Entity

Time filter

Source Type


Oddo P.,Italian National Institute of Geophysics and Volcanology | Oddo P.,Science and Technology Organization Center for Maritime Research and Experimentation | Bonaduce A.,Centro Euromediterraneo per i Cambiamenti Climatici | Pinardi N.,Italian National Institute of Geophysics and Volcanology | And 3 more authors.
Geoscientific Model Development | Year: 2014

The sensitivity of the dynamics of the Mediterranean Sea to atmospheric pressure and free surface elevation formulation using NEMO (Nucleus for European Modelling of the Ocean) was evaluated. Four different experiments were carried out in the Mediterranean Sea using filtered or explicit free surface numerical schemes and accounting for the effect of atmospheric pressure in addition to wind and buoyancy fluxes. Model results were evaluated by coherency and power spectrum analysis with tide gauge data. We found that atmospheric pressure plays an important role for periods shorter than 100 days. The free surface formulation is important to obtain the correct ocean response for periods shorter than 30 days. At frequencies higher than 15 days-1 the Mediterranean basin's response to atmospheric pressure was not coherent and the performance of the model strongly depended on the specific area considered. A large-amplitude seasonal oscillation observed in the experiments using a filtered free surface was not evident in the corresponding explicit free surface formulation case, which was due to a phase shift between mass fluxes in the Gibraltar Strait and at the surface. The configuration with time splitting and atmospheric pressure always performed best; the differences were enhanced at very high frequencies. © Author(s) 2014. Source


Noviello C.,CNR Institute of Neuroscience | Fornaro G.,CNR Institute of Neuroscience | Braca P.,Science and Technology Organization Center for Maritime Research and Experimentation | Martorella M.,University of Pisa
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2015

The work addresses the problem of compensating the distortion effects induced by the translational motion of moving targets in Inverse Synthetic Aperture Radar (ISAR) imaging systems. The ISAR motion compensation is the most crucial step in the Autofocusing ISAR technique; this task is typically solved by implementing exhaustive search algorithms by adopting proper functionals based f.i. on image entropy or image contrast. In this work, we discuss an innovative and fast motion compensation procedure that is based on the estimation of two Doppler key Parameters: the Doppler Centroid and the Doppler Rate, which are related to the target motion parameters. The effectiveness of the proposed method is tested on real data acquired by a static Frequency Modulated Continuous Wave radar with an azimuth wide beamwidth; the radar is installed near the inner harbor of La Spezia (Italy) and it owned to the Centre for Maritime Research and Experimentation of the North Atlantic Treaty Organization (CMRE-NATO). © 2015 IEEE. Source


Bonaduce A.,Centro Euro Mediterraneo sui Cambiamenti Cimatici | Pinardi N.,University of Bologna | Oddo P.,Italian National Institute of Geophysics and Volcanology | Oddo P.,Science and Technology Organization Center for Maritime Research and Experimentation | Spada G.,Universita` Degli Studi Of Urbino Carlo Bo
Climate Dynamics | Year: 2016

Sea-level variability in the Mediterranean Sea was investigated by means of in-situ (tide-gauge) and satellite altimetry data over a period spanning two decades (from 1993 to 2012). The paper details the sea-level variations during this time period retrieved from the two data sets.Mean sea-level (MSL) estimates obtained from tide-gauge data showed root mean square differences (RMSDs) in the order of 40–50 % of the variance of the MSL signal estimated from satellite altimetry data, with a dependency on the number and quality of the in-situ data considered. Considering the individual time-series, the results showed that coastal tide-gauge and satellite sea-level signals are comparable, with RMSDs that range between 2.5 and 5 cm and correlation coefficients up to the order of 0.8. A coherence analysis and power spectra comparison showed that two signals have a very similar energetic content at semi-annual temporal scales and below, while a phase drift was observed at higher frequencies. Positive sea-level linear trends for the analysis period were estimated for both the mean sea-level and the coastal stations. From 1993 to 2012, the mean sea-level trend ((Formula presented.) mm year(Formula presented.)) was found to be affected by the positive anomalies of 2010 and 2011, which were observed in all the cases analysed and were mainly distributed in the eastern part of the basin. Ensemble empirical mode decomposition showed that these events were related to the processes that have dominant periodicities of (Formula presented.)10 years, and positive residual sea-level trend were generally observed in both data-sets. In terms of mean sea-level trends, a significant positive sea-level trend ((Formula presented.)95 %) in the Mediterranean Sea was found on the basis of at least 15 years of data. © 2016 The Author(s) Source


Grasso R.,Science and Technology Organization Center for Maritime Research and Experimentation | Braca P.,Science and Technology Organization Center for Maritime Research and Experimentation | Osler J.,Science and Technology Organization Center for Maritime Research and Experimentation | Hansen J.,U.S. Navy | Willett P.,University of Connecticut
IEEE Aerospace and Electronic Systems Magazine | Year: 2014

Piracy on the high seas is a problem of worldwide concern. According to the International Chamber of Commerce International Maritime Bureau's (IMB) global piracy report, East and West Africa accounted for the majority of world attacks in 2011, a rising trend. Of the 439 attacks reported to the IMB in 2011, 275 took place off Somalia on the east coast and in the Gulf of Guinea on the west coast of Africa [1]. International coalitions are involved in efforts to inhibit pirate attacks, protect vessels, and increase the level of security in those regions where the risk of piracy is higher. Examples of such efforts include Operation Ocean Shield (OOS), the NATO's counterpiracy mission (see Figure 1) [2], [3], and the European Union Operation Atalanta [4], both conducted in the Gulf of Aden and off the Horn of Africa. © 1986-2012 IEEE. Source


Ferreira F.,Science and Technology Organization Center for Maritime Research and Experimentation | Djapic V.,SPAWARSYSCEN Pacific | Micheli M.,Science and Technology Organization Center for Maritime Research and Experimentation | Caccia M.,CNR Institute of Intelligent Systems for Automation
Annual Reviews in Control | Year: 2015

Forward looking sonars (FLS) are nowadays popular for many different applications. In particular, they can be used for Automatic Target Recognition (ATR) in the context of Mine Countermeasures. Currently, ATR techniques are applied to raw data which generates many false positives and the need for human supervision. Mosaicing FLS data increases target contrast and thus reduces false positive rate. Moreover, it implies a considerable data size reduction which is important if one thinks of exchange of data in real time through an acoustic channel with very limited bandwidth. Results of applying a real-time mosaicing algorithm to FLS data generated during Mine Countermeasures missions are shown and discussed thoroughly in this article. © 2015 International Federation of Automatic Control. Source

Discover hidden collaborations