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1. Variation of sea ice and perspectives of the Northwest Passage in the Arctic Ocean

Author

Min Xu, Zhi-Min Zhang, Shichang Kang, Junming Guo, and Jinlei Chen

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Northwest passage, Sea ice, Temperature salinity diagrams, Management, Monitoring, Policy and Law, 010502 geochemistry & geophysics, 01 natural sciences, Arctic, Meteorology. Climatology, Sound (geography), 0105 earth and related environmental sciences, H1-99, Global and Planetary Change, geography, geography.geographical_feature_category, Social sciences (General), Oceanography, Canadian arctic archipelago, Strait, Archipelago, Sea ice thickness, Environmental science, Seawater, QC851-999, Channel (geography)
Abstract

The continued warming of the Arctic atmosphere and ocean has led to a record retreat of sea ice in the last decades. This retreat has increased the probability of the opening of the Arctic Passages in the near future. The Northwest Passage (NWP) is the most direct shipping route between the Atlantic and Pacific Oceans, producing notable economic benefits. Decadal variations of sea ice and its influencing factors from a high-resolution unstructured-grid finite-volume community ocean model were investigated along the NWP in 1988–2016, and the accessibility of the NWP was assessed under shared socioeconomic pathways (SSP245 and 585) and two vessel classes with the Arctic transportation accessibility model in 2021–2050. Sea ice thickness has decreased with increasing seawater temperature and salinity, especially within the Canadian Arctic Archipelago (CAA) in 1988–2016, which has facilitated the opening of the NWP. Complete ship navigation is projected to be possible for polar class 6 ships in August–December in 2021–2025, after when it may extends to July under SSP585 in 2026–2030, while open water ships will not be able to pass through the NWP until September in mid-21st century. The navigability of the NWP is mainly affected by the ice within the CAA. For the accessibility of the Parry Channel, the west part is worse than that of the eastern part, especially in the Viscount-Melville Sound.

Published
2021

2. Northern Hemisphere atmospheric pattern enhancing Eastern Mediterranean Transient-type events during the past 1000 years

Author

A. Cortina-Guerra, J. J. Gomez-Navarro, B. Martrat, J. P. Montávez, A. Incarbona, J. O. Grimalt, M.-A. Sicre, P. G. Mortyn, Ministerio de Ciencia, Innovación y Universidades (España), Grimalt, Joan O. [0000-0002-7391-5768], Institute of Environmental Assessment and Water Research (IDAEA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Universidad de Murcia, Dipartimento di Scienze della Terra e del Mare [Palermo] (DiSTeM), Università degli studi di Palermo - University of Palermo, Variabilité de l'Océan et de la Glace de mer (VOG), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut de Ciencia i Tecnologia Ambientals (ICTA), Universitat Autònoma de Barcelona (UAB), Departamento de Física [Murcia], 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)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-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)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Cortina-Guerra A, Gomez-Navarro JJ, Martrat B, Montavez JP, Incarbona A, Grimalt JO, Sicre MA, Mortyn PG, Grimalt, Joan O., Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPC)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPC)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPC), 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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and 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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
Mediterranean climate, 010506 paleontology, Alkenone, EUROPE, GULF, 010504 meteorology & atmospheric sciences, DEEP, Stratigraphy, CIRCULATION, Geopotential height, Structural basin, Environmental protection, 01 natural sciences, Environmental pollution, REGIONAL CLIMATE PALAEOSIMULATIONVARIABILITY, Eastern Mediterranean Transient, TD169-171.8, GE1-350, SOLAR, [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, Global and Planetary Change, SEA, Northern Hemisphere, Paleontology, Climate model simulations, Environmental sciences, MODEL, Sea surface temperature, Eastern mediterranean, TD172-193.5, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, Climate model, STRAIT, Geology
Abstract

High-resolution climate model simulations for the last millennium were used to elucidate the main winter Northern Hemisphere atmospheric pattern during enhanced Eastern Mediterranean Transient (EMT-type) events, a situation in which an additional overturning cell is detected in the Mediterranean at the Aegean Sea. The differential upward heat flux between the Aegean Basin and the Gulf of Lion was taken as a proxy of EMT-type events and correlated with winter mean geopotential height at 500 mbar in the Northern Hemisphere (20–90∘ N and 100∘ W–80∘ E). Correlations revealed a pattern similar to the East Atlantic/Western Russian (EA/WR) mode as the main driver of EMT-type events, with the past 1000 years of EA/WR-like mode simulations being enhanced during insolation minima. Our model results are consistent with alkenone sea surface temperature (SST) reconstructions that documented an increase in the west–east basin gradients during EMT-type events., This work started as a collaboration between researchers with the PALEOLINK project by the PAGES 2k Network. We acknowledge support from the PAGES (Past Global Changes) 2k Network, funded by the US and Swiss National Science Foundations (NSF) and NOAA. We want also to acknowledge project PGC2018-102288-B-I00 funded by Ministerio de Ciencia, Innovación y Universidades. Juan José Gomez-Navarro acknowledges the funding obtained through the “Juan de la Cierva-Incorporación” program (IJCI-2015-26914).

Published
2021
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3. Post-LGM coastline evolution of the NW Sicilian Channel: Comparing high-resolution geophysical data with Glacial Isostatic Adjustment modeling

Author

Massimo Zecchin, Dario Civile, Mathilde Bressoux, Gaia Galassi, Emanuele Lodolo, Giorgio Spada, Emanuele Lodolo, Gaia Galassi, Giorgio Spada, Massimo Zecchin, Dario Civile, and Mathilde Bressoux

Subjects
ISLAND, Topography, 010504 meteorology & atmospheric sciences, Glaciology, Marine and Aquatic Sciences, Social Sciences, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Paleooceanography, Tectonic uplift, Mediterranean sea, CAPO GRANITOLA, Plateaus, TECTONIC EVOLUTION, Multidisciplinary, geography.geographical_feature_category, Geography, Physics, MEDITERRANEAN SEA, Last Glacial Maximum, Geology, Biological Evolution, Plate Tectonics, Geophysics, Archaeology, SEA-LEVEL CHANGE, Paleogeography, RIFT, Physical Sciences, Medicine, ICE-AGE, Marine transgression, Research Article, Ice Sheets, SHELF, FAULT ZONE, Geological Phenomena, Science, Sea Level Rise, Deglaciation, 14. Life underwater, Sea level, 0105 earth and related environmental sciences, geography, Landforms, Models, Statistical, Biology and Life Sciences, Paleontology, Shores, Geomorphology, Post-glacial rebound, 15. Life on land, 13. Climate action, Earth Sciences, Ice sheet, STRAIT
Abstract

Since about 20,000 years ago, the geography of the Earth has been profoundly modified by the gradual sea-level rise caused by the melting of continental ice sheets. Flat areas and regions characterized by very low gradients experienced, more than others, rapid flooding, with the progressive disappearance of vast coastal territories. Here we present a recon- struction of the late Quaternary coastline evolution of the north-western sector of the Sicilian Channel, constrained by high-resolution seismic profiles where the marker of the post-Last Glacial Maximum (LGM) marine transgression has been clearly identified and mapped. The locations of the post-LGM seismic horizon have been compared with predictions of a Glacial Isostatic Adjustment (GIA) model, which accounts for the migration of the shorelines in response to sea-level rise and for Earth’s rotational and deformational effects associated with deglaciation. We have verified that most of the points mapped through seismic data interpretation fall along the palaeo-coastline that the GIA model predicts for the 21 kyrs B.P. time frame. However, the model shows a misfit in the marine sector between Mazara del Vallo and Sciacca, where the available data indicate a Quaternary tectonic uplift. The analy- sis of the seismic profiles provides useful constraints to current GIA models. These add on existing histories of relative sea level in the Mediterranean Sea, allowing to gain new insight into the evolution of the palaeo-geography of the region of study and of the whole Sicilian Channel since the LGM, even in areas where direct geophysical observations are not avail- able yet. In this respect, one of the most attractive implications of the ancient coastline evo- lution is linked with the underwater archaeology. The sea-level rise heavily impacted the distribution of human settlements, possibly forcing site abandonment and migrations, and this is particularly relevant in the Mediterranean basin, the cradle of the western civilization. The underwater traces left by these ancient populations represent the fundamental proofs to reconstruct the early history of our precursors.

Published
2020

4. Modeling of Nonhydrostatic Dynamics and Hydrology of the Lombok Strait

Author

Ivan Kuznetsov, Alexey Androsov, Vera Fofonova, and N. Voltzinger

Subjects
lcsh:Hydraulic engineering, 010504 meteorology & atmospheric sciences, Geography, Planning and Development, Aquatic Science, 01 natural sciences, Biochemistry, law.invention, lcsh:Water supply for domestic and industrial purposes, Hydrology (agriculture), lcsh:TC1-978, law, 14. Life underwater, hydrostatic/nonhydrostatic, 0105 earth and related environmental sciences, Water Science and Technology, lcsh:TD201-500, Throughflow, Curvilinear coordinates, Water transport, Atmospheric pressure, residual circulation, 010505 oceanography, nonlinearity, strait, Solver, Global simulation, Climatology, transport, Hydrostatic equilibrium, numerical model, tidal dynamic, Geology, energy
Abstract

The long-wave dynamics of the Lombok Strait, which is the most important link of the West Indonesian throughflow connecting the Pacific and Indian Ocean waters, was simulated and analyzed. A feature of the strait is its extremely complex relief, on which water transport creates a field of pronounced vertical velocities, which requires consideration of the nonhydrostatic component of pressure. The work presents a 3-D nonhydrostatic model in curvilinear coordinates, which is verified on a test problem. Particular attention is paid to the method of solving the 3-D elliptical solver for a nonhydrostatic problem in boundary-matched coordinates and a vertical &sigma, level. The difference in transport through the Lombok Strait is determined by the difference in atmospheric pressure over the Pacific and Indian Oceans. Based on the results of the global simulation, the role of these factors in terms of their variability is analyzed, and the value of nonhydrostatic pressure in the dynamics of the Lombok Strait is revealed and evaluated. The vertical dynamics of the Lombok Strait are considered in detail based on hydrostatic and nonhydrostatic approaches.

Published
2020
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5. Turbulence in the Sicily Channel from microstructure measurements

Author

Yannis Cuypers, Pascale Bouruet-Aubertot, Mireno Borghini, Stephane Leizour, Sana Ben Ismail, Katrin Schroeder, Bruno Ferron, Anda Vladoiu, Processus et interactions de fine échelle océanique (PROTEO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), 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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-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)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Physique et mécanique des milieux hétérogenes (UMR 7636) (PMMH), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Istituto di Scienze Marine [Venezia] (ISMAR-CNR), Istituto di Science Marine (ISMAR ), Consiglio Nazionale delle Ricerche (CNR)-Consiglio Nazionale delle Ricerche (CNR), Consiglio Nazionale delle Ricerche (CNR), Istituto di Scienze Marine [La Spezia] (CNR-ISMAR-SP), Institut National des Sciences et Technologies de la Mer [Salammbô] (INSTM), ANR-310 JC05-50690 pas dans AUREHAL le 20180823 (vérifier le numéro!), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Physique et mécanique des milieux hétérogenes (PMMH (UMR_7636)), Université Paris Diderot - Paris 7 (UPD7)-ESPCI ParisTech-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences et Technologies de la Mer (INSTM), Université de Monastir - University of Monastir (UM), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), EGU, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR)-National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), and Pinsard, Françoise

Subjects
010504 meteorology & atmospheric sciences, [PHYS.PHYS.PHYS-GEO-PH] Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 010505 oceanography, Turbulence, Mixed layer, MEDITERRANEAN SEA, INTERNAL WAVES, STRAIT, CIRCULATION, VARIABILITY, SHELF, TIDES, DISSIPATION, SIMULATION, EFFICIENCY, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Aquatic Science, Dissipation, Oceanography, Microstructure, 01 natural sciences, Shear (geology), Hotspot (geology), Turbulence kinetic energy, 14. Life underwater, Geomorphology, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

International audience; The Sicily Channel controls the exchange between the Eastern and Western Mediterranean Basins, with a dynamics characterised by strong shear at the interface between the south-eastward surface flow and the strong north-westward bottom flow. Microstructure measurements taken in the two main deep passages of the Sicily Channel show that this region is a hotspot for turbulent mixing. At the north-eastern location (C01), just downstream of where the strong bottom flow crosses a sill, turbulent kinetic energy dissipation rates for the deep flow were of the order of 10-8-10-7 W kg-1. At the south-western location (C02) on the milder slope of Talbot Bank, the observed bottom flow was weaker and along the isobaths, with lower dissipation rates of the order of 10-9 W kg-1. Furthermore, a recirculation of the western deep flow around Talbot Bank was hypothesised based on current measurements and a decrease in dissipation rates in the canyon north of C01. Strong shear, internal tides and interactions with the rough topography were found to be responsible for turbulence. The dynamical regime was dominated by mechanically driven turbulence with a large range of turbulence intensities. Favourable conditions for double diffusive salt fingers and double diffusive convection also occurred, however double diffusion prevailed in only 0.5% of the observations. Mixing efficiency was computed from the microstructure measurements, and its variability was explored in the context of variable turbulence intensities. The vertical diapycnal diffusivity computed from the measurements was higher at C01 (1.1×10-3 ± 3.2×10-3 m2 s-1) than at C02 (1.8×10-4 ± 7.6×10-4 m2 s-1). Moreover, upward salinity dominated density fluxes of the order of 10-6 and 10-7 kg m-2 s-1 were found to be characteristic of the transitional and intermediate waters, respectively. Significant changes in water mass properties in the Sicily Channel were thus inferred.

Published
2018
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6. The mediterranean overflow in the Gulf of Cadiz: a rugged journey

Author

Jose Carlos Sanchez-Garrido, César González-Pola, David Roque, Luis Miguel Fernández-Salas, Álvaro Peliz, Marc Gasser-Rubinat, Francisco Javier Hernandéz-Molina, Paulo Relvas, M.J. Bellanco, Josep Lluís Pelegrí, R.F. Sánchez-Leal, Jesús García-Lafuente, Simone Sammartino, and Manuel Ruiz-Villarreal

Subjects
Mediterranean climate, Ocean, Buoyancy, 010504 meteorology & atmospheric sciences, Medio Marino y Protección Ambiental, Velocity, Flux, Sede Central IEO, engineering.material, Oceanography, 010502 geochemistry & geophysics, 01 natural sciences, Currents, Variability, Research Articles, 0105 earth and related environmental sciences, geography, Gibraltar, Multidisciplinary, geography.geographical_feature_category, SciAdv r-articles, Water, Outflow, Channel, Gravity current, Current (stream), Ridge, Strait, engineering, Hydrography, North-Atlantic, Geology, Research Article
Abstract

Sánchez Leal, Ricardo ... et al.-- 11 pages, 5 figures, supplementary material http://advances.sciencemag.org/cgi/content/full/3/11/eaao0609/DC1, The pathways and transformations of dense water overflows, which depend on small-scale interactions between flow dynamics and erosional-depositional processes, are a central piece in the ocean’s large-scale circulation. A novel, high-resolution current and hydrographic data set highlights the intricate pathway travelled by the saline Mediterranean Overflow as it enters the Atlantic. Interaction with the topography constraints its spreading. Over the initial 200 km west of the Gibraltar gateway, distinct channels separate the initial gravity current into several plunging branches depth-sorted by density. Shallow branches follow the upper slope and eventually detach as buoyant plumes. Deeper branches occupy mid slope channels and coalesce upon reaching a diapiric ridge. A still deeper branch, guided by a lower channel wall marked by transverse furrows, experiences small-scale overflows which travel downslope to settle at mid-depths. The Mediterranean salt flux into the Atlantic has implications for the buoyancy balance in the North Atlantic. Observations on how this flux enters at different depth levels are key to accurately measuring and understanding the role of Mediterranean Outflow in future climate scenarios, We also acknowledge funding and data provided by projects INGRES3 (CTM2010-21229), STOCA (IEO 2009), PESCADIZ (IEO), INDEMARES (LIFE07 NAT/E/000732+), MOC2 (CTM2008-06438-C02-01), MED-OUTFLOW (CTM2008-03422-E/MAR and CTM2010-11488-E), PELCOSAT (IEO), SEMANE (X. Carton), DILEMA (CTM2014-59244-C3-2-R), and INPULSE (CTM2016-75129-C3-1-R) as well as SISMER, PANGEA, IEO, ICES, BODC, and NOAA data centers. Additional funding was provided by the CONTOURIBER (CTM2008-06399-C04-01/MAR) project. Part of the research was conducted in the framework of the “Drifters” Research Group of the Royal Holloway, University of London, UK

Published
2017

7. Phylogeography of a widespread species: pre-glacial vicariance, refugia, occasional blocking straits and long-distance migrations

Author

Rodolfo Barreiro, Rubén Retuerto, Xabier Santiso, Lua Lopez, and Universidade de Santiago de Compostela. Departamento de Bioloxía Funcional

Subjects
0106 biological sciences, 0301 basic medicine, Philogeny, Range (biology), Population, Vicariance, Refugia, Plant Science, Mediterranean, Biology, 010603 evolutionary biology, 01 natural sciences, Arbutus unedo, 03 medical and health sciences, refugia, cpDNA, vicariance, Genetics, Glacial period, education, Research Articles, education.field_of_study, Lusitianian, Ecology, clades, strait, Clades, Last Glacial Maximum, Genomics, Phylogeography, 030104 developmental biology, Strawberry tree, Strait, Biological dispersal, Lusitanian
Abstract

The strawberry tree diverged into two groups during the Quaternary, but before the LGM, surviving in refugia located in the western end of the Mediterranean region and with the Eastern Mediterranean being colonized more recently. This migration was possible because Europe and North Africa were occasionally connected through the straits of Gibraltar and Sicily. Likewise, our evidence supports arrival in Ireland from northern Iberia in post-glacial times. Altogether, our results reveal the considerable ability of the strawberry tree for dispersal, allowing it to migrate over thousands of kilometres and cross stretches of sea, which may be crucial for its future survival., Phylogeographic studies give us the opportunity to reconstruct the historical migrations of species and link them with climatic and geographic variation. They are, therefore, a key tool to understanding the relationships among biology, geology and history. One of the most interesting biogeographical areas of the world is the Mediterranean region. However, in this area, the description of concordant phylogeographic patterns is quite scarce, which limits the understanding of evolutionary patterns related to climate. Species with one-dimensional distribution ranges, such as the strawberry tree (Arbutus unedo), are particularly useful to unravel these patterns. Here, we describe its phylogeographic structure and check for concordance with patterns seen in other Mediterranean plants: longitudinal/latitudinal clines of diversity, evidence for glacial refugia and the role of sea straits in dispersal. We also identify the most likely source for the disjunct Irish population. With this aim, we sequenced four chloroplast non-coding fragments of A. unedo from 23 populations covering its whole distribution. We determined the genetic diversity, population structure, haplotype genealogy and time to the most recent common ancestor. The genealogy revealed two clades that separated during the last 700 ky but before the last glacial maximum. One clade occupies Atlantic Iberia and North Africa, while the other occurs in the Western Mediterranean. The Eastern Mediterranean is inhabited by newer haplotypes derived from both clades, while the Irish population is closely related to Iberian demes. The straits of Sicily and Gibraltar partially restricted the gene flow. We concluded that a vicariance event during the Late Quaternary in the western end of the species' range followed by eastward migration seems a likely explanation for the observed phylogeographic pattern. The role of straits indicates an occasional communication between Europe and North Africa, suggesting that the latter was a novel refugia. The East–West genetic split in Iberia is consistent with the refugia-within-refugia model. Finally, the strawberry tree possibly reached Ireland from Iberia instead of throughout the maritime fringe of France as previously thought.

Published
2015
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8. Mediterranean intermediate circulation estimated from Argo data in 2003-2010

Author

Pierre-Marie Poulain and Milena Menna

Subjects
0106 biological sciences, Mediterranean climate, 010504 meteorology & atmospheric sciences, Linear displacement, north atlantic, Temperature salinity diagrams, Structural basin, 01 natural sciences, Mediterranean Basin, features, Bathymetry, Mean flow, 14. Life underwater, currents, lcsh:Environmental sciences, Argo, 0105 earth and related environmental sciences, lcsh:GE1-350, variability, 010604 marine biology & hydrobiology, lcsh:Geography. Anthropology. Recreation, strait, floats, Geodesy, waters, Oceanography, lcsh:G, deep, surface circulation, tyrrhenian sea, Geology
Abstract

Data from 38 Argo profiling floats are used to describe the intermediate Mediterranean currents for the period October 2003–January 2010. These floats were programmed to execute 5-day cycles, to drift at a neutral parking depth of 350 m and measure temperature and salinity profiles from either 700 or 2000 m up to the surface. At the end of each cycle the floats remained at the sea surface for about 6 h, enough time to be localised and transmit the data to the Argos satellite system. The Argos positions were used to determine the float surface and intermediate displacements. At the surface, the float motion was approximated by a linear displacement and inertial motion. Intermediate velocities estimates were used to investigate the Mediterranean circulation at 350 m, to compute the pseudo-Eulerian statistics and to study the influence of bathymetry on the intermediate currents. Maximum speeds, as large as 33 cm/s, were found northeast of the Balearic Islands (western basin) and in the Ierapetra eddy (eastern basin). Typical speeds in the main along-slope currents (Liguro-Provençal-Catalan, Algerian and Libyo-Egyptian Currents) were ~20 cm/s. In the central and western part of Mediterranean basin, the pseudo-Eulerian statistics show typical intermediate circulation pathways which can be related to the motion of Levantine Intermediate Water. In general our results agree with the qualitative intermediate circulation schemes proposed in the literature, except in the southern Ionian where we found westward-flowing intermediate currents. Fluctuating currents appeared to be usually larger than the mean flow. Intermediate currents were found to be essentially parallel to the isobaths over most of the areas characterized by strong bathymetry gradients, in particular, in the vicinity of the continental slopes.

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