter 2009. This choice was motivated by several reasons, among which the existence of a well consolidated and continuously updated oceanographic, bathymetric and seismic databases, the presence of different oceanographic characteristics such as fronts and filaments, and the bottom topography modified by cascading and overflow processes.
The benefits resulting from the proposed activity appear to be multiple: (a) the availability of new seismic-hydrological data that would be impossible to be collected by a purely national team, (b) if present, the 3-D mapping of the NAdDW deep water structure when exiting from the Palagruza Sill and starting its cascading process along the slope of the south Adriatic pit, (c) the increase in the distributed knowledge onside the EU; the unlocking of a large quantity of seismic data previously acquired; the foundation of a national research theme in the field of the seismic oceanography where CNR would be the leading institution.