Interaction flow bathymetry at tidal scale in the main sill of the Strait of Gibraltar

Data collected in the north and south channels of the main sill of the Strait of Gibraltar (Camarinal sill) are used to investigate processes connected to the internal hydraulics of the exchange through the Strait at tidal frequencies. Observations strongly suggest the setting up of hydraulic jumps at both the western and eastern flank of the sill, the latter associated with the reversal of the Mediterranean undercurrent during spring tides. The northern site is more sensitive to processes triggered by the formation and release of the jump formed east of the sill during intense enough ebb tide cycles, which is thus better traced at this location; the southern site detects more neatly the fluctuations and footprints associated with the hydraulic jump regularly formed to the west of the sill during flood tides. A detailed inspection of the high resolution bathymetry of the area reveals the existence of two enclosed depressions at either side of the sill, almost certainly carved by the bottom flow over the millennia, whose shape and morphology are suggestive of this spatial differentiation.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Labour flexibility and productivity in the hotel sector

In this paper, we analyze the effect of labour flexibility on productivity in the Andalusian hotel industry using raw data of our own database and applying an expanded version of the standard production function by distinguishing between part-time, temporary, and full-time labour inputs. Our results show that productivity is lower the higher the percentage of temporary and part-time workers and there are no differences between the impacts on productivity of both types of labour contract. Future studies should analyze the differential impact of all the types of contracts discussed on the mean cost per employee in this sector.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Lagrangian particle tracking for the assessment of the flushing efficiency of harbor structures: the case of the Port of the Bay of Algeciras, Strait of Gibraltar

The Bay of Algeciras, an inlet of about 9 x 11 km located at the eastern margin of the Strait of Gibraltar, opens to the south, where the Atlantic jet leaves the Strait and starts spreading into the Alboran Sea. In its western side, the Bay hosts one of the main ports in Europe, neuralgic base of the major traffic load from Europe to Africa and from Europa to the rest of the oversea countries. The massive transport of liquid and solid bulk or bunkering activity, daily carried out in the Bay, combined with the harsh weather conditions that often lash the zone, give the ideal scenario for an incipient ecological disaster. This high environmental risk motivates the interest for a deeper understanding of the small scale dynamics of the Bay and the role played by the port structures in case of oil spill or other surface contaminations. A series of Lagrangian particles tracking (LPT) experiments were carried out to investigate the flushing patterns of the Bay and 8 different docks inside the local port, under a representative variety of external conditions, such as tide phase and strength, and winds. A 2D LPT algorithm has been adapted to fully exploit the outputs of a very high resolution (∼30m) three-domain-nested hydrodynamic model, with the aim of resolving the complex circulation within the structures of the harbor. Winds are a clearly dominant factor, with westerlies featuring e-folding times one order of magnitude lower than easterlies. Fortnightly tidal modulation presents a counter-intuitive effect, with spring tides that, despite promoting higher ventilation in a first instance, end up providing higher accumulation of particles inside the docks and higher e-folding times than neap tides. Tide phase affects the current direction at the entrance of the docks during the first few hours of simulation and its effect is progressively masked throughout the experiment. In the 45% of the experiments, a significant quantity of particles flow out to the Alboran Sea (55% in the whole Bay experiment), confirming the importance of the Bay on the exportation of pollutant/properties to the nearby basin.Universidad de Málaga. Campus de Excelencia Internacional del Mar, CEIMAR. Campus de Excelencia Internacional Andalucía Tec

Mediterranean outflow and its link with upstream conditions in Alboran Sea

The Western Alboran Gyre (WAG) at the eastern entrance of the Strait of Gibraltar can influence the Mediterranean outflow (MOW) by favoring or hampering the flow of Levantine and Western Mediterranean (LIW and WMDW) waters, the main constituents of the MOW. Observations collected at Camarinal sill in the Strait and AVISO data are used to investigate this issue.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

The influence of tides on the exchange through the Strait of Gibraltar and on properties of the Mediterranean Sea

A. Ishlinsky Institute for Problems in Mechanics, Rusi

Blackspot seabream early life stages dispersal by hydrodynamic modelling (Strait of Gibraltar - Alboran Sea)

The Blackspot seabream (Pagellus bogaraveo) is a commercially appreciated demersal fish, widespread in the north-eastern Atlantic and middle-western Mediterranean. The Strait of Gibraltar (SoG) is an important fishing area where artisanal fleets from Spain and Morocco target this species using special longline gears known as “voracera”. Different studies on the health status of this species claim an overexploitation of the resource without any kind of objective management measures implemented yet by the associated countries. Improving the knowledge of the population dynamics, and particularly during the spawning window, is crucial for a better management of the fishing effort for this species. There is an agreement in literature in considering the SoG as an especially energetic and dispersive spawning zone for this species. Once spawned, eggs and larvae (ELS) are assumed to be scattered by the currents towards both sides of the SoG, mostly to the eastwards Alboran basin, where high concentrations of juveniles occur. A high resolution hydrodynamic model coupled to a Lagrangian particle tracking system is employed to assess the potential dispersal pathways of blackspot seabream ELS spawned in the SoG. Recursive releases of passive tracers in different virtual spawning spots and depths within the SoG region are tracked under different tidal conditions in order to obtain an overall characterization of the spatial dispersion patterns of the studied species. Semidiurnal tidal currents emerge as the primary factor in determining the horizontal dispersion and pathway of the spawning products, although the spring-neap tidal cycle and the spawning depth can be also important variables depending on the region considered as well as the arrival zone for the ELS dispersal paths over the Alboran SeaUniversidad de Málaga. Campus de Excelencia Internacional CEIMA

Security Assessment of the Spanish Contactless Identity Card

The theft of personal information to assume the identity of a person is a common threat. Individual criminals, terrorists, or crime rings normally do it to commit fraud or other felonies. Recently, the Spanish identity card, which provides enough information to hire on-line products such as mortgages or loans, was updated to incorporate a Near Field Communication (NFC) chip as electronic passports do. This contactless interface brings a new attack vector for these criminals, who might take advantage of the RFID communication to secretly steal personal information. In this paper, we assess the security of contactless Spanish identity card against identity theft. In particular, we evaluated the resistance of one of the contactless access protocol against brute-force attacks and found that no defenses were incorporated. We suggest how to avoid brute-force attacks. Furthermore, we also analyzed the pseudo-random number generator within the card, which passed all performed tests with good results.MINECO CyCriSec (TIN2014-58457-R).University of Zaragoza and Centro Universitario de la Defensa UZCUD2016-TEC-06.Project TEC2015-69665-R (MINECO/FEDER, UE)

Water renewal mechanisms of the Bay of Algeciras in the Strait of Gibraltar

The Bay of Algeciras (BA) is a marine environment subject to high levels of anthropogenic pressure. Here we analyze observations collected at the Bay and the results of an ocean circulation model to investigate its circulation and variability. Special attention is paid to the identification of the mechanisms enhancing the exchange of water with the adjacent Strait of Gibraltar and therefore contributing to maintain satisfactory levels of water quality.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Efectos de la dinámica mareal en los patrones de conectividad del voraz (Pagellus bogaraveo) en el Mar de Alborán

El voraz (Pagellus bogaraveo) es una especie de pez teleósteo demersal altamente apreciada tanto por su valor económico como gastronómico, que tiene un importante caladero en el Estrecho de Gibraltar. Dentro del ámbito científico, existe un consenso que considera que, para optimizar las pesquerías, simultáneamente a dejar de sobre explotar el recurso, es necesario hacer estudios de dinámica poblacional y conectividad. Con el objetivo de conocer mejor la dinámica poblacional de la especie y sus mecanismos de dispersión en el Mar de Alborán, se ha estudiado su conectividad hidrodinámica a partir de un modelo numérico [MITgcm], utilizando los estadios de vida temprana (huevos y larvas) como partículas virtuales lagrangianas advectadas por la dinámica mareal. Se han realizado análisis de sensibilidad en función de la variabilidad espacial y temporal. Para determinar la sensibilidad espacial, se definieron tres zonas de suelta en el Estrecho de Gibraltar, zona preferencial de desove del voraz y cinco profundidades de liberación desde la superficie hasta los 81 metros. Para determinar la sensibilidad temporal, se definieron ocho combinaciones de marea en función de la fase mareal y de la modulación quincenal (marea viva-marea muerta). Para cada uno de estos escenarios mareales iniciales se hicieron simulaciones de 60 días, que es la duración pelágica del voraz, en distintas fechas para estudiar la variabilidad subinercial asociada al forzamiento meteorológico, todo ello en el periodo comprendido entre diciembre de 2004 y abril de 2005 En conjunto se realizaron 480 simulaciones, de cuyo análisis se ha deducido que la modulación quincenal es el factor predominante para la dispersión horizontal, siendo el escenario de marea muerta el que produce una dispersión más baja y velocidad más uniforme de los huevos y larvas.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Measuring the bottom layer dynamics of the mediterranean outflow in the Strait of Gibraltar

Since 2004 a monitoring station located at the western exit of the Strait of Gibraltar (Espartel Sill), maintained with the joint efforts of the Physical Oceanography Group of the University of Málaga, the Spanish Institute of Oceanography laboratory of Cádiz and the Marine Science Institute of Andalusia, has been providing the longest series of water column current profiles ever collected in such a strategic site. The line is equipped with an up-looking long range current profiler capable to sample the water column up to few tents of meters from the surface. However, for both physical limitations of the line structure and electronic constraints of the instrument, the profiles miss the first 30 meters above the seafloor, a significant concern for a precise calculation of the Mediterranean outflow and the bottom layer dynamics. Since September 2016 a new high frequency down-looking current profiler has been included in the line, with the aim of covering the missing portion of the water column and precisely assessing the closure profile of the flow above the seafloor. The preliminary results are very encouraging and show a remarkable agreement between the profiles measured by both instruments: the boundary layer profile not only matches the closure curve suggested by the overhead profile, but even confirms the near-bottom diurnal modulation of the current suggested by previous observations, a feature that is expected to modify earlier estimations of the outflow. The resulting boundary layer is only few meters thick, revealing the high energy of the Mediterranean outflow in the strait, with flow speeds exceeding 1 m s-1 at only 3 m above the seafloor.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec