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Fátima Abrantes - One of the best experts on this subject based on the ideXlab platform.

  • Suspended particulate matter in the Mediterranean Water at the Gulf of Cadiz and off the southwest coast of the Iberian Peninsula
    Deep-sea Research Part Ii-topical Studies in Oceanography, 2020
    Co-Authors: Pedro Seabra Freitas, Fátima Abrantes
    Abstract:

    Abstract Suspended particulate matter (SPM) data from two surveys carried as part of the Canary Islands Azores Gibraltar Observations (CANIGO) project, in September 1997 and January 1998, are presented for the Gulf of Cadiz and the SW coast of Portugal. Analysis of total suspended mass, particulate organic to inorganic matter ratio, δ13C(PDB), and a microscopic analysis of particle composition were performed. Our objective was to quantify and characterise SPM in the Water masses present in the study area, North Atlantic central Water (NACW), North Atlantic deep Water (NADW), and especially in the Mediterranean Water (MW). MW was usually characterised by values of SPM higher than NADW but similar to NACW, and was different in terms of SPM composition: higher δ13C(PDB) values and relative abundance of mineral and biogenic particles, but lower relative abundance of particles

  • Suspended particulate matter in the Mediterranean Water at the Gulf of Cadiz and off the southwest coast of the Iberian Peninsula
    Deep-Sea Research Part II: Topical Studies in Oceanography, 2002
    Co-Authors: Pedro Seabra Freitas, Fátima Abrantes
    Abstract:

    Suspended particulate matter (SPM) data from two surveys carried as part of the Canary Islands Azores Gibraltar Observations (CANIGO) project, in September 1997 and January 1998, are presented for the Gulf of Cadiz and the SW coast of Portugal. Analysis of total suspended mass, particulate organic to inorganic matter ratio, δ13C(PDB), and a microscopic analysis of particle composition were performed. Our objective was to quantify and characterise SPM in the Water masses present in the study area, North Atlantic central Water (NACW), North Atlantic deep Water (NADW), and especially in the Mediterranean Water (MW). MW was usually characterised by values of SPM higher than NADW but similar to NACW, and was different in terms of SPM composition: higher δ13C(PDB)values and relative abundance of mineral and biogenic particles, but lower relative abundance of particles < 10 μm. The higher values of δ13C(PDB)and biogenic material in MW suggest the presence of "fresher" particulate material relative to the other Water masses. In terms of SPM, two different MW can be described, a well-defined high-salinity and high-temperature slope MW, and an offshore MW in areas away from the continental slope and the seafloor. Slope MW showed higher particle abundance than offshore MW. It also showed a different particle composition, with higher values of δ13C(PDB), mineral particles, biogenic particles, and lower values of particles < 10 μm than offshore MW. No significant difference in SPM composition was observed between the upper and lower cores of MW. Three SPM sources to MW are proposed: a MW origin source (Gibraltar Straits or Mediterranean Sea), bottom sediment resuspension, and surface Waters. We suggest the occurrence of a constant particle source in surface Waters near Gibraltar and/or in the Mediterranean Sea during both surveys. In the eastern Gulf of Cadiz, the input of sedimentary particle into slope MW was slight or non-existent. On the western Gulf of Cadiz and off the west coast of Portugal, both surface and sediment inputs appear to be important particle sources into slope MW. © 2002 Elsevier Science Ltd. All rights reserved.

Pedro Seabra Freitas - One of the best experts on this subject based on the ideXlab platform.

  • Suspended particulate matter in the Mediterranean Water at the Gulf of Cadiz and off the southwest coast of the Iberian Peninsula
    Deep-sea Research Part Ii-topical Studies in Oceanography, 2020
    Co-Authors: Pedro Seabra Freitas, Fátima Abrantes
    Abstract:

    Abstract Suspended particulate matter (SPM) data from two surveys carried as part of the Canary Islands Azores Gibraltar Observations (CANIGO) project, in September 1997 and January 1998, are presented for the Gulf of Cadiz and the SW coast of Portugal. Analysis of total suspended mass, particulate organic to inorganic matter ratio, δ13C(PDB), and a microscopic analysis of particle composition were performed. Our objective was to quantify and characterise SPM in the Water masses present in the study area, North Atlantic central Water (NACW), North Atlantic deep Water (NADW), and especially in the Mediterranean Water (MW). MW was usually characterised by values of SPM higher than NADW but similar to NACW, and was different in terms of SPM composition: higher δ13C(PDB) values and relative abundance of mineral and biogenic particles, but lower relative abundance of particles

  • Suspended particulate matter in the Mediterranean Water at the Gulf of Cadiz and off the southwest coast of the Iberian Peninsula
    Deep-Sea Research Part II: Topical Studies in Oceanography, 2002
    Co-Authors: Pedro Seabra Freitas, Fátima Abrantes
    Abstract:

    Suspended particulate matter (SPM) data from two surveys carried as part of the Canary Islands Azores Gibraltar Observations (CANIGO) project, in September 1997 and January 1998, are presented for the Gulf of Cadiz and the SW coast of Portugal. Analysis of total suspended mass, particulate organic to inorganic matter ratio, δ13C(PDB), and a microscopic analysis of particle composition were performed. Our objective was to quantify and characterise SPM in the Water masses present in the study area, North Atlantic central Water (NACW), North Atlantic deep Water (NADW), and especially in the Mediterranean Water (MW). MW was usually characterised by values of SPM higher than NADW but similar to NACW, and was different in terms of SPM composition: higher δ13C(PDB)values and relative abundance of mineral and biogenic particles, but lower relative abundance of particles < 10 μm. The higher values of δ13C(PDB)and biogenic material in MW suggest the presence of "fresher" particulate material relative to the other Water masses. In terms of SPM, two different MW can be described, a well-defined high-salinity and high-temperature slope MW, and an offshore MW in areas away from the continental slope and the seafloor. Slope MW showed higher particle abundance than offshore MW. It also showed a different particle composition, with higher values of δ13C(PDB), mineral particles, biogenic particles, and lower values of particles < 10 μm than offshore MW. No significant difference in SPM composition was observed between the upper and lower cores of MW. Three SPM sources to MW are proposed: a MW origin source (Gibraltar Straits or Mediterranean Sea), bottom sediment resuspension, and surface Waters. We suggest the occurrence of a constant particle source in surface Waters near Gibraltar and/or in the Mediterranean Sea during both surveys. In the eastern Gulf of Cadiz, the input of sedimentary particle into slope MW was slight or non-existent. On the western Gulf of Cadiz and off the west coast of Portugal, both surface and sediment inputs appear to be important particle sources into slope MW. © 2002 Elsevier Science Ltd. All rights reserved.

Xavier Carton - One of the best experts on this subject based on the ideXlab platform.

  • Structure and Temporal Variability of Mediterranean Water in Hydrological and Marine Seismic Data South of Portimao Canyon (Gulf of Cadiz), from 1999 to 2002
    International Journal of Geosciences, 2020
    Co-Authors: Elise Quentel, Xavier Carton, Marc Andre Gutscher
    Abstract:

    Hydrological and marine seismic data, collected in the Gulf of Cadiz (respectively in July 1999, 2000, 2001 and 2002, and in April 2000 and 2001) are analysed to reveal the various structures of Mediterranean Water (MW). Both the hydrological and seismic data clearly identify the MW undercurrents on the Iberian slope, detached MW eddies (meddies and a cyclone) and smaller fragments of MW (filaments and small eddies). Seismic reflectivity and synthetic reflectivity computed from hydrology, indicate that strong acoustic reflectors, associated with 8 - 64 m thick homogeneous Water layers, are found above and below meddies and filaments, around the MW undercurrents, but mostly in the lower part of cyclones and below submesoscale eddies. Reflectors are also observed in the near surface layers where thermohaline contrasts are quite pronounced. The successful use of seismic data to locate submesoscale MW structures, superior to that of hydrology, is related to the improved horizontal resolution

  • Surface signature of Mediterranean Water eddies in a long-term high-resolution simulation
    Deep Sea Research Part I: Oceanographic Research Papers, 2017
    Co-Authors: D. Ciani, Xavier Carton, Igor Bashmachnikov, A.c. Barbosa Aguiar, Álvaro Peliz, Federico Ienna, B. Chapron, Rosalia Santoleri
    Abstract:

    Abstract We study the surface signatures of Mediterranean Water eddies (Meddies) in the context of a regional, primitive equations model simulation (using the Regional Oceanic Modeling System, ROMS). This model simulation was previously performed to study the mean characteristics and pathways of Meddies during their evolution in the Atlantic Ocean. The advantage of our approach is to take into account different physical mechanisms acting on the evolution of Meddies and their surface signature, having full information on the 3D distribution of all physical variables of interest. The evolution of around 90 long-lived Meddies (whose lifetimes exceeded one year) was investigated. In particular, their surface signature was determined in sea-surface height, temperature and salinity. The Meddy-induced anomalies were studied as a function of the Meddy structure and of the oceanic background. We show that the Meddies can generate positive anomalies in the elevation of the oceanic free-surface and that these anomalies are principally related to the Meddies potential vorticity structure at depth (around 1000 m below the sea-surface). On the contrary, the Meddies thermohaline surface signatures proved to be mostly dominated by local surface conditions and little correlated to the Meddy structure at depth. This work essentially points out that satellite altimetry is the most suitable approach to track subsurface vortices from observations of the sea-surface.

  • Properties and pathways of Mediterranean Water eddies in the Atlantic
    Progress in Oceanography, 2015
    Co-Authors: Igor Bashmachnikov, F. Neves, T. Calheiros, Xavier Carton
    Abstract:

    Abstract Data from ship vertical casts (NODC data-set), ARGO profiling floats (Coriolis data-set) and RAFOS-type neutral density floats (WOCE data-set) are used to study characteristics of meddies in the Northeast Atlantic. In total 241 Mediterranean Water eddies (meddies) and 236 parts of float trajectories within meddies are selected for detailed analysis. The results suggest that the meddy generation rate at the southern and southwestern Iberian Peninsula (Portimao Canyon, cap St. Vincent, Estremadura Promontory, Gorringe Bank) is 3 times that at the northwestern Iberian Peninsula (Porto-Aveiro Canyons, Cape Finisterre and Galicia Bank). Meddies generated south of Estremadura Promontory (the southern meddies), as compared to those generated north of it (the northern meddies), have smaller radii, smaller vertical extension, higher aspect ratio, higher Rossby number and higher stability (stronger potential vorticity anomaly). These latter properties result from the southern meddies higher relative vorticity and stronger buoyancy frequency anomaly. Away from the generation regions, meddy drift concentrates along four main paths: three quasi-zonal paths (Northern, Central, Southern) and a path following the African coast (Coastal). The quasi-zonal paths are aligned to the isolines of the ambient potential vorticity field. Several cross-path exchanges, identified in this work, are aligned to topographic rises. Northward translation of the northern meddies within the North Atlantic Current to the subpolar gyre is detected. Within the first 600 km from the coast, meddy merger is proved to be a common event. This explains the observed difference in radii between the newly generated meddies and those away from the Iberian margin. The decay of the southern meddies proceeds mainly via the loss of their skirts and does not affect meddy cores until the latest stages. The decay of the northern meddies goes in parallel with the decay of their cores. In average meddy decay is achieved within 1–2 years, although may take over 3 years. Collisions with the Mid-Atlantic Ridge and seamounts sensibly decrease meddy lifetimes. Meddy decay also speeds up when meddies meet the Azores Current or the North Atlantic Current. A rapid drop in the number of meddies south of the Azores Current proves that it represents a dynamic barrier for weak meddies.

  • Characteristics of surface signatures of Mediterranean Water eddies
    Journal of Geophysical Research, 2014
    Co-Authors: Igor Bashmachnikov, Xavier Carton, T. V. Belonenko
    Abstract:

    In this work, we obtain new results on the manifestation of meddies (or of other deep eddies) at the sea-surface, further developing the results by Bashmachnikov and Carton (2012). The quasi-geostrophic equations are used to describe a near-axisymmetric vortex in the upper ocean, forced at its lower boundary by the isopycnal elevation of a moving meddy. The solution thus obtained provides a better approximation of the characteristics of meddy surface signals. The results show that in subtropics large meddies with dynamic radius Rm ≥ 30 km are always seen at the sea-surface with AVISO altimetry, that medium-size meddies with Rm = 20 km may be seen at the sea-surface only if they are sufficiently shallow and strong, while small meddies with Rm = 10 km generally cannot be detected with the present accuracy of altimetry data. The intensity of meddy surface signals decreases to the south with the decrease of the f/N ratio. The seasonal variation in intensity of the surface signal for northern meddies (45°N) is on the order of 2–3 cm, but for subtropical meddies (35°N) it can be on the order of 5–10 cm. The radii of meddy surface signals range from 1 to 2 times the radii of the corresponding meddies. For most of the observed subtropical meddies, the upper limit should be used. Numerical experiments show that surface signals of meddies translated with β-drift are efficiently dispersed by the radiation of Rossby waves. At the same time, for meddies translated by a background current, the surface signal does not show strong dissipation.

  • Vortex stability in a multi-layer quasi-geostrophic model: application to Mediterranean Water eddies
    Fluid Dynamics Research, 2014
    Co-Authors: Xavier Carton, Claire Ménesguen, Ana Barbosa Aguiar, Mikhail A. Sokolovskiy, Thomas Meunier
    Abstract:

    The stability of circular vortices to normal mode perturbations is studied in a multi-layer quasi-geostrophic model. The stratification is fitted on the Gulf of Cadiz where many Mediterranean Water (MW) eddies are generated. Observations of MW eddies are used to determine the parameters of the reference experiment; sensitivity tests are conducted around this basic case. The objective of the study is two-fold: (a) determine the growth rates and nonlinear evolutions of unstable perturbations for different three-dimensional (3D) velocity structures of the vortices, (b) check if the different structure of our idealized vortices, mimicking MW cyclones and anticyclones, can induce different stability properties in a model that conserves parity symmetry, and apply these results to observed MW eddies. The linear stability analysis reveals that, among many 3D distributions of velocity, the observed eddies are close to maximal stability, with instability time scales longer than 100 days (these time scales would be less than 10 days for vertically more sheared eddies). The elliptical deformation is most unstable for realistic eddies (the antisymmetric one dominates for small eddies and the triangular one for large eddies); the antisymmetric mode is stronger for cyclones than for anticyclones. Nonlinear evolutions of eddies with radii of about 30 km, and elliptically perturbed, lead to their re-organization into 3D tripoles; smaller eddies are stable and larger eddies break into 3D dipoles. Horizontally more sheared eddies are more unstable and sustain more asymmetric instabilities. In summary, few differences were found between cyclone and anticyclone stability, except for strong horizontal velocity shears.

Annarita Mariotti - One of the best experts on this subject based on the ideXlab platform.

  • Analyzing the Mediterranean Water Cycle Via Satellite Data Integration
    Pure and Applied Geophysics, 2018
    Co-Authors: Victor Pellet, Annarita Mariotti, Filipe Aires, Diego Fernández-prieto
    Abstract:

    The Water cycle components are being retrieved by an increasing number of satellite missions. However, the monitoring of the Water cycle by satellite Earth Observations is still a challenge. Data sets suffer from numerous systematic and random errors and they are often not coherent with each other. We focus here on the Mediterranean basin, one of the regions most sensitive to climate change. A satellite-based analysis of the Water cycle is undertaken using a collection of available satellite data sets. Our satellite data set combination uses a simple bias correction and weighted average, and provides a better Water budget closure results than any raw satellite data set. Our almost purely satellite data set allows to better describe the full Water cycle, not only over the continents, but also in the atmosphere and over the ocean. The limitation/possibilities of this satellite multi-component data set are described: (1) although improved, the Water cycle is still not closed by satellite data and the satellite community should focus on this issue, (2) our combined data set shows good coherency with the ERA-I reanalysis which is the reference so far, both in terms of seasonal climatology and long-term trends. This means that, even if the Water budget is not yet closed by satellite data, our monitoring of the Water cycle using satellite observations is improving, even over complex regions such as the Mediterranean basin.

  • recent changes in the Mediterranean Water cycle a pathway toward long term regional hydroclimatic change
    Journal of Climate, 2010
    Co-Authors: Annarita Mariotti
    Abstract:

    Abstract An observational analysis of Mediterranean Sea Water cycle variability based on recently available datasets provides new insights on the long-term changes that affected the region since the 1960s. Results indicate an overall increase in evaporation during 1958–2006, with a decrease up until the mid-1970s and an increase thereafter. Precipitation variability is characterized by substantial interdecadal variations and a negative long-term trend. Evaporation increase, primarily driven by SST variability, together with precipitation decrease resulted in a substantial increase in the loss of freshWater from the Mediterranean Sea toward the overlying atmosphere. An increase in the freshWater deficit is consistent with observed Mediterranean Sea salinity tendencies and has broad implications for the Mediterranean Water cycle and connected systems. These observational results are in qualitative agreement with simulated Mediterranean Sea Water cycle behavior from a large ensemble of models from the Couple...

  • Future changes in the Mediterranean Water budget projected by an ensemble of regional climate models
    Geophysical Research Letters, 2009
    Co-Authors: Emilia Sanchez-gomez, Samuel Somot, Annarita Mariotti
    Abstract:

    [1] The Mediterranean basin is a region characterized by its vulnerability to changes in the Water cycle. Hence, the impact of global warming on the Water resources in the Mediterranean zone is one of the major concerns for the scientific community. The future climate projections used to elaborate the IPCC report of 2007 show great alterations in the evaporation and precipitation over the Mediterranean Sea at the end of 21st century. In this work we investigate the changes in the Mediterranean Sea Water budget by using SRES-A1B scenario experiments performed with high resolution (25 km) regional climate models (RCMs). The RCMs provide good estimates of the Water budget components, in particular with a significant improvement of the runoff and Black Sea discharge terms compared to the coarser resolution general circulation models (GCMs) used in the last Intergovernmental Panel of Climate Change (IPCC) report. As for the case of GCMs, the RCMs show that the Mediterranean Water budget is likely to be significantly altered at the end of 21st century. The response of the hydrological variables to global warming starts to be statistically significant from 2050, though some alterations are already observed before 2050. The RCMs predict an increase of evaporation, and a decrease of precipitation, and river and Black Sea discharge, yielding to a large increase of the Mediterranean fresh Water deficit. The freshWater deficit for the period 2070–2099 related to 1950–1999 presents a mean increase of +40% for both RCMs and GCMs.

  • Mediterranean Water cycle changes transition to drier 21st century conditions in observations and cmip3 simulations
    Environmental Research Letters, 2008
    Co-Authors: Annarita Mariotti, Ning Zeng, Jinho Yoon, V Artale, Antonio Navarra, Pinhas Alpert, Laurent Li
    Abstract:

    We use CMIP3 multi-model simulations to show how individual hydroclimatic changes will concur to determine even greater alterations of 21st century Mediterranean Water cycle characteristics, with contrasting behavior over land and sea. By 2070–2099, the average of the models predicts a 20% decrease in land surface Water availability and a 24% increase in the loss of fresh Water over the Mediterranean Sea due to precipitation reduction and warming-enhanced evaporation, with a remarkably high consensus among analyzed models. The projected decrease in river runoff from the surrounding land will further exacerbate the increase in Mediterranean Sea fresh Water deficit. 20th century simulations indicate that the 'transition' toward drier conditions has already started to occur and has accelerated around the turn of the century towards the larger rates projected for the 21st century. These tendencies are supported by observational evidence of century-long negative trends in regionally averaged precipitation, PDSI and discharge from numerous rivers; and are consistent with reported increases in Mediterranean sea Water salinity.

Isabel Ambar - One of the best experts on this subject based on the ideXlab platform.

  • Observations and Laboratory Modeling of Meddy Generation at Cape St. Vincent
    Journal of Physical Oceanography, 2020
    Co-Authors: Nuno Serra, Isabel Ambar, S. Sadoux, D. Renouard
    Abstract:

    Abstract The AMUSE, CANIGO, and AMPOR observations provided a large amount of subsurface float data showing evidence of several distinctly different flow behaviors within the Mediterranean Water layers in the vicinity of Cape St. Vincent (southwest Portugal). Some of the floats followed the coastline and moved northward, and some were trapped either in anticyclonic lenses of Mediterranean Water (meddies) generated at Cape St. Vincent or in cyclonic structures. These observations clearly indicated that the anticyclones were accompanied by cyclones, at least during their early stages. As the dipolar structure moves away from the cape, the cyclone tends to shift slowly away from the anticyclone while decaying so that after some time only the meddy persists. These in situ observations are compared with large-scale laboratory experiments and the agreement between the two sets of observations is remarkably good. Near the cape and shortly after the generation, the nondimensional radius, relative vorticity, and r...

  • Comparative studies of the spreading of Mediterranean Water through the Gulf of Cadiz
    Deep-sea Research Part Ii-topical Studies in Oceanography, 2020
    Co-Authors: John A. Johnson, Isabel Ambar, Nuno Serra, Ian Stevens
    Abstract:

    Abstract A comparative study is made of observations and model results of the spreading of Mediterranean Water (MW) from the Strait of Gibraltar through the Gulf of Cadiz past Cape St. Vincent into the eastern North Atlantic. The observations include a set of hydrographic sections from west of Gibraltar to offshore of Lisbon, the tracking of RAFOS floats, and current-meter data. The model is a very fine resolution limited-area model of the region around Cape St. Vincent and includes model floats. Both the observational data and the model results show the MW descending into two distinct layers around 800 and 1200 m depth in the Gulf of Cadiz. As the MW leaves the slope, meddies are generated and have been tracked by the RAFOS floats and can be seen in the paths of the model floats.

  • Evidence of Mediterranean Water dipole collision in the Gulf of Cadiz
    Journal of Geophysical Research, 2014
    Co-Authors: Pierre L'hégaret, Xavier Carton, Isabel Ambar, Claire Ménesguen, Laurent M. Chérubin, Ana Barbosa Aguiar, Bernard Le Cann, Nathalie Daniault, Nuno Serra
    Abstract:

    A collision of Mediterranean Water dipoles in the Gulf of Cadiz is studied here, using data from the MedTop and Semane experiments. First, a Mediterranean Water eddy (meddy) was surveyed hydrologically in November 2000 southwest of Cape Saint Vincent. Then, this meddy drifted northeastward from this position, accompanied by a cyclone (detected only via altimetry), thus forming a first dipole. In February 2001, a dipole of Mediterranean Water was measured hydrologically just after its formation near Portimao Canyon. This second dipole drifted southwestward. The western and eastern meddies had hydrological radii of about 22 and 25 km, respectively, with corresponding temperature and salinity maxima of (13.45°C, 36.78) and (11.40°C, 36.40). Rafos float trajectories and satellite altimetry indicate that these two dipoles collided early April 2001, south of Cape Saint Vincent, near 35°30′N, 10°15′W. More precisely, the eastern meddy wrapped around the western one. This merger resulted in an anticyclone (a meddy) which drifted southeastward, coupled with the eastern cyclone. Hydrological sections across this final third resulting dipole, performed in July 2001 in the southern Gulf of Cadiz, confirm this interaction: the thermohaline characteristics of the final meddy can be tracked back to the original structures. The subsequent evolution of this dipole was analyzed with Rafos float trajectories. A numerical simulation of the interaction between the two earlier dipoles is also presented. We suggest that these dipole collisions at the Mediterranean Water level may represent a mechanism of generation of the larger meddies that finally leave the Gulf of Cadiz.

  • Hydrological Structure, Circulation and Water Mass Transport in the Gulf of Cadiz
    International Journal of Geosciences, 2011
    Co-Authors: J. M. R. Alves, Xavier Carton, Isabel Ambar
    Abstract:

    Hydrological and LADCP data from four experiments at sea (Semane 1999, 2000/1 2000/3, 2001) are used to describe the structure and circulation of Mediterranean Water in the Gulf of Cadiz. These data were gathered on meridional sections along 8?20′W and 6?15′W and between these longitudes on a zonal section along 35?50′N. The mesoscale and the submesoscale structures (Mediterranean Water Undercurrents, meddies, cyclones) observed along these sections are characterized in terms of thermohaline properties and of velocity. The transports of mass and salt in each class of density (North Atlantic Central Water, Mediterranean Water, North Atlantic Deep Water) are computed with an inverse model. The model indicates a general eastward flux in the Central Water layer, and a westward flux in the Mediterranean Water layer, but there is also a horizontal recirculation and entrainment in these two layers, as well as strong transports associated with the meddy and cyclone found during Semane 1999.

  • Surface expression of Mediterranean Water dipoles and their contribution to the shelf/slope – open ocean exchange
    Ocean Science, 2010
    Co-Authors: Nuno Serra, Isabel Ambar, D. Boutov
    Abstract:

    Abstract. The generation of dipolar eddies within the Mediterranean Water (MW) layers, at the Portuguese continental slope, was observed using subsurface RAFOS floats. The surface expression of these mid-depth dipoles is here characterized with remote sensing data, namely with sea surface temperature, chlorophyll concentration and sea surface height measurements. Two cases are presented demonstrating the remote detection of these underWater structures in the Gulf of Cadiz during 1998 and 2001. The presence of subsurface MW dipoles in the Iberian coastal zone is shown to influence the development of coastal upwelling filaments. The surface circulation induced by the dipoles causes the upwelling filaments to extend offshorewards and thus to enhance the transport of physical, chemical and biological properties into the open ocean. A numerical model simulation of the ocean circulation around the Iberian Peninsula forced by heat and freshWater fluxes (computed using the NCEP reanalysis atmospheric state) and by the overflow of MW at the Strait of Gibraltar, corroborates the connection between the surface and the mid-depth flows. The high-resolution numerical experiment is used to help clarifying the occurrence of the MW dipoles surface expression and the impact of these dipoles on the eddy kinetic energy of the upper ocean and on the exchange of volume and salt between the shelf/slope and the open ocean.