scholarly journals An integrated open-coastal biogeochemistry, ecosystem and biodiversity observatory of the eastern Mediterranean – the Cretan Sea component of the POSEIDON system

Ocean Science ◽  
2018 ◽  
Vol 14 (5) ◽  
pp. 1223-1245 ◽  
Author(s):  
George Petihakis ◽  
Leonidas Perivoliotis ◽  
Gerasimos Korres ◽  
Dionysios Ballas ◽  
Constantin Frangoulis ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Mediterranean Sea ◽  
Added Value ◽  
Global Ocean ◽  
Sensor Technology ◽  
Marine Policy ◽  
Test Bed ◽  
Chl A ◽  
The Mediterranean ◽  
Cretan Sea

Abstract. There is a general scarcity of oceanic observations that concurrently examine air–sea interactions, coastal–open-ocean processes and physical–biogeochemical processes, in appropriate spatiotemporal scales and under continuous, long-term data acquisition schemes. In the Mediterranean Sea, the resulting knowledge gaps and observing challenges increase due to its oligotrophic character, especially in the eastern part of the basin. The oligotrophic open Cretan Sea's biogeochemistry is considered to be representative of a greater Mediterranean area up to 106 km2, and understanding its features may be useful on even larger oceanic scales, since the Mediterranean Sea has been considered a miniature model of the global ocean. The spatiotemporal coverage of biogeochemical (BGC) observations in the Cretan Sea has progressively increased over the last decades, especially since the creation of the POSEIDON observing system, which has adopted a multiplatform, multivariable approach, supporting BGC data acquisition. The current POSEIDON system's status includes open and coastal sea fixed platforms, a Ferrybox (FB) system and Bio-Argo autonomous floats that remotely deliver fluorescence as a proxy of chlorophyll-a (Chl-a), O2, pH and pCO2 data, as well as BGC-related physical variables. Since 2010, the list has been further expanded to other BGC (nutrients, vertical particulate matter fluxes), ecosystem and biodiversity (from viruses up to zooplankton) variables, thanks to the addition of sediment traps, frequent research vessel (R/V) visits for seawater–plankton sampling and an acoustic Doppler current profiler (ADCP) delivering information on macrozooplankton–micronekton vertical migration (in the epipelagic to mesopelagic layer). Gliders and drifters are the new (currently under integration to the existing system) platforms, supporting BGC monitoring. Land-based facilities, such as data centres, technical support infrastructure, calibration laboratory and mesocosms, support and give added value to the observatory. The data gathered from these platforms are used to improve the quality of the BGC-ecosystem model predictions, which have recently incorporated atmospheric nutrient deposition processes and assimilation of satellite Chl-a data. Besides addressing open scientific questions at regional and international levels, examples of which are presented, the observatory provides user-oriented services to marine policy makers and the society, and is a technological test bed for new and/or cost-efficient BGC sensor technology and marine equipment. It is part of European and international observing programs, playing a key role in regional data handling and participating in harmonization and best practices procedures. Future expansion plans consider the evolving scientific and society priorities, balanced with sustainable management.

scholarly journals An integrated open-coastal biogeochemistry, ecosystem and biodiversity observatory of the Eastern Mediterranean. The Cretan Sea component of POSEIDON system

2018 ◽  
Author(s):  
George Petihakis ◽  
Leonidas Perivoliotis ◽  
Gerasimos Korres ◽  
Dionysis Ballas ◽  
Constantin Frangoulis ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Mediterranean Sea ◽  
Added Value ◽  
Global Ocean ◽  
Marine Policy ◽  
Physical Parameters ◽  
Test Bed ◽  
Chl A ◽  
The Mediterranean ◽  
Cretan Sea

Abstract. There is a general scarcity of oceanic observations that concurrently examine air–sea interactions, coastal-open ocean processes, and biogeochemical (BGC) parameters, in appropriate spatiotemporal scales, and under continuous, long-term data acquisition schemes. In the Mediterranean Sea, the resulting knowledge gaps and observing challenges increase, due to its oligotrophic character, especially in the eastern part of the basin. The oligotrophic open Cretan Sea's biogeochemistry is considered to be representative of a greater Mediterranean area up to 106 km2, and understanding its features may be useful on even larger oceanic scales, since the Mediterranean Sea has been considered a miniature model of the global ocean. The spatiotemporal coverage of BGC observations in the Cretan Sea has progressively increased over the last decades, especially since the creation of the POSEIDON observing system, which has adopted a multiplatform-multiparameter approach, supporting BGC data acquisition. The current POSEIDON system's status includes open and coastal sea fixed platforms, a Ferrybox (FB) system, and Bio-Argo autonomous floats, that deliver remotely Chlorophyll-a (Chl-a), O2, pH and pCO2 data, as well as BGC-related physical parameters. Since 2010, the list has been further expanded to other BGC (nutrients, vertical particulate matter fluxes), ecosystem and biodiversity (from viruses up to zooplankton) parameters, thanks to the addition of sediment traps, frequent R/V visits for seawater-plankton sampling, and of an ADCP delivering information on macrozooplankton-micronekton vertical migration (in the epi-, mesopelagic layer). Gliders and drifters are the new, currently under integration to the existing system, platforms, supporting BGC monitoring. Land-based facilities, such as data centers, technical support infrastructures, calibration laboratory, mesocosms, support and give added value to the observatory. The data gathered from these platforms are used to improve the quality of the BGC-ecosystem model predictions, which have recently incorporated atmospheric nutrient deposition processes and assimilation of satellite Chl-a data. Besides addressing open scientific questions at regional and international level, examples of which are presented, the observatory provides user oriented services to marine policy-makers and the society, and is a technological test bed for new and/or cost-efficient BGC sensor technology and marine equipment. It is part of European and international observing programs, playing key role in regional data handling and participating in harmonization and best practices procedures. Future expansion plans consider the evolving scientific and society priorities, balanced with sustainable management.

scholarly journals On the vertical distribution of the chlorophyll <i>a</i> concentration in the Mediterranean Sea: a basin scale and seasonal approach

2015 ◽  
Vol 12 (5) ◽  
pp. 4139-4181 ◽  
Author(s):  
H. Lavigne ◽  
F. D'Ortenzio ◽  
M. Ribera D'Alcalà ◽  
H. Claustre ◽  
R. Sauzède ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Mediterranean Sea ◽  
Global Ocean ◽  
Control Procedure ◽  
Chl A ◽  
Basin Scale ◽  
In Situ Experiments ◽  
The Mediterranean ◽  
The Vertical Distribution ◽  
Surface Observations

Abstract. The distribution of the chlorophyll a concentration ([Chl a]) in the Mediterranean Sea, which is mainly obtained from satellite surface observations or from scattered in situ experiments, is updated by analyzing a database of fluorescence profiles calibrated into [Chl a]. The database, which includes 6790 fluorescence profiles from various origins, was processed with a dedicated quality control procedure. To ensure homogeneity between the different data sources, 65% of fluorescence profiles have been inter-calibrated on the basis of their concomitant satellite [Chl a] estimation. The climatological pattern of [Chl a] vertical profile in four key sites of the Mediterranean Sea has been analyzed. Climatological results confirm previous findings on the range of [Chl a] values and on the main Mediterranean trophic regimes. It also provides new insights on the seasonal variability of the shape of the vertical [Chl a] profile, inaccessible from remote sensing observations. An analysis based on the recognition of the general shape of the fluorescence profile was also performed. Although the shape of [Chl a] vertical distribution characterized by a deep chlorophyll maximum (DCM) is ubiquitous during summer, different forms are observed during winter, suggesting thus that factors affecting the vertical distribution of the biomass are complex and highly variable. The [Chl a] distribution in the Mediterranean Sea mimics, at smaller scales, what is observed in the Global Ocean. As already evidenced by analyzing satellite surface observations, mid-latitude and subtropical like phytoplankton dynamics coexist in the Mediterranean Sea. Moreover, the Mediterranean DCM variability appears characterized by patterns already observed at global scale.

scholarly journals On the vertical distribution of the chlorophyll <i>a</i> concentration in the Mediterranean Sea: a basin-scale and seasonal approach

2015 ◽  
Vol 12 (16) ◽  
pp. 5021-5039 ◽  
Author(s):  
H. Lavigne ◽  
F. D'Ortenzio ◽  
M. Ribera D'Alcalà ◽  
H. Claustre ◽  
R. Sauzède ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Mediterranean Sea ◽  
Global Ocean ◽  
Control Procedure ◽  
Chl A ◽  
Basin Scale ◽  
In Situ Experiments ◽  
The Mediterranean ◽  
The Vertical Distribution ◽  
Surface Observations

Abstract. The distribution of the chlorophyll a concentration ([Chl a]) in the Mediterranean Sea, mainly obtained from satellite surface observations or from scattered in situ experiments, is updated by analyzing a database of fluorescence profiles converted into [Chl a]. The database, which includes 6790 fluorescence profiles from various origins, was processed with a specific quality control procedure. To ensure homogeneity between the different data sources, 65 % of fluorescence profiles have been intercalibrated on the basis of their concomitant satellite [Chl a] estimation. The climatological pattern of [Chl a] vertical profiles in four key sites of the Mediterranean Sea has been analyzed. Climatological results confirm previous findings over the range of existing [Chl a] values and throughout the principal Mediterranean trophic regimes. They also provide new insights into the seasonal variability in the shape of the vertical [Chl a] profile, inaccessible through remote-sensing observations. An analysis based on the recognition of the general shape of the fluorescence profile was also performed. Although the shape of [Chl a] vertical distribution characterized by a deep chlorophyll maximum (DCM) is ubiquitous during summer, different forms are observed during winter, thus suggesting that factors affecting the vertical distribution of the biomass are complex and highly variable. The [Chl a] spatial distribution in the Mediterranean Sea mimics, on smaller scales, what is observed in the global ocean. As already evidenced by analyzing satellite surface observations, midlatitude- and subtropical-like phytoplankton dynamics coexist in the Mediterranean Sea. Moreover, the Mediterranean DCM variability appears to be characterized by patterns already observed on the global scale.

Vanadium behaviour in the global ocean and in the Mediterranean sea

1987 ◽  
Vol 21 (1) ◽  
pp. 51-74 ◽  
Author(s):  
C Jeandel ◽  
M Caisso ◽  
J.F Minster
Keyword(s):  
Mediterranean Sea ◽  
Global Ocean ◽  
The Mediterranean

scholarly journals Acoustic correction factor estimate for compensating vertical diel migration of small pelagics

2021 ◽  
Author(s):  
ANGELO BONANNO ◽  
MARCO BARRA ◽  
ANDREA DE FELICE ◽  
MARIANNA GIANNOULAKI ◽  
MAGDALENA IGLESIAS ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Mediterranean Sea ◽  
Correction Factor ◽  
Pelagic Fish ◽  
Tyrrhenian Sea ◽  
Fish Community Structure ◽  
Northern Spain ◽  
Small Pelagic Fish ◽  
Acoustic Data ◽  
The Mediterranean

Differences in acoustic estimates of small pelagic fish biomass, due to data acquisition during daytime and nighttime surveys, have been recognized for many years as a problem in acoustic surveys. In the absence of a single rule for all species and for all locations, some expert groups identified specific time intervals for acoustic data acquisition in relation to the schooling behavior of the target species. In the Mediterranean Sea, the research groups working in the MEDIAS (Mediterranean International Acoustic Survey) agreed on the importance that acoustic sampling are conducted only during day-time. Only when available time does not permit to complete the survey during daytime, data collection might be extended. In this case, working on data collected during both daytime and nighttime, a bias may occur in the biomass estimates. In order to evaluate and correct such bias, specific experiments were performed in some geographical sub-areas of the Mediterranean Sea. The data analysis allowed the estimation of a mean correction factor for the Strait of Sicily, where five surveys were carried out in different years. The correction factor was estimated also for the Adriatic Sea, Tyrrhenian Sea and Northern Spain; the observed variability among areas highlighted the importance of the spatial and temporal coverage of the survey area in order to obtain reliable estimates of the correction factor. Further studies are necessary to improve the interpretation of the obtained estimates in relation to area-related peculiarities such as zooplankton composition and abundance along with small pelagic fish community structure. 

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

&lt;p&gt;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.&lt;/p&gt;&lt;p&gt;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 &amp;#8220;MSM72&amp;#8221;, carried out on board the R/V MARIA S.MERIAN (Institut f&amp;#252;r Meereskunde der Universit&amp;#228;t Hamburg). The stations cover both the EMED and the WMED, from Gibraltar to the Crete Island.&lt;/p&gt;&lt;p&gt;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).&lt;/p&gt;&lt;p&gt;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 &amp;#956;M 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.&lt;/p&gt;&lt;p&gt;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.&lt;/p&gt;

scholarly journals A nested Atlantic-Mediterranean Sea general circulation model for operational forecasting

Ocean Science ◽  
2009 ◽  
Vol 5 (4) ◽  
pp. 461-473 ◽  
Author(s):  
P. Oddo ◽  
M. Adani ◽  
N. Pinardi ◽  
C. Fratianni ◽  
M. Tonani ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
General Circulation Model ◽  
Ocean Circulation ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean Model ◽  
Global Ocean ◽  
Lateral Boundary ◽  
The Mediterranean ◽  
The Impact

Abstract. A new numerical general circulation ocean model for the Mediterranean Sea has been implemented nested within an Atlantic general circulation model within the framework of the Marine Environment and Security for the European Area project (MERSEA, Desaubies, 2006). A 4-year twin experiment was carried out from January 2004 to December 2007 with two different models to evaluate the impact on the Mediterranean Sea circulation of open lateral boundary conditions in the Atlantic Ocean. One model considers a closed lateral boundary in a large Atlantic box and the other is nested in the same box in a global ocean circulation model. Impact was observed comparing the two simulations with independent observations: ARGO for temperature and salinity profiles and tide gauges and along-track satellite observations for the sea surface height. The improvement in the nested Atlantic-Mediterranean model with respect to the closed one is particularly evident in the salinity characteristics of the Modified Atlantic Water and in the Mediterranean sea level seasonal variability.

scholarly journals Satellite and In Situ Monitoring of Chl-a, Turbidity, and Total Suspended Matter in Coastal Waters: Experience of the Year 2017 along the French Coasts

2020 ◽  
Vol 8 (9) ◽  
pp. 665
Author(s):  
Francis Gohin ◽  
Philippe Bryère ◽  
Alain Lefebvre ◽  
Pierre-Guy Sauriau ◽  
Nicolas Savoye ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Water Clarity ◽  
In Situ Monitoring ◽  
Free Atmosphere ◽  
Chl A ◽  
Southern Bight ◽  
In Situ Data ◽  
Satellite Retrievals ◽  
The Mediterranean

The consistency of satellite and in situ time series of Chlorophyll-a (Chl-a), Turbidity and Total Suspended Matters (TSM) was investigated at 17 coastal stations throughout the year 2017. These stations covered different water types, from relatively clear waters in the Mediterranean Sea to moderately turbid regions in the Bay of Biscay and the southern bight of the North-Sea. Satellite retrievals were derived from MODIS/AQUA, VIIRS/NPP and OLCI-A/Sentinel-3 spectral reflectance. In situ data were obtained from the coastal phytoplankton networks SOMLIT (CNRS), REPHY (Ifremer) and associated networks. Satellite and in situ retrievals of the year 2017 were compared to the historical seasonal cycles and percentiles, 10 and 90, observed in situ. Regarding the sampling frequency in the Mediterranean Sea, a weekly in situ sampling allowed all major peaks in Chl-a caught from space to be recorded at sea, and, conversely, all in situ peaks were observed from space in a frequently cloud-free atmosphere. In waters of the Eastern English Channel, lower levels of Chl-a were observed, both in situ and from space, compared to the historical averages. However, despite a good overall agreement for low to moderate biomass, the satellite method, based on blue and green wavelengths, tends to provide elevated and variable Chl-a in a high biomass environment. Satellite-derived TSM and Turbidity were quite consistent with in situ measurements. Moreover, satellite retrievals of the water clarity parameters often showed a lower range of variability than their in situ counterparts did, being less scattered above and under the seasonal curves of percentiles 10 and 90.

scholarly journals The Mean Sea Level Equation and Its Application to the Mediterranean Sea

2014 ◽  
Vol 27 (1) ◽  
pp. 442-447 ◽  
Author(s):  
N. Pinardi ◽  
A. Bonaduce ◽  
A. Navarra ◽  
S. Dobricic ◽  
P. Oddo
Keyword(s):  
Surface Water ◽  
Mediterranean Sea ◽  
Sea Level ◽  
Water Flux ◽  
Mass Conservation ◽  
Volume Transport ◽  
Conservation Equation ◽  
Global Ocean ◽  
Mean Sea Level ◽  
The Mediterranean

Abstract A formalism to obtain a mean sea level equation (MSLE) is constructed for any limited ocean region and/or the global ocean by considering the mass conservation equation with compressible effects and a linear equation of state. The MSLE contains buoyancy fluxes terms representing the steric effects and the mass flux is represented by surface water fluxes and volume transport terms. The MSLE is studied for the Mediterranean Sea case using a simulation experiment for the decade 1999–2008. It is found that the Mediterranean MSL tendency is made of a steric contribution that is almost periodic in time superimposed on a stochastic-like signal due to the mass balance, dominating the MSL tendency. The MSL tendency stochastic-like term is a result of the imbalance between the volume flux at Gibraltar and the area average surface water flux.

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