scholarly journals WAVE STATISTICS AND SPECTRAL MONITORING IN THE MEDITERRANEAN SEA (i.e. SICILY CHANNEL): 9 YEARS OF WAVE DATA MONITORING

2012 ◽  
Vol 1 (33) ◽  
pp. 3 ◽  
Author(s):  
Emanuele Terrile ◽  
Gianluigi De Filippi ◽  
Ostilio Spadaccini
Keyword(s):  
Mediterranean Sea ◽  
Wave Spectrum ◽  
Intermediate Water ◽  
Spectral Parameters ◽  
Wave Statistics ◽  
Wave Data ◽  
The Mediterranean ◽  
Sicily Channel ◽  
Wave Models ◽  
Definition Of

The main aim of the work if to define and characterized the wave filed in the intermediate water depth of the mediterranean Sea, in particular in the Sicily channel. Even if is not the appropriate wave spectrum, the jONSWAP spectrum is often used in the Mediterranean Sea as input for the most common third-generation spectral wave models, e.g. SWAN (Booij et al. 1996). The definition of site-specific spectral parameters by means of measured wave data allows to get a better assessment of the wave field in the coastal area with consequent better description of the wave characteristics to be used to design coastal structures.

scholarly journals Characterization of the Atlantic Water and Levantine Intermediate Water in the Mediterranean Sea using Argo Float Data

2021 ◽  
Author(s):  
Giusy Fedele ◽  
Elena Mauri ◽  
Giulio Notarstefano ◽  
Pierre Marie Poulain
Keyword(s):  
Mediterranean Sea ◽  
Thermohaline Circulation ◽  
Internal Variability ◽  
Warming Trend ◽  
Atlantic Water ◽  
Western Mediterranean ◽  
Water Masses ◽  
Intermediate Water ◽  
Starting Point ◽  
The Mediterranean

Abstract. The Atlantic Water (AW) and Levantine Intermediate Water (LIW) are important water masses that play a crucial role in the internal variability of the Mediterranean thermohaline circulation. In particular, their variability and interaction, along with other water masses that characterize the Mediterranean basin, such as the Western Mediterranean Deep Water (WMDW), contribute to modify the Mediterranean Outflow through the Gibraltar Strait and hence may influence the stability of the global thermohaline circulation. This work aims to characterize the AW and LIW in the Mediterranean Sea, taking advantage of the large observational dataset provided by Argo floats from 2001 to 2019. Using different diagnostics, the AW and LIW were identified, highlighting the inter-basin variability and the strong zonal gradient that characterize the two water masses in this marginal sea. Their temporal variability was also investigated focusing on trends and spectral features which constitute an important starting point to understand the mechanisms that are behind their variability. A clear salinification and warming trend have characterized the AW and LIW in the last two decades (~0.007 and 0.008 yr−1; 0.018 and 0.007 °C yr−1, respectively). The salinity and temperature trends found at subbasin scale are in good agreement with previous results. The strongest trends are found in the Adriatic basin in both the AW and LIW properties. A subbasin dependent spectral variability emerges in the AW and LIW salinity timeseries with peaks between 2 and 10 years.

scholarly journals A Synergetic Approach for the Space-Based Sea Surface Currents Retrieval in the Mediterranean Sea

2019 ◽  
Vol 11 (11) ◽  
pp. 1285 ◽  
Author(s):  
Daniele Ciani ◽  
Marie-Hélène Rio ◽  
Milena Menna ◽  
Rosalia Santoleri
Keyword(s):  
Numerical Model ◽  
Mediterranean Sea ◽  
Mediterranean Area ◽  
Hf Radar ◽  
Sea Surface ◽  
Reconstruction Method ◽  
Surface Currents ◽  
Basin Scale ◽  
The Mediterranean ◽  
Sicily Channel

We present a method for the remote retrieval of the sea surface currents in the Mediterranean Sea. Combining the altimeter-derived currents with sea-surface temperature information, we created daily, gap-free high resolution maps of sea surface currents for the period 2012–2016. The quality of the new multi-sensor currents has been assessed through comparisons to other surface-currents estimates, as the ones obtained from drifting buoys trajectories (at the basin scale), or HF-Radar platforms and ocean numerical model outputs in the Malta–Sicily Channel. The study yielded that our synergetic approach can improve the present-day derivation of the surface currents in the Mediterranean area up to 30% locally, with better performances for the the meridional component of the motion and in the western section of the basin. The proposed reconstruction method also showed satisfying performances in the retrieval of the ageostrophic circulation in the Sicily Channel. In this area, assuming the High Frequency Radar-derived currents as reference, the merged multi-sensor currents exhibited improvements with respect to the altimeter estimates and numerical model outputs, mainly due to their enhanced spatial and temporal resolution.

A revised definition of the genus Epileucon Jones (Crustacea, Cumacea) with descriptions of species from the deep Atlantic

1981 ◽  
Vol 291 (1052) ◽  
pp. 353-409 ◽  
Keyword(s):  
New Species ◽  
New Zealand ◽  
Continental Shelf ◽  
Mediterranean Sea ◽  
Geographical Distribution ◽  
Deep Water ◽  
Mediterranean Species ◽  
Males And Females ◽  
The Mediterranean ◽  
Definition Of

The genus Epileucon Jones, 1956 is redefined on the basis of carapace, pereon and appendage characters. The following species are transferred to Epileucon from the genus Leucon Kröyer, 1846: E. spiniventris (Hansen, 1920), E. longirostris (G. O. Sars, 1871), E. tenuirostris (G. O. Sars, 1887), E. latispina (Jones, 1963) and E. bengalensis (Lomakina, 1967). A lectotype is selected for E. spiniventris . Known Atlantic and Mediterranean species are redescribed, and five new species, E. ensis, E. pusillus, E. craterus, E. socius and E. acclivis , are described. Keys to males and females of the Atlantic and Mediterranean species are provided. The geographical distribution of the group is discussed. The genus is known in deep water (> 200 m) in the Atlantic, Pacific and Indian oceans and in the Mediterranean Sea, and also on the continental shelf (at around 100 m depth) off New Zealand.

DOM DYNAMICS IN THE MEDITERRANEAN SEA. Can a new fluorescence SENSOR contribute to its understanding?

2020 ◽  
Author(s):  
Simona Retelletti Brogi ◽  
Marta Furia ◽  
Giancarlo Bachi ◽  
Vanessa Cardin ◽  
Giuseppe Civitarese ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Mediterranean Sea ◽  
Water Column ◽  
Fluorescence Sensor ◽  
Global Ocean ◽  
Intermediate Water ◽  
Physical Processes ◽  
Open Sea ◽  
The Mediterranean

<p>The Mediterranean Sea (Med Sea) can be considered as a natural laboratory for the study of dissolved organic matter (DOM) dynamics. Despite its small size, it is characterized by the same physical processes and dissolved organic carbon (DOC) concentration and distribution as the global ocean. The Med Sea deep water DOC pool is however older than the Atlantic one and differences in the microbial loop and in DOM dynamics have been observed between the eastern (EMED) and western (WMED) basins. Fluorescence is a fast, cheap and highly sensitive tool to study DOM dynamics, it can therefor give useful information about the main processes affecting DOM distribution.</p><p>The main aims of this study were: (i) to investigate DOM dynamics in both Med Sea basins, in relation to the physical processes (e.g. vertical stratification, irradiation); and (ii) to validate the use of a new fluorescence sensor, developed in the framework of the SENSOR project (POR FESR, Tuscany Region), for the rapid, in-situ measurements of open-sea fluorescent DOM (FDOM). DOM dynamics was investigated by measuring dissolved organic carbon (DOC) and the fluorescence of FDOM. Samples were collected from surface to bottom in 26 stations during the trans-Mediterranean cruise “MSM72”, carried out on board the R/V MARIA S.MERIAN (Institut für Meereskunde der Universität Hamburg). The stations cover both the EMED and the WMED, from Gibraltar to the Crete Island.</p><p>Six fluorescent components were identified by applying the parallel factorial analysis (PARAFAC) to the measured excitation-emission matrices (EEMs). Two components were identified as marine humic-like, two as terrestrial humic-like, one as protein-like and one as polycyclic aromatic hydrocarbon-like (PAH-like).</p><p>Temperature and salinity increased moving from the WMED to the EMED. A surface minimum in salinity, was observed in the WMED, indicating the occurrence of the Atlantic Water (AW), whereas the presence of the Levantine Intermediate Water (LIW) was observed south of Crete. The vertical distribution of both DOC and humic-like FDOM was strongly affected by the water masses circulation and water column stratification. In the upper 200 m, DOC markedly increased from 50 to 80 μM moving eastward, likewise the protein-like component dominates the upper layer and increased moving from Gibraltar to Crete. In contrast, the humic-like components showed a minimum in the surface layer, and a decreasing moving eastward, probably due to photobleaching. The PAH-like component showed its maximum in correspondence with the areas characterized by intensive naval traffic. The accumulation of DOC, observed in the EMED, could be explained by a change in DOM quality, supported by the differences in FDOM.</p><p>In 2 selected stations, the fluorescence of humic-like and protein-like compounds was also measured along the water column by using the new fluorescence sensor and compared with PARAFAC results, in order to evaluate its performance for open sea waters.</p>

The Long-Term Wind and Wave Spectra of the Mediterranean Sea

2005 ◽  
Author(s):  
Christos N. Stefanakos
Keyword(s):  
Time Series ◽  
Standard Deviation ◽  
Stochastic Processes ◽  
Mediterranean Sea ◽  
Mean Value ◽  
Residual Time ◽  
Wave Data ◽  
The Mediterranean ◽  
Periodic Components

It is a well-known fact that long-term time series of wind and wave data are modelled as nonstationary stochastic processes with yearly periodic mean value and standard deviation (periodically correlated or cyclostationary stochastic processes). Using this model, the initial nonstationary series are decomposed to a seasonal (periodic) mean value m(t) and a residual time series W(t) multiplied by a seasonal (periodic) standard deviation s(t), of the form Y(t) = m(t) + s(t)W(t). The periodic components m(t) and s(t) are estimated using mean monthly values, and the residual time series W(t) is examined for stationarity. For this purpose, spectral densities of W(t) are obtained from different seasonal segments, calculated and compared with each other. It is shown that W(t) can indeed be considered stationary, and thus Y(t) can be considered periodically correlated. This analysis has been applied to model wind and wave data from several locations in the Mediterranean Sea. It turns out that the spectrum of W(t) is very weakly dependent on the site, a fact that might be useful for the geographic parameterization of wind and wave climate.

scholarly journals Analysis of Wave Height Variability Using Altimeter Measurements: Application to the Mediterranean Sea

2007 ◽  
Vol 24 (12) ◽  
pp. 2078-2092 ◽  
Author(s):  
Pierre Queffeulou ◽  
Abderrahim Bentamy
Keyword(s):  
Mediterranean Sea ◽  
Interannual Variability ◽  
Wave Height ◽  
Measurement Data ◽  
Altimeter Data ◽  
Mean Values ◽  
The Mediterranean ◽  
Standard Deviations ◽  
Wave Models ◽  
Ocean Topography

Abstract Altimeter significant wave height (SWH) measurement data from six satellite missions covering 14 yr were analyzed over the Mediterranean Sea. First, data correction and screening were performed using the same method for the six altimeters [European Remote Sensing Satellites (ERS-1 and ERS-2), Ocean Topography Experiment (TOPEX), Geosat Follow-On, Jason, and Environmental Satellite (Envisat)]. The data from the TOPEX and Jason missions enabled the construction of seasonal maps of along-track SWH mean values and standard deviations. These reveal the regional short-scale sea state features associated with the specific meteorological patterns of the various geographical basins. Time series of monthly SWH mean values and standard deviations from each satellite and over the whole Mediterranean Sea were calculated and seen to be in good agreement, thus demonstrating interannual variability. The six altimeter missions used together enable the investigation of the monthly annual cycle at the short scales of the various subbasins. Significant differences are observed between the western and eastern parts of the Mediterranean Sea. The annual SWH cycle changes in both shape and amplitude depending on the subbasin. Analysis of the seasonal interannual variability confirms the existence of some degree of independence between the subbasins. Thanks to multisatellite missions and homogeneous corrections of the altimeter data, SWH time and space characteristics were able to be obtained at regional short scales. These results are independent of numerical wind and wave models. This method can be applied to any geographical region.

scholarly journals The transient distributions of nuclear weapon-generated tritium and its decay product <sup>3</sup>He in the Mediterranean Sea, 1952–2011, and their oceanographic potential

2013 ◽  
Vol 10 (2) ◽  
pp. 649-690 ◽  
Author(s):  
W. Roether ◽  
P. Jean-Baptiste ◽  
E. Fourré ◽  
J. Sültenfuß
Keyword(s):  
Mediterranean Sea ◽  
Transit Time ◽  
Nuclear Weapon ◽  
Eastern Mediterranean ◽  
Decay Product ◽  
Intermediate Water ◽  
Tyrrhenian Sea ◽  
Transit Times ◽  
Time Dispersion ◽  
The Mediterranean

Abstract. We present a comprehensive account of tritium and 3He in the Mediterranean Sea since the appearance of the tritium generated by the atmospheric nuclear-weapon testing in the 1950's and early 1960's, based on essentially all available observations. Tritium in surface waters rose to 20–30 TU in 1964 (TU = 1018 · [3H]/[H]), a factor of about 100 above the natural level, and thereafter declined 30-fold up to 2011. The decline was largely due to radioactive tritium decay, which produced significant amounts of its stable daughter 3He. We present the scheme by which we separate the tritiugenic part of 3He and the part due to release from the sea floor (terrigenic part). We show that the tritiugenic component can be quantified throughout the Mediterranean waters, typically to a &amp;pm;0.15 TU equivalent, mostly because the terrigenic part is low in 3He. This fact makes the Mediterranean unique in offering a potential for the use of tritiugenic 3He as a tracer. The transient distributions of the two tracers are illustrated by a number of sections spanning the entire sea and relevant features of their distributions are noted. By 2011, the 3He concentrations in the top few hundred meters had become low, in response to the decreasing tritium concentrations combined with a flushing out by the general westward drift of these waters. Tritium-3He ages in Levantine Intermediate Water (LIW) were obtained repeated in time at different locations, defining transit times from the LIW source region east of Rhodes. The ages show an upward trend with the time elapsed since the surface-water tritium maximum, which arises because the repeated observations represent increasingly slower moving parts of the full transit time spectrum of LIW. The transit time dispersion found by this new application of tritium-3He dating is considerable. We find mean transit times of 12 &amp;pm; 2 yr up to the Strait of Sicily, 18 &amp;pm; 3 yr up to the Tyrrhenian Sea, and 22 &amp;pm; 4 yr up into the Western Mediterranean. We furthermore present full Eastern Mediterranean sections of terrigenic 3He and tritium-3He age in 1987, the latter one similarly showing an effect of the transit time dispersion. We conclude that the available tritium and 3He data, in particular if combined with other tracer data, are useful for constraining the subsurface circulation and mixing of the Mediterranean Sea.

A neural-based bio-regionalization of the Mediterranean Sea using satellite and Argo-float records

2020 ◽  
Author(s):  
Roy El Hourany ◽  
Chris Bowler ◽  
Carlos Mejia ◽  
Michel Crépon ◽  
Sylvie Thiria
Keyword(s):  
Mediterranean Sea ◽  
Deep Convection ◽  
Global Ocean ◽  
Marine Biodiversity ◽  
Intermediate Water ◽  
Tropical Ocean ◽  
Phytoplankton Diversity ◽  
Winter Convection ◽  
Phytoplankton Communities ◽  
The Mediterranean

&lt;p&gt;The regionalization of the Mediterranean Sea has been the subject of many studies. It is a miniature ocean where most of the processes of the global ocean are encountered (Lejeusne et al., 2010). Several features of the Mediterranean (near-tropical ocean in summer with a well-formed thermocline, near-polar ocean in winter with deep convection, multiple basins with different characteristics) make it a hotspot of marine biodiversity (Coll and al., 2010) and consequently vulnerable to climate change. It is therefore important to characterize the present state of the Mediterranean Sea with robust estimators in order to study the long-term evolution of this mesocosm.&lt;/p&gt;&lt;p&gt;We present a partitioning of the Mediterranean Sea in regions having well defined characteristics with respect to Sea Surface Temperature and surface chlorophyll observed by satellite, and Argo mixed layer depth. This regionalization was performed by using an innovative classification based on neural networks, the so-called 2S-SOM. Its major advantage is to consider the specificity of the variables by adding automatically, through machine learning, specific weights to each of them, which facilitates the classification and consequently highlights the regional correlations. The 2S-SOM provided a well differentiated regionalization of the Mediterranean Sea waters into seven bioregions governed by specific physical and biogeochemical processes such as Intermediate-water formation in the Aegean Sea, large surface currents in the Adriatic and the Alboran, deep winter convection phenomena in the Balearic and stratification phenomena during summer in the eastern part of the Mediterranean Sea.&lt;/p&gt;&lt;p&gt;Besides, in order to highlight the phytoplankton diversity in these regions, we processed the satellite ocean color observations with a specific neural network approach (SOM-PFT, El Hourany et al., 2019). As a result, specific phytoplankton communities characterized by their seasonal variability are associated with the obtained Mediterranean bioregions; the dominance of the Nanophytoplankton groups is largely observed in the western basin during the period ranging from autumn to spring. While the dominance of different types of cyanobacteria Synechococcus and Prochlorococcus is highlighted in summer and more precisely in the waters of the eastern basin. Diatoms dominate throughout the year in the coastal and shallow regions, which can be explained by the presence of terrigenous input necessary for the development of this type of phytoplankton. Diatoms also largely benefit from the strong deep convection in the Balearic Sea marked by a large bloom at the end of winter convection in March.&lt;/p&gt;&lt;p&gt;This work will be further extended to study the phytoplankton diversity at global scale using various data set from the Tara Oceans.&lt;/p&gt;

scholarly journals Modeling of the circulation in the Northwestern Mediterranean Sea with the Princeton Ocean Model

Ocean Science ◽  
2007 ◽  
Vol 3 (1) ◽  
pp. 77-89 ◽  
Author(s):  
M. A. Ahumada ◽  
A. Cruzado
Keyword(s):  
Mediterranean Sea ◽  
General Circulation ◽  
Large Scale ◽  
Circulation Model ◽  
Western Mediterranean ◽  
Ocean Model ◽  
Intermediate Water ◽  
Princeton Ocean Model ◽  
The Mediterranean ◽  
Northwestern Mediterranean

Abstract. The Princeton Ocean Model – POM (Blumberg and Mellor, 1987) has been implemented in the Northwestern Mediterranean nested (in one-way off-line mode) to a general circulation model of the Mediterranean Sea – OGCM (Pinardi and Masetti, 2000; Demirov and Pinardi, 2002) in order to investigate if this model configuration is capable of reproducing the major features of the circulation as known from observations and to improve what has been made by previous numerical modeling works. According to the model results, the large-scale cyclonic circulation in the northern part of the Northwestern Mediterranean is, at least in the upper layers, less coherent in winter and spring than in summer and autumn. Furthermore, there is evidence that the mesoscale structure (eddies and meanders) is, during all year, a significant dynamic characteristic in this region of the Mediterranean Sea. Finally, concerning the circulation in the lower layers, the model results have confirmed that Levantine Intermediate Water (LIW) and Western Mediterranean Deep Water (WMDW) follow essentially a cyclonic path during all year.

scholarly journals Assimilation of radar altimeter data in numerical wave models: an impact study in two different wave climate regions

2007 ◽  
Vol 25 (3) ◽  
pp. 581-595 ◽  
Author(s):  
G. Emmanouil ◽  
G. Galanis ◽  
G. Kallos ◽  
L. A. Breivik ◽  
H. Heiberg ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Mediterranean Sea ◽  
European Space Agency ◽  
Wave Climate ◽  
Altimeter Data ◽  
Radar Altimeter ◽  
The Indian Ocean ◽  
Numerical Wave ◽  
The Mediterranean ◽  
Wave Models

Abstract. An operational assimilation system incorporating significant wave height observations in high resolution numerical wave models is studied and evaluated. In particular, altimeter satellite data provided by the European Space Agency (ESA-ENVISAT) are assimilated in the wave model WAM which operates in two different wave climate areas: the Mediterranean Sea and the Indian Ocean. The first is a wind-sea dominated area while in the second, swell is the principal part of the sea state, a fact that seriously affects the performance of the assimilation scheme. A detailed study of the different impact is presented and the resulting forecasts are evaluated against available buoy and satellite observations. The corresponding results show a considerable improvement in wave forecasting for the Indian Ocean while in the Mediterranean Sea the assimilation impact is restricted to isolated areas.

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