Modelling Study of Transformations of the Exchange Flows Along the Strait of Gibraltar
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Improved Modelling of the Messinian Salinity Crisis and Conceptual Implications
Palaeogeography, Palaeoclimatology, Palaeoecology 238 (2006) 349–372 www.elsevier.com/locate/palaeo Improved modelling of the Messinian Salinity Crisis and conceptual implications Paul-Louis Blanc Institut de Radioprotection et de Sûreté Nucléaire, Boîte Postale 17, 92262 Fontenay-aux-roses Cedex, France Received 17 April 2003; accepted 7 March 2006 Abstract This paper presents the last developments of a simple oceanographic modelling of the water and salt budgets of the Mediterranean Sea during the late Miocene Salinity Crisis. The Messinian Mediterranean is treated as analogous to the present one, i.e. divided into two main basins separated by a sill at shallow or intermediate depth. When the supply of marine water from the Atlantic is progressively reduced, both basins undergo a rise in salinity, until saturation is reached: this is when the true evaporitic sedimentation begins, before the level drawdown. The partition of the Mediterranean into two mains basins causes a shift in the evaporitic sedimentation from the distal (eastern) basin to the proximal (western) basin, so that the evaporitic deposits are not fully contemporaneous in the western and the eastern basin. The drawdown is limited by the equilibrium of the evaporation and chemical activity of the brines at the surface, against the surface area and evaporation. Attempts at adjusting the model both to an accurate stratigraphic frame and to a rough budget of the evaporites shows that the Upper Evaporites and brackish-water Lago-mare series must have been deposited as secondary deposits, after the closure of the Atlantic passages was completed. The present evaporitic potentialities of the Mediterranean Sea remains quite as strong as during the Miocene, so that climatic change cannot be inferred from the MSC itself. -
The Mediterranean Outflow Water: Transformations and Pathways Into the Gulf of Cádiz
The Mediterranean Outflow Water: Transformations and Pathways into the Gulf of Cádiz Marc Gasser i Rubinat Doctoral thesis as a compilation of publications September 2018 Advisor: Josep Lluís Pelegrí Llopart Thesis submitted to the Civil and Environmental Engineering Department, Marine Sciences Program, Universitat Politècnica de Catalunya in partial fulfillment of the requirements for the degree of Doctor of Philosophy Marc Gasser i Rubinat When anxious, uneasy and bad thoughts come, I go to the sea, and the sea drowns them out with its great wide sounds, cleanses me with its noise, and imposes a rhythm upon everything in me that is bewildered and confused". Rainer Maria Rilke III The Mediterranean Outflow Water IV Marc Gasser i Rubinat Abstract The Mediterranean Outflow Water (MOW) is La sortida d'aigua mediterrània (MOW) és un a dense ( r>1028.5 kg/m 3), saline (38.5 g/kg) corrent oceànic dens ( r>1028.5 kg/m3) i salí ocean stream originated in the evaporative (38.5 lg/m3) originat en la conca evaporativa Mediterranean basin flowing westward past de la Mar Mediterrània que flueix passant la Espartel Sill as a fast (>1 m/s) and often baixa d'Espartel en forma d'un corrent de unstable (as indicated by its gradient gravetat molt ràpid (>1 m/s) i sovint inestable Richardson number) gravity current. During (tal i com indica el número de gradient de its descense into the Gulf of Cadiz, the MOW Richardson). Durant el seu descens al Golf entrains the overlying North Atlantic Central de Cadis, la MOW incorpora les aigües Water (NACW), until the density difference atlàntiques (NACW) suprajacents fins que la between both water masses vanishes, and diferència de densitat entre ambdues masses reaches its equilibrium depth. -
The Mediterranean Outflow in the Strait of Gibraltar and Its Connection
Ocean Sci., 13, 195–207, 2017 www.ocean-sci.net/13/195/2017/ doi:10.5194/os-13-195-2017 © Author(s) 2017. CC Attribution 3.0 License. The Mediterranean outflow in the Strait of Gibraltar and its connection with upstream conditions in the Alborán Sea Jesús García-Lafuente, Cristina Naranjo, Simone Sammartino, José C. Sánchez-Garrido, and Javier Delgado Physical Oceanography Group, Department of Applied Physics 2, University of Málaga, Málaga, Spain Correspondence to: Jesús García-Lafuente ([email protected]) Received: 23 November 2016 – Discussion started: 13 December 2016 Revised: 24 February 2017 – Accepted: 28 February 2017 – Published: 24 March 2017 Abstract. The present study addresses the hypothesis that the mediate and the Tyrrhenian Dense waters, both of interme- Western Alborán Gyre in the Alborán Sea (the westernmost diate nature. The Winter Intermediate Water is formed along Mediterranean basin adjacent to the Strait of Gibraltar) in- the continental shelf of the Liguro-Provençal sub-basin and fluences the composition of the outflow through the Strait Catalan Sea (Conan and Millot, 1995; Vargas-Yáñez et al., of Gibraltar. The process invoked is that strong and well- 2012), exhibits marked interannual fluctuations that include developed gyres help to evacuate the Western Mediterranean years of no formation (Pinot et al., 2002; Monserrat et al., Deep Water from the Alborán basin, thus increasing its pres- 2008), and is characterized by an absolute minimum of po- ence in the outflow, whereas weak gyres facilitate the outflow tential temperature. Its volume transport is much less than the of Levantine and other intermediate waters. To this aim, in Levantine Intermediate Water and it flows embedded inside situ observations collected at the Camarinal (the main) and this water mass at relatively shallow depths. -
The Zanclean Megaflood of the Mediterranean
Earth-Science Reviews 201 (2020) 103061 Contents lists available at ScienceDirect Earth-Science Reviews journal homepage: www.elsevier.com/locate/earscirev The Zanclean megaflood of the Mediterranean – Searching for independent evidence T ⁎ Daniel Garcia-Castellanosa, , Aaron Micallefb,c, Ferran Estradad, Angelo Camerlenghie, Gemma Ercillad, Raúl Periáñezf, José María Abrilf a Instituto de Ciencias de la Tierra Jaume Almera, ICTJA-CSIC, Barcelona, Spain b Marine Geology and Seafloor Surveying, Department of Geosciences, University of Malta, Msida, MSD 2080, Malta c Helmholtz Centre for Ocean Research, GEOMAR, Kiel, Germany d Instituto de Ciencias del Mar, ICM-CSIC, Barcelona, Spain e Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Trieste, Italy f University of Sevilla, Spain ABSTRACT About six million years ago, the Mediterranean Sea underwent a period of isolation from the ocean and widespread salt deposition known as the Messinian Salinity Crisis (MSC), allegedly leading to a kilometer-scale level drawdown by evaporation. One of the competing scenarios proposed for the termination of this en- vironmental crisis 5.3 million years ago consists of a megaflooding event refilling the Mediterranean Sea through the Strait of Gibraltar: the Zanclean flood. The main evidence supporting this hypothesis is a nearly 390 km long and several hundred meters deep erosion channel extending from the Gulf of Cádiz (Atlantic Ocean) to the Algerian Basin (Western Mediterranean), implying the excavation of ca. 1000 km3 of Miocene sediment and bedrock. Based on the understanding obtained from Pleistocene onshore megaflooding events and using ad-hoc hydrodynamic modeling, here we explore two predictions of the Zanclean outburst flood hypothesis: 1) The formation of similar erosion features at sills communicating sub-basins within the Mediterranean Sea, specifically at the Sicily Sill; and 2) the accumulation of the eroded materials as megaflood deposits in areas of low flow energy. -
Exchange Flow Through the Strait of Gibraltar As Simulated by a Σ-Coordinate Hydrostatic Model and a Z-Coordinate Nonhydrostatic Model
3 Exchange Flow through the Strait of Gibraltar as Simulated by a σ-Coordinate Hydrostatic Model and a z-Coordinate Nonhydrostatic Model Gianmaria Sannino1, J. C. Sánchez Garrido2, L. Liberti3, and L. Pratt4 3.1. INTRODUCTION 2007; Sannino et al., 2009a]. The simultaneous presence in the SoG of at least two cross sections in which the The Mediterranean Sea is a semi-enclosed basin dis- exchange is controlled drives the strait dynamics toward playing an active thermohaline circulation (MTHC) that the so-called maximal regime [Bryden and Stommel, 1984; is sustained by the atmospheric forcing and controlled by Armi and Farmer, 1988]. If the exchange is subject to only the narrow and shallow Strait of Gibraltar (hereinafter one hydraulic control, the regime is called submaximal. SoG). The atmospheric forcing drives the Mediterranean The two regimes have different implications for property basin toward a negative budget of water and heat. Over fluxes, response time, and other physical characteristics the basin, evaporation exceeds the sum of precipitation of the coupled circulation in the SoG and Mediterranean and river discharge, while a net heat flux is transferred to Sea. The maximal regime can be expected to have larger the overlying atmosphere through the sea surface. These heat, salt, and mass fluxes and to respond more slowly to fluxes are balanced by the exchange flow that takes place changes in stratification and thermohaline forcing within in Gibraltar. Within the SoG, the MTHC takes the form the Mediterranean Sea and the North Atlantic Ocean of a two-way exchange: an upper layer of fresh and [Sannino et al., 2009a]. -
Vertical Structure of Tidal Currents Over Espartel and Camarinal Sills, Strait of Gibraltar ⁎ A
Available online at www.sciencedirect.com Journal of Marine Systems 74 (2008) 120–133 www.elsevier.com/locate/jmarsys Vertical structure of tidal currents over Espartel and Camarinal sills, Strait of Gibraltar ⁎ A. Sánchez-Román a, , F. Criado-Aldeanueva a, J. García-Lafuente a, J.C. Sánchez a,b a Departamento de Física Aplicada II, Universidad de Málaga, Málaga, Spain b Grupo de Puertos y Costas, Universidad de Granada, Granada, Spain Received 23 July 2007; received in revised form 7 November 2007; accepted 19 November 2007 Available online 5 February 2008 Abstract ADCP velocity data collected in the two main sills of the Strait of Gibraltar (Camarinal and Espartel sills) have been used for analysing the vertical structure of main tidal constituents (M2,S2,O1 and K1) currents in this area. Two different periods (winter and summer) were considered in correspondence to seasonal variations in density profiles. Amplitudes and phases of the various tidal constituents have been compared for both periods and locations. Barotropic and baroclinic parts of the tidal currents have been extracted using the dynamical mode decomposition technique and the relative importance of each mode has been established in terms on the energy associated. In Espartel sill, the barotropic mode is more energetic in wintertime for all constituents except for K1. Baroclinic modes have smaller contribution to total energy. Second and third baroclinic modes tend to be more energetic than the first one, especially during winter, this indicating a relatively complex vertical structure of the tidal currents. Over Camarinal sill, barotropic mode accounts for more than 90% of total energy in all the tidal constituents, the highest value (97%) observed for M2. -
Hydraulic Criticality of the Exchange Flow Through the Strait of Gibraltar
NOVEMBER 2009 S A N N I N O E T A L . 2779 Hydraulic Criticality of the Exchange Flow through the Strait of Gibraltar GIANMARIA SANNINO Ocean Modelling Unit, ENEA, Rome, Italy LAWRENCE PRATT Woods Hole Oceanographic Institution, Woods Hole, Massachusetts ADRIANA CARILLO Ocean Modelling Unit, ENEA, Rome, Italy (Manuscript received 17 June 2008, in final form 9 January 2009) ABSTRACT The hydraulic state of the exchange circulation through the Strait of Gibraltar is defined using a recently developed critical condition that accounts for cross-channel variations in layer thickness and velocity, applied to the output of a high-resolution three-dimensional numerical model simulating the tidal exchange. The numerical model uses a coastal-following curvilinear orthogonal grid, which includes, in addition to the Strait of Gibraltar, the Gulf of Cadiz and the Alboran Sea. The model is forced at the open boundaries through the specification of the surface tidal elevation that is characterized by the two principal semidiurnal and two diurnal harmonics: M2, S2, O1, and K1. The simulation covers an entire tropical month. The hydraulic analysis is carried out approximating the continuous vertical stratification first as a two-layer system and then as a three-layer system. In the latter, the transition zone, generated by entrainment and mixing between the Atlantic and Mediterranean flows, is considered as an active layer in the hydraulic model. As result of these vertical approximations, two different hydraulic states have been found; however, the simulated behavior of the flow only supports the hydraulic state predicted by the three-layer case. Thus, analyzing the results obtained by means of the three-layer hydraulic model, the authors have found that the flow in the strait reaches maximal exchange about 76% of the tropical monthlong period. -
Antarctic Glacio-Eustatic Contributions to Late Miocene Mediterranean Desiccation and Reflooding
ARTICLE Received 13 Dec 2014 | Accepted 29 Sep 2015 | Published 10 Nov 2015 DOI: 10.1038/ncomms9765 OPEN Antarctic glacio-eustatic contributions to late Miocene Mediterranean desiccation and reflooding Christian Ohneiser1, Fabio Florindo2, Paolo Stocchi3, Andrew P. Roberts4, Robert M. DeConto5 & David Pollard6 The Messinian Salinity Crisis (MSC) was a marked late Neogene oceanographic event during which the Mediterranean Sea evaporated. Its causes remain unresolved, with tectonic restrictions to the Atlantic Ocean or glacio-eustatic restriction of flow during sea-level lowstands, or a mixture of the two mechanisms, being proposed. Here we present the first direct geological evidence of Antarctic ice-sheet (AIS) expansion at the MSC onset and use a d18O record to model relative sea-level changes. Antarctic sedimentary successions indicate AIS expansion at 6 Ma coincident with major MSC desiccation; relative sea-level modelling indicates a prolonged B50 m lowstand at the Strait of Gibraltar, which resulted from AIS expansion and local evaporation of sea water in concert with evaporite precipitation that caused lithospheric deformation. Our results reconcile MSC events and demonstrate that desiccation and refilling were timed by the interplay between glacio-eustatic sea-level variations, glacial isostatic adjustment and mantle deformation in response to changing water and evaporite loads. 1 Department of Geology, University of Otago, PO Box 56, Dunedin 9054, New Zealand. 2 Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, Rome 00143, Italy. 3 NIOZ Royal Netherlands Institute for Sea Research, Physical Oceanography (FYS), PO Box 59, 1790AB Den Burg, Texel, The Netherlands. 4 Research School of Earth Sciences, The Australian National University, Canberra, Australian Capital Territory 0200, Australia. -
Modelling Study of Transformations of the Exchange Flows Along the Strait of Gibraltar
Ocean Sci. Discuss., https://doi.org/10.5194/os-2018-57 Manuscript under review for journal Ocean Sci. Discussion started: 4 June 2018 c Author(s) 2018. CC BY 4.0 License. Modelling study of transformations of the exchange flows along the Strait of Gibraltar Antonio Sanchez-Roman1, Gabriel Jorda1, Gianmaria Sannino2 and Damia Gomis1 1 IMEDEA (UIB-CSIC), Mallorca, Spain 5 2 Energy and Environmental Modeling Unit, ENEA, Italy Correspondence to: Antonio Sánchez-Román ([email protected]) Abstract. Vertical transfers of heat, salt and mass between the inflowing and outflowing layers at the Strait of Gibraltar are explored basing on the outputs of a three-dimensional, fully non-linear numerical model. The model covers the entire Mediterranean basin and has a very high spatial resolution around the Strait (1/200o). Another distinctive feature of the 10 model is that it includes a realistic barotropic tidal forcing (diurnal and semidiurnal), in addition to atmospheric pressure and heat and water surface fluxes. The results show a significant transformation of the properties of the inflowing and outflowing water masses along their path through the Strait. This transformation is mainly induced by the recirculation of water, and therefore of heat and salt, between the inflowing and outflowing layers. The underlying process seems to be the hydraulic control acting at the Espartel section, Camarinal Sill and Tarifa Narrows, which limits the amount of water than can cross the 15 sections and forces a vertical recirculation. This results in a complex spatio-temporal pattern of vertical transfers, with the sign of the net vertical transfer being opposite in each side of Camarinal Sill. -
Articles That Have Been Tracked for 30 Days in the Lowest Sigma Layer, I.E
Clim. Past, 11, 233–251, 2015 www.clim-past.net/11/233/2015/ doi:10.5194/cp-11-233-2015 © Author(s) 2015. CC Attribution 3.0 License. Changes in Mediterranean circulation and water characteristics due to restriction of the Atlantic connection: a high-resolution ocean model R. P. M. Topper1,* and P. Th. Meijer1 1Department of Earth Sciences, Utrecht University, Budapestlaan 4 3584CD Utrecht, the Netherlands *now at: MARUM – Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, P.O. Box 330440, 28334, Germany Correspondence to: R. P. M. Topper ([email protected]) Received: 27 June 2014 – Published in Clim. Past Discuss.: 25 July 2014 Revised: 14 January 2015 – Accepted: 26 January 2015 – Published: 16 February 2015 Abstract. A high-resolution parallel ocean model is set up to surface forcing and the use of a bathymetry different from examine how the sill depth of the Atlantic connection affects that in the Late Miocene. We also tentatively conclude that circulation and water characteristics in the Mediterranean blocked outflow, as found in experiments with a sill depth Basin. An analysis of the model performance, comparing ≤ 10 m, is a plausible scenario for the second stage of the model results with observations of the present-day Mediter- Messinian Salinity Crisis during which halite was rapidly ac- ranean, demonstrates its ability to reproduce observed water cumulated in the Mediterranean. characteristics and circulation (including deep water forma- With the model setup and experiments, a basis has been es- tion). A series of experiments with different sill depths in tablished for future work on the sensitivity of Mediterranean the Atlantic–Mediterranean connection is used to assess the circulation to changes in (palaeo-)bathymetry and external sensitivity of Mediterranean circulation and water character- forcings. -
Definitive Evidence of the Mediterranean Outflow Heterogeneity
Ocean Sci. Discuss., https://doi.org/10.5194/os-2017-52 Manuscript under review for journal Ocean Sci. Discussion started: 1 August 2017 c Author(s) 2017. CC BY 4.0 License. Definitive evidence of the Mediterranean Outflow heterogeneity. Part 1: at the Strait of Gibraltar entrance Claude Millot 5 Les Katikias, 83150 Bandol, France Correspondence to: Claude Millot ([email protected]) Abstract. All most recent papers about the Mediterranean Outflow (MO) assume that it is homogeneous at least in the western side of the Strait of Gibraltar and that its splitting into veins in the Atlantic Ocean is due to 10 bathymetric effects at the Strait exit while we demonstrate that proofs about the MO heterogeneity within the whole Strait have been available since the mid 1980's at least. We focus herein on data collected at the Strait entrance in 1985 (Part 1), before analyzing 1985-1986 data within the Strait (Part 2) and data collected during the MO-2009 experiment at the Strait exit (Part 3). Having demonstrated that the MO is markedly heterogeneous from the Strait entrance to the Strait exit, our three papers demonstrate that the splitting into veins is essentially a 15 direct consequence of the sea functioning. Indeed, veins have hydrological characteristics mainly dependent on those of the intermediate and deep Mediterranean Waters (MWs) formed in both the eastern and the western basins of the Sea, as well as on those of the Atlantic Waters (AWs) that mixed in the Strait with these MWs, the bathymetry at and downstream from the Strait exit playing a negligible role. -
A Single-Stage Megaflood at the Termination
A single-stage megaflood at the termination of the Messinian salinity crisis: Geophysical and modelling evidence from the eastern Mediterranean Basin Daniele Spatola, José David del Moral-Erencia, Aaron Micallef, Angelo Camerlenghi, Daniel Garcia-Castellanos, Sanjeev Gupta, Patricio Bohorquez, Marc-André Gutscher, Claudia Bertoni To cite this version: Daniele Spatola, José David del Moral-Erencia, Aaron Micallef, Angelo Camerlenghi, Daniel Garcia- Castellanos, et al.. A single-stage megaflood at the termination of the Messinian salinity crisis: Geo- physical and modelling evidence from the eastern Mediterranean Basin. Marine Geology, Elsevier, 2020, 10.1016/j.margeo.2020.106337. hal-03024715 HAL Id: hal-03024715 https://hal.archives-ouvertes.fr/hal-03024715 Submitted on 26 Nov 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. 1 Manuscript submitted to Marine Geology: 2 3 A single-stage megaflood at the termination of the Messinian salinity crisis: Geophysical 4 and modelling evidence from the eastern Mediterranean Basin 5 6 Daniele Spatola1, José