The trajectories' prediction of floating objects above the sea surface represents an important task in search and rescue (SAR) operations. In this paper we show how it is possible to estimate the most probable search area by means of a stochastic model, schematizing the shape of the object appropriately and evaluating the forces acting on it. The LEEWAY model,a Monte Carlo-based ensemble trajectory model, has been used; here, both statistical law to calculate the leeway and an almost deterministic law inspired by the boundary layer theory have been considered. The model is nested within the subregional hydrodynamic model TSCRM (Tyrrhenian Sicily Channel Regional Model) developed in the framework of PON-TESSA (Programma Operativo Nazionale; National Operative Program – TEchnology for the Situational Sea Awareness) project. The main objective of the work is to validate a new approach of leeway calculation that relies on a real person in water (PIW) event, which occurred in the Tyrrhenian Sea in July 2013. The results show that by assimilating a human body to a cylinder and estimating both the transition from laminar to turbulent boundary layer and the drag coefficients, it can be possible to solve a force balance equation, which allows the search area to be estimated with good approximation. This new point of view leads to the possibility of also testing the same approach for other different categories of targets, so as to overcome the limitations associated with the calculation of the leeway in the future by means of standard statistical law.
Oil spill models are used to simulate the evolution of an oil slick that occurs after an accidental ship collision, malfunctioning of oil extraction platforms, or illegal discharges intentionally released by ships into the marine environment. We present an integrated operational oil spill prediction system that improves capacities in preventing and mitigating maritime risks from oil spills. The objective is to provide forecast information about the transport and the fate of a hypothetical oil spill under Nearly-Real Time hydrodynamic conditions in the western and central Mediterranean Sea. This complex forecast system is developed in the framework of the project SOS-Piattaforme & Impatti Off-Shore to the needs of Italian Coast Guard and other institutions, such as the Ministry of the Environment. This service has been operational since July 2020. The innovative aspect of this work is a graphical user interface (the GUI), which allows to select properties, time, and location of a potential oil spill and show the evolution of oil slick concentration and oil fate parameters. This platform represents the first component of a future Decision Support System aimed to identify the risk assessment of oil spills in order to better manage emergencies and minimize economic damages.
Physical and biological processes of the marine ecosystem have a high spatial and temporal variability, whose study is possible only through high resolution and synoptic observations. The Temperature and Fluorescence Launchable Probe was charted in order to answer to the claim of a cost effective temperature and fluorescence expendable profiler, to be used in ships of opportunity. The development of the expendable fluorometer has followed similar concepts of the XBT (a wire conducting the signal to a computer card), but differently from the latter it was developed with an electronic system which can be improved and adapted to several variables measure channels. To reach the aim of a low-cost probe, were utilized commercial components: a glass bulb temperature resistor for the temperature measurement, blue LEDs, a photodiode and available selective glass filters, for the fluorescence measurement. The measurement principle employed to detect phytoplankton's biomass is the active fluorescence. This method is an in vivo chlorophyll estimation, that can get the immediate biophysical reaction of phytoplankton inside the aquatic environment; it is a non-disruptive method which gives real time estimation and avoids the implicit errors due to the manipulation of samples. The possibility of using a continuous profiling probe, with an active fluorescence measurement, is very important in real time phytoplankton's study; it is the best way to follow the variability of sea productivity. In fact, because of the high time and space variability of phytoplankton, due to its capability to answer in a relatively short time to ecological variations in its environment and because of its characteristic patchiness, there isn't a precise quantitative estimation of the biomass present in the Mediterranean Sea.
The interannual variability of the physical properties of the shelf waters in Sardinia, western Mediterranean Sea, is studied by using hydrological data gathered during three oceanographic cruises: two in late summer of 2019 and 2021 respectively and another one in early autumn of 2020. The data consist of vertical profiles of salinity and potential temperature acquired by a multiparametric probe for a total of 171 casts performed along a set of transects extending from the nearshore to the continental slope, up to the depth of 200 m. Satellite remote sensing and numerical modelling oceanographic products support the phenomenological analysis. Atlantic Water, characterised by low salinity signatures (S<37.0), is detected in the surface waters of the southwestern shelf areas, induced by the Algerian Eddies, and with differences between years. It is also observed on the southern-eastern and north-eastern shelf areas of Sardinia, mainly driven by the interaction with large-scale circulation features like the southeast Sardinia Gyre and the Bonifacio Gyre. An upwelling phenomenology is identified as one of the major features of the coastal circulation on the western shelf area. The study provides the first assessment of the thermohaline features on the Sardinian shelf; an enhanced contribution to the current knowledge of the coastal sea phenomena, and contributes to numerical modelling applications and implementations for ecosystem services.
A modern approach to the study of pelagic ecosystems requires both an appropriate spatial and temporal resolution and a synoptic observation. For this reason, it is indispensable a rapid and high-resolution data acquisition along the water column. During the CNR project PRISMA II, four oceanographic cruises were performed in the Northern Adriatic Sea to analyse the high variability of ecological processes related to the frontal system. The SARAGO, a towed undulating vehicle, allowed a fine description of physical and biological acquired parameters (CTD, chlorophyll a concentration, photosynthetic efficiency, PAR). In succession, CTD and bottle carousel casts were performed to analyse physical and biogeochemical features. In this work, we compare the distribution and quantification of the relevant variables acquired by the two different sampling methods. A mathematical model was applied to estimate primary production.