Francisco Machín

Universidad de Las Palmas de Gran Canaria | ULPGC · Department of Physics

The radial offset by diffusion (ROD) approach uses the radial deviations between actual drifters and numerical simulated drifters to compute horizontal diffusivities. These radial distances are assumed to respond to subgrid processes not considered by the numerical circulation models.

Distributions of dissolved (DOM) and suspended (POM) organic matter, and their chromophoric (CDOM) and fluorescent (FDOM) fractions, are investigated at high resolution (< 10 km) in the Cape Verde Frontal Zone (CVFZ) during fall 2017. In the epipelagic layer (< 200 m), meso- and submesoscale structures (meanders, eddies) captured by the high resolu...

In this work, the microplastic content of sediments collected in July 2020 between 5 and 7 m depth was studied in four locations of La Palma island (Canary Islands, Spain). At each sampling location, three samples were taken parallel to the shoreline. The microplastic content in each sampling corer was studied every 2.5 cm depth after digestion wit...

Temperature and conductivity fluctuations caused by the hydrothermal emissions released during the degasification stage of the Tagoro submarine volcano (Canary Islands, Spain) have been analysed as a robust proxy for characterising and forecasting the activity of the system. A total of 21 conductivity-temperature-depth time series were gathered on...

The global upper ocean has been warming during the last decades accompanied with a chlorophyll‐a (Chl‐a) and productivity decrease. Whereas subtropical gyres show similar trends, Eastern Boundary Upwelling Systems are thought to increase in productivity due to increased trade winds. This study analyzes recent trends in sea surface temperature (SST)...

Southern Ocean waters enter the South Atlantic Ocean through the Scotia Sea along pathways constrained by the bathymetry of the northern Scotia Sea passages. We use the Argo profiling‐float data set to calculate the water transports in and out of the region, focusing on the water balances down to the deepest isoneutral sampled in all passages (γⁿ =...

The circulation patterns in the confluence of the North Atlantic subtropical and tropical gyres delimited by the Cape Verde Front (CVF) were examined during a field cruise in summer 2017. We collected hydrographic data, dissolved oxygen (O2) and inorganic nutrients along the perimeter of a closed box embracing the Cape Verde Frontal Zone (CVFZ). Th...

Nowadays it is widely known that pollution by microplastics (MP) at the open ocean covers immense areas. Buoyant plastics tend to accumulate in areas of convergence at the sea surface such as subtropical gyres, while non-buoyant plastics accumulate at the seafloor. However, previous studies have revealed that the total amount of plastic in the diff...

The circulation patterns in the confluence of the North Atlantic Subtropical and Tropical gyres delimited by the Cape Verde Frontal Zone (CVFZ) in summer 2017 were examined. Hydrology, dissolved oxygen (O2) and inorganic nutrients data collected in a closed box embracing the CVFZ allowed estimating transports of water masses, O2 and inorganic nutri...

The circulation patterns and the impact of the lateral export of nutrients and organic matter off NW Africa are examined by applying an inverse model to two hydrographic datasets gathered in fall 2002 and spring 2003. These estimates show significant changes in the circulation patterns at central levels from fall to spring, particularly in the sout...

The Coastal-Ocean Carbon Exchange in the Canary Region Project (COCA) arises in order to analyse and get to understand the impact of lateral export of nutrients and organic matter from the highly productive Coastal Upwelling System off NW Africa in the biogeochemical cycles during two different seasons. The circulation patterns off NW African Upwel...

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...

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 (M...

Coastal upwellings along the eastern margins of major ocean basins represent regions of large ecological and economic importance due to the high biological productivity. The role of these regions for the global carbon cycle makes them essential in addressing climate change. The physical forcing of upwelling processes that favor production in these...

Coastal upwelling along the eastern margins of major ocean basins represent regions of large economic importance due to the high biological productivity. However, the physical forcing of upwelling processes that favor the production in these areas are being affected by global warming, which will modify the intensity of the upwelling and, consequent...

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 moo...

The water mass pathways to the North Atlantic Oxygen Minimum Zone (naOMZ) are traditionally sketched within the cyclonic tropical circulation via the poleward branching from the eastward flowing jets that lie south of 10°N. However, our water mass analysis of historic hydrographic observations together with numerical Lagrangian experiments consiste...

We use a combination of satellite, in situ and numerical data to provide a comprehensive view of the seasonal coastal upwelling cycle off NW Africa in terms of both wind forcing and sea surface temperature (SST) response. Wind forcing is expressed in terms of both instantaneous (local) and time-integrated (non-local) indices, and the ocean response...

In this study we estimate diffusive nutrient fluxes in the northern region of Cape Ghir upwelling system (Northwest Africa) during autumn 2010. The contribution of two co-existing vertical mixing processes (turbulence and salt fingers) is estimated through micro- and fine-structure scale observations. The boundary between coastal upwelling and open...

Del 18 al 29 de octubre de 2010 se llevó a cabo la campaña oceanográfica PROMECA en la parte occidental de la Cuenca Canaria con en el buque oceanográfico García del Cid, figura 1. Uno de los objetivos principales del proyecto se centra en el estudio del sistema de afloramiento noroccidental africano en la región de Cabo Ghir. En dicha región se re...

The eastern boundary of the North Atlantic subtropical gyre (NASG) is an upwelling favorable region characterized by a mean southward flow. The Canary Upwelling Current (CUC) feeds from the interior ocean and flows south along the continental slope off NWAfrica, effectively providing the eastern boundary condition for the NASG.We followa joint appr...

We use three transatlantic cruises (1957, 1993 and 2010) along 7.5°N to analyse inter-decadal variations of the neutral buoyancy frequency (with neutral density replacing potential density) and Turner angle. We also use Argo data from the 2003-2011 period to show that, within central and intermediate waters, the changes between the three sections a...

Analysis of in situ and remove-sensed data over the North Atlantic revealed that 2010 was an atypical year: the surface temperatures were the highest during the last 30 years, the wind intensity has strongly decreased in the subtropical and tropical North Atlantic Ocean, the North Atlantic Oscillation (NAO) index reached a strongly negative value....

One oceanographic survey was carried out within a project multidisciplinary (PROMECA) from 18 to 29 October 2010 in the Canary Basin. During three days, Conductivity -Temperature depth (CTD), Expandable Bathytermograph (XBT) and Microstructure turbulence (free fall profilers: turboMAP and Baklán) data were obtained in several stations in the Cape G...

During the year 2008, using the commercial passenger ship Volcán de Tauce of the Naviera Armas company several months, it was possible to obtain vertical profiles of temperature from expandable bathythermograph probes in eight stations across the Tenerife - La Gomera channel. With these data of temperature we have been estimated vertical sections o...

An oceanographic survey was carried out from 18 to 29 October 2010 in the Canary Basin (PROMECA project). Near Cape Ghir, in the Northwest Africa coastal upwelling, 17 CTD casts were made to obtain continuous records of conductivity and temperature with depth, and to collect waters samples for nutrients analyses. Additionally, free-fall turbulence...

One of the longest current meter time series in the Lanzarote Passage in the eastern boundary of the North Atlantic Subtropical Gyre has been used to determine and quantify the 9-year mean transport, the inter-annual and seasonal mass transport variability for the three water masses present in the area. Results show North Atlantic Central Water (NA...

Numerous climatologies are available at different resolutions and cover various parts of the global ocean. Most of them have a resolution too low to represent suitably regional processes and the methods for their construction are not able to take into account the influence of physical effects (topographic constraints, boundary conditions, advection...

Two 9-yr current-meter and salinity records, together with climatological data, reveal marked seasonal variability of the intermediate flow at a key location in the Canary Basin. The region is characterized by a summer (July-September) and early fall (October) northward progression of Antarctic Intermediate Water followed by a fall (November-Decemb...

We test the skill of a polynomial fit to reproduce the upper ocean (down to 750 m) salinity in the eastern North Atlantic (from the Canary Islands to the Iberian Peninsula, approximately 12° × 12°) as a function of temperature and depth. A historical database, constructed by merging several regional datasets, is used. An ANOVA test is performed to...

We report, from remote sensing and in situ observations, a new type of permanent structure in the eastern subtropical Atlantic Ocean, that we call the “Canary Eddy Corridor”. The phenomenon, is a zonal long-lived (>3 months) mesoscale eddy corridor, whose source is the flow perturbation of the Canary Current and the Trade Winds at the Canary Island...

During years 2003 and 2004 both Sedlo and Seine Seamounts, lying in the area of influence of the Mediterranean water outflow in the Northeast Atlantic, were investigated in the framework of the EUfunded project OASIS. Analysis of CTD data shows that the levels of major variability in temperature and salinity were confined to the upper ocean layer,...

Mediterranean Water eddies (meddies) are thought to play an important climatic role. Nevertheless, their dynamics are not sufficiently known because of difficulties encountered in their observation. Though propagating below the main thermocline, a number of pieces of evidence of sea surface manifestation of meddies are collected. The present work i...

WeusedatafromahydrographiccruiseinNovember2003overSedloSeamount,inconjunctionwith historical hydrographicandaltimeterdata,todescribethecirculationpatternsneartheseamountand withintheregion.Amixingmodelthatincorporatestwowatertypesandtwowatermassesassessesthe watercompositionwithintheregion,andaninversemodelprovidesestimatesofmasstransports withindi...

Seismic reflection profiling is applied to the study of large scale physical oceanographic processes in the Gulf of Cádiz and western Iberian coast, coinciding with the path of the Mediterranean Undercurrent. The multi-channel seismic reflection method provides clear images of thermohaline fine structure with a horizontal resolution approximately t...

We propose a simple polynomial expression for neutral density and nutrients as a function of potential temperature, pressure and salinity. The expression is applied to the 1988 North Atlantic A16N WOCE meridional section and the polynomial coefficients are calculated using an inverse technique. The resulting polynomials show good skill in reproduci...

Numerous climatologies are available at different resolution and cover various part of the global ocean. Most of them have a resolution too low to represent suitably regional processes and are not able to not take into account the influence of physical effects (coast, boundaries, advection etc). We developed a high-resolution atlas for temperature...

In this article, historical and climatological datasets are used to investigate the seasonal northward propagation of Antarctic Intermediate Waters (AAIW) along the eastern margin of the North Atlantic subtropical gyre. A cluster analysis for data north of 26°N shows the presence of a substantial number of hydrographic stations with AAIW characteri...

This work illustrates the great potential of multichannel seismic reflection data to extract information from the finestructure of meddies with exceptional lateral resolution (10-15 m). We present seismic images of three meddies acquired in the Gulf of Cadiz (SW Iberian Peninsula), which consist of concentric reflectors forming oval shapes that sha...

The Azores-Canary region, located off NW Africa, is characterised by a strong mesoscale variability induced by the presence of the Canary archipelago in the passage of the Canary Current, the outflow of Mediterranean water and up-welling filaments generated near the capes (Ghir, Jubi, Blanco) of the NW Africa coast. The available climatologies (Wor...

Diva (Data-Interpolating Variational Analysis) is a method designed to per-form data-gridding (or analysis) tasks, with the assets of taking into account the intrinsic nature of oceanographic data, i.e. the uncertainty on the in situ measurements and the anisotropy due to advection and irregular coastlines and topography. In the present work, three...

Based on hydrographic sections carried out during the last decade in the Canary region at 29° 10′N, we show that there has been a statistically significant rise in temperature and salinity on isobars between 1500 and 2300 db. The maximum increase, found at 1600 db, is occurring at a rate of 0.29°C and 0.047 per decade. Isobaric change decomposition...

[EN] A methodology for recovering salinity from expendable bathythermograph (XBT) data is presented. The procedure exploits climatological relationships between temperature, salinity and depth to build regional characteristic curves by fitting a polynomial function that minimises both the variance of residuals and unknowns. Hence, salinity is compu...

We study the dependence of salinity on temperature in two by two degrees latitude-longitude boxes, for surface and upper-thermocline waters of the eastern North Atlantic subtropical gyre. The initial data set, from historical databases as well as from recent hydrographic cruises in the region, is carefully scrutinized to reject dubious measurements...

Esta contribución pretende divulgar el proyecto ESASSI, un proyecto coordinado planteado por el IMEDEA y la Universidad de Málaga (con participación de personal del ICM de Barcelona) y con la colaboración de la Texas A&M University. El proyecto se presentó a la convocatoria extraordinaria del Ministerio de Educación y Ciencia para proyectos a desar...

Ocean studies in the 1970s provided an improved knowledge of the coastal upwelling region off NW Africa while in the 1980s and 1990s they led to a good description of the open ocean flow patterns in the Canary Basin. It was not until the late 1990s that major research addressed the open-coastal ocean coupled response. Here we examine the mean and s...

We study the dependence of salinity on temperature in two by two degrees latitude-longitude boxes, for surface and upper-thermocline waters of the eastern North Atlantic subtropical gyre. The initial data set, from historical databases as well as from recent hydrographic cruises in the region, is carefully scrutinized to reject dubious measurements...

We have used several data sets (expandable bathythermograph sections, buoy trajectories, current-meter moorings, and surface wind stress) to investigate the temporal variation of the upper-thermocline (North Atlantic Central Waters) circulation patterns in the southern Gulf of Cádiz. The main data set consists of eight expandable bathythermograph s...

We study the dependence of salinity on temperature in two by two degrees latitude-longitude boxes, for surface and upper-thermocline waters of the eastern North Atlantic subtropical gyre. The initial data set, from historical data-bases as well as from recent hydrographic cruises in the region, is carefully scrutinized to reject dubious measurement...

The Lagrangian nature of cycling floats is evaluated in the framework defined by the Deep Western Boundary Current of the Mid-Atlantic Ridge. In a statistical approach, speeds and drifts are estimated for an APEX cycling float and compared with the velocities inferred from a park ensemble of four eddy-resolving RAFOS floats. They were deployed at t...

The Lagrangian nature of cycling floats is evaluated in the framework defined by the Deep Western Boundary Current of the Mid-Atlantic Ridge. In a statistical approach, speeds and drifts are estimated for an APEX cycling float and compared with the velocities inferred from a park ensemble of four eddy-resolving RAFOS floats. They were deployed at t...

We apply an inverse model to a hydrographic cruise that completely closes the Canary Islands to investigate their effect on the water masses transports. Most central waters are transported south between the eastern islands and the African coast, with 2.5 Sv out of a total of 3.5 Sv. Intermediate waters are effectively blocked by the islands passage...

La tesis doctoral titulada Variabilidad espacio temporal de la Corriente de Canarias, del afloramiento costero al noroeste de África y de los intercambios atmósfera-océano de calor y agua dulce, cuyo autor es Francisco José Machín Jiménez, dirigida por el profesor del Departamento de Física Alonso Hernández Guerra trata sobre la circulación oceánic...

We show the mean and seasonal ocean circulation in the Canary basin, as result from an inverse model. For this purpose, a high-quality data set, obtained during the CANIGO (Canary Islands, Azores and Gibraltar Observations) project, has been used. It is composed of CTD casts carried out in four cruises along the four seasons. Basically, mean surfac...

The variability of the Canary Current is investigated using bimonthly expandable bathythermograph sections from Gran Canaria Island to the African coast between November 1996 and September 1998. The geostrophic transport of the easternmost branch of the Canary Current is estimated by integrating the thermal wind equation using the layer of neutral...

Publicación online disponible en: http://www.icm.csic.es/scimar/index.php CTD sections carried out in September 1998 are used to describe the water masses, geostrophic circulation and mass transport in the easternmost branch of the Canary Current. The surface water mass (<600 m) consists of North Atlantic Central Water (NACW) flowing south with a n...