Paulo Relvas

• PhD
• CCMAR at University of Algarve

This article presents an Eulerian physical and biogeochemical dataset from the Iberian Margin Cape St. Vincent Ocean observatory (IbMa-CSV), a facility of the European Multidisciplinary Seafloor and water column Observatory European Research Infrastructure Consortium (EMSO-ERIC), located 10 nautical miles south of Cape St. Vincent (Portugal), the s...

Three-Stage Cluster Modeling for the Spatiotemporal Analysis of Coastal Upwelling

This article presents an Eulerian physical and biogeochemical data set from the Iberian Margin Cape São Vicente Ocean Observatory (IbMa-CSV), a facility of the European Multidisciplinary Seafloor and water column Observatory – European Research Infrastructure Consortium (EMSO-ERIC) located 10 nautical miles south of Cape São Vicente (Portugal), the...

Under certain environmental and oceanographic conditions, macroalgae can overgrow and accumulate in massive quantities on beaches, causing serious ecological and economic impacts. To address this problem, a citizen science monitoring platform was created to determine the spatial and temporal distribution of macroalgae accumulations along the beache...

A comprehensive approach is presented to analyse season's coastal upwelling represented by weekly sea surface temperature (SST) image grids. Our three‐stage data recovery clustering method assumes that the season's upwelling can be divided into shorter periods of stability, ranges, each to be represented by a constant core and variable shell parts....

The current study aims to analyse the vertical structure of the ocean during upwelling events using in situ and modelled data. Additionally, the influence of climate patterns, namely the North Atlantic Oscillation (NAO) and the East Atlantic (EA) pattern, on the vertical structure and their impact on the upwelling activity are assessed for a period...

This work proposes a spatiotemporal clustering approach for the analysis of coastal upwelling from Sea Surface Temperature (SST) grid maps derived from satellite images. The algorithm, Core-Shell clustering, models the upwelling as an evolving cluster whose core points are constant during a certain time window while the shell points move through an...

The current study aims to analyse the vertical structure of the ocean during upwelling events using in situ and modelled data. Additionally, the influence of climate patterns, namely the North Atlantic Oscillation (NAO) and the East Atlantic (EA) pattern, on the vertical structure and their impact on the upwelling activity is assessed for a period...

The subtidal surface water circulation at the northern margin of the Gulf of Cádiz, at the southern extremity of the Iberian upwelling system, is described based on validated hourly high-frequency radar measurements from 2016 to 2020. Statistical analyses (mean, standard deviation, eccentricity and empirical orthogonal functions) are applied to the...

Harmful algal blooms (HABs) negatively impact coastal ecosystems, fisheries, and human health, and their prediction has become imperative for effective coastal management. This study aimed to evaluate spatial-temporal variability patterns and phenology for key toxigenic phytoplankton species off southern Portugal, during a 6-year period, and identi...

The subtidal surface water circulation at the northern margin of the Gulf of Cadiz, at the southern extremity of the Iberian upwelling system, is described based on validated hourly high frequency radar measurements from 2016 to 2020. Statistical analyses (mean, standard deviation, eccentricity and empirical orthogonal functions) are applied to the...

The study of dynamic features of the ocean, in which complex physical, chemical, and biological interactions evolve on multiple time scales, poses significant sampling challenges because the required spatial and temporal resolutions are not possible by ship or satellite studies alone. Satellite remote sensing captures only surface effects while exp...

This work explores the potential of along-tracks CryoSat-2 SAR altimetry to investigate coastal upwelling at the (E-W oriented) south Portugal-Spain coast in the Gulf of Cadiz.

Study of ocean processes is important to understanding climatic variability especially on the productive upper water-column. Ocean currents regulate the climate, it captures CO\(_2\) from the atmosphere and oxygen is generated by its plankton communities, all of which are part of the global environmental cycle which are being impacted by anthropoge...

The alongshore subtidal water circulation along the South Portugal inner shelf is characterised by the temporal alternation of equatorward (i.e., broadly eastward) flows related to coastal upwelling processes and poleward (i.e., broadly westward) Coastal Counter Currents (CCCs). The objective of this study is to get insights about the main drivers...

Study of ocean processes is important to understanding climatic variability especially on the productive upper water-column. Ocean currents regulate the climate, it captures CO2 from the atmosphere and oxygen is generated by its plankton communities, all of which are part of the global environmental cycle which are being impacted by anthropogenic c...

Upwelling is of major environmental and economic importance for coastal regions. Sea Surface Temperature (SST) satellite imagery provide an expedited method of monitoring its variability. This work proposes a one-by-one extracting version of a spatial clustering algorithm with self-tuning thresholding derived from anomalous clustering , able to pre...

Artificial nourishment of sandy beaches using sediment from borrow areas located on the continental shelf is increasingly a recommended solution for reversing the erosion process that affects the coastal zone. However, the impact of sand extraction in the shelf and deposition on the beach on the benthic communities (structure and functioning) is st...

Deep-ocean islands have long been associated with the generation of oceanic eddies in their wakes, but their interaction with incoming eddies has seldom been considered. This study aimed to fill this gap, focusing in the Cabo Verde Archipelago between 2003-2014, an ideal location given the complex islands disposition and shape, and its exposure to...

Resumo O projeto "Caracterização do impacte da extração de areias e avaliação da taxa de recuperação do ecossistema-ECOEXA" tem por objetivo estudar o impacto associado à extração de areia em manchas de empréstimo de sedimento, destinadas à alimentação artificial de praias, na integridade do fundo marinho. A monitorização servirá para estudar a evo...

Wind is a marine coastal factor that is little understood but has a strong interaction with biological productivity. In this study, northerly wind trends in three regions of the Portuguese coast (Northwestern: NW, Southwestern: SW, and Southern: S) were analyzed. Two datasets with long-term (ICOADS: 1960–2010) and short-term data (Satellite: 1989–2...

All figure captions are not accurate. Also, there is a repeated error in most figures because the vertical scales incorrectly show “Wind Strenght” instead of “Wind Strength” and in Fig. 4 (mid-panel) “2003” instead of “2004”.

Coastal upwelling has a significant local impact on marine coastal environment and on marine biology, namely fisheries. This study aims to evaluate climate and environmental changes in upwelling trends between 1950 and 2010. Annual, seasonal and monthly upwelling trends were studied in three different oceanographic areas of the Portuguese coast (no...

The Portuguese coast is located in a biogeographic transition zone, between temperate and subtropical waters where the northern or southern distribution limits of many species are found. Portuguese coastline is characterized by specific hydrographical features with a cooler northern region affected by both upwelling and rainfall leading to higher v...

ADCP time series (2008-2017) were collected on the inner shelf (23 m water depth) over 13 deployments of 1-3 months long (Fig. 1). Parameters were selected to characterize inversions based on the depth average, near bed, and surface alongshore velocities, low-passed filter at 40 h (Fig. 2, 3). Statistics analyses were applied to these parameters, c...

Velella velella is a pleustonic colonial organism found in temperate and tropical oceanic waters worldwide. During certain periods of the year, large numbers of the species can wash up on coastal beaches. However, little information exists on the ecology and dispersal patterns of this cosmopolitan species, especially on their distribution at sea. H...

Alongshore coastal counter-currents (CCCs) are worldwide features of upwelling systems, alternating with upwelling jets of opposite direction. At the Gulf of Cadiz, CCCs are observed all year-round, i.e. including during the non-upwelling season. In this study, the current inversion patterns (i.e., the change of current direction from eastward to w...

The pathways and transformations of dense water overflows, which depend on small-scale interactions between flow dynamics and erosional-depositional processes, are a central piece in the ocean's large-scale circulation. A novel, high-resolution current and hydrographic data set highlights the intricate pathway travelled by the saline Mediterranean...

Overall an increase in sea surface temperature (SST) has been recorded over the last century. However, changes in SST are not homogeneous across the ocean. Most studies focus on the processes and mechanisms setting SST variability across broad scales and neglect changes occurring at a regional scale. So, this study aims to describe annual, seasonal...

An operational oil spill modelling system developed for the SW Iberia Coast is used to investigate the relative importance of the different components and technologies integrating an oil spill monitoring and response structure. A backtrack of a CleanSeaNet oil detection in the region is used to demonstrate the concept. Taking advantage of regional...

There is a general consensus that many shark species are declining in numbers. However, effective management measures often depend on knowing how trends in abundance and distribution are influenced by environmental conditions. Several efforts to describe the occurrence and distribution of basking sharks Cetorhinus maximus have been made in northern...

Over the last decade, ocean sunfish movements have been monitored worldwide using various satellite tracking methods. This study reports the near-real time monitoring of fine-scale (< 10 m) behaviour of sunfish. The study was conducted in southern Portugal in May 2014 and involved satellite tags and underwater and surface robotic vehicles to measur...

Northward (left) and Eastward (right) daily component provided by the Wave Glider (line) and model output (dots) averaged over two days and registered at 18 m depth. (TIF)

a) Example of a drifter (red line, with dates) and particles (blue lines) tracks, b) Atlantic section of the drifter track before entering the Mediterranean Sea (red line) and mean trajectory of the 200 particles released in the Lagrangian model (green line). (TIF)

Supplementary Material for integrated monitoring of Mola mola behaviour in space and time. (DOCX)

Example of a drifter track superimposed on a MODIS SST map composite from May 25th to June 1th (top) and June 2th to 9th June (bottom), both 2014. (TIF)

Archive of Drifter data. (ZIP)

Archive of AUV tracks data. (ZIP)

At the Gulf of Cadiz (GoC), poleward currents leaning along the coast alternate with coastal upwelling jets of opposite direction. Here the patterns of these coastal countercurrents (CCCs) are derived from ADCP data collected during 7 deployments at a single location on the inner shelf. The multiyear (2008-2014) time-series, constituting ~. 18. mon...

Multiyear (2008-2014) ADCP data were collected during 7 deployments at a single location on the inner shelf of the Gulf of Cadiz. The time series (~18 months of hourly records) are used to characterise the patterns of coastal counter currents (CCCs) that alternate with upwelling jets of opposite (eastward) direction in this area. The observations i...

Under northerly winds upwelling is recurrent at the Cape São Vicente, SW Iberia, and plays a major role on the distribution of dissolved nutrients and metals. The aim of this work was to characterize the dissolved metals distribution of zinc (Zn), cadmium (Cd) and lead (Pb), associated with a filament of upwelled water that stretches seaward from t...

The existence of a wide bed of the crinoid Leptometra celtica (M'Andrew and Barrett 1857), at approx-imately 500 m depth, off the Portuguese south coast is inferred from remotely operated vehicle (ROV) transects carried out as part of a research project (IMPACT) aimed at evaluating the impact of bottom trawling on the burrowing crustacean Norway lo...

The existence of a wide bed of the crinoid Leptometra celtica (M’Andrew and Barrett 1857), at approximately 500 m depth, off the Portuguese south coast is inferred from remotely operated vehicle (ROV) transects carried out as part of a research project (IMPACT) aimed at evaluating the impact of bottom trawling on the burrowing crustacean Norway lob...

Iberia Peninsula (IP) constitutes the northern sector of the Canary Current Upwelling System. This study analyses the influence of upwelling on phytoplankton variability over a 15-year time series (1998-2012) off southwestern IP. Three polygons were delimited within the study area: west (WC) and south (SC) coasts and Cape São Vicente (CSV), the inf...

Upwelling filaments are mesoscale structures of cold water that stretch seaward in a tongue-like shape with origin in the coastal upwelling zone. Filaments represent preferred pathways for the exchange of water, dissolved and particulate matter from the productive shelf region towards the oligotrophic offshore regions. Upwelling filaments are a com...

The present paper describes the chemical characteristics and biological implications during an upwelling event that took place in the beginning of October 2006 off the South Portuguese coast. The study is based on a total of 90 CTD casts regularly distributed in 10 meridional 35 km long sections, along with wind and current ADCP velocity measuremen...

Portugal is strongly vulnerable to sea hazards due to intense vessel traffic and sea conditions. The southwest region off the Iberian Peninsula lies in the main route from the Mediterranean and Southern Hemisphere to the Northern Europe, causing a ship concentration in a narrow band off Cape São Vicente. Tankers represent a significant part of the...

The region off southwestern Iberia (NE Atlantic) encompasses a wide variety of oceanographic regimes, including differently (geographic) oriented coastal areas impacted by upwelling, riverine inputs and submarine groundwater discharge, submarine canyons and seamounts, and open ocean waters, thereby potentially promoting zone-specific phytoplankton...

The region off southwestern Iberia (NE Atlantic) encompasses a wide variety of oceanographic regimes, including differently (geographic) oriented coastal areas impacted by upwelling, riverine inputs and submarine groundwater discharge, submarine canyons and seamounts, and open ocean waters, thereby potentially promoting zone-specific phytoplankton...

Portugal is strongly vulnerable to sea hazards due to intense vessel traffic and sea conditions. The southwest region off the Iberian Peninsula lies in the main route from the Mediterranean and Southern Hemisphere to the Northern Europe, causing a ship concentration in a narrow band off Cape São Vicente. Tankers represent a significant part of the...

Satellite-derived sea surface temperature (SST) trends are built at the pixel scale to investigate long term changes in oceanic patterns. We consider that the SST time-series already available is long enough to attempt the analysis at the decadal scale. The analysis extends from 1982 to 2009 and is applied to the eastern boundary of the North Atlan...

The present paper describes the chemical and biological characteristics of an upwelling filament off southern Iberia in October 2004, based on a total of 42 CTD casts, along with ADCP velocity measurements distributed by an almost regular grid of 15 km mean spacing. Stations were sampled from the surface to a maximum depth of 400 dbar, for nutrient...

1] Analysis of sea surface temperature (SST) time series since 1960 from existing data bases shows a generalized warming trend in the northern Canary upwelling system. The field of the satellite-derived SST trends off Western Iberia was built at the pixel scale (4 Â 4 km) for the period 1985 – 2008, revealing significant spatial differences in the...

The Western Iberia constitutes the northern limb of the Canary Current Upwelling System, one of the four Eastern Boundary Upwelling Systems of the world ocean. The strong dynamic link between the atmosphere and the ocean makes these systems highly sensitive to global change, ideal to monitor and investigate its effects. In order to investigate deca...

This chapter focuses on the importance of remote sensing and GIS for oceanography and fisheries research and support. It provides a brief description of principles, technologies and methodologies of satellite oceanography (visible, infrared and microwaves) and marine GIS applications (with a short introduction to geostatistics). With the help of ca...

1] The present paper describes the physical characteristics of an upwelling filament off Cape St. Vincent (southern Iberia) in October 2004, based on remote sensing, hydrographic, ADCP and wind data. It was associated with a meandering jet similar to eastern Pacific or Canary filaments, though its dynamical features were weaker as a result of the s...

Cold water filaments have important implications in the biological and chemical exchanges between the coastal and offshore ocean. The Cape Sao Vicente area in the Southwest coast of Portugal is a well know region where such phenomenon is observed. In October 2004, the multidisciplinary project ATOMS, involving oceanographers and acousticians, was c...

Atmosphere–ocean coupling off the western Iberian Peninsula (IP) was empirically explored using Canonical Correlation Analysis (CCA) of Sea Surface Temperatures (SST) and ocean winds. The analyses were performed at three different spatio-temporal levels: a) regional-scale, 1° × 1°, monthly data (1981–1997), b) mesoscale 0.25° × 0.25° winds with 4 k...

The present review is focused on the mesoscale physical processes recognized in the Western Iberia Ecosystem, complementing earlier reviews dedicated to larger scales. Recent studies support the idea that the mesoscale processes, superimposed on the larger scale variability, are the major factor controlling the ecosystem functioning in the region....

A set of 25-km QuikSCAT wind measurements have been compared with 10-m winds from anemometer stations in the southwestern Iberian Peninsula. Comparisons were made for anemometer observations co-located in time to the QuikSCAT pass and scatterometer vectors with direction differences not exceeding a fixed directional threshold co-located in space wi...

A new look at the inner-shelf circulation in the northern Gulf of Cádiz (SW Iberian Peninsula) is taken. Results reveal the introduction of a sharp spatial heterogeneity in the wind field by the coastal geometry around Cape St. Vincent and nearby mountain chains. Direct observations taken in November–December 2001 reveal the alternating nature of t...

The circulation and structure of the coastal upper ocean during the relaxation after an upwelling event around Cape São Vicente, the southwestern tip of Iberian Peninsula, are described. Hydrographic, ADCP, wind, and remotely sensed SST data during the upwelling season reflect the interplay of two contrasting regimes in the region: coastal upwellin...

Geostrophic transport and hydrographic measurements derived from a historical database (1900-1998) were used to study the spring-summer mean circulation in the upper layer south and west of Cape St. Vincent, Southwest (SW) Portugal. The larger-scale circulation scheme is forced by equatorward winds from May to September, when the Iberian coastal tr...

The objective of this study is to investigate the recurrent development of a warm countercurrent over the inner shelf next to the coast off the southwest of the Iberian Peninsula, following the weakening or relaxation of upwelling favourable winds, as observed in the SST satellite imagery. Sea level data are examined in a monthly basis, taking adva...

It has recently been documented the occurrence of warm, poleward counter-currents featuring the circulation inshore the upwelling jet along SW Portugal during the upwelling season. Apparently, this flow is strongly wind-dependent and it has its source at the inner Gulf of Cádiz. It flows at mean velocities of ~20 cm/s separating the coastal jet off...

1] The coastal upwelling region near Cape São Vicente, the southwestern tip of the Iberian Peninsula where the southern zonal coast meets the meridional western coast, was studied using over 1200 advanced very high resolution radiometer (AVHRR) satellite images of sea surface temperature and time series of sea level height, wind velocities, and nea...

Geostrophic transport and hydrographic measurements taken from an historical database (1900-1998) were used to study the spring-summer mean circulation in the upper layer along SW Portugal. The larger-scale circulation scheme is forced by the equatorward, upwelling favorable winds produced by the Azores High. It shows a partially separated surface...

Thesis (Ph. D.)--University of Wales Bangor (Ocean Sciences), 1999.