Originally trained as a physical oceanographer, I am currently interested in studying boundary layer processes in geophysical fluids i.e. ocean and atmosphere. In recent years, I have focused on the study of island-induced boundary layer perturbations i.e. wakes. Island wakes generate a rich variety of (sub-) mesoscale systems such as eddies, fronts, upwelling cells, filaments and jets (http://wakes.uma.pt). I am also involved in studies of the lower atmospheric boundary layer and its response to ocean feedbacks. An ongoing study of the Douro river plume is proving new opportunities to explore the interactions between local atmospheric forcing, waves and ocean currents in the coastal boundary layer. I am fond of a multiplatform, multidisciplinary approach. This approach out bounds the classical modus operandi, often forcing me to become involved in the construction of my own research tools, including High Performance Computational platforms, numerical models and laboratory setting, and in the design and undertaking of in-situ and airborne campaigns. For fun, I like to challenge my working tools testing its forecasting capabilities (http://cod.ciimar.up.pt). Forecasts are valuable products to private and public organisations and thus I have been making complementary efforts to deliver this information in near-real time via the web and/or via mobile platforms. In my view, only good quality scientific products can adequately assist the decision making process!
ABSTRACT Thesis (Ph. D.)--University of California, Los Angeles, 2002. Typescript (photocopy). Vi... more ABSTRACT Thesis (Ph. D.)--University of California, Los Angeles, 2002. Typescript (photocopy). Vita. Includes bibliographical references.
This paper is aimed to overview, including derived preliminary-results, glider missions carried o... more This paper is aimed to overview, including derived preliminary-results, glider missions carried out in waters of the Macaronesia region, connecting Portugal mainland and the archipelagos of Madeira and Canary Islands, within the framework of H2020-AtlantOS and Interreg Atlantic iFADO projects. The missions conducted represents the first attempt in this context aiming to stablish glider endurance-lines across the area, to increase ocean-observation capability from a sustainable and cost effective perspective by the use of cutting-edge technologies, and at the same time, to contribute to the regional marine-monitoring strategy in support to the main international ocean-observations programs and initiatives.
The Macaronesia is a vast area playing a key role in the East boundary of the Central North-Atlan... more The Macaronesia is a vast area playing a key role in the East boundary of the Central North-Atlantic Ocean-circulation system. Despite a significant research activity in ocean monitoring for decades using a wide range of observing systems and methodologies, the area is still under-sampled, mainly due access and coverage constrains, as well as the observation sustainability. Ocean gliders offer a new approach in terms of capacity and sustainability, allowing undertake ocean-monitoring in spatiotemporal scales hitherto unavailable. The present work shows preliminary results from the latest mission with buoyancy-driven and surface ocean gliders in the area, whose main goal focuses on to improve and expand ocean observation capabilities strengthening glider endurance lines between archipelagos, as part of the global ocean-observation strategy conducted by the Marine & Maritime Network (R3M), as contributing party aligned with the European and international efforts in the North Atlantic basin.
Idealized studies of island wakes often use a cylinder-like island to generate the wake, whereas ... more Idealized studies of island wakes often use a cylinder-like island to generate the wake, whereas most realistic studies use a close representation of the oceanic bathymetry immersed in a complex representation of the “ambient” geophysical flows. Here, a system of multiple islands was placed into numerical and experimental channels, in order to focus on the complexity of the archipelago wake, including (a) the influence of small neighboring islands and (b) the role of the island-shelf. The numerical geostrophic and stratified channel was built using a three-dimensional primitive equation model, considering a realistic representation of the Madeira archipelago bathymetry, with prescribed initial and boundary conditions. Results from the simulations show that the neighboring islands alter the near-field wake. Small eddies generated by the neighboring islands lead to destabilization of the shear layers of the larger island. Laboratory experiments carried out in the Coriolis rotating tank corroborated this near-field disruptive mechanism. The neighboring island perturbation effect was present whatever the direction of the incoming flow, but under different regimes. North–south wakes produced geostrophic eddies (≥ Rd), whereas west–east wakes produced (exclusively) ageostrophic submesoscale eddies (< < Rd) which traveled offshore with wave-like motion. The archipelago shelf contributed to the asymmetric vertical migration of oceanic vorticity. Cyclonic vorticity dominated the surface dynamics, whereas anticyclonic circulation prevailed at the bottom part of the linearly stratified upper layer. This study identifies several likely wake scenarios induced by the Madeira archipelago, and may serve as guide for future multiscale numerical studies and in situ campaigns.
Abstract The capacity of the Azores Archipelago to capture and retain incoming particles and orga... more Abstract The capacity of the Azores Archipelago to capture and retain incoming particles and organisms that are drifting with the oceanic currents was the main focus of this study. Using the Hybrid Coordinate Ocean Model coupled with the Connectivity Modeling System (an offline Lagrangian tool) a series of experiments were conducted to determine: i) the origin of the particles that reach the archipelago, ii) the capacity of each island sub-group to retain incoming particles and organisms, as well as the iii) oceanographic phenomena that lead to their transport and retention. The Gulf Stream (GS) and the westward propagating eddy corridors were identified as the main transport pathways affecting the Azores region. Eddy Kinetic Energy from altimetry data and Lyapunov exponent analysis suggest that eddies and filaments are the main delivery mechanisms. In the upper mixed layer, the GS and its associated eddies are a predominant regional oceanographic feature injecting particles from the north and west boundaries toward the Azores. The capacity to capture particles of each island sub-group was directly proportional to their size, while the retention time within the Azores region increased with depth, associated with the decrease in velocity of the intermediate water currents. This study opens new prospects to understand transport in the Mid-Atlantic (Azores) region and the islands' role in marine colonization, dispersal, fisheries recruitment and speciation.
Quarterly Journal of the Royal Meteorological Society, Jun 19, 2020
Madeira island is a well‐known source of atmospheric and oceanic eddy activity, with relevant dow... more Madeira island is a well‐known source of atmospheric and oceanic eddy activity, with relevant downstream impact in both media. Previous studies focused on the dynamics of the island wake environment, suggesting the relevance of different atmosphere–ocean interactions in its maintenance. Here, results from one summer (two months) of fully coupled atmosphere–ocean high‐resolution simulations are used to explore such interactions and to further understand the dynamics of Madeira's wake. Those results, validated against available in situ and remote‐sensing data, indicate that the atmospheric and ocean circulations near Madeira are dominated by the variability of two quasi‐permanent features, its tip‐jets, and more so by the variability of its eastern jet. While both jets are of comparable magnitude and present similar intraseasonal variability at the multi‐week time‐scale, they are associated with qualitatively different forcing. The jets dominate the atmosphere forcing over the upper ocean, leading to enhanced mixing and deeper mixed‐layer depth. Oceanic eddies are more frequent in the east jet region, as shedding anticyclones, confirming observational evidence. A comparison with a similar one‐way coupled atmospheric simulation indicates that atmosphere–ocean feedbacks are relevant to the coastal surface temperature.
The role of low-level jets in the intra-seasonal variability of the Canary upwelling system durin... more The role of low-level jets in the intra-seasonal variability of the Canary upwelling system during summer is assessed with a fully coupled, high resolution (3km) ocean-atmosphere numerical simulation. Here, low-level jets include the main continental coastal jet, the tip jets of Madeira and the tip-jets of the steep Canary Islands. The coastline shape, orography of northwest Africa and the proximity of Canary islands lead to complex interactions between the jets, that result in strong surface wind intra-seasonal variability on the multiweek time scale. That variability is forced by oscillations in the shape and position of the Azores subtropical anticyclone, through a strong oscillation in the atmospheric boundary layer height. At the coast, coastal-trapped oscillations with a propagation speed, planetary boundary height, offshore extension, and surface pressure compatible with a Kelvin wave occasionally propagate northward, against the synoptic scale surface pressure. While similar processes have already been observed in California, the mechanisms here described appear to result from interactions of continental coastal processes with a set of steep islands close to the coast. The sensitivity of these dynamics to climate change is a challenging question.
ABSTRACT Thesis (Ph. D.)--University of California, Los Angeles, 2002. Typescript (photocopy). Vi... more ABSTRACT Thesis (Ph. D.)--University of California, Los Angeles, 2002. Typescript (photocopy). Vita. Includes bibliographical references.
This paper is aimed to overview, including derived preliminary-results, glider missions carried o... more This paper is aimed to overview, including derived preliminary-results, glider missions carried out in waters of the Macaronesia region, connecting Portugal mainland and the archipelagos of Madeira and Canary Islands, within the framework of H2020-AtlantOS and Interreg Atlantic iFADO projects. The missions conducted represents the first attempt in this context aiming to stablish glider endurance-lines across the area, to increase ocean-observation capability from a sustainable and cost effective perspective by the use of cutting-edge technologies, and at the same time, to contribute to the regional marine-monitoring strategy in support to the main international ocean-observations programs and initiatives.
The Macaronesia is a vast area playing a key role in the East boundary of the Central North-Atlan... more The Macaronesia is a vast area playing a key role in the East boundary of the Central North-Atlantic Ocean-circulation system. Despite a significant research activity in ocean monitoring for decades using a wide range of observing systems and methodologies, the area is still under-sampled, mainly due access and coverage constrains, as well as the observation sustainability. Ocean gliders offer a new approach in terms of capacity and sustainability, allowing undertake ocean-monitoring in spatiotemporal scales hitherto unavailable. The present work shows preliminary results from the latest mission with buoyancy-driven and surface ocean gliders in the area, whose main goal focuses on to improve and expand ocean observation capabilities strengthening glider endurance lines between archipelagos, as part of the global ocean-observation strategy conducted by the Marine & Maritime Network (R3M), as contributing party aligned with the European and international efforts in the North Atlantic basin.
Idealized studies of island wakes often use a cylinder-like island to generate the wake, whereas ... more Idealized studies of island wakes often use a cylinder-like island to generate the wake, whereas most realistic studies use a close representation of the oceanic bathymetry immersed in a complex representation of the “ambient” geophysical flows. Here, a system of multiple islands was placed into numerical and experimental channels, in order to focus on the complexity of the archipelago wake, including (a) the influence of small neighboring islands and (b) the role of the island-shelf. The numerical geostrophic and stratified channel was built using a three-dimensional primitive equation model, considering a realistic representation of the Madeira archipelago bathymetry, with prescribed initial and boundary conditions. Results from the simulations show that the neighboring islands alter the near-field wake. Small eddies generated by the neighboring islands lead to destabilization of the shear layers of the larger island. Laboratory experiments carried out in the Coriolis rotating tank corroborated this near-field disruptive mechanism. The neighboring island perturbation effect was present whatever the direction of the incoming flow, but under different regimes. North–south wakes produced geostrophic eddies (≥ Rd), whereas west–east wakes produced (exclusively) ageostrophic submesoscale eddies (< < Rd) which traveled offshore with wave-like motion. The archipelago shelf contributed to the asymmetric vertical migration of oceanic vorticity. Cyclonic vorticity dominated the surface dynamics, whereas anticyclonic circulation prevailed at the bottom part of the linearly stratified upper layer. This study identifies several likely wake scenarios induced by the Madeira archipelago, and may serve as guide for future multiscale numerical studies and in situ campaigns.
Abstract The capacity of the Azores Archipelago to capture and retain incoming particles and orga... more Abstract The capacity of the Azores Archipelago to capture and retain incoming particles and organisms that are drifting with the oceanic currents was the main focus of this study. Using the Hybrid Coordinate Ocean Model coupled with the Connectivity Modeling System (an offline Lagrangian tool) a series of experiments were conducted to determine: i) the origin of the particles that reach the archipelago, ii) the capacity of each island sub-group to retain incoming particles and organisms, as well as the iii) oceanographic phenomena that lead to their transport and retention. The Gulf Stream (GS) and the westward propagating eddy corridors were identified as the main transport pathways affecting the Azores region. Eddy Kinetic Energy from altimetry data and Lyapunov exponent analysis suggest that eddies and filaments are the main delivery mechanisms. In the upper mixed layer, the GS and its associated eddies are a predominant regional oceanographic feature injecting particles from the north and west boundaries toward the Azores. The capacity to capture particles of each island sub-group was directly proportional to their size, while the retention time within the Azores region increased with depth, associated with the decrease in velocity of the intermediate water currents. This study opens new prospects to understand transport in the Mid-Atlantic (Azores) region and the islands' role in marine colonization, dispersal, fisheries recruitment and speciation.
Quarterly Journal of the Royal Meteorological Society, Jun 19, 2020
Madeira island is a well‐known source of atmospheric and oceanic eddy activity, with relevant dow... more Madeira island is a well‐known source of atmospheric and oceanic eddy activity, with relevant downstream impact in both media. Previous studies focused on the dynamics of the island wake environment, suggesting the relevance of different atmosphere–ocean interactions in its maintenance. Here, results from one summer (two months) of fully coupled atmosphere–ocean high‐resolution simulations are used to explore such interactions and to further understand the dynamics of Madeira's wake. Those results, validated against available in situ and remote‐sensing data, indicate that the atmospheric and ocean circulations near Madeira are dominated by the variability of two quasi‐permanent features, its tip‐jets, and more so by the variability of its eastern jet. While both jets are of comparable magnitude and present similar intraseasonal variability at the multi‐week time‐scale, they are associated with qualitatively different forcing. The jets dominate the atmosphere forcing over the upper ocean, leading to enhanced mixing and deeper mixed‐layer depth. Oceanic eddies are more frequent in the east jet region, as shedding anticyclones, confirming observational evidence. A comparison with a similar one‐way coupled atmospheric simulation indicates that atmosphere–ocean feedbacks are relevant to the coastal surface temperature.
The role of low-level jets in the intra-seasonal variability of the Canary upwelling system durin... more The role of low-level jets in the intra-seasonal variability of the Canary upwelling system during summer is assessed with a fully coupled, high resolution (3km) ocean-atmosphere numerical simulation. Here, low-level jets include the main continental coastal jet, the tip jets of Madeira and the tip-jets of the steep Canary Islands. The coastline shape, orography of northwest Africa and the proximity of Canary islands lead to complex interactions between the jets, that result in strong surface wind intra-seasonal variability on the multiweek time scale. That variability is forced by oscillations in the shape and position of the Azores subtropical anticyclone, through a strong oscillation in the atmospheric boundary layer height. At the coast, coastal-trapped oscillations with a propagation speed, planetary boundary height, offshore extension, and surface pressure compatible with a Kelvin wave occasionally propagate northward, against the synoptic scale surface pressure. While similar processes have already been observed in California, the mechanisms here described appear to result from interactions of continental coastal processes with a set of steep islands close to the coast. The sensitivity of these dynamics to climate change is a challenging question.
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