Search results for "Oceanography"
showing 10 items of 1567 documents
A Magnetohydrodynamic Auxiliary Propulsion system for docking assistance of autonomous vehicle
2016
In this article we present an approach to the description of Magnetohydrodynamic Auxiliary Propulsion system for docking assistance of autonomous vehicle. Preliminarily, an analytical model which includes an electromagnetic model and a thermal model is presented. Successively, in order to move beyond the analytical model, a 3-D MHD modeling tool and a Runge Kutta method based solver are presented and they are used to investigate an alternative MHD solutions. Some numerical analysis are given
The helicoidal magnetic generator
2016
Recently helicoidal generator for the exploitation of sea wave energy has been proposed. This device can convert both the vertical and rotational movement of seawaves. The electrical energy generated by such a device must be converted and conditioned in order to match the instantaneous utility requirements and a power link from the sea to an interconnection is needed. In this paper, the authors propose a mathematical model of this device and preliminarily present a prototype of the machine.
Surface sediment dynamics along the shore of Hammamet Gulf (Tunisia, southern Mediterranean)
2016
International audience; In the summer of 2015 the authors analysed grain size and surface sediment composition through high spatial resolution from samples taken at 53 stations along the Hammamet coast (southern Mediterranean Sea). The Acoustic Doppler Current Profiler deployed in this study showed that the surface current flows toward the north-east, parallel to the coast at a maximum speed along the main axis of about 5.9 cm s−1. Near the bottom the current flows toward the north-west at a maximum speed of 2.2 cm s−1. The tide plays a relatively small role in water circulation in Hammamet Gulf. Spatial distribution of particle size, along with speed and current direction analysis, furnish…
Annually resolved δ13Cshell chronologies of long-lived bivalve mollusks (Arctica islandica) reveal oceanic carbon dynamics in the temperate North Atl…
2011
Abstract The ability of the ocean to absorb carbon dioxide is likely to be adversely affected by recent climate change. However, relatively little is known about the spatiotemporal variability in the oceanic carbon cycle due to the lack of long-term, high-resolution dissolved inorganic carbon isotope ( δ 13 C DIC ) data, especially for the temperate North Atlantic, which is the major oceanic sink for anthropogenic CO 2 . Here, we report shell carbon isotope values ( δ 13 C shell ), a potential proxy for δ 13 C DIC , of old-grown specimens of the long-lived bivalve mollusk, Arctica islandica . This paper presents the first absolutely dated, annually resolved δ 13 C shell record from surface …
Modeling Rain Isotopic Composition under Orographic Control: A Landscape Approach for Hydrogeological Applications
2021
Oxygen isotopic composition is useful for individuating recharge areas of groundwater bodies by the comparison with those of local rainfalls. While on a global scale general relationships, such as the isotopic vertical gradient or continentality effects, efficiently describe spatial variations of the isotopic signature, hydrogeological applications need spatial models that are more focused on the effects of local topographic structures and/or subsoil geology. This work presents a case study in northeastern Sicily (Italy) characterized by complex geological and orographic structures, in which isotopic composition of rainfalls is governed by orographic effects and the varying initial composit…
Dimensionless Stage-Discharge Relationship for a Non-Linear Water Reservoir: Theory and Experiments
2020
In the field of hydrology, stage&ndash
Influence of Wind on Suspended Matter in the Water of the Albufera of Valencia (Spain)
2021
Wind is one of the factors that has a great influence on suspended matter in lakes, especially in shallow lagoons. In order to know how wind affects the water in Albufera of Valencia, a shallow coastal lagoon, the measured variables of turbidity and transparency have been correlated with the estimates by processing Sentinel-2 satellite images with the Sen2Cor processor. Data from four years of study show that most of them are light to gentle easterly breezes and moderate to fresh westerly breezes. The results obtained show significant correlations between the measured variables and those obtained from the satellite images for total suspended matter and water transparency and with the averag…
Geographic and temporal variations in turbulent heat loss from lakes : A global analysis across 45 lakes
2018
Heat fluxes at the lake surface play an integral part in determining the energy budget and thermal structure in lakes, including regulating how lakes respond to climate change. We explore patterns in turbulent heat fluxes, which vary across temporal and spatial scales, using in situ high-frequency monitoring data from 45 glob- ally distributed lakes. Our analysis demonstrates that some of the lakes studied follow a marked seasonal cycle in their turbulent surface fluxes and that turbulent heat loss is highest in larger lakes and those situated at low latitude. The Bowen ratio, which is the ratio of mean sensible to mean latent heat fluxes, is smaller at low lati- tudes and, in turn, the rel…
Bathymetric estimation using MERIS images in coastal sea waters.
2007
Bathymetric estimation using remote sensing images has previously been applied to high spatial resolution imagery such as CASI, Ikonos, or SPOT but not on medium spatial resolution images (i.e., MERIS). This choice can be justified when there is a need to map the bathymetry on large areas. In this letter, we present the results of the bathymetry estimation over a large known area, the Gulf of Lion (France), expanding over 270times180 km
Neocomian to early Aptian syn-rift evolution of the normal to oblique-rifted North Gabon Margin (Interior and N'Komi Basins).
2009
18 pages; International audience; The North Gabon coastal rift basins consist of a set of 130–150 long-segment asymmetrically tilted half grabens (Interior Basin) and 000–020 short-segment en échelon half grabens (N'Komi Basin) separated by 040–060 major transverse faults. Tectono-sedimentary analysis of field and subsurface data reveals the control exerted by extensional tectonism over continental sedimentation. During Berriasian to early Barremian times, uniform uniaxial 040–060 extension was responsible for the stretching of the brittle upper crust over a 100-km wide domain. During late Barremian–early Aptian times, the main locus of extension stepped westward resulting in severe end-rif…