No abstract

Abstract. 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.

Abstract. 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.

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.

The coastal area located in front of the Volturno river estuary (the Gulf of Gaeta, central-eastern Tyrrhenian Sea) was synoptically sampled in seven surveys between June 2012 and October 2014. Vertical profiles of temperature and salinity were acquired on a high-resolution nearly-regular grid in order to describe the spatial and temporal variability of the characteristics of the waters. Moreover, the three-dimensional velocity field associated with each survey was computed through the full momentum equations of the Princeton Ocean Model to provide a first assessment of the steady-state circulation at small scale. The data analysis shows the entire water column to be characterized by an evident thermal cycle and a vertical thermohaline structure, dominated by three types of waters: the freshwater of the river, the saltier coastal Tyrrhenian waters, and transitional waters originating from their mixing. The inflow of freshwater strongly affects the density distribution, leading to strong temporal variability in the upper layer. Its impact is more evident in winter, sometimes inducing a vertical temperature inversion. In case of rainy events, and also in conditions of high vertical temperature stratification, it forms a surface-trapped layer with high density gradients. These and wind forcing contribute to the formation of small-scale shallow features, such as longshore currents and cyclonic and anticyclonic eddies. The latter influence the vertical stratification and modify the coastal circulation, preserving the transitional waters from the surrounding saltier ones.