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Since 2004, high resolution profiles of the 3D velocity of the water column have been collected at the westernmost sill of the Strait of Gibraltar (Espartel Sill), with the aim of monitoring the Mediterranean water outflow and evaluate its short and long term variability. A 75 kHz up-looking Acoustic Doppler Profiler (ADP) and, more recently, another 500 kHz model installed in down-looking mode, have been embedded in a subsurface buoy, deployed ∼20m above the seafloor at a depth of approximately 360m. The averaged profile of the observed along-strait current uses to show local minima ∼50m above seafloor, which has been interpreted as the diurnal-semidiurnal interaction of tidal currents (Sammartino et al., 2015). The prevailing semidiurnal tide drives periodic accelerations of the westward Mediterranean current flowing at the bottom, whereas diurnal constituents slow them down, giving rise to a local minimum in amplitude, and prompting severe drops in measurements accuracy. In year 2019, the main ADP was replaced by a 100 kHz model sporting an additional vertical beam that collects high resolution echograms of the water column. This new information reveals the key role of scatterers concentration, which undergoes diel migrations, and affects the reliability of the velocity observations which rely on the amplitude of scattered echo recorded by the instruments. Actually, echo amplitude reaches average correlations of 0.7 with measurement uncertainties. In light of these new insights, an accurate update of the Mediterranean outflow calculations is performed and new values of trend and long-term variability, are estimated. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

The Daily Egg Production Method (DEPM) to estimate the Anchovy Spawning Stock Biomass (SSB) in the Gulf of Cádiz (ICES, Subdivision 9a South) is conducted by Spain (Centro Nacional Instituto Español de Oceanografía, CSIC) every three years, since 2005. BOCADEVA 0720 is the sixth survey of the historical DEPM series for anchovy in the Gulf of Cádiz and was delivered on board R/V Ramón Margalef (CNIEO) from the 9th to the 17th of July 2020. The surveyed area extended from Strait of Gibraltar to Cape San Vicente (Spanish and Portuguese waters in the Gulf of Cadiz). Plankton samples, along a grid of 21 transects perpendicular to the coast were obtained for the spawning area delimitation and density estimation of the daily egg production. The survey objectives also included the characterization of the oceanographic and meteorological conditions in the study area. The samples to estimate adult parameters (sex ratio, female mean weight, batch fecundity and spawning fraction) were obtained in the acoustic survey “ECOCADIZ 2020-07”, carried out during the same period. This working document provides a d escription of the survey, laboratory analysis and estimation procedures used to obtain the Gulf of Cadiz Anchovy SSB by DEPM for 2020 in the South-Atlantic Iberian Stock.

Spatio-temporal variations in the partial pressure of CO2 (pCO2) were studied during eight oceanographic cruises conducted between March 2014 and February 2016 in surface waters of the eastern shelf of the Gulf of Cádiz (SW Iberian Peninsula) between the Guadalquivir river and Cape Trafalgar. pCO2 presents a range of variation between 320.6 and 513.6 µatm with highest values during summer and autumn and lowest during spring and winter. For the whole study, pCO2 shows a linear dependence with temperature, and spatially there is a general decrease from coastal to offshore stations associated with continental inputs and an increase in the zones deeper than 400 m related to the influence of the eastward branch of the Azores Current. The study area acts as a source of CO2 to the atmosphere during summer and autumn and as a sink in spring and winter with a mean value for the study period of −0.18±1.32 mmol m−2 d −1 . In the Guadalquivir and Sancti Petri transects, the CO2 fluxes decrease towards offshore, whereas in the Trafalgar transect fluxes increase due to the presence of an upwelling. The annual uptake capacity of CO2 in the Gulf of Cádiz is 4.1 Gg C yr−1 ., Sí

European Geosciences Union (EGU) General Assembly 2018, 8-13 April 2018, Vienna, Austria.-- 1 page, 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

Almost ten year of Acoustic Doppler Current Profiler (ADCP) observations collected at the westernmost sill (Espartel sill) of the Strait of Gibraltar by a monitoring station, first installed in year 2004, have been carefully processed to provide the most updated estimation of the outflow of Mediterranean water through the Strait. A comprehensive quality control of the factors affecting the uncertainty of the measurements has been carried out and a great care has been paid to infer the current at the bottom layer, where direct observations are lacking. The mean outflow in the southern channel of the sill section, where the monitoring station is installed, has been estimated as 0.82 Sv (1 Sv = 1x10^6 m^3/s), with an average contribution of the eddy fluxes of 0.04 Sv. This figure is an overestimation, as the vertical profile at the mooring site was assumed valid for the whole section, thus ignoring the lateral friction. On the other hand, it only gives the flow through the south channel and disregards the fraction flowing through shallower north part. Both drawbacks have been addressed by investigating the crossstrait structure of the outflow from hindcasts produced by the MITgcm numerical model, which was run in a highresolution domain covering the Gulf of Cádiz and Alboran Sea basins. An overall rectifying factor of 1.039 was found satisfactory to correct the first estimate, so that the final mean outflow computed from this dataset is 0.85 Sv, which is complemented with an uncertainty of ±0.03 Sv based on the interannual variability of the series. The time analysis of the series shows an outflow seasonality of around the 8% of the mean value, with maximum outflow in early spring. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.

Trabajo presentado en ECSA 56 (Unbounded boundaries and shifting baselines: estuaries and coastal seas in a rapidly changing world), celebrado en Londres del 6 al 9 de septiembre de 2015.

Over the past decade, recruitment processes of the two species of Lepidorhombus that overlap in the southern Bay of Biscay seem to respond to similar patterns. This appears to be partially explained by density independent factors. Before summer, egg and larval drift by the currents over the continental shelf play a key role. After summer, the upwelling strength seems to influence survival of juveniles through food availability., Sí

Biological-physical data from 1993-2000 have evidenced the variability of the oceanographic scenarios in the Cantabrian Sea. A wide casuistic of summer upwelling has been shown. Year-to-year variability of hake recruitments is explained upon aggregation-dispersion of pre-recruits, and survival after area recruitment. Reversal of the current pattern above the continental shelf may affect first the aggregation pattern of larvae and then their survival via blockage of the trophic chain at the primary level. 0