BUSCADOR RECOLECTA

24 pages, 7 figures, 10 tables, 2 appendices, supplementary material https://doi.org/10.1016/j.pocean.2019.102136, Mass transports for the thermocline, intermediate, deep and abyssal layers in the Atlantic Ocean, at 30°S and for 2003 and 2011, have been estimated using data from GO-SHIP hydrographic transoceanic sections and applying three inverse models with different constraints. The uppermost layers comprise South Atlantic Central Water (SACW) and Antarctic Intermediate Water (AAIW), with a net northward transport in the range of 12.1–14.7 Sv in 2003 and 11.7–17.7 Sv in 2011, which can be considered as the northward returning limb of the Meridional Overturning Circulation (MOC). The western boundary Brazil Current transports twice as much SACW in 2003 (−20.2 ± 0.7 Sv) than in 2011 (−9.7 ± 0.7 Sv). A poleward current consisting of AAIW and Upper Circumpolar Deep Water (UCDW) flows beneath the Brazil Current. The eastern boundary Benguela Current, characterized by a high mesoscale eddy activity, transports 15.6 ± 0.9 Sv in 2003 and 11.2 ± 0.8 Sv in 2011, east of the Walvis Ridge. In the ocean interior, the northward flow is mainly located east of the Mid Atlantic Ridge (MAR) where Agulhas Rings (ARs), observed in both 2003 and 2011, transport warm and salty water from the Indian to the Atlantic Ocean. For the deep layers, the southward transport of North Atlantic Deep Water (NADW) occurs as the Deep Western Boundary Current and also in the eastern basin. The western and eastern basins transport similar amounts of NADW to the south during both years, although the eastern pathway changes substantially between both years. The total NADW transport, which is also considered the MOC, is in the range 16.3–24.5 Sv in 2003 and 17.1–29.6 Sv in 2011, hence with no significant change, This study has been performed as part of projects: US CLIVAR Repeat Hydrography Program, which is now part of the International GO-SHIP project, with US funding from the US National Oceanic and Atmospheric Administration (NOAA) Climate Program Office, and National Science Foundation Geoscience Division, BOUNDARY (ProID2017010083) funded by RIS-3, PO Feder Canarias, VA-DE-RETRO (CTM2014-56987-P) and SAGA (RTI2018-100844-B-C31) funded by the Spanish Government. [...] EM was supported by NERC national capability funding through the ORCHESTRA (NE/N018095/1) and CLASS (NE/R015953/1) projects, Peer Reviewed

19 pages, 14 figures, 1 table, supporting information https://doi.org/10.1002/joc.6247, We combine daily in situ precipitation data with meteorological reanalysis data in order to explore the contribution of cut-off low systems to the seasonal and inter-annual rainfall variations over Baghdad from 2005 to 2016. During these 12 years (average rainfall of 131 ± 67 mm/year), 38 rainy cut-off lows brought 43% of the total precipitation, with extreme inter-annual variations. Indeed, precipitation associated with autumn cut-off lows was the principal factor that turned an arid into a wet year: during the three most arid years cut-off lows contributed about 25% of the average rainfall (10 out of 40 mm/year) while during the three wettest years they contributed near 67% (171 out of 254 mm/year). The extreme-rain cut-off low systems displayed analogous synoptic characteristics: upper-atmosphere divergence, upwards vertical motions in the middle atmosphere, and lower-atmosphere winds into central Iraq at times when the surface Red Sea and Persian Gulf waters were warmer than the surface air. During those days previous to an extreme event, the surface waters cooled substantially and the amount of precipitable water increased largely, suggesting high latent heat transfer. In order to characterize those conditions that favour rainfall, we focus on the November 18–20, 2013 cut-off low system, which led to the largest flooding and wettest year in Baghdad between 2005 and 2016. The distribution of properties in the middle (500 hPa) and upper (250 hPa) troposphere shows that the region was affected by intense horizontal divergence and upwards motions, coinciding with a surface low over the Arabian Peninsula that caused intense northwards winds over the Persian Gulf and brought substantial moisture to central Iraq. The analysis of several stability indexes indicates that convective instability played a secondary role during the episode., This work has been supported by projects VA‐DE‐RETRO (CTM2014‐56987‐P), FLUXES (CTM2015‐69392‐C3‐3‐R), TECBIOMET (CTM2017‐89565‐C2‐1‐P), and SAGA (RTI2018‐100844‐B‐C33), funded by the Spanish government. Ali Raheem Al‐Nassar wishes to thank the Iraqi Ministry of Higher Education and Scientific Research and the Mustansiriyah University for their support to carry out this research, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

10 pages, 4 figures, supporting information https://doi.org/10.1029/2020GL087108.-- The HadISST1 data were provided by UK Met Office at https://www.metoffice.gov.uk/hadobs/hadisst. The NCEP‐NCAR reanalysis, the NOAA gauge observation‐based global land precipitation reconstruction data, the COBE data and the ERSST5 data were provided by NOAA/ESRL/PSD at http://www.esrl.noaa.gov/psd. The ORAS4 data were provided by the Copernicus Marine Environment Monitoring Service (CMEMS) at ftp://ftp‐icdc.cen.uni‐hamburg.de/EASYInit/ORA‐S4/monthly_1x1, The spatiotemporal evolutions of equatorial Atlantic sea surface temperature anomalies (SSTAs) during Atlantic Niño events and the associated climate impacts on the surrounding continents are extremely diverse. In this study, we construct longitude‐time maps of equatorial Atlantic SSTAs for each observed Atlantic Niño event during 1948–2019 and perform a spatiotemporal empirical orthogonal function analysis to identify the four most frequently recurring Atlantic Niño varieties. The first two contrast the timing of dissipation (early terminating vs. persistent) and the other two the timing of onset (early onset vs. late onset). Largely consistent with the differences in the timings of onset and dissipation, these four varieties display remarkable differences in rainfall response over West Africa and South America. Most of the varieties are subject to onset mechanisms that involve preconditioning in boreal spring by either the Atlantic meridional mode or Pacific El Niño, while for the late onset variability there is no clear source of external forcing, This work was supported by the Spanish Government funding through projects VA‐DE‐RETRO (CTM2014‐56987‐P) and SAGA (RTU2018‐100844‐B‐C33) and by NOAA's Climate Program Office, Climate Variability and Predictability Program (award GC16‐207) and NOAA/AOML. I. V. C. was funded through FPI contract (BES‐2015‐071314), With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

28 pages, We present the historical development of the nutrient stream concept, from the initial ideas on the nutrient‐bearing stratum and the transport of inorganic nutrients by the Gulf Stream to the large‐scale inorganic and organic connections in the entire Atlantic Ocean. We mostly analyze and discuss available literature but also present some novel calculations using cruise data and the velocity fields from numerical re‐analysis data. We first examine and discuss the structure of the Gulf Nutrient Stream, the significance of boundary exchange, and the importance of epipycnal and diapycnal processes. We then move to explore the subtropical and remote pathways into the Gulf Nutrient Stream, including the effect of the returning limb of the global overturning circulation, and end up reviewing the concept of nutrient irrigation of the subpolar gyre and its relevance in the spring–fall maintenance of the spring bloom. We close the chapter with some thoughts on the role of streams in the Earth system, as the key conduit for recycling properties within any ocean subsystem while simultaneously connecting the different subsystems, hence bringing about the complexity of the living planet, This research has been supported by the Spanish government through project VA-DE-RETRO (reference number CTM2014-56987-P). Ignasi VallèsCasanova and Dorleta Orúe-Echeverria have been supported by scholarships from the Spanish government, respectively from the FPI and FPU programs

11 pages, 5 figures, 1 appendix, supplementary movies https://doi.org/10.1017/jfm.2019.730, An exact solution of a stable vortex tripole in two-dimensional (2-D) Euler flows is provided. The stable tripole is composed of an inner elliptical vortex and two small-amplitude lateral vortices. The non-vanishing vorticity field of this tripole, referred to as here as an embedded tripole because of the closeness of its vortices, is given in elliptical coordinates (,) by the even radial and angular order-0 Mathieu functions Je0 () ce0 () truncated at the external branch of the vorticity isoline passing through the two critical points closest to the vortex centre. This tripole mode has a rigid vorticity field which rotates with constant angular velocity equal to 0 Je0 (1) ce0 (0)/ 2, where 1 is the first zero of Jef0 () and 0 is a constant modal amplitude. It is argued that embedded 2-D tripoles may be conceptually regarded as the superposition of two asymmetric Chaplygin–Lamb dipoles, separated a distance equal to 2R, as long as their individual trajectory curvature radius R is much shorter than their dipole extent radius, Partial supportfor this study was obtained through project CTM2014-56987-P (Spanish Ministry of Science and Innovation)

11 pages, 7 figures, 3 tables, This dataset, gathered during the RETRO-BMC cruise, reports multiple-scale measurements at the Confluence of the Brazil and Malvinas Currents. The cruise was carried out between 8 and 28 April 2017 onboard R/V Hespérides, departing from Ushuaia and arriving to Santos. Along its track, the vessel recorded near-surface temperature and salinity, as well as the horizontal flow from 20 m down to about 800 m. A total of 33 hydrographic stations were completed in a region off the Patagonian Shelf, within 41.2°S–35.9°S and out to 53.0°W. At each station, a multiparametric probe and velocity sensors were deployed inside the frame of a rosette used to collect water samples at selected depths; these samples were later used for several water analyses, including inorganic nutrient concentrations. Microstructure measurements were carried out in 11 of these hydrographic stations. In addition, two high-resolution three-dimensional surveys were conducted with an instrumented undulating vehicle between 40.6°S–39.0°S and 55.6°W–53.8°W. Lastly, eight high-frequency vertical profilers were deployed in the region and five position-transmitting drifters were launched. These data allow the description of the Confluence from the regional scale to the microscale, and provide a view of the variability of the frontal region on time scales from days to weeks, This research has been supported by the Spanish government (Ministerio de Economía and Competitividad through project VA-DE-RETRO, CTM2014-56987-P, and Ministerio de Ciencia, Innovación y Universidades through project SAGA, RTI2018‐100844‐BC33). Dorleta Orúe-Echevarría (FPU2013-02884) and Ignasi Vallés-Casanova (BES‐2015‐071314) have also been funded with PhD scholarships by the Spanish government (Ministerio de Ciencia, Innovación y Universidades). Paola Castellanos has been partly supported by the Portuguese government (Fundação para a Ciência e a Tecnologia through project COASTNET, PINFRA/22128/2016), With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

11 pages, 7 figures, 4 tables, supplementary material https://doi.org/10.1016/j.ijheatmasstransfer.2020.120185.-- This article is a publication of the Unidad Océano y Clima of the Universidad de Las Palmas de Gran Canaria, a R+D+I CSIC-associate unit, The large uncertainties in the forecasting of future global climatic conditions endorse the need of developing simple yet credible predicting tools. Here we propose a three-zone steady-state radiative model that maximizes latitudinal heat fluxes and considers the potential effect of the Earth's declination. The model is formulated as a set of five equations and six unknowns (zonal temperatures and widths, and the latitudinal heat transport) that requires specifying the reflected (albedo) and back-to-Earth (greenhouse) radiation fractions and obliges turning the low-latitude temperature into an additional parameter. The results do depend on the Earth declination, with changes of 0.5/1.5 K in the intermediate/high zones, which is interpreted as potentially affecting the greenhouse and high-latitude albedo coefficients. Therefore, we focus on identifying the effects of changes in these parameters – properly selected to represent last-glacial-maximum, modern and end-of the-century conditions. The main change is a large rise of the high-latitude temperature, favored both by a decrease in the high-latitude albedo and an increase in the greenhouse factor. For the other variables, the temporal changes in albedo and greenhouse gases compete among them, resulting in one trend from glacial to modern times and a reversal between preindustrial times and the end of the 21st century (currently a warming-narrowing of the intermediate region and the widening of both the low- and high-latitude zones); however, we note that an increase in the low-latitude temperature would tend to alleviate these changes. Despite its simplicity, the model leads to realistic global trends, becoming a useful simple tool for exploring the sensitivity of the Earth's heat distribution to changes in radiative fluxes and endorsing the validity of the maximum latitudinal-heat-transport premise, This work has been funded by the Spanish Government through projects VA-DE-RETRO (Ministerio de Economía y Competitividad, ref. no. CTM2014-56987-P) and SAGA (Ministerio de Ciencia, Innovación y Universidades, ref. no. RTI2018-100844-B-C33), With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

8 pages, 5 figures, [EN] The oceans are origin and instrument for the life of a planet that, paradoxically, we call Earth. The oceans keep most of the water and other properties that flow in the cycle of life, all of them conditioned by the energy that comes from the Sun. This insolation reaches the surface waters according to latitude and time, and it is incorporated and distributed through the oceans as heat and mechanical and chemical energy. During the processes of incorporation and transformation, the thermodynamic and dynamic conditions of the regional habitats are defined, which give rise to biogeochemical properties and typical communities, and the ocean currents, with a broad range of temporal patterns and spatial structures, shape a circulatory system analogous to other living organisms. A complex network of subsystems with complementary tasks is established: the great planetary organism emerges!, [CAT] Els oceans són origen i instrument per a la vida del planeta que, paradoxalment, anomenem Terra. Els oceans guarden la major part de l’aigua i altres propietats que flueixen en el cicle de la vida, totes elles condicionades per l’energia que ens ve del Sol. Aquesta insolació arriba a les aigües superficials en funció de la latitud i el temps, i s’incorpora i distribueix pels oceans en forma de calor i energia mecànica i química. Durant els processos d’incorporació i transformació, es defineixen les condicions termodinàmiques i dinàmiques dels hàbitats regionals, que donen peu a característiques biogeoquímiques i comunitats pròpies, i són els corrents oceànics els que, amb tot un ventall de patrons temporals i d’estructures espacials, conformen un sistema circulatori anàleg al d’altres éssers vius. S’estableix una xarxa complexa de subsistemes amb tasques complementàries: sorgeix el gran organisme planetari!, Les idees aquí presentades han sorgit al llarg de més d’una dècada de feina en el marc de nombrosos projectes finançats pel Plan Nacional de I+D (CANOA, referència CTM2005-00444/MAR; MOC2, referència CTM2008-06438-CO2; TIC-MOC, referència CTM2011-28867; VA-DE-RETRO, referència CTM2014-56987-P; SAGA, referència RTI2018-100844-B-C33) i pel CSIC (FISIO-CEAN, referència PIF2008-30F0061), Peer reviewed

VII International Symposium on Marine Sciences (ISMS 2020), 1-3 July 2020 (Barcelona).-- 2 pages, Warm phases of the Atlantic Zonal Mode (AZM), known as Atlantic Niño (AN), are caused by a variety of mechanisms. In this study we analyze the diversity of AN-events through an inter-event empirical orthogonal function (EOF) methodology. The first two orthogonal modes, which explain 30% and 24% of the inter-annual variability, allow describing four of the principal spatio-temporal patterns in sea surface temperature (SST). The first two contrast the timing of dissipation (i.e., early-terminating versus persistent), while the other two the timing of onset (i.e., early-onset versus late-onset). Largely consistent with the differences in the timings of onset and dissipation, these four varieties display remarkable differences in rainfall response over West Africa and South America. Some are also subject to onset mechanisms that involve preconditioning in boreal spring from the Atlantic Meridional Mode or El Niño in the Pacific, while for others there is no clear source of external forcing, This work was supported by the Spanish Government funding through projects VA-DE-RETRO (CTM2014-56987-P) and SAGA (RTU2018-100844-B-C33), and by NOAA’s Climate Program Office, Climate Variability and Predictability Program (award GC16-207) and NOAA/AOML. I.V.C. was funded through FPI contract (BES-2015-071314), Peer reviewed

25 pages, 18 figures, 3 tables, 1 appendix, The encountering of the subtropical Brazil Current (BC) and the subantarctic Malvinas Current (MC) along the western margin of the Argentine Basin forms the Brazil-Malvinas Confluence (BMC), one of the most intense open-ocean fronts in the world ocean and a site for the formation of intermediate water masses. Here, we provide a comprehensive description of the BMC based on physical and biogeochemical data – hydrographic stations, profiling floats and subsurface drifters – gathered in March 2015. We use these data in order to characterize the impinging and outflowing currents and to describe the cross- and along-frontal thermohaline structure. In addition, we compare the in-situ measurements with both climatological data and the Mercator Ocean eddy-resolving reanalysis. The hydrographic sections illustrate the contrasting properties between the two western boundary currents: warm, salty, nutrient- and oxygen-poor oligotrophic subtropical waters carried southward by the BC and the cold, fresh, oxygen- and nutrient-rich subantarctic waters carried northward by the MC. The frontal system is also characterized by the presence of thermohaline intrusions, with the cross-frontal gradients and along-front velocities sharpening as the colliding currents shape the frontal system. We also observe brackish waters spreading on top of the frontal jet as a result of both the confluence dynamics and off-shelf advection favored by north-easterly winds. These low-salinity waters are positively correlated with surface ageostrophic speeds over the frontal jet. The cruise data illustrates the high regional and mesoscale variability as compared with climatological conditions, and further document the submesoscale subsurface complexity, which is not properly captured by available operational models, We acknowledge support from the Spanish Government through grants CTM2011-28867 (TIC-MOC project), CTM2014-56987-P (VA-DE-RETRO project) and RTI2018-100844-B-C33 (SAGA project), and through the funding of PhD scholarships for D.O.E. (FPU2013-02884), C.H. (CSIC JAE-Predoc program), S.R.G. (BES-2012-055970) and I.V.C. (BES-2015-071314). We also recognize the institutional support of the Spanish Government through the Severo Ochoa Centre of Excellence accreditation (CEX2019-000928-S), Peer reviewed

Memoria de tesis doctoral presentada por Ignasi Berenguer Vallès Casanova para obtener el título de Doctor en Ciències del Mar por la Universitat Politècnica de Catalunya (UPC), realizada bajo la dirección del Dr. Josep Lluís Pelegrí del Institut de Ciències del Mar (ICM-CSIC).-- 143 pages, figures, appendix, [EN] In the tropical Atlantic, the upper ocean circulation is the area of confluence of two major vertical cells: the large-scale overturning Atlantic Meridional Overturning Circulation (AMOC) and the regional relatively shallow Subtropical Cells (STCs). Both meridional cells interact in a complex system of zonal currents driven by fluctuations of the trade winds. The thermocline waters that subduct in the subtropical South Atlantic join the northward AMOC limb in the western boundary North Brazil Current (NBC). When the NBC crosses the equator it retroflects forced by fluctuations in the easterly winds. These changes in the wind field are part of coupled ocean-atmosphere variations that span across the entire Atlantic and cover a wide range of timescales. The present thesis aims at describing the NBC retroflection in the equatorial band and improving our current knowledge on the upper-ocean circulation in the tropical Atlantic and its interaction with the climate variability.
The NBC system carries warm and highly saline waters from the subtropical gyre to the tropics, for a total of 38.5 Sv and 2.0 PW, in what represents the main AMOC cross-equatorial pathway. This subtropical-tropical transfer accounts for water-mass and heat contributions coming from the eastern subtropical boundary (14.9 Sv, 0.82 PW) and the interior subtropical gyre (7.4 Sv, 0.28 PW). As an opposite path, shallow tropical waters transfer 1.4 Sv and 0.14 PW to the subtropics. Adding interior pathways and tropical recirculation transports, a total of 20.6 Sv and 1.0 PW are effectively exported northward through 5°S.
As the NBC crosses the equator, 11.4±1.3 Sv of South Atlantic waters retroflect into the eastward Equatorial Undercurrent (EUC) at 32°W, which join 2.8±0.4 Sv arriving from the northern hemisphere. The NBC-EUC retroflection takes place at different latitudinal bands. Most of the waters turn eastward south of 3°N (7.2±0.6 Sv) but a substantial amount does so north of this latitude (5.1±0.4 Sv). The variability of the EUC transport at 32°W is characterized by principal spring and secondary fall monthly-mean maximum, with the fall maximum only present in the northern retroflection. At interannual scales the EUC transport shows a weak yet significant correlation with the Atlantic Niño index, and reflects a major increase in the contribution from the South Atlantic tropical waters during 2008-2016 as compared with 1997-2007.
The NBC retroflection occurs within an area where changes in Sea Surface Height (SSH) anomalies (SSHA) respond to the two main modes of Tropical Atlantic Variability (TAV): the Meridional Mode (MM) and Equatorial Mode (EM). During the development of warm (cold) MM events, all North Equatorial Countercurrent (NECC), EUC and north South Equatorial Current (nSEC) intensify (weaken). Conversely, during the decaying phase, anomalous wind curl north of the equator, triggers a downwelling (upwelling) Rossby wave that propagates westward and is reflected at the South American coast. The resultant downwelling (upwelling) Kelvin wave reverses the equatorial zonal gradients in boreal summer, weakening (strengthening) both equatorial nSE and EUC. The activation of the RW-reflected mechanisms shifts the zonal SSHA, enhancing (weakeking) the nSEC and favoring the termination of the EM event. Remarkably, the EUC displays a non-linear response probably as a result of external forcings and/or the intrinsic diversity of the EM. The development of warm EM is accompanied by an anomalous reduction (intensification) of equatorial nSEC and NECC during boreal spring.
The diversity of EM has been studied by applying an empirical orthogonal function (EOF) analysis of a sample of 22 time series of warm EM events (referred as Atlantic Niño). This technique reveals four different types of spatio-temporal distributions of SST anomalies (SSTA) in the equatorial Atlantic in the period 1982-2019. Early-terminanting and persistent categories are associated with different dissipation times for the Atlantic Niño. While early-onset and late-onset refers to the diverse Atlantic Niño timings found in the sample. These four different types of Atlantic Niño are associated with different climatic response on the surrounding continents. Interestingly, early-terminating, persistent and early-onset Atlantic Niño seem to be preceded by local (i.e: MM) and remote (i.e: ENSO) forcings in boreal spring. While, late-onset Atlantic Niño is more related with internal variability, [CAT] La circulació oceànica a les capes superiors de l’Atlàntic tropical es caracteritza per la confluència de dos importants sistemes de circulació meridional: la circulació meridional de gran escala de l’Atlàntic (AMOC, per les seves sigles en anglès) i el sistemes regionals de cèl·lules subtropicals (STCs). Ambdues cèl·lules circulatòries interactuen en un complex sistema de corrents zonals governat pel patró de vents alisis. Les aigües que convergeixen al subtròpic de l’Atlàntic Sud per bombament d’Ekman es situen a la termoclina i retornen cap a l’equador, juntament amb la branca de retorn de la AMOC. Les dos aigües conflueixen al marge occidental constituint el sistema de corrents nord del Brasil (NBUC/NBC). Quan la NBC creua l’equador esdevé inestable per l’absència de Coriolis i es sotmesa als gradients d’altura de la superfície del mar (SSH) associats amb el sistema de vents de component est. Part de la NBC es desenganxa del talús per alimentar les diferents corrents zonals esdevenint un important sistema de retroflexió. La variabilitat d’aquesta retroflexió està per tant lligada a les oscil·lacions del camp de vent predominant i les modificacions associades dels gradients de SSH. Aquestes fluctuacions formen part d’un complex sistema acoblat entre l’atmosfera i l’oceà que es presenta a diferents escales temporals i espacials. L’objectiu d’aquesta tesi és descriure el sistema de retroflexió a la banda equatorial i millorar el nostre coneixement sobre la interacció entre aquest sistema de corrents de les capes superficials i termoclina amb diferents modes de variabilitat climàtica.
El sistema NBC/NBUC transporta un total de 38.5 Sv i 2.0 PW d’aigües relativament salines del gir subtropical de l’Atlàntic Sud que representen el principal camí de retorn de la AMOC. Aquesta transferència subtropical-tropical conté aigües del marge meridional (14.9 Sv, 0.82 PW) i aigües interiors de la conca subtropical (7.4 Sv, 0.28 PW). Per altra banda, aigües de capes superficials provinents del gir tropical es traspassen al gir subtropical amb un total de 1.4 Sv i 0.14 PW. Tenint en compte aquest traspàs, i la recirculació tropical, el resultat es un transport net en direcció nord de 20.6 Sv i 1.0 PW a 5°S. Un cop la NBC creua l’equador 11.4 ± 1.3 Sv de l’Atlàntic Sud alimenten la corrent equatorial situada a la capa de la termoclina (EUC) a 32°W. Aquestes aigües es sumen als 2.8 ± 0.4 Sv provinents de l’hemisferi nord. La retroflexió NBC-EUC es dona lloc a diferents bandes latitudinals al voltant de l’equador. La majoria d’aigües giren en direcció est per sota els 3°N (7.2 ± 0.6 Sv) però una important contribució es dona lloc més al nord (5.1 ± 0.4 Sv). La variabilitat de la EUC a 32°W està caracteritzada per dos màxims a la primavera i tardor boreal. Però el màxim de tardor només es troba present en les aigües del gir més septentrional. A escala interanual, el transport de la EUC mostra una correlació negativa dèbil però significativa amb l’índex de l’Atlàntic Niño i curiosament presenta una tendència positiva entre el període 2008 al 2016 en comparació amb el període 1997-2007.
La retroflexió de la NBC es dona lloc en una àrea on canvis anòmals en l’altura de la superfície del mar (SSHA) responen als dos modes principals de variabilitat climàtica interanual de l’Atlàntic tropical (TAV): el mode meridional (MM) i el mode equatorial (EM), aquest últim conegut també com Atlantic Niño/Niña. Durant el desenvolupament d’un episodi positiu (negatiu) de MM la contracorrent nord equatorial (NECC), EUC i la branca nord de la corrent sud-equatorial (nSEC) s’intensifiquen (es debiliten). Contràriament, durant el decaïment del MM el mecanisme de reflexió d’ona Rossby (RW) al marge occidental esdevé en ona Kelvin que es propaga cap a l’est al llarg de l’equador. Quan arriba al marge oriental de l’Atlàntic tropical la situació es reverteix desenvolupant una zona de convergència o divergència respectivament que equivaldria a EM positiu (negatiu). Tant la corrent superficial nSEC com la NECC es debiliten en situacions de EM positiu, contràriament la EUC no mostra una resposta linear indicant possibles forçaments externs o una alta diversitat dels episodis de EM.
En aquest sentit la diversitat d’episodis positius de EM, anomenats també Atlantic Niño, han estat estudiats aplicant anàlisi de funcions ortogonals en una sèrie temporal de 22 casos. Els resultats mostren quatre tipus de distribució en l’espai-temps d’anomalies de temperatura superficial del mar (SSTA) a l’Atlàntic equatorial. La classificació és en funció del temps en que apareixen i la seva extensió temporal i espacial. Cada un d’aquest quatre tipus d’Atlàntic Niño està associat a una resposta climàtica a les zones continentals del nord-est d’Amèrica del Sud i l’Àfrica Occidental. Curiosament, tres dels quatre tipus s’expliquen per les condicions prèvies locals (i.e: MM) i remotes (i.e: ENSO) durant la primavera anterior, The development of this thesis have been funded by:
• FPI contract BES2015-071314 as part of VADERETRO project. Ministerio de Economia y Competitividad
• VADERETRO. Western boundary retroflections. Ref.: CTM2014-56987-P. Ministerio de Economia y Competitividad.
• Pati Científic. Development of a citizen monitoring program for the Barcelona coastal waters, www.paticientific.org. Ref. 19S01645-006. Institut de cultura de Barcelona. Ajuntament de Barcelona.
• SAGA. South Atlantic Gate-Away. Ref.: RTI2018-100844-B-C33. Ministerio de Economia y Competitividad.
• CLIMATE-COVID19. Ref.: PIM-E-202030E222, Peer reviewed

12 pages, 8 figures, 1 table.-- Data availability: Data will be made available on request, Subpolar coastal waters are key hotspots in the global carbon cycle. However, the small-scale distribution of partial pressure of carbon dioxide (pCO2) in these environments and the physical and biological controls underlying this variability are still poorly understood. Here, we examine simultaneous high-resolution spatial measurements of wind speed and pCO2, temperature, salinity, and in-vivo chlorophyll-a fluorescence (chl-a fluo, a proxy of phytoplankton biomass) in surface waters that were obtained during an oceanographic survey in the Argentinian Beagle Channel (subantarctic Atlantic Patagonian) in early fall 2017. The 240 km study transect (centered at 55°S - 67°W) was divided into two zones: (A1) The Beagle Channel innermost portion, semi-enclosed and subject to strong continental influence and (A2) its eastern outlet towards the open Southwest Atlantic. Discrete seawater samples were also collected for apparent oxygen utilization (AOU), nutrients and pH measurements. High-resolution spatial measurements revealed the persistence of pCO2 below atmospheric equilibrium, increasing in median (interquartile range 25–75%) from 314 μatm in the inner Beagle Channel (A1) to 348 μatm towards the adjacent open sea (A2). A decrease in atmospheric CO2 sequestration was associated with an increase in water temperature from 9.5 °C to 10.7 °C, salinity from 30.8 to 32.5, and chl-a fluo from 2.24 to 2.91 mg m−3 along the coastal-offshore gradient. Low AOU and nutrient levels were found in regions inside the channel. Indeed, the relationships between CO2 and temperature or salinity were significantly different from those expected from the theoretical solubility effect, indicating a dominance of metabolic over physicochemical controls on this gas. Moreover, physical factors such as vertical stratification contributed to the variable surface pCO2 values. These findings reveal the existence of short-scale spatial variability of CO2 in the Beagle Channel, improving our understanding of the multiple controls on atmospheric carbon sequestration in extensive subpolar continental shelves, We acknowledge support from the Spanish Government through grants CTM2014-56987-P (VA-DE-RETRO Project) and RTI2018-100844-B-C33 (SAGA project) and also recognize the institutional support of the Spanish Government through the Severo Ochoa Centre of Excellence accreditation (CEX2019-000928-S). This study was funded by grants from the Council for Research and Scientific Development of Brazil (CNPq, 203366/2019-0, 314995/2020-0) and the Research Support Foundation of the State of Rio de Janeiro (E-26/211.329/2021 and E-26/201.118/2022). H.M. and L.C.C. were awarded by CNPq Research Productivity and FAPERJ Scientist of Our State fellowships. L.C.C. was awarded by UERJ/PROCIENCIA fellowship, Peer reviewed

VII Encuentro de Oceanografía Física (EOF) - Expanding Ocean Frontiers Conference, VIII International Symposium on Marine Sciences, 6-8 July 2022, Las Palmas de Gran Canaria, España, The northward warm North Brazil Current (NBC) in the western tropical Atlantic is the main cross-equatorial pathway of the Atlantic Meridional Overturning Circulation (AMOC). An important part is distributed through the recirculation pathways of the interior basin, which mostly take place through a complex retroflection system. The Equatorial Undercurrent (EUC) arise from the NBC retroflection at the equator transporting thermocline waters from the western to eastern equatorial Atlantic basin.
In this study we characterize this NBC-EUC retroflection with temperature, salinity and velocity data acquired in the framework of MOC2 oceanographic cruise in April 2010. Moreover, we expand our analysis by performing off-line Lagrangian modelling on the 3D velocity field form the ocean-reanalysis GLORYS2v4. From particle trajectories, and their associated transport, we reveal four main water sources and water mass transformations from tropical and subtropical North and South Atlantic regions that feed the NBC-EUC retroflection. The predominant water contribution changes as we shift between density classes and each one is dominated by distinct retroflection latitudinal pathway. Additionally, we describe the seasonal-to-interannual transport variability associated with the coupled ocean-atmosphere tropical Atlantic system. Outstandingly, we show a transport increase of tropical South Atlantic waters from 2008 onwards consistent with the recently reported Subtropical Cells (STCs) intensification, This work has been funded by the Spanish Government through project VADERETRO (Ministerio de Economia y Competitividad, ref. no. CTM2014-56987-P), SAGA (Ministerio de Ciencia, Innovacion y Universidades, ref. no. RTI2018-100844-B-C33) and supported by the Israeli Science Foundation grant 1022/21, Peer reviewed

13 pages, 5 figures, supporting information https://doi.org/10.1029/2022JC018730.-- Data Availability Statement: Microstructure data are available at https://microstructure.ucsd.edu/#/cruise/740H20111224. World Ocean Atlas 2018 climatological data are available from https://www.ncei.noaa.gov/archive/accession/NCEI-WOA18, The rates of isopycnal stirring and water mass transport by mesoscale eddies, and of diapycnal mixing by small-scale turbulence, across the Brazil-Malvinas Confluence (BMC) are assessed from a set of microstructure and hydrographic measurements in the Argentine Basin. This assessment is founded on a theoretical framework that applies a triple decomposition to the temperature variance equation and assumes eddies to transfer potential vorticity downgradient. The BMC is found to host widespread intense isopycnal stirring at rates of O(103–104 m2 s−1), and generally weak diapycnal mixing at rates of O(10−6–10−5 m2 s−1). Despite such disparity, both diapycnal mixing and isopycnal stirring play roles of comparable importance in determining regional water mass properties within surface and mode waters. In deeper layers, isopycnal stirring prevails. Eddies are further diagnosed to effect an important cross-BMC transport, at rates of O(1 m2 s−1). When scaled by the along-stream extent of the BMC, these rates integrate to volume transports that may be as large as O(10 Sverdrups). This suggests that cross-BMC transfers of waters are substantially effected by eddy-induced flows, We acknowledge support from NSF Grant #OCE-1208454 for collection and analysis of the data and the Spanish Government through grants CTM2014-56987-P (VA-DE-RETRO Project) and RTI2018-100844-B-C33 (SAGA project) and through the funding of PhD scholarship for D.O.E. (FPU2013-02884). We also recognize the institutional support of the Spanish Government through the Severo Ochoa Centre of Excellence accreditation (CEX2019-000928-S), Peer reviewed

Special issue Economics of Bioenergy 2015.-- 36 pages, 1 figure, 6 tables, 9 appendix, A feasible way to avoid the risk of energy decline and combat climate change is to build a 100% renewable global energy mix. However, a globally electrified economy cannot grow much above 12 electric terawatts without putting pressure on the limits of finite mineral reserves. Here we analyze whether 12 TW of electricity and 1 TW of biomass (final) power will be able to fuel a future post-carbon economy that can provide similar services to those of a contemporary economy. Contrarily to some pessimistic expectations, this analysis shows that the principle economic processes can be replaced with sustainable alternatives based on electricity, charcoal, biogas and hydrogen. Furthermore, those services that cannot be replaced are not as crucial so as to cause a return to a pre-industrial society. Even so, land transport and aviation are at the limit of what is sustainable, outdoor work should be reorganized, metal primary production should be based on hydrogen reduction when possible, mineral production should be increasingly based on recycling, the petrochemical industry should shrink to a size of 40%–43% of the 2012 petrochemical sector, i.e., a size similar to that the sector had in 1985–1986, and agriculture may require organic farming methods to be sustainable., This work has been partially supported through the project “Vade Retro” (CTM2014-56987-P) of the Research and Development Spanish program. We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI), We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)., Peer Reviewed

28 pages, 13 figures, 3 appendix, The steady flow of three-dimensional isolated axisymmetric baroclinic geophysical vortices in cyclo-geostrophic and hydrostatic balance with spheroidal pressure anomaly gradients is investigated through the analysis of three-parameter vortex families. The vortices have an inner core in near solid-body rotation and zero, or negligibly small, pressure anomaly gradient at the vortex boundary. Thus, these isolated vortices have zero amount of potential vorticity anomaly. As the vortex amplitude parameter a1 is increased in cyclones, static instability at some depth along the vortex vertical axis is reached before centrifugal instability occurs at the minimum of negative vertical vorticity at the surface vortex outer core. In anticyclones, as |a1| increases, centrifugal instability occurs before static instability at the vortex centre. The first vortex family analyzed, denoted V(p,q), is characterized by spheroidal pressure anomaly gradients F′(p,q;x) such that the first ⌊p⌋ (integer part of p) derivatives of F′′(p,q;x) at the vortex centre x=0, and the first ⌊q⌋ derivatives of F(p, q; x) at the vortex boundary x=1 are zero. For comparison purposes two other three-parameter vortex families are introduced, namely the exponential E and the hyperbolic tangent H vortex families. The relation between the parameter values in each vortex family leading to statically stable vortices is provided. The main static instability properties of the three vortex families are similar, but each vortex family has their own qualities which make them more or less appropriate to a particular application, Partial support for this research has come from the Spanish Ministerio de Economía y Competividad (grant numbers CTM2011-2886 and CTM2014-56987-P), Peer Reviewed

Special volume: Planet Ocean. Scientia Marina 80(Suppl.1) 2016.-- 10 pages, 7 figures, [EN] In this work we report short-term measurements of the thermohaline structure and velocity field inside a narrow submarine canyon by means of a yo-yo–like profiler. An Aqualog profiler was deployed inside the Besòs Canyon in the northwestern Mediterranean continental margin, providing a unique data set on the vertical evolution of water column characteristics with unprecedented fine-scale spatial and temporal resolution. The observations reported here show a very dynamic transient short-term response with a complex vertical structure not observed previously in any submarine canyon of this region. The vertical distribution of water masses was characteristic of the western Mediterranean basin with Atlantic waters (AW) at the surface, Western Intermediate waters (WIW) in the middle and Levantine Intermediate (LIW) waters below. Turner angle and empirical orthogonal functions show that double-diffusive and isopycnal mixing are the main dominant processes at small scales. The interfaces of the three layers exhibit highly vertical excursions in relatively short times. At the surface, deepening of AW was observed, associated with flow intensification events. Deeper in the water column, within the submarine canyon confinement, the WIW-LIW interface uplifts about 100-150 m. These motions are associated with relatively up- and down-canyon–enhanced current events (up to 15-20 cm s–1 at 500 and 800 m depths) along the canyon axis. The time scales of the vertical variability were concentrated in a broad band around the semi-diurnal and local inertial frequencies within the WIW and LIW layers, [ES] En este trabajo se muestran medidas a corto plazo de la estructura termohalina y del campo de velocidad dentro de un estrecho cañón submarino a través de un perfilador tipo yo-yo. Este perfilador Aqualog se desplegó dentro del cañón del Besòs en el noroeste del margen continental del Mediterráneo, proporcionando un conjunto de datos único sobre la evolución vertical de las características de la columna de agua, con una resolución espacial y temporal a escala fina sin precedentes. Las observaciones aportadas aquí muestran una respuesta de un periodo transitorio muy dinámico con una estructura vertical compleja no observada anteriormente en ningún cañón submarino de esta región. La distribución vertical de las masas de agua es característica de la cuenca mediterránea occidental con aguas del Atlántico (AW) en la superficie, aguas occidentales Intermedias (WIW) debajo de estas y aguas de Levante Intermedio (LIW) por debajo. Los ángulos de Turner calculados y sus EOFs muestran que la estabilidad a la difusión y mezcla isopicna son los principales procesos dominantes a escalas pequeñas. Las interfaces de las tres capas exhiben excursiones notablemente verticales en tiempos relativamente cortos. En la superficie, la profundización de AW se observó asociada a eventos de intensificación del flujo. A más profundidad en la columna de agua, dentro del régimen de cañón submarino, la interfase WIW-LIW se eleva unos 100-150 m. Tales movimientos se asocian al flujo de agua hacia arriba y hacia abajo del cañón (hasta 15-20 cm s–1 a 500 y 800 m de profundidad) a lo largo del eje del cañón. Las escalas de tiempo de variabilidad vertical aparecen concentradas en una amplia banda de frecuencias alrededor de los periodos inerciales semidiurnos y locales dentro de las capas WIW y LIW, This work was supported by the projects VA-DE-RETRO (CTM2014-56987-P), funded by the Spanish government. EU funded J.S. through the project Marine-Vectors (FP7-KBBE 266445). J.S. also acknowledges a CSIC JAE-Doc contract co-funded by the ESF, Peer Reviewed

Special volume: Planet Ocean. Scientia Marina 80(Suppl.1) 2016.-- 10 pages, 8 figures, 1 table, [EN] Mediterranean Water lenses (meddies) in the eastern North Atlantic, north of the Canary Islands, appear to often have their salty and nutrient-poor core accompanied by relatively fresh and nutrient-rich waters on top. We describe several occurrences of freshwater halos and berets for meddies sampled north of the Canary Islands—with instrumented moorings, Argo floats and oceanographic cruises—and identify the source of these fresh anomalies as diluted Antarctic Intermediate Water (AAIW). We propose that this capping takes place off Northwest Africa, as the southward-advected meddy interacts with the northward-advected AAIW. This interpretation is consistent with a simple analysis of the relevant advective-diffusive time scales associated with the passage of meddies under a layer of AAIW, and suggests that meddies may be a mechanism for AAIW export far into the North Atlantic Ocean, [ES] Los Meddies en el Atlántico Norte oriental, al norte de las Islas Canarias, a menudo parecen tener su núcleo salado y pobre en nutrientes acompañado de aguas relativamente frescas y ricas en nutrientes en la parte superior. Se describen varios casos de halos y boinas de agua dulce para meddies muestreados al norte de las Islas Canarias -con instrumentos anclados, perfiladores Argo y campañas oceanográficas- identificando así el origen de estas anomalías frescas como Agua Intermedia Antártica (AIAA) diluida. Proponemos que esta interacción se lleva a cabo en el noroeste de África, cuando el meddy advectado hacia el sur interactúa con el AIAA advectada hacia el norte. Esta interpretación es coherente con un simple análisis de las escalas de tiempo advectivo-difusivas asociadas con el paso de meddies bajo una capa de AIAA, y sugiere que los meddies pueden ser un mecanismo para exportar AIAA hacia el océano interior en el Atlántico Norte, This work was supported by the projects CANOA (CTM2005-00444/MAR), TIC-MOC (CTM2011-28867) and VA-DE-RETRO (CTM2014-56987-P), funded by the Spanish government. [...] FM was partly supported by the Spanish Ministry of Education and Science through the Juan de la Cierva Programme, Peer Reviewed

Special volume: Planet Ocean. Scientia Marina 80(Suppl.1) 2016.-- 14 pages, 7 figures, 4 appendixes, [EN] Offshore wind is proposed as an energy source to upwell nutrient-rich deep water to the ocean photic layers. A spar-buoy wind turbine with a rigid tube about 300 m long is proposed as a pipe to drive deep water up to the surface. The minimum energy required to uplift the water is the potential energy difference between surface waters inside and outside the pipe, which depends on the background density profile. The corresponding surface jump or hydraulic head, h, calculated for several analytical and experimental density profiles, is of the order of 10 cm. If the complete turbine power (of the order of several MW) is used for raising the water (assuming a 100% pump efficiency), in a frictionless flow, very large water volumes, of the order of thousands of m3 s−1, will be transported to the photic layers. In a more realistic case, taking into account pipe friction in wide pipes, of the order of 10 m radius, and a power delivered to the fluid of 1 MW, the volume transport is still very large, about 500 m3 s−1. However, such a large amount of dense water could sink fast to aphotic layers due to vertical static instability (the fountain effect), ruining the enhancement of primary production. Hence, some ways to increase the turbulent entrainment and avoid the fountain effect are proposed. From the energetic viewpoint, artificial upwelling using offshore wind energy is a promising way to fertilize large open sea regions. This mariculture application is, however, severely subjected to atmosphere and ocean climatology, as well as to ecological dynamics. The general problem is multidisciplinary, and some important physical, engineering and ecological questions need to be seriously addressed to improve our confidence in the approach presented here, [ES] Analizamos el uso de la energía eólica marina como fuente de energía para aflorar aguas profundas ricas en nutrientes a las capas fóticas del océano. Una turbina de viento tipo boya-pértiga, con un tubo rígido de unos 300 m de largo, se propone para transportar las aguas profundas hasta la superficie. La energía mínima necesaria para elevar el agua es la diferencia de energa potencial entre las aguas superficiales dentro y fuera de la tubería, que depende del perfil de densidad de fondo. El salto superficial de agua, o cabezal hidráulico h, calculado para varios perfiles analíticos y experimentales de densidad, resulta ser del orden de 10 cm. Si la potencia total de la turbina (del orden de varios MW) se utiliza para elevar el agua (suponiendo una eficiencia de la bomba del 100%), en un flujo sin fricción, el transporte de volumen de agua transportado a las capas fóticas es muy elevado, del orden de miles de m3 s−1. En un caso más realista, teniendo en cuenta la fricción en tuberías de un ancho del orden de 10 m radio, y una potencia proporcionada al fluido de 1 MW, el transporte volumen sigue siendo muy grande, de alrededor de 500 m3 s−1. Sin embargo, una cantidad tan grande de agua densa podría hundirse rápidamente a las capas afóticas debido a la inestabilidad estática vertical (efecto fuente) arruinando la mejora de la producción primaria. Por lo tanto se proponen algunas maneras de aumentar el arrastre turbulento y evitar el efecto fuente. Desde el punto de vista energético, el afloramiento artificial utilizando energía eólica marina parece una manera prometedora de fertilización de grandes regiones del mar abierto. Esta aplicación de maricultura, sin embargo, depende severamente de la climatología atmosférica y océanica, así como de la dinámica ecológica. El problema global es multidisciplinar, y algunos aspectos importantes de física, ingeniería, y ecología tienen que ser mejor estudiados para poder aumentar nuestra confianza en el método aquí presentado, Partial support for this study was obtained through projects CTM2011-28867 and CTM2014-56987-P (Spanish Ministry of Science and Innovation), Peer Reviewed

Special volume: Planet Ocean. Scientia Marina 80(Suppl.1) 2016.-- 12 pages, 4 tables, [EN] A feasible way to avoid the risk of energy decline and to combat climate change is to build a worldwide, 100% renewable energy mix. Renewable energy can be scaled up to the range of 12 electric terawatts (TWe) if 10% of continental shelves are exploited with floating turbines to depths as low as 225 m, 5% of continents with ground turbines, and 5% of the main deserts with concentrating solar power (CSP) farms. However, a globally electrified economy cannot grow much above 12 TWe without approaching the limit of terrestrial copper reserves. New photovoltaic silicon panels do not use silver metallization pastes and could contribute up to 1 TW of decentralized residential power. Hydroelectricity has a potential of 1 TW but a fraction of this would have to be sacrificed for energy storage purposes. Hydro, CSP, wave energy and grid integration at continental scales may be sufficient to fit supply to demand, avoiding intermittency. The renewable energy mix would have an energy return on energy invested about 18, which is 25% lower than the estimated present one. That should be sufficient to sustain an industrialized economy provided that the substitution of electricity for fossil fuels is done intelligently, [ES] Una forma posible de evitar el riesgo de declive energético y luchar contra el cambio climático sería construir un sistema energético global 100% renovable. Un sistema de energía renovable (ER) se podría escalar hasta el rango de 12 terawatios de electricidad (TWe) si el 10% de las plataformas continentales fueran explotadas con molinos flotantes hasta profundidades de unos 225 m, 5% de los continentes con turbinas terrestres, y el 5% de los principales desiertos fueran utilizados para estaciones de concentración solar (CSP). Sin embargo, una economía electrificada a nivel mundial no puede crecer muy por encima de 12 TWE sin acercarse al límite de las reservas globales de cobre. Los paneles fotovoltaicos (PV) de silicio más recientes no utilizan metalizaciones de plata y podrían contribuir con hasta 1 TW de energía residencial descentralizada. La hidroelectricidad tiene un potencial de 1 TW aunque una fracción de ello tendría que ser sacrificado con fines de almacenamiento de energía. Hidroelectricidad, CSP, energía de las olas y redes integradas de escala continental pueden ser suficientes para ajustar la oferta a la demanda, evitando la intermitencia. El nuevo mix eléctrico tendría una Tasa de Retorno Energético (TRE) de alrededor de 18, un 25% menos que la TRE actual estimada. Eso debería ser suficiente para sostener una economía industrializada, siempre que la sustitución de los combustibles fósiles por electricidad se haga de forma inteligente, This Work has been partially supported by projects “TIC-MOC”, ref. No. CTM2011-28867 and “VA-DE-RETRO”, ref. No. CTM2014-56987-P, financed by the Ministerio de Economía y Competitividad, from the Spanish National Research Programme, Peer Reviewed

18 pages, 13 figures, 2 tables, 1 appendix supplemental material https://dx.doi.org/10.1016/j.dsr.2016.10.003, We explore the associations between larval fish assemblages and oceanographic conditions in the upper ocean (top 200 m) along the African slope, from tropical (15°N) to subtropical (35°N) latitudes, during a period of intense upwelling. In this extensive region, the northward Mauritanian Current and Poleward Undercurrent carry South Atlantic Central Waters (SACW) while the southward Canary Upwelling Current transports North Atlantic Central Waters (NACW). South of Cape Blanc we only find SACW, and north of Cape Blanc there is NACW far offshore and a combination of NACW and SACW nearshore, separated by the Canary Upwelling Front (CUF). The larvae of different myctophid species serve as indicators of the water masses, e.g. S. veranyi and M. punctatum were found in some coastal stations that were dominated by NACW, while the tropical mesopelagic B. argyrogaster, H. macrochir, M. affine and S. kreffti were associated to the SACW. The along-slope offshore convergence of NACW and SACW takes place at the Cape Verde Frontal Zone (CVFZ), representing a region of extensive offshore export for larvae of coastal species, S. pilchardus and E. encrasicolus, far from their nearshore spawning area. The large-scale frontal systems (CVFZ and CUF) and mesoscale eddies contribute to retain larvae within productive waters, influencing both coastal and oceanic species, This research has been funded by the Spanish Ministerio de Ciencia e Innovacion through projects MOC2 (Reference no. CTM2008-06438-C02-01) and VA-DE-RETRO (Reference no. CTM2014-56987-P), Peer Reviewed

29 pages, 15 figures, 1 table, supporting information https://dx.doi.org/10.1002/2016JC012611, Horizontal and vertical motions associated with coherent mesoscale structures, including eddies and meanders, are responsible for significant global transports of many properties, including heat and mass. Mesoscale vertical fluxes also influence upper ocean biological productivity by mediating the supply of nutrients into the euphotic layer, with potential impacts on the global carbon cycle. The Brazil-Malvinas Confluence (BMC) is a western boundary current region in the South Atlantic with intense mesoscale activity. This region has an active role in the genesis and transformation of water masses and thus is a critical component of the Atlantic meridional overturning circulation. The collision between the Malvinas and Brazil Currents over the Patagonian shelf/slope creates an energetic front that translates offshore to form a vigorous eddy field. Recent improvements in gridded altimetric sea level anomaly fields allow us to track BMC mesoscale eddies with high spatial and temporal resolutions using an automated eddy tracker. We characterize the eddies across fourteen 5° × 5° subregions. Eddy-centric composites of tracers and geostrophic currents diagnosed from a global reanalysis of surface and in situ data reveal substantial subregional heterogeneity. The in situ data are also used to compute the evolving quasi-geostrophic vertical velocity (QG-ω) associated with each instantaneous eddy instance. The QG-ω eddy composites have the expected dipole patterns of alternating upwelling/downwelling, however, the magnitude and sign of azimuthally averaged vertical velocity varies among subregions. Maximum eddy values are found near fronts and sharp topographic gradients. In comparison with regional eddy composites, subregional composites provide refined information about mesoscale eddy heterogeneity, E.M. is supported by a postdoctoral grant from the Conselleria d'Educació, Cultura i Universitats del Govern de les Illes Balears (Mallorca, Spain) and the European Social Fund. S.R. and E.M. have been partially supported by the Copernicus Marine Environment Monitoring Service (CMEMS) MedSUB project. P.G. acknowledges the support of NASA grant NNX16AH9G and NSF grant OCE-1558809. J.L.P. wishes to acknowledge support from the VA-DE-RETRO project (CTM2014-56987-P) funded by the Spanish National Research Program. ACC frontal positions were provided by CTOH (http://ctoh.legos.obs-mip.fr). ARMOR3D data supplied by Copernicus Marine Environment Monitoring Service (CMEMS) at http://marine.copernicus.eu/. SRTM bathymetry data taken from http://topex.ucsd.edu/www_html/srtm30_plus.html, Peer Reviewed

35 pages, 23 figures, The Cape Verde (CV) Basin is the site of fronts and currents that function as both barriers and connectors between the tropical and subtropical oceans. Here we review former studies and analyze historical, satellite and numerical data in order to portray the oceanography of the CV Basin, with emphasis on its eastern boundary—the Mauritania Slope (MS) Ocean. This is complemented with the analysis of novel hydrographic data from the continental slope. The CV Basin is a dynamic region, forced by seasonally varying winds that drive both coastal and offshoreupwelling, the latter linked to the Guinea Dome. Its circulation is controlled by the seasonally changing Dome to the south and southwest, with associated cyclonic currents, and by the CV frontal system to the north, with along-slope flow convergence and offshore export. The MS Ocean is the site of the Poleward Undercurrent, undistinguishable from the offshore Mauritania Current during winter–spring. The predominant thermocline water–mass is the nutrient-rich South Atlantic Central Water, almost pure in upper layers (100–300 m)—providing for the high primary production in the entire region—and with substantial North–Atlantic contribution in its lower part (300–550 m)—in what constitutes the poorly–ventilated low oxygen minimum zone; nutrient concentrations keep increasing with depth until the core of the AntarcticIntermediate Waters (700–800 m). The CV Basin holds both the highest primary production and lowest oxygen concentrations for the entire tropical and subtropicalNorth Atlantic gyres, with extensive implications on fisheries, but yet remains a largely unexplored oceanic region, This research has been supported by the VA-DE-RETRO project (CTM2014-56987) with funding from the Spanish government, Peer Reviewed

12 pages, 6 figures, 2 appendixes, supplementary movies https://doi.org/10.1017/jfm.2017.440, Long-term marginal stability of a new family of isolated oceanic vortices is analysed. Sign reversal of the radial gradient of the potential vorticity anomaly, as implied by the isolation requirement, leads to vortex unsteadiness but does not break the coherence of the vortex, which remains marginally stable even for high absolute Rossby numbers . The marginally stable vortices are characterized by a zero amount of potential vorticity anomaly on every isopycnal. The marginally stable final state is an unsteady vortex whose inner one-signed potential vorticity anomaly experiences revolution, rotation, precession and nutation, Partial support for this study was obtained through project CTM2014-56987-P (Spanish Ministry of Science and Innovation), Peer Reviewed

17 pages, 12 figures, A South Atlantic ring is studied through remote sensing altimetry, hydrographic stations, and drifters' trajectories. The ring's core was characterized by warmer and saltier Indian Ocean waters. At the time of the cruise, the ring's signature extended radially out to 124 km and vertically down to 2000 m, and its core absolute dynamic topography (ADT) exceeded the surrounding Atlantic Ocean waters in 0.4 m. The geostrophic velocities were anticyclonic with maximum speeds about 35 cm s−1 at 100 m and reaching negligible values near 4500 m. The rotational transport inside the ring was 33 Sv in the thermocline and intermediate layers. The drifters' data distinguish a 30-km core revolving as a solid body with periodicity near 5 days and a transitional band that revolves with constant tangential velocity, resembling a Rankine vortex. The ADT data identify the ring's track, showing that it was shed by the Agulhas Current retroflection in November 2009 and propagated northwest rapidly during the first 2 months (mean speed of about 10 cm s−1) but slowed down substantially (3–4 cm s−1) between March and July 2010, when it was last detected. The altimetry data also outlines the evolution of the ring's core ADT, radius, vorticity, and, through a simple calibration with the cruise data, rotational transport. In particular, the ring surface and vertical-mean vorticity decay with time scales of 373 and 230 days, respectively, indicating that most of the property anomalies contained by the ring are diffused out to the subtropical gyre before it reaches the western boundary current system, This study has been performed as part of projects MOC2 (CTM2008-06438), VA-DE-RETRO (CTM2014-56987-P), and SeVaCan (CTM2013-48695) funded by the Spanish Government through the Ministerio de Economía y Competitividad, Peer Reviewed

Gasser, Marc ... et al.-- 25 pages, 19 figures, 1 table, supplementary material https://doi.org/10.1016/j.pocean.2017.05.015, The Mediterranean Water leaves the western end of the Strait of Gibraltar as a bottom wedge of salty and warm waters flowing down the continental slope. The salinity of the onset Mediterranean Outflow Water (MOW) is so high that leads to water much denser (initially in excess of 1.5 kg m¿3) than the overlying central waters. During much of its initial descent, the MOW retains large salinity anomalies ¿ causing density anomalies that induce its gravity current character ¿ and relatively high westward speeds ¿ causing a substantial Coriolis force over long portions of its course. We use hydrographic data from six cruises (a total of 1176 stations) plus velocity data from two cruises, together with high-resolution bathymetric data, to track the preferential MOW pathways from the Strait of Gibraltar into the western Gulf of Cadiz and to examine the relation of these pathways to the bottom topography. A methodology for tributary systems in drainage basins, modified to account for the Coriolis force, emphasizes the good agreement between the observed trajectories and those expected from a topographically-constrained flow. Both contour avenues and cross-slope channels are important and have complementary roles steering the MOW along the upper and middle continental slope before discharging as a neutrally buoyant flow into the western Gulf of Cadiz. Our results show that the interaction between bottom flow and topography sets the path and final equilibrium depths of the modern MOW. Furthermore, they support the hypothesis that, as a result of the high erosive power of the bottom flow and changes in bottom-water speed, the MOW pathways and mixing rates have changed in the geological past, This research has been carried out with the support of the Spanish government, through projects MOC2 (CTM2008-06438-C02-01), MED-OUTFLOW 2009 (CTM2008-03422-E/MAR), MED-OUTFLOW-2011 (CTM2010-11488-E) and VA-DE-RETRO (CTM2014-56987-P), Peer Reviewed

Pelegrí, Josep Lluís ... et al.-- Informe de Campaña RETRO-BMC, BIO Hespérides, Ushuaia‐Santos, 8‐28 abril 2017.-- 73 pages, 9 figures, 5 tables, annexes, La campaña RETRO‐MC se realizó a bordo del BIO Hespérides con salida de Ushuaia el 8 de abril y llegada a Santos el 28 de abril de 2017. La campaña se hizo en dos fases, una primera fase de 24 horas de trabajo (8 y 9 de abril) en el Canal de Beagle y una segunda fase de 12 días de trabajo (13 a 24 de abril) en la Confluencia de Brasil‐Malvinas, Proyecto VA‐DE‐RETRO (CTM2014‐56987‐P) Ministerio de Economía y Competitividad, Peer Reviewed

13 pages, 7 figures, 4 tables, supplementary material http://journals.ametsoc.org/doi/suppl/10.1175/JTECH-D-17-0090.1, The variability of a biogeochemical property in the ocean is the outcome of both nonconservative (such as respiration and photosynthesis) and conservative (mixing of water masses with distinct concentrations at origin) processes. One method to separate both contributions is based on a multiple regression of the biogeochemical property in terms of temperature θ and salinity S as conservative proxies of water masses. This regression delivers the variability related to the conservative fraction and hence allows for identifying the residual as the biogeochemical anomaly. Here, the standard multiple linear regression (MLR) method, which assumes that water masses mix locally and linearly, is compared with a nonlinear polynomial regression (PR) over the entire (θ, S) space. The PR method has two important advantages over MLR: allows for simultaneous nonlinear mixing of all water masses and does not require knowing the end-member water types. Both approaches are applied to data along 7.5°N in the equatorial Atlantic Ocean, and the biogeochemical anomalies are calculated for humic-like fluorescent dissolved organic matter, apparent oxygen utilization, and nitrate—all of them related through in situ remineralization processes. The goodness of both approaches is assessed by analyzing the linear dependence and the coefficient of correlation between the anomalies. The results show that the PR method can be applied over the entire water column and yet retains the local variability associated with nonconservative processes. The potential of the PR approach is also illustrated by calculating the oxygen–nitrate stoichiometric ratio for the entire 7.5°N transatlantic section, This research was supported by the Spanish government through projects MOC2 (CTM2008-06438-CO2) and VA-DE-RETRO (CTM2014-56987-P). Patricia De La Fuente would like to thank the Agència de Gestió d’Ajuts Universitaris i de Recerca de la Generalitat de Catalunya (AGAUR) for its financial support through an FI-AGAUR fellowship, Peer Reviewed

48th Liège Colloquium: Submesoscale Processes. Mechanisms, Implications and New Frontiers, 23-27 May 2016, Liège, Belgium.-- 1 page, 7 figures, The Brazil-Malvinas Confluence (BMC), the encountering site of waters of subtropical and subantarctic origin, is one of the most energetic regions in the world ocean. During March 2015, the R/V Hespérides carried out the TIC-MOC cruise, with 14 days of measurements in the BMC region. Field and remote-sensing data collected during the TIC-MOC cruise clearly illustrate the presence of mesoscale and submesoscale structures of different sort on top of the very energetic large-scale Brazil and Malvinas Currents. These two meridional currents, each of the order of 100 km wide, collide frontally before diverting east, leaving behind vortices of opposite sign near the collision region, but also much farther away, as well as multiple submesoscale structures. Here we characterize the spatial structure of the two colliding currents and of three (one cyclone and two anti-cyclones) vortices found in the near field (at distances less than 500 km from the collision point). We use the satellite images to identify several submesoscalar structures at the frontal system and in the margins of both the main currents and the mesoscalar structures. We also employ high resolution field data to study two different types of submesoscale structures observed in the frontal system. These are a very shallow (5-20 m), thin (5-50 km) and intense (velocities close to 2 m s-1) filament that flows east over the frontal system, carrying brackish waters from Rio de la Plata, and a number of relatively small thermohaline intrusions (thickness 10-100 m and width of the order of 10 km) that intrude several tens of km into both sides of the frontal system. An energy analysis of the frontal system shows that the flux of kinetic energy into the confluence region,associated with the two large scale currents,is of the order of 10 GW while the mesoscalar structures in the near field contain some 107-108 GJ of kinetic energy, giving a residence time of the order of 10-100 days. While some of these mesoscalar structures may flow away from the BMC region during these time intervals, others remain in the area for longer periods, hence requiring substantial energy transfer from the meso- to the submesoscale, This work has been supported through projects TIC-MOC (ref. CTM 2011-28867) and VA-DE-RETRO (ref. CTM2014-56987-P) of the R+D Spanish national program. DOE was supported by a pre-doctoral fellowship (ref. FPU13/02884) from the Spanish Ministry of Education, Peer Reviewed

2016 Ocean Sciences Meeting, 21-26 February 2016, New Orleans.-- 1 page, 7 figures, The Inter-Tropical Convergence Zone (ITCZ) oscillates seasonally in the North Atlantic Ocean, its mean position moving between the Equator in February and 10°N in August-September. Further, during its annual march, the ITCZ remains oriented SW-NE, with 10° of latitude difference across the Atlantic. As a consequence, Ekman convergence-divergence changes zonally and seasonally, setting up the sea-surface absolute dynamic topography (ADT) that drives geostrophic currents in the tropical ocean and the adjacent subtropical gyres. The clearest example is the seasonal growth of the North Equatorial Counter Current (NECC) at 6-8°N, as an intense eastward jet in the tropical North Atlantic amid the westward South Equatorial Current (SEC). The NECC starts in the eastern Atlantic in May and progresses west, fed by a northern diversion of the SEC, until it reaches the western boundary in August, causing the retroflection of the North Brazil Current (NBC). The NECC results from the boreal-summer northward penetration of the ITCZ and the associated South Atlantic High: the surface winds cause zonal bands of meridional Ekman convergence (3-7°N) and divergence (7-13°N) that lead to a ridge-valley ADT pattern, with the NECC unfolding at those latitudes of large latitudinal ADT gradients (6-8°N). The NECC intensifies through input from the interior gyres - anticyclonic near the low-latitude ridge and cyclonic around the northern valley, the latter related to the northern subtropical cell - and only after August it fuels from the NBC retroflection. The northern position of the ITCZ prevents analogous jets and retroflections to occur in the southern hemisphere, yet the location where the SEC bifurcates (into the northward NBC and the southward Brazil Current) changes between January (8°S) and June (16°S). Further, between April and July, a ridge-valley ADT distribution appears in the western tropical South Atlantic, giving rise to cyclonic-anticyclonic motions near 12°S-6°S. Here we (1) integrate recent work on the tropical Atlantic, (2) examine several types of observational and numerical data, and (3) use an idealized wind-driven model for the surface ocean, in order to stress the relevance of the ITCZ motion on both the surface circulation patterns and the net latitudinal transport in the tropical and subtropical Atlantic, This research has been supported by the Spanish government through the TIC-MOC (CTM2011- from the ECCO2 model, and (right) at (5.5S, 34W), as inferred from the 200-m climatological outputs from the ECCO2 model. The color bar represents days before 28867) and VA-DE-RETRO (CTM2014-56987-P) projects, Peer Reviewed

12 pages, 11 figures, supplementary data https://doi.org/10.1016/j.dynatmoce.2017.11.004, The interdecadal variability of the atmospheric and oceanic meridional overturning circulation is studied, using a coupled model with two narrow meridional barriers representing the land and a flat bottomed Aquaplanet. Empirical orthogonal function (EOF) analysis are used in the atmospheric and oceanic meridional overturning cells, revealing the atmospheric interdecadal variability is dominated by an annular mode, in both hemispheres, which introduces in the ocean a set of patterns of variability. The most energetic EOFs in the ocean are the barotropic responses from the annular mode. The interaction between the heat anomalies, due to the barotropic response, and the thermohaline circulation of each basin leads to a resonance mechanism that feeds back to the atmospheric forcing, modulating the annular mode spectrum. Besides the barotropic response, the annular mode introduces anomalies of salinity and temperature in the subtropical Atlantic that affects its upper buoyancy. These anomalies are incorporated within the ocean circulation and advected until the areas of deep sinking in the northern Atlantic, impacting on its overturning circulation as well, We are very grateful to the Brazilian National Council of Scientific and Technologic Development (CNPq) for the fellowship (140821/2013-9) and we want specially to acknowledge to the Vale Institute of Technology (ITV) for the financial and academic support to this project. The numerical experiments were conducted at the IO-USP Ocean Modeling Laboratory (LABMON) using computer resources funded by the São Paulo State Foundation for Research Support (FAPESP, Grants 2010/01943-8, and 2011/50552-4). Furthermore, the co-authors acknowledges the Brazilian National Council for Scientific and Technological Development (CNPq) for a Research Fellowship (Grant 302018/2014-0), and the support of the Spanish government, through project VA-DE-RETRO (CTM2014-56987-P), Peer Reviewed

23 pages, 9 figures, 3 tables, supporting information https://doi.org/10.1002/2017JC013509, Ventilation of the eastern South Pacific Oxygen Minimum Zone (ESP-OMZ) is quantified using climatological Argo and dissolved oxygen data, combined with reanalysis wind stress data. We (1) estimate all oxygen fluxes (advection and turbulent diffusion) ventilating this OMZ, (2) quantify for the first time the oxygen contribution from the subtropical versus the traditionally studied tropical-equatorial pathway, and (3) derive a refined annual-mean oxygen budget for the ESP-OMZ. In the upper OMZ layer, net oxygen supply is dominated by tropical-equatorial advection, with more than one-third of this supply upwelling into the Ekman layer through previously unevaluated vertical advection, within the overturning component of the regional Subtropical Cell (STC). Below the STC, at the OMZ's core, advection is weak and turbulent diffusion (isoneutral and dianeutral) accounts for 89% of the net oxygen supply, most of it coming from the oxygen-rich subtropical gyre. In the deep OMZ layer, net oxygen supply occurs only through turbulent diffusion and is dominated by the tropical-equatorial pathway. Considering the entire OMZ, net oxygen supply (3.84 ± 0.42 µmol kg yr) is dominated by isoneutral turbulent diffusion (56.5%, split into 32.3% of tropical-equatorial origin and 24.2% of subtropical origin), followed by isoneutral advection (32.0%, split into 27.6% of tropical-equatorial origin and 4.4% of subtropical origin) and dianeutral diffusion (11.5%). One-quarter (25.8%) of the net oxygen input escapes through dianeutral advection (most of it upwelling) and, assuming steady state, biological consumption is responsible for most of the oxygen loss (74.2%), P.J. Llanillo acknowledges support from CONICYT/FONDECYT through the Postdoctorado project 3150229. J.L. Pelegrí and J. Peña-Izquierdo acknowledge funding by the Spanish Ministerio de Economía y Competitividad through projects TIC-MOC (CTM2011-28867) and VA-DE-RETRO (CTM2014-56987-P), Peer Reviewed

13 pages, 10 figures, 2 tables, supporting information https://doi.org/10.1002/joc.5424, The role that the Indonesian Throughflow plays on climate is investigated in an alternative scenario, expected during glacial ages. The equatorwards shift of the Southern Hemisphere westerlies found in glacial ages acts to decrease the Agulhas Leakage (AL) and the thermohaline circulation (THC) in the Atlantic. Recent results suggest that these changes are followed by an increased THC in the Pacific, through an inter-basin seesaw mechanism. The enhanced circulation in the Pacific demands thermocline water to cross the equator towards northern latitudes, which shifts the water source of the throughflow from the low-salinity North Pacific to the relative saltier South Pacific. It is shown that in this equilibrium, the salinity anomalies of the throughflow impact the inter-basin seesaw towards the restoration of the modern climate, enhancing the North Atlantic Deep Water (NADW) formation and decreasing the THC in the Pacific. These results are consistent with paleo-observations and provide new insights to interpreting the climate changes in glacial periods., We are very grateful to the Brazilian National Council of Scientific and Technologic Development (CNPq) for the fellowship (140821/2013‐9) and we want specially to acknowledge to the Vale Institute of Technology (ITV) for the financial and academic support to this project. The numerical experiments were also a contribution to Projects SAMOC (grant 2011/5055‐4) and SANSAO (grant 2008/58101‐9), funded by the São Paulo State Foundation for Research Support (FAPESP). Furthermore, the co‐authors acknowledges the Brazilian National Council for Scientific and Technological Development (CNPq) for a Research Fellowship (grant 302018/2014‐0), and the support of the Spanish government, through project VA‐DE‐RETRO (CTM2014‐56987‐P), Peer Reviewed

18 pages, 13 figures, tables, 5 appendices, Two fundamental modes of vertical velocity (w) in mesoscale subsurface eddies are described using the quasigeostrophic (QG) approximation and nonhydrostatic numerical modeling. The first mode of w (the spheroidal mode) arises when a spheroidal upright subsurface eddy acquires horizontal eccentricity and becomes an ellipsoid, still upright, vertically symmetric vortex. In this case, the vertical displacement of isopycnals vanishes at the middepth z = 0. Conservation of potential vorticity anomaly (PVA) on elliptical concave/convex isopycnals entails a three‐dimensional octupolar pattern of w which also vanishes at z = 0. The second mode of w (the tilted mode) arises when the eddy remains spheroidal but its vertical axis tilts relative to the vertical direction. In this case, the displacement of isopycnals is largest at the middepth z = 0 and has a dipolar distribution. The associated w is largest at the middepth and develops also a dipolar pattern. In both spheroidal and tilted modes, the vertical velocity pattern may be inferred from the fast advection of PVA conserving fluid particles on slower translating concave/convex or tilted isopycnals. This implies that the vertical velocity of both modes is approximately QG and may be correctly inferred from the QG omega equation as long as the Rossby number remains small. Under more general circumstances, the vortex is both spheroidal and tilted. In this case, both spheroidal and tilted modes coexist but remain, to a large extent, uncoupled, rotating with different and, at least at a first order of approximation, constant phase speeds, Partial support for this study was obtained through project CTM2014-56987‐P (Spanish Ministry of Science and Innovation), Peer reviewed

Emelianov, Mikhail ... et al.-- IV Encuentro Oceanografía Física Española, celebrado del 20 al 22 de julio de 2016 en Alicante,España.-- 2 pages, 1 figure, La Confluencia de Brasil-Malvinas (CBM), donde confluyen las masas de agua de origen subtropical (Corriente de Brasil) y subantártico (Corriente de Malvinas), juega un papel clave en la transferencia meridional de masa, calor y sal, como parte del ramal de retorno de la cinta transbordadora global en el Océano Atlántico. En marzo de 2015 se realizó a bordo del BIO Hespérides la campaña TIC-MOC, con el fin de caracterizar las condiciones oceanográficas en la región de la BMC. Durante la campaña se hicieron 66 estaciones hidrográficas y se lanzaron 8 flotadores y 9 perfiladores de deriva, en lo que resultó ser un muestreo de alta resolución espacio-temporal de los procesos que se desarrollan en la Confluencia a distintas escalas. Las observaciones revelan la colisión frontal de las dos corrientes, cada una de ellas con altas velocidades, que en superficie pueden exceder 1 m s-1. Este choque crea un complejo sistema frontal, con elevados gradientes horizontales de variables físicas y biogeoquímicas, que está caracterizado por intrusiones termohalinas y remolinos de ambos signos, además de un filamento superficial que se extiende hacia el este con velocidades cercanas a 2 m s-1, Este trabajo ha sido posible gracias a la financiación del Ministerio de Economía y Competitividad del gobierno de España, a través de los proyectos TIC-MOC (CTM2011-28867) y VA-DE-RETRO (CTM2014-56987-P), Peer Reviewed

IV Encuentro Oceanografía Física Española, celebrado del 20 al 22 de julio de 2016 en Alicante,España.-- 2 pages, 2 figures, Recent studies have shown that sea surface temperature (SST) and surface wind speed (SWS) are directly related at ocean mesoscales (10-100 km). Here we examine this relationship in the Brazil-Malvinas Confluence region, where we find one of the most intense regional-scale SST gradients in the world's oceans. We analyze SST and SWS collected in situ during an oceanographic cruise done in March 2015. Data is processed to emphasize the variability of SST and SWS associated with oceanic fronts, both at regional and mesoscalar scales, taking into account the latitudinal SST gradients, the passage of atmospheric synoptic disturbances, and the diurnal variability of SWS. We observe that SST has an influence on SWS - a temperature raise of 1ºC involves a wind-speed increase of 0.36 m s-1, with a correlation coefficient of 0.43 and a 95% confidence level - a relationship that is corroborated using wind data from the European Copernicus Project. Finally, we assess the influence of SST on the lower atmosphere through the changes in sensible and latent heat fluxes across the front. The results point at the existence of significant coupling between the upper ocean and the lower atmosphere, This research has been supported by the Ministerio de Economía y Competitividad of the Spanish Government through projects TIC-MOC (CTM2011-28867) and VA-DE-RETRO (CTM2014-56987-P), Peer Reviewed

IV Encuentro Oceanografía Física Española, celebrado del 20 al 22 de julio de 2016 en Alicante,España.-- 2 pages, 2 figures, 1 table, The Brazil Current (BC) and the Malvinas Current (MC) meet at the Brazil-Malvinas Confluence (BMC) region. This encounter is characterized by a complex mesoscale structure, with numerous eddies, filaments and thermohaline intrusions that lead to meridional exchange of mass, heat and salt between both currents. Therefore, the BMC is the site where the subtropical gyre and the ACC exchange key properties, thus playing a fundamental role in the Earth's climate. During March 2015, the R/V Hespérides carried out the TIC-MOC cruise in the BMC with the objective of sampling the BMC with high resolution. Here we use 28 hydrographic sections from this cruise that, together with the South American coast, constitute a closed ocean volume with sides about 400 km, and build an inverse box model to quantify the mass exchange through its contour. We find that mass enters the region predominantly from the north, carried by the BC, and leave through the eastern section; most of the flow from the south also leaves the region through the southern boundary. The results are consistent with the velocity field as measured during the cruise, This research has been supported by the Ministerio de Economía y Competitividad of the Spanish Government through projects TIC-MOC (CTM2011-28867) and VA-DE-RETRO (CTM2014-56987-P). Dorleta Orue-Echeverría has been funded through a FPU contract of the Ministerio de Educación y Ciencia, Peer Reviewed

IV Encuentro Oceanografía Física Española, celebrado del 20 al 22 de julio de 2016 en Alicante,España.-- 2 pages, 2 figues, The Earth's climate is the outcome of numerous feedback energetic mechanisms. Paleoclimatic data tells us that the Earth has shifted between glacial and interglacial periods during the last 3 Myr, alternating between different temperature and atmospheric-CO2 states. Variations in key global processes are responsible for these transitions: CO2 atmospheric concentration, incoming solar radiation, meridional overturning circulation and albedo. Here we propose two simple box-models in order to analyze the effect of these processes on the heat content of the atmosphere and the upper-ocean during the last 450 kyr. The simplest model has only three boxes: atmosphere, upper-ocean and deep-ocean. The atmosphere and upper-ocean are allowed to exchange heat while the upper and deep oceans are connected through the meridional overturning circulation (MOC); it allows assessing the effects of cloud cover, greenhouse gases and MOC on climate but presents several important limitations, e.g. in the absence of a cooling mechanism, the deep ocean would warm up in times scales of order 10 kyr. Hence, we move to a more realistic five-box model, distinguishing now between high- and low-latitude atmospheric and upper-ocean compartments. This model, which adequately reproduces current estimates of preindustrial temperatures and heat fluxes, is used to estimate how these variables changed during glacial periods. Most important, the model helps us assess the relevance of the different physical processes on the Earth's climate, such as the latitudinal exchange within the ocean and atmospheric compartments, the intensity of the MOC and the reflecting power of albedo at high latitudes, This research has been supported by the Ministerio de Economía y Competitividad of the Spanish Government through project VA-DE-RETRO (CTM2014-56987-P). Dorleta Orúe-Echeverría has been funded through a FPU contract of the Ministerio de Educación y Ciencia, Peer Reviewed

IV Encuentro Oceanografía Física Española, celebrado del 20 al 22 de julio de 2016 en Alicante,España.-- 1 page, 1 figure, Temperature-salinity (T-S) diagrams are widely used to spot the temperature (T) and salinity (S) relations at different places and times. They also help visualize how water masses with different T and S values mix up as they propagate away from the formation regions. Potential density (rho) is typically included in these diagrams to emphasize the vertical stability of a given hydrographic cast or to illustrate how two water masses remain at different density levels. Alternatively, we may introduce a new variable that sets a surrogate orthonormal space, with rho on one axis and spiciness (pi) on the other (Flament, 2002; but see Veronis, 1972, and Jackett and McDougall, 1985). Here we discuss how the rho and pi anomalies in this space may be interpreted as latent diapycnal and epipycnal mixing, or mixing yet feasible to take place, between two water masses. We illustrate these concepts with casts that sample the Mediterranean Outflow (MO) running under the North Atlantic Central Waters (NACW) stratum in the eastern Gulf of Cádiz (Fig. 1), This research has been supported by the Ministerio de Economía y Competitividad of the Spanish Government through project VA-DE-RETRO (CTM2014-56987-P), Peer Reviewed

IV Encuentro Oceanografía Física Española, celebrado del 20 al 22 de julio de 2016 en Alicante,España.-- 2 pages, 2 figures, El objetivo del estudio es validar un modelo regional tridimensional que simula la salida de agua mediterránea desde el Estrecho de Gibraltar hacia el Golfo de Cádiz en la época actual. Este modelo está únicamente forzado por la diferencia de densidad existente entre dos aguas tipo idealizadas: agua Atlántica y Mediterránea. La densidad de cada tipo de agua está definida por los correspondientes perfiles de temperatura y salinidad. Mediante la diferente carga hidráulica en el Estrecho, se estudia el ajuste en profundidad del agua mediterránea en su salida desde el Estrecho de Gibraltar hacia la cuenca Atlántica, Este trabajo ha sido financiado por el Ministerio de Economía y Competitividad del gobierno de España a través de los proyectos TIC-MOC (CTM2011-28867) y VA-DE-RETRO (CTM2014-56987-P). Durante la realización de este trabajo, Sergio Ramírez Garrido ha tenido un contrato FPI del Ministerio de Economía y Competitividad vinculado al proyecto TIC-MOC (CTM2011-28867), Peer Reviewed

IV Encuentro Oceanografía Física Española, celebrado del 20 al 22 de julio de 2016 en Alicante,España.-- 2 pages, 2 figures, Un modelo oceánico de cajas, al que se imponen condiciones de conservación de energía interna, de salinidad y de masa, permite establecer (a) en que escenarios se forma agua de mayor densidad en la alta latitud norte, en lo que denominamos situación de estuario inverso o negativo (flujo en sentido norte-sur por el fondo oceánico), y (b) en que otros escenarios dicha formación se produce en las latitudes tropicales, en lo que sería un estuario directo o positivo. Se contrastan los escenarios resultantes a la vista de las condiciones del océano actual, JLP agradece el apoyo recibido por parte del Ministerio de Economía y Competitividad del gobierno de España a través del proyecto VA-DE-RETRO (CTM2014-56987-P), Peer Reviewed

IV Encuentro Oceanografía Física Española, celebrado del 20 al 22 de julio de 2016 en Alicante,España.-- 1 page, 1 figure, Maps of velocity vectors and streamlines, calculated after integration from some reference contour, can be very useful to illustrate the gross characteristics of the changing velocities. Nevertheless, they are only snapshots of the velocity field that cannot be used to directly infer exchange between different oceanic regions. In order to do so, we must use of a Lagrangian approach, where we actually track water parcels as they move under the influence of the spatially and temporally changing velocity fields. Here we present a simple model that integrates monthly velocity fields in time, either forward or backward, in order to track the origin or fate of water parcels. In our case, the velocity fields are inferred from the positions of Argo floats. We illustrate the model by examining the recirculation of intermediate waters in the southern South Atlantic Ocean. The model allows us tracking whether and how the water parcels at these intermediate depths recirculate zonally or drift meridionally. In this application, we carefully explore the important role of the Brazil-Malvinas Confluence and the Agulhas Leakage. We estimate that most of the intermediate waters recirculate across the ocean in time periods between about 15 and 30 years, eventually meeting at the Brazil-Malvinas Confluence region. Our results show no water transfer from the Indian Ocean, i.e. they show no Agulhas Leakage, although this may be an artefact caused by the absence of rings in the mean fields. A remarkable feature is the presence of a meridionally pulsating behaviour in the transoceanic trajectories, best visible in an accompanying video, This research has been supported by the Ministerio de Economía y Competitividad of the Spanish Government through project VA-DE-RETRO (CTM2014-56987-P), Peer Reviewed

IV Encuentro Oceanografía Física Española, celebrado del 20 al 22 de julio de 2016 en Alicante,España.-- 1 page, 1 figure, Since 2007, in the world's oceans there are over 3000 Argo floats that transmit position data typically once every 10 days. This represents some 100.000 positions yearly that lead to an equivalent number of velocity vectors. This massive amount of velocity data allows us constructing monthly-mean fields with spatial resolution of the order of 1º in latitude-longitude. Here we present, for the first time, the monthly sea-surface velocity fields for all oceans, unravelling the spatial distribution of the seasonally evolving fields. The velocity fields are predominantly zonal except for the western boundary subtropical regions. Further, these zonal fields change spatially following the evolution of the Intertropical Convergence Zone and the accompanying low- and high-pressure centres in both hemispheres. The resulting patterns appear as a transoceanic meridional seasonal pulse, typically propagating from south to north and from east to west. This work illustrates the potential of the Argo-inferred velocity data for an improved description of the surface currents at regional and, most remarkably, global scales, This research has been supported by the Ministerio de Economía y Competitividad of the Spanish Government through project VA-DE-RETRO (CTM2014-56987-P), Peer Reviewed

IV Encuentro Oceanografía Física Española, celebrado del 20 al 22 de julio de 2016 en Alicante, España.-- 3 pages, 1 figure, Satellite-tracked drifting buoys are useful for sampling sea-surface currents. Standard drifting buoys have drogues centred at a depth of 15 m, a fundamental element that guarantees that the direct wind force on the buoy is much smaller than the drag on the anchor. When a drifter loses its drogue, it no longer becomes a good tracker of the surface currents, hence the relevance of identifying when this happens. Here we propose a spectral-based approach to analyse drifter velocity data so as to detect when a drifter loses its drogue without the need of concurrent wind data. The method, applied to data obtained during the SPURS 2013 cruise, shows a substantial increase in the band-passed velocity energy at the time the drifter loses its drogue, as deduced with an independent method that considers the temporal change of the correlation between wind and positioning data. The results are very promising, pointing at a new method that can detect drogue loss from a relatively simple analysis of positioning data, This research has been supported by the Ministerio de Economía y Competitividad of the Spanish Government through project VA-DE-RETRO (CTM2014-56987-P). Ignasi Vallès has been funded through a FPI contract of the Ministerio de Competitividad y Economía. The drifter data was obtained following deployments during the SPURS cruise, in the frame of the MIDAS-6 (AYA2010-22062-C05-01) project, financed by the Ministerio de Economía y Competitividad of the Spanish Government, Peer Reviewed

Any ocean perturbation tends towards an equilibrium situation where the vertical balance is hydrostatic and the dominant horizontal forces are pressure gradients and Coriolis force, the so called geostrophic balance. Any motion that represents a desviation from this balance is named ageostrophic. At spatial and temporal scales of order 10-100 km (mesoscale) and longer, these desviations are small except within boundary layers related to the sea-surface wind stress and the sea-bottom friction. At shorter scales (submesoscale), however, they may represent a major part of the motion: these ageostrophic movements correspond to high Rossby values (the ratio of the inertial period, of order 1 day, and the advective time scale) and are usually accompanied by significant vertical motions.
The Brazil-Malvinas Confluence (BMC) region is located approximately 200-400 km offshore from Rio de la Plata, where the Brazil Current (BC) and Malvinas Current (MC) collide [1]. This clash leads to the generation of very energetic mesoscale and submesoscale features, as well as to different kinds of propagating waves. During March 2015, the R/V Hespérides sampled the BMC with several high resolution transects of the BMC frontal region (Figure 1), including velocity, temperature and salinity measurements (TIC-MOC cruise). These field data is complemented with data from satellites, the Argo program and the Copernicus operational model. Here we present the results of the data analysis, including the determination of vertical velocities as obtained solving the Omega equation. The BMC turns out to be a region with very energetic ageostrophic motions, characterized by a surface filament and subsurface thermohaline intrusions, as well as substantial vertical velocities, This research has been supported by the Ministerio de Economía y Competitividad of the Spanish Government through projects TIC-MOC (CTM2011-28867) and VA-DE- RETRO (CTM2014-56987-P), Peer Reviewed

12 pages, 3 figures, tables, 1 appendix, supplementary movies are available at https://doi.org/10.1017/jfm.2018.892, Exact solutions for multipolar azimuthal-mode vortices in two-dimensional Euler flows are presented. Flow solutions with non-vanishing far-field velocity are provided for any set of azimuthal wavenumbers m and arbitrary number n of vorticity shells. For azimuthal wavenumbers m=0 and m=1, the far-field velocity is a rigid motion and unsteady flow solutions with vanishing far-field velocity are obtained by means of a time-dependent change of reference frame. Addition of these first two modes, in the case of n = 1, results in a particular Chaplygin-Lamb (C-L) dipole, with continuous and vanishing vorticity at the vortex boundary. Numerical simulations suggest that this particular C-L dipole is stable, Partial support for this study was obtained through project CTM2014-56987-P (Spanish Ministry of Science and Innovation), Peer Reviewed

Orúe-Echevarría, Dorleta ... et al.-- 10 pages, 7 figures,4 tables, supplementary material https://doi.org/10.1016/j.dib.2018.12.004, This oceanographic dataset was gathered during the TIC-MOC cruise, which was designed to characterize the dynamics of the Brazil-Malvinas Confluence. The cruise was carried on board the R/V Hespérides, with departure from Ushuaia and arrival to Salvador de Bahía. A total of 66 conductivity-temperature-depth (CTD) stations were completed between 8 and 22 March 2015, offshore from the continental platform and within 45°S-35°S and 61°W-50°W. At each station, water samples were collected, which were used to calibrate the CTD salinity-oxygen sensors and to determine inorganic nutrient concentrations, and the horizontal current was measured. Along its track, the vessel recorded surface temperature and salinity, as well as the horizontal flow down to about 700 m. Lastly, eight position-transmitting drifters were launched and two profiling floats were deployed and later recovered, This research has been supported by the Spanish Government, through projects TIC-MOC (CTM2011-28867) and VA-DE-RETRO (CTM2014-56987-P) and through the funding of PhD scholarships for D.O.E. (FPU2013–02884), S.R.G. (BES-2012–055970) and C.H. (CSIC JAE-Predoc program), Peer Reviewed

28 pages, 17 figures, 4 tables, supporting information https://doi.org/10.1029/2018JC014733, The Brazil‐Malvinas Confluence arises from the frontal encountering of the subtropical Brazil Current and subantarctic Malvinas Current. It displays a complex regional circulation that is accompanied by mesoscale features and thermohaline intrusions. Here we combine altimetry and cruise data to describe the circulation pattern in the upper 2,000 m at two spatial scales encircling the frontal system. The major regional features appear south of the confluence latitude at 39–40°S: (a) a relatively weak Malvinas Current near 41°S, 56°W (28.3 ± 1.4 Sv), followed by its cyclonic retroflection; (b) an intense subtropical anticyclone (59.3 ± 10.7 Sv) that replaces the Brazil Current overshoot; and (c) a very intense subantarctic inflow (78.9 ± 13.7 Sv) near 53°W that is maintained through both an upstream (near 42°S) earlier diversion of the Malvinas Current and the cyclonic recirculation of the flow exiting east along the confluence. North of the confluence, the Brazil Current provides a net input of 30.8 ± 12.0 Sv (29.1 ± 8.3 Sv along the slope). The southern inflow splits nearly equal between barotropic and baroclinic contributions while the entire northern flow is essentially baroclinic. These northern and southern inputs add to an eastward along‐front transport of 109.7 ± 15.1 Sv, with significant contribution of highly oxygenated, relatively fresh Subantarctic Mode and Antarctic Intermediate Waters (58.7 ± 5.6 Sv). The regional circulation experiences substantial temporal variability, with southern waters flowing into the Brazil‐Malvinas Confluence through along‐slope and interior pathways and partly recirculating within the subtropical South Atlantic gyre, This research has been supported by the Spanish Government through projects TIC‐MOC (CTM2011‐28867) and VA‐DE‐RETRO (CTM2014‐56987‐P), and by RIS‐3, PO Feder Canarias through project BOUNDARY (ProID2017010083). Dorleta Orúe‐Echevarría has been funded through an FPU contract (ref. FPU2013‐02884)., Peer Reviewed

6th Euro-Argo Users Meeting, 4-5 July 2017, Paris, France, Ten years ago we began deploying Argo drifters during regional cruises, and this has been repeated for several regions: the Canary and Cape Verde Basins, the western equatorial Atlantic and the Brazil-Malvinas Confluence (BMC). Suring a field experiment, several floats were deployed in different areas of the study region, such as in both sides of a frontal system. The floats were always simultaneous with a CTD cast whose data was immediately transmitted to the Euro-Argo centre. In all instances the floats provided additional data for characterizing the study area. Here we report on floats deployed during a recent cruise (RETRO-BMC) carried out in the BMC, between 8 and 28 April 2017 onboard the R/V Hespérides. The vessel departed from Ushuaia (Argentina) and arrived to Santos (Brazil). A total of 6 floats were deployed during the cruise, four of them in the frontal system itself and two of them in the Malvinas and Brazil Currents before arrival and after departing the BMC. Those floats deployed near the frontal system had a high-frequency cycling of once per day down to 2000 m during the first 20 days of operation, providing for a total of 80 additional CTD casts in the area of study, synoptic with the cruise CTD casts. These experiments are a good example of a highly beneficial synergetic effort of Euro-Argo and the research teams, VA-DE-RETRo CTM2014-56987-P, Peer Reviewed

17 pages, 8 figures, supplementary material https://doi.org/10.3390/rs11070802, Three of the world’s most energetic regions are in the tropical and South Atlantic: the North Brazil Current Retroflection, the Brazil-Malvinas Confluence, and the Agulhas Current Retroflection. All three regions display offshore diversions of major boundary currents, which define the intensity of the returning limb of the Atlantic meridional overturning circulation. In this work, we use a sea-surface salinity (SSS) satellite product, combined with a high-resolution numerical model and in situ measurements, in order to explore the seasonal variation of the surface currents and transports in these three regions. The analysis of the model output shows that the SSS patterns reflect the surface velocity structure, with the largest horizontal SSS gradients coinciding with those areas of highest velocity and the most predominant velocity vector being 90° anticlockwise (clockwise) from the horizontal SSS gradient in the northern (southern) hemisphere. This information is then applied to the SSS satellite product to obtain maps of water velocity and salt transports, leading to a quantitative tool to estimate both water and salt transports in key regions of the world ocean, This work has been funded by the Spanish government through the National R+D Plan through projects VA-DE-RETRO (reference number CTM2014-56987-P), Promises (reference number ESP2015-67549-C3) and L-Band (reference number ESP2017-89463-C3-1-R). The HYCOM numerical experiment was supported by the São Paulo State Foundation for Research Support (FAPESP, Grants: 2008/58101-9, 2010/01943-8, and 2011/50552-4). E. Campos acknowledges the Brazilian National Council for Scientific and Technological Development (CNPq) for a Research Fellowship (Grant 302018/2014-0) and FAPESP (Grants, 2017/09659-6), We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)