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© 2015. American Geophysical Union. All Rights Reserved. More than 10 year of Acoustic Doppler Current Profiler observations collected at the westernmost sill (Espartel sill) of the Strait of Gibraltar by a monitoring station have been carefully processed to provide the most updated estimation of the Mediterranean outflow. A comprehensive quality control of the factors affecting the uncertainty of the measurements has been carried out and 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 has been estimated as -0.82 Sv (1 Sv = 1 × 106 m3 s-1), with an average contribution of the eddy fluxes of -0.04 Sv. This figure is an overestimation, as the mooring measurements, assumed valid for the whole section, ignore the lateral friction. On the other hand, it only gives the flow through the southern channel and disregards the fraction flowing through shallower northern part. Both drawbacks have been addressed by investigating the cross-strait structure of the outflow from hindcasts produced by the MITgcm numerical model, run in a high-resolution 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 data set is -0.85 Sv, complemented with an uncertainty of ±0.03 Sv based on the interannual variability of the series. The temporal analysis of the series shows an outflow seasonality of around the 8% of the mean value, with maximum outflow in early spring. ; The series of current measurements analyzed in this work has been collected during the INGRES Projects, INGRES (REN2003_01608), INGRES2 (CTM2006_02326/MAR), and INGRES3 (CTM2010_21229-C02-01/MAR), and Special Action CTM2009-05810-E/MAR, funded by the Spanish Government. The mooring line is included in the Mediterranean Sea monitoring network of the HYDROCHANGES project sponsored by CIESM. The CTD/LADCP data set has been provided by the Spanish Oceanographic Institute (IEO) who is coordinate partner of the INGRES3 project. The numerical simulations have been carried out in the framework of the SAMPA project developed in collaboration with the Spanish Port Authority. Partial support has been also provided by projects ENCIBA (CTM2013-40886-P) from the Spanish Government and MOCBASE (RNM1540) from the Junta de Andalucıa ; Peer Reviewed

Time series collected from 2004 to 2020 at an oceanographic station located at the westernmost sill of the Strait of Gibraltar to monitor the Mediterranean outflow into the North Atlantic have been used to give some insights on changes that have been taking place in the Mediterranean basin. Velocity data indicate that the exchange through the Strait is submaximal (that is, greater values of the exchanged flows are possible) with a mean value of ¿0.847 ± 0.129 Sv and a slight trend to decrease in magnitude (+0.017 ± 0.003 Sv decade¿1). Submaximal exchange promotes footprints in the Mediterranean outflow with little or no-time delay with regards to changes occurring in the basin. An astonishing warming trend of 0.339 ± 0.008°C decade¿1 in the deepest layer of the outflow from 2013 onwards stands out among these changes, a trend that is an order of magnitude greater than any other reported so far in the water masses of the Mediterranean Sea. Biogeochemical (pH) data display a negative trend indicating a gradual acidification of the outflow in the monitoring station. Data analysis suggests that these trends are compatible with a progressively larger participation of Levantine Intermediate Water (slightly warmer and characterized by a pH lower than that of Western Mediterranean Deep Water) in the outflow. Such interpretation is supported by climatic data analysis that indicate diminished buoyancy fluxes to the atmosphere during the seven last years of the analyzed series, which in turn would have reduced the rate of formation of Western Mediterranean Deep Water. The flow through the Strait has echoed this fact in a situation of submaximal exchange and, ultimately, reflects it in the shocking temperature trend recorded at the monitoring station. Introduction ; Time series analyzed in this paper have been collected within the frame of INGRES Projects, INGRES1 (REN2003_01608), INGRES2 (CTM2006_02326/MAR), and INGRES3 (CTM2010_21229-C02-01/MAR), Special Action CTM2009-05810-E/MAR, funded by the Spanish Government. Since year 2016, the monitoring station is part of the Spanish Oceanographic Institute (IEO) internal project STOCA in which frame the station is presently serviced with the participation of Málaga University and researchers of the Interdisciplinary Thematic Platform of the CSIC WATER:iOS, with funding provided by the Ministry of Science and Innovation (EQC2018-004285-P) and the European Commission through the project COMFORT (H2020-820989). The mooring line is included in the Mediterranean Sea monitoring network of HYDROCHANGES project sponsored by CIESM, which is part of the CMEMS Marine Copernicus In Situ TAC Program, registered as WMO ID 6202100 in the JCOMM in situ Observations Program Support.

9 pages, 5 figures.-- Under a Creative Commons license ; Small microplastics (SMPs) in the gulf of Cadiz was sampled at 5 m depth by pumping it through the ship's pipe system and filtered through a 45 μm mesh size net. Our study reveals that higher densities have been found (130 mg·m−3) compared to other regions worldwide and these densities decreased from the coastline to the outer stations, showing a general coastal gradient influenced by estuarine outflows. SMPs with a size range between 45 and 193 μm were predominant and most of them composed by polyethylene and polypropylene. The metals associated with the MPs were mainly Na (21.1%), K (11.3%), Fe (8.5%), Ca (2.1%), Cr (1.8%), Zr (13.3%) and Hf (0.7%). The high proportion of Zr compared to Fe, which is different from what can be found in the environment, suggests that this metal is intrinsic to the materials used in catalytic processes during plastic production ; Financial support to EGO and the instrument was given by CSIC through Intramural Research program 2018 under grant number 201830I081. MS is grateful to the Spanish Ministry of Science, Innovation and Universities for the Juan de la Cierva (TJFI-2017-32493) contract. DGF was funded by European Union's H2020-MSCA-IF-2018 846843—LitRivus ; Peer reviewed

Since its foundation, 100 years ago, the Spanish Institute of Oceanography (IEO) has been observing and measuring the ocean characteristics. Here is a summary of the initiatives of the IEO in the field of the operational oceanography. Some systems like the tide gauges network has been working for more than 70 years. The standard sections began at different moments depending on the local projects, and nowadays there are more than 180 coastal stations and deep-sea ones that are systematically sampled, obtaining physical and biochemical measurements. At this moment, the Observing System includes six permanent moorings equipped with current meters, an open-sea ocean-meteorological buoy offshore Santander and a sea-surface temperature satellite image station. It also supports the Spanish contribution to the Argo international programme with 47 deployed profilers, and continuous monitoring thermosalinometers, meteorological stations and vessel-mounted acoustic Doppler current profilers on the research vessel fleet. The system is completed with the contribution to the Northwest Iberian peninsula and Gibraltar observatories, and the development of regional prediction models. All these systematic measurements allow the IEO to give responses to ocean research activities, official agencies requirements and industrial and main society demands such as navigation, resource management, risks management, recreation, as well as for management development pollution-related economic activities or marine ecosystems. All these networks are linked to international initiatives, framed largely in supranational programmes of Earth observation sponsored by the United Nations or the European Union. The synchronic observation system permits a spatio-temporal description of some events, such as new deep water formation in the Mediterranean Sea and the injection of heat to intermediate waters in the Bay of Biscay after some colder northern storms in winter 2005.

Since its foundation, 100 years ago, the Spanish Institute of Oceanography (IEO) has been observing and measuring the ocean characteristics. Here is a summary of the initiatives of the IEO in the field of the operational oceanography. Some systems like the tide gauges network has been working for more than 70 years. The standard sections began at different moments depending on the local projects, and nowadays there are more than 180 coastal stations and deep-sea ones that are systematically sampled, obtaining physical and biochemical measurements. At this moment, the Observing System includes six permanent moorings equipped with current meters, an open-sea ocean-meteorological buoy offshore Santander and a sea-surface temperature satellite image station. It also supports the Spanish contribution to the Argo international programme with 47 deployed profilers, and continuous monitoring thermosalinometers, meteorological stations and vessel-mounted acoustic Doppler current profilers on the research vessel fleet. The system is completed with the contribution to the Northwest Iberian peninsula and Gibraltar observatories, and the development of regional prediction models. All these systematic measurements allow the IEO to give responses to ocean research activities, official agencies requirements and industrial and main society demands such as navigation, resource management, risks management, recreation, as well as for management development pollution-related economic activities or marine ecosystems. All these networks are linked to international initiatives, framed largely in supranational programmes of Earth observation sponsored by the United Nations or the European Union. The synchronic observation system permits a spatio-temporal description of some events, such as new deep water formation in the Mediterranean Sea and the injection of heat to intermediate waters in the Bay of Biscay after some colder northern storms in winter 2005.