Search

Your search keyword '"Vassilis Zervakis"' showing total 5 results
Start Over Author "Vassilis Zervakis" Publisher hal ccsd
5 results on '"Vassilis Zervakis"'

1. Holocene Climatic Optimum centennial-scale paleoceanography in the NE Aegean (Mediterranean Sea)

Author

Dimitris Velaoras, Dominik Fleitmann, V. Lykousis, Antonia Diamantopoulou, Angeliki Sampatakaki, Grigoris Roussakis, Alexandra Gogou, Vassilis Zervakis, Constantine Parinos, Sofia Kostopoulou, Maria Triantaphyllou, Ioanna Bouloubassi, Margarita D. Dimiza, Maria Geraga, Institute of Oceanography, Hellenic Centre for Marine Research (HCMR), Biogéochimie-Traceurs-Paléoclimat (BTP), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université de Bern, Inst. Geol. Sciences, Universität Bern [Bern] (UNIBE), Department of Marine Science, Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and Université de Bern

Subjects
010506 paleontology, Alkenone, 010504 meteorology & atmospheric sciences, biology, Terrigenous sediment, Holocene climatic optimum, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Sapropel, 15. Life on land, Environmental Science (miscellaneous), Geotechnical Engineering and Engineering Geology, Oceanography, biology.organism_classification, 01 natural sciences, Foraminifera, Mediterranean sea, 13. Climate action, Paleoceanography, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, Holocene, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

Combined micropaleontological and geochemical analyses of the high-sedimentation gravity core M-4G provided new centennial-scale paleoceanographic data for sapropel S1 deposition in the NE Aegean Sea during the Holocene Climatic Optimum. Sapropel layer S1a (10.2–8.0 ka) was deposited in dysoxic to oxic bottom waters characterized by a high abundance of benthic foraminiferal species tolerating surface sediment and/or pore water oxygen depletion (e.g., Chilostomella mediterranensis, Globobulimina affinis), and the presence of Uvigerina mediterranea, which thrives in oxic mesotrophic-eutrophic environments. Preservation of organic matter (OM) is inferred based on high organic carbon as well as loliolide and isololiolide contents, while the biomarker record and the abundances of eutrophic planktonic foraminifera document enhanced productivity. High inputs of terrigenous OM are attributed to north Aegean borderland riverine inputs. Both alkenone-based sea surface temperatures (SSTs) and δO18G. bulloides records indicate cooling at 8.2 ka (S1a) and ~7.8 ka (S1 interruption). Sapropelic layer S1b (7.7–6.4 ka) is characterized by rather oxic conditions; abundances of foraminiferal species tolerant to oxygen depletion are very low compared with the U. mediterranea rise. Strongly fluctuating SSTs demonstrate repeated cooling and associated dense water formation, with a major event at 7.4 ka followed by cold spells at 7.0, 6.8, and 6.5 ka. The prominent rise of the carbon preference index within the S1b layer indicates the delivery of less degraded terrestrial OM. The increase of algal biomarkers, labile OM-feeding foraminifera and eutrophic planktonic species pinpoints an enhanced in situ marine productivity, promoted by more efficient vertical convection due to repeated cold events. The associated contributions of labile marine OM along with fresher terrestrial OM inputs after ~7.7 ka imply sources alternative/additional to the north Aegean riverine borderland sources for the influx of organic matter in the south Limnos Basin, plausibly related to the inflow of highly productive Marmara/Black Sea waters.

Published
2016

2. Toward an integrated HF radar network in the Mediterranean Sea to improve search and rescue and oil spill response: the TOSCA project experience

Author

Annalisa Griffa, A. Vetrano, Lucio Bellomo, Pierre-Marie Poulain, P. Guterman, Aránzazu Lana, Mireno Borghini, Juan Manuel Sayol, Maristella Berta, Pierpaolo Falco, Céline Quentin, Zoi Kokkini, Q. Dagneaux, Alejandro Orfila, Joel Gaggelli, Riccardo Gerin, Enrico Zambianchi, Anne Molcard, Antonio Bussani, Lorenzo Corgnati, Ioannis Mamoutos, Yves Barbin, Carlo Mantovani, Marcello G. Magaldi, Alkiviadis Kalampokis, Simone Cosoli, Vassilis Zervakis, Didier Mallarino, Julien Marmain, Joaquín Tintoré, Marco Uttieri, Emmanuel Potiris, A. Mazzoldi, Ilaria Iermano, Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Istituto di Science Marine (ISMAR ), Consiglio Nazionale delle Ricerche (CNR), Università Napoli, Istituto Nazionale di Geofisica e di Oceanografia Sperimentale (OGS), Laboratoire de sondages électromagnétiques de l'environnement terrestre (LSEET), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut Pythéas (OSU PYTHEAS), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut de Recherche pour le Développement (IRD), Institut Jacques Monod (IJM (UMR_7592)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Image, de l'Informatique et de la Télédétection (LSIIT), Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Consorzio Nazionale Interuniversitario per le Scienze del Mare [Rome, Italie] (CoNISma), University of the Aegean, Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN)-Aix Marseille Université (AMU)-Institut de Recherche pour le Développement (IRD), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Consorzio Nazionale Interuniversitario per le Scienze del Mare (CoNISma), European Commission, Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), and Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Meteorology, RADIOFREQUENCY INTERFERENCE, OPERATIONAL OCEANOGRAPHY, Oceanography, Electromagnetic interference, law.invention, OCEAN SURFACE CURRENTS, HIGH-FREQUENCY RADAR, DRIFTER DATA, Mediterranean sea, law, Software deployment, HF radar, network, Mediterranean, TOSCA, Range (aeronautics), CURRENT METERS, Ecosystem management, Environmental science, 14. Life underwater, Radar, Radar configurations and types, Search and rescue, Remote sensing
Abstract

Lucio Bellomo et al., High-frequency (HF) coastal radars measure current velocity at the ocean surface with a 30-100 km range and 1-3 km resolution, every 0.25-1 h. HF radars are well suited to many applications, such as search and rescue (SaR), oil-spill mitigation and ecosystem management. Here we present a first organized core of 12 HF radars installed in five sites in four countries (Greece, Italy, France and Spain) within the European MED project, the Tracking Oil Spill and Coastal Awareness (TOSCA) network. Dedicated experiments tested radar capabilities to estimate transport driven by currents, which is the key feature for all the above applications. Experiments involved the deployment of drifters, i.e., floating buoys, acting as proxies for substances passively advected by currents. Using HF radars the search range is reduced by a factor of 1.6 to 5.3 after 24 h. The paper also underlines the importance of sharing common tools for HF radar data processing and the need to mitigate radio frequency interference. The effort can be regarded as an initial step toward the creation of a Mediterranean or European HF radar network, crucial for any European integrated ocean observing system (IOOS)., This work was supported by the Tracking Oil Spills and Coastal Awareness (TOSCA) Network project [grant number 2G-MED09-425], co-financed by the European Regional Development Fund in the framework of the MED programme

Published
2015

3. STRING: A new drifter for HF radar validation

Author

Anna-Maria Rammou, Vassilis Zervakis, Lucio Bellomo, Zoi Kokkini, Céline Quentin, Carlo Mantovani, Alkiviadis Kalampokis, Department of Marine Sciences [Aegean], University of the Aegean, Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN), Consiglio Nazionale delle Ricerche (CNR), Universita degli studi di Napoli 'Parthenope' [Napoli], Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), and Università degli Studi di Napoli 'Parthenope' = University of Naples (PARTHENOPE)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2015

4. Dense water formation and cascading in the Gulf of Thermaikos (North Aegean) from observations and modelling

Author

L. Perivoliotis, Francis Auclair, Anastasios Papadopoulos, Claude Estournel, Elina Tragou, Vassilis Zervakis, Patrick Marsaleix, Laboratoire d'aérologie (LA), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Hellenic Centre for Marine Research (HCMR), Laboratoire d'aérologie (LAERO), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
Ekman layer, Dense water formation, 010504 meteorology & atmospheric sciences, Aquatic Science, Oceanography, Spatial distribution, 01 natural sciences, Thessaloniki, Open sea, Aegean Sea, 14. Life underwater, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Greece, 010505 oceanography, Geology, Thermaikos Gulf, Mooring, Numerical modelling, Period (geology), Formation water, Cascading, Bay
Abstract

International audience; Observations of dense water formation on the shelf of the Gulf of Thermaikos (North Aegean) are presented, based mainly on continuous monitoring of temperature and currents, during the winter of 2001–2002, at an instrumented mooring and a CTD survey carried out in early February 2002. A 2.5-month realistic simulation, corresponding to the period of observation, was performed to investigate the processes of dense water formation and cascading. The simulation is first compared to the main characteristics of the dense water, time variation of bottom temperature and spatial distribution of the dense water on the shelf. Subsequently, the simulation is used (a) to show that the formation of dense water takes place within the semi-enclosed Thessaloniki Bay and (b) to explain the intermittence of cascading out of the bay in relation to wind variations. The pathways of the dense water through the shelf are investigated with an emphasis on the role of the bottom slope and friction in the Ekman layer. The export of dense water towards the open sea occurs primarily along the slope bounding the western coast.

Published
2005

5. Carbon flow in the planktonic food web along a gradient of oligotrophy in the Aegean Sea (Mediterranean Sea)

Author

F. Van Wambeke, Vassilis Zervakis, Lydia Ignatiades, Stella Psarra, Epaminondas Christou, Paraskevi Pitta, Kalliopi Pagou, M. Bianchi, Ioanna Siokou-Frangou, Urania Christaki, Ekaterini Souvermezoglou, Antonia Giannakourou, O Gotsis, Laboratoire de MicrobiologiE de Géochimie et d'Ecologie Marines (LMGEM), Centre National de la Recherche Scientifique (CNRS)-Université de la Méditerranée - Aix-Marseille 2, Institute of Oceanography, Hellenic Centre for Marine Research (HCMR), and Université de la Méditerranée - Aix-Marseille 2-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, Aquatic Science, Oligotrophy, Oceanography, 01 natural sciences, Mediterranean sea, Phytoplankton, 14. Life underwater, Autotroph, Ecology, Evolution, Behavior and Systematics, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, E Mediterranean, Biomass (ecology), Microbial food web, biology, Ecology, 010604 marine biology & hydrobiology, fungi, Food web, Plankton, biology.organism_classification, [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology, Carbon flow, Environmental science, E. Mediterranean, Copepod
Abstract

International audience; This work is a study of plankton food web structure and carbon flow in March and September 1997 in the Aegean Sea, area of outflow of Black Sea waters in the Mediterranean Sea. Biomass and production of autotrophs were measured by size fraction as well as bacterial biomass and production; furthermore, we studied heterotrophic nanoflagellates (HNAN), ciliates and mesozooplankton biomass, copepod production and grazing impact on phytoplankton. The obtained low values of nutrients and plankton biomass and production confirmed the oligotrophic character of this region. Despite the fact that there was no significant horizontal variability in the spatial distribution of nutrients throughout the study area, the planktonic biomass and production revealed a gradual decrease from the Northeast Aegean (NEA) towards the South Aegean (SA). In the Northeast Aegean, a large part of the fixed carbon was channelled through the microbial food web towards copepods; in contrast there was a low transfer of energy in the South Aegean where the multivorous food web was developed. Throughout the study area, almost 60 – 70% of autotrophic biomass and primary production was performed by cells < 3 Am. D

Published
2002

Catalog

Books, media, physical & digital resources
See catalog results