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  • 1
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    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Publication Date: 2023-07-20
    Description: The processes involved in deep-sea variability and their impact on climate are still unclear, due to a lack of long-term observations above 2000 m of depth. Given the paucity of data and the difficulties implied in such observations, it is important to integrate different resources and methodologies to make the best use of the limited data available for answering open questions about deep-sea dynamics. A set of different analyses was developed and applied for both in situ seafloor time series data and full-depth CTD profiles collected in the Ionian Sea (Mediterranean Sea). Time series spectral analysis revealed the presence of a near-inertial peak in the current kinetic energy spectrum hinting at the presence of local vorticity, while modal analysis applied to CTD profiles disclosed a variability at tidal periodicity in the deepest layers, suggesting a connection with the surface and subsurface layers. This data depicts a dense water mass in the Ionian deep layers that could be a key condition for catching this variability, from tidal to decadal time scale (e.g. the Eastern Mediterranean Transient ). The observed mean structure of the stratification shows that a 4-layer scheme should be enough to have a realistic yet straightforward theoretical representation. Thus, a quasi-geostrophic equation with 4 coupled layers, simulated with a custom-designed algorithm, has been considered to investigate the role that the stratification of the water column can have on the propagation of vorticity, and how the relative layer thicknesses and different densities can trigger instability transport throughout the water column.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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  • 2
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    Unknown
    Elsevier
    In:  In: Science Technology Synergy for Research in the Marine Environment: Challenges for the XXI Century. , ed. by Beranzoli, L., Favali, P. and Smirglio, G. Developments in marine technology, 12 . Elsevier, Amsterdam, Netherlands, p. 2000. ISBN 0-7803-8669-8
    Publication Date: 2020-05-27
    Description: The paper presents an overview of recent seafloor long-term single-frame multiparameter platform developed in the framework of the European Commission and Italian projects starting from the GEOSTAR prototype. The main features of the different systems are described as well as the sea missions that led to their validation. The ORION seafloor observatory network recently developed, based on the GEOSTAR-type platforms and engaged in a deep-sea mission at 3300 m w.d. in the Mediterranean Sea, is also described
    Type: Book chapter , NonPeerReviewed
    Format: text
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  • 3
    Publication Date: 2020-04-01
    Description: The paper presents an overview of recent seafloor long-term single-frame multiparameter platform developed in the framework of the European Commission and Italian projects starting from the GEOSTAR prototype. The main features of the different systems are described as well as the sea missions that led to their validation. The ORION seafloor observatory network recently developed, based on the GEOSTAR-type platforms and engaged in a deep-sea mission at 3300 m w.d. in the Mediterranean Sea, is also described.
    Type: Conference or Workshop Item , NonPeerReviewed
    Format: text
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  • 4
    Publication Date: 2017-04-04
    Description: The Benthic Boundary Layer (BBL) is considered a quite homogeneous environment where a wide variety of processes (chemical, physical, geological and biological) occur often producing front structures or inducing turbulence phenomena. The typical stratification of these zones can be interrupted by episodic events which effects can diffuse to the ocean interior exploiting by local current and mixing processes. According to hydrodynamic definition, the BBL thickness may vary from few millimetres up to 100 metres depending on the friction intensity with the sea bed and the stability of water column above it. Generally in deep-sea condition, the BBL thickness is defined by the ratio between the friction velocity and the Coriolis parameter according to the Ekman scale. In the latest years several experiments have been carried out in the deep water of Mediterranean Sea, focusing on the survey and study of benthic processes following a multidisciplinary approach. Benthic observatories, such as SN-1 and GEOSTAR, allow to record long time-series of geochemical, seismological, geomagnetic, geodetic and oceanographic data and allow to understand the dynamics and evolution of the processes though comparison and interpolation of different types of signals. From a oceanographic point of view, the technology of these benthic observatories brings the possibility to observe and measure directly the hydrological properties at the seafloor collecting data for long-time series and with high sampling rate. The observatories deployed in Mediterranean Sea, have provided good information about variations and oscillations of hydrological parameters in deep water where the monitoring is almost lacking. In some cases it has been possible to link these deep-sea datasets with upper data collected by ship-handled system during the same period or during different cruises. This allows to have a more complete idea of the linkage between surface, intermediate and bottom sea. Hence the multidisciplinary approach represents a very important aspect for this kind of study, because it allows not only a cross check of functionality among all the instruments but also an important tool to recognise and better understand possible nonphysical- oceanographic phenomena.
    Description: Published
    Description: Vienna, Austria
    Description: open
    Keywords: Benthic Boundary Layer ; Mediterranean Sea ; 03. Hydrosphere::03.01. General::03.01.05. Operational oceanography ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
    Format: 2471252 bytes
    Format: application/pdf
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  • 5
    Publication Date: 2017-04-04
    Description: The investigation of the Benthic Boundary Layer (BBL) involves the study of a wide spectrum of different, but connected, processes. In order to study the evolution of physical, geochemical, geological and biological phenomena, and to comprehend their possible relationships, a long-term monitoring with the seafloor observatory support is necessary. Unlike mooring approach, the sea bottom observatories represent a more stable platform wherein a wide variety of instrument can be mounted, giving several advantages on power autonomy and higher sampling rate. In addition, the shortest distance to the bottom of observatory instruments, permits to appreciate even phenomena that can happen close to the sea bottom. The stable localisation of all the instruments at the same bottom depth and their accurate unit time reference allow a relatively easier and efficient comparison of different kind of signals recorded in situ, offering a new and interesting possibility to better understand and describe possible benthic processes. Although to collect long-time series often can give some instrumental drifting problems (especially for the electrode sensors or, in shallow environment, due to bigger befouling activity), an efficient instrumental pre and post-calibration, as well as the possibility to collect water samples during the long period of measurements, guarantee to restore the signals recorded during the data processing phases. The versatility of these observatories then offers a good opportunity to investigate, in the same time, different natural fields and with different instrumental approaches. In addition, it permit to discover that the BBL is not at all a stable environment but, as all the interface layers, it is dominated by strong dynamics processes.
    Description: Published
    Description: Vienna, AUSTRIA
    Description: open
    Keywords: Boundary Layer ; geochemical ; 03. Hydrosphere::03.01. General::03.01.05. Operational oceanography ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
    Format: 2161515 bytes
    Format: application/pdf
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  • 6
    Publication Date: 2017-04-04
    Description: Nell' ambito del progetto NEAREST finanziato dalla EC sono stati sviluppati alcuni elementi di un sistema di allerta per tsunami, fra i quali un prototipo di detector di onde anomale istallato a bordo dell' osservatorio abissale GEOSTAR: l' osservatorio con il detector di onde anomale ha operato per un anno nel Golfo di Cadice, a 3200m di profondità
    Description: Published
    Description: Sassari
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: open
    Keywords: seafloor observatories, ; tsunami detection ; 1775 earthquake ; Cadiz Gulf ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Extended abstract
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  • 7
    Publication Date: 2017-04-04
    Description: A new seafloor observatory, the gas monitoring module (GMM), has been developed for continuous and long-term measurements of methane and hydrogen sulphide concentrations in seawater, integrated with temperature (T), pressure (P) and conductivity data at the seafloor. GMM was deployed in April 2004 within an active gas-bearing pockmark in the Gulf of Patras (Greece), at a water depth of 42 m. Through a submarine cable linked to an onshore station, it was possible to remotely check, via direct phone connection, GMM functioning and to receive data in nearreal time. Recordings were carried out in two consecutive campaigns over the periods April–July 2004, and September 2004–January 2005, amounting to a combined dataset of ca. 6.5 months. This represents the first long-term monitoring ever done on gas leakage from pockmarks by means of CH4+H2S+T+P sensors. The results show frequent T and P drops associated with gas peaks, more than 60 events in 6.5 months, likely due to intermittent, pulsation-like seepage. Decreases in temperature in the order of 0.1–1°C (up to 1.7°C) below an ambient T of ca. 17°C (annual average) were associated with short-lived pulses (10–60 min) of increased CH4+H2S concentrations. This seepage “pulsation” can either be an active process driven by pressure build-up in the pockmark sediments, or a passive fluid release due to hydrostatic pressure drops induced by bottom currents cascading into the pockmark depression. Redundancy and comparison of data from different sensors were fundamental to interpret subtle proxy signals of temperature and pressure which would not be understood using only one sensor.
    Description: Published
    Description: 297-302
    Description: JCR Journal
    Description: reserved
    Keywords: methane-seeping ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
    Publication Date: 2017-04-04
    Description: The ‘‘Santa Maria di Leuca" Cold-Water Coral (CWC) province (northern Ionian Sea) was investigated for the first time to detect eventual occurrence of methane anomalies as a possible indication of hydrocarbon seepage stimulating the coral growth. Most coral mounds have developed in correspondence with tectonic scarps and faults, orthogonal to the southern margin and trending NW-SE, which could be potential sites of gas escape. A visual and instrumental inspection was performed by using a new deep-sea probe equipped with video-cameras, sonar, CTD, methane sensors, and a water sampler. Eight areas were explored by 10 surveys, depths ranging from 380 to 1100 m, for a total of more than 26h of continuous video and instrumental recording. Sediments were also sampled by gravity corers and analysed in laboratory. The images allowed to assess distribution, abundance and geometry of the colonies, most of which are developed on morphological highs often characterised by tectonic scarps. All data indicate however the lack of a significant occurrence of methane, both in seawater and sediments. No direct or indirect expressions of gas seepage were recognised on the seabed. Weak methane anomalies were detected only in seawater at the base of some fault-linked scarps, where more reducing conditions and bacterial methanogenesis are possibly enhanced by less water circulation. The faults are not fluid-bearing as previously suggested by high-resolution geophysical signatures. The development of the coral colonies thus cannot be attributed to seeping fluids, but to a favourable physiographic position with exposure to nutrient-rich currents.
    Description: In press
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: Methane ; Corals ; Seepage ; Marine geology ; 03. Hydrosphere::03.04. Chemical and biological::03.04.02. Carbon cycling ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
    Publication Date: 2017-04-04
    Description: The hydrography of intermediate and deep-water masses in the Northern Ionian Sea (Apulian Plateau) was studied through four quasi-synoptic multidisciplinary surveys carried out in 2004–2006 as an ancillary oceanographic activity in the frame of the APLABES project. This area plays a crucial role for the entire Mediterranean Basin, being influenced by the water outflow of Adriatic origin, which, under severe winter conditions, is a primary source of dense water for the Eastern Mediterranean. At the end of the 1980s such outflow showed a different behavior, and only in the recent years has a gradual re-establishing of the former condition been detected. As such, the Adriatic Sea has regained its role as a main source of the East Mediterranean Deep Water, which was temporarily inhibited during the well-known Eastern Mediterranean Transient which progressively modified the intermediate and deep layers of the Mediterranean Sea. The general structure of water masses was similar through the investigated period, but interesting differences within the bottom layer have been detected. The interaction of the different water types present in the basin is reviewed by means of property–property plots, vertical sections, isopycnal analyses and using an Optimum Multiparameter Analysis (OMP), which is an objective method to measure the mixing of water masses. Due to the lack of any direct information about the dynamics of the water column in the area of the Apulian Plateau during the whole analyzed period, the classical method to infer the baroclinic velocity from the mass field has been applied to hydrographic data. The well-known indeterminacy of this method due to the barotropic component of the velocity field has been resolved using a short time series of current velocities acquired synoptically by a mooring located in the northern part of the studied area. The wavelet transform was adopted for localizing and quantifying the variability of currents simultaneously in both frequency and time domains. The presence of the Adriatic Deep Water close to the bottom was detected on all four surveys, with different signature as underlined by the objectively analysis (with the Optimum Multiparameter Analysis) of the thermohaline field. A core of cold, less-saline and oxygenated water of Adriatic origin coming from the Otranto Channel was identified. This water mass moved in geostrophic balance along the isobaths at 600–1000 m depth at the isopycnal surface of 29.18 kg m−3, not being dense enough to reach the deeper layers of the Ionian Basin, carrying 0.27–0.36 Sv.
    Description: Published
    Description: 441-457
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: Hydrography ; Currents, ; Ionian Sea; ; Apulian Plateau ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
    Publication Date: 2017-04-04
    Description: GEMS (Gamma Energy Marine Spectrometer) is a prototype of an autonomous radioactivity sensor for underwater measurements, developed in the framework for a development of a submarine telescope for neutrino detection (KM3NeT Design Study Project). The spectrometer is highly sensitive to gamma rays produced by 40K decays but it can detect other natural (e.g., 238U,232Th) and anthropogenic radio-nuclides (e.g., 137Cs). GEMS was firstly tested and calibrated in the laboratory using known sources and it was successfully deployed for a long-term (6 months) monitoring at a depth of 3200 m in the Ionian Sea (Capo Passero, offshore Eastern Sicily). The instrument recorded data for the whole deployment period within the expected specifications. This monitoring provided, for the first time, a continuous time-series of radioactivity in deep-sea.
    Description: Published
    Description: S145–S147
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: JCR Journal
    Description: restricted
    Keywords: NaI(Tl) sensor ; Underwater spectrometer ; Marine radioactivity ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 05. General::05.04. Instrumentation and techniques of general interest::05.04.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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