Correction to: Northerly wind trends along the Portuguese marine coast since 1950

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.info:eu-repo/semantics/publishedVersio

Does leverage affect asset returns? Theory and evidence

Mestrado em Economia Monetária e FinanceiraO estouro da bolha imobiliária nos EUA que culminou na crise financeira de 2008-09 reacendeu o interesse no estudo das vulnerabilidades que resultam de elevados níveis de alavancagem financeira. Para estudar a relação entre a alavancagem e os preços dos ativos, esta dissertação apresenta um modelo que replica uma economia com dois períodos, dois ativos diferentes, sendo um mais arriscado que o outro, onde dois estados da natureza podem ocorrer. As crenças heterogéneas dos agentes que pertencem a esta economia resultam em diferentes expectativas acerca do retorno esperado do ativo com risco. Esta heterogeneidade dita que apenas os agentes mais otimistas participam do mercado de ativos de risco. Assim, quando o crédito é introduzido nesta economia essa taxa de participação diminui em função do aumento do preço do ativo com risco. Do modelo apresentado retira-se que a taxa de retorno do ativo com risco depende positivamente do índice de alavancagem do agente (ou rácio Financiamento-Garantia). Esta dissertação realiza ainda uma análise de regressão multivariada, através de dados trimestrais do mercado de habitação que constam na base de dados do BCE, e descobre que a taxa de retorno da habitação na área euro reage negativamente ao aumento da alavancagem financeira das famílias observado no trimestre em análise, mas tem uma reação positiva e mais forte ao nível de alavancagem observado no trimestre anterior. Estes resultados sugerem que a taxa de retorno do mercado imobiliário pode demorar a responder a alterações nos requisitos dos financiamentos hipotecários.The housing bubble burst following the emergence of leverage-fuelled property booms observed in the US culminated in the financial crisis of 2008-09 did regain the interest on the vulnerabilities that result from higher levels of leverage. To capture the relation between leverage and its influence on asset bubbles, this paper presents a model to replicate an economy with two periods, two different assets, with one riskier than the other, where two states of nature can occur. The heterogeneous beliefs of agents belonging to this economy result in different assignments on the expected return of the risky asset which in turn dictates that only the more optimistic agents participate in the risky asset market. When agents have access to credit to purchase the risky asset, this participation rate diminishes as a result of the increasing price of the risky asset. One can also derive from this model that the rate of return of the risky asset depends positively on the agent?s leverage ratio (or Loan-to-Value ratio). By using quarterly housing data from the European Central Bank Data Warehouse, this paper does a multivariate regression analysis to find the housing return rate in the Euro area reacts negatively to increasing households? leverage observed in the current quarter, but has a higher positive reaction from the leverage level observed in the previous quarter. The results suggest the rate of return of the housing market may show some delay to reply to looser margin requirements.info:eu-repo/semantics/publishedVersio

Variability patterns and phenology of harmful phytoplankton blooms off southern Portugal: looking for region-specific environmental drivers and predictors

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 spatialtemporal variability patterns and phenology for key toxigenic phytoplankton species off southern Portugal, during a 6-year period, and identify region-specific environmental drivers and predictors. Total abundance of species responsible for amnesic shellfish poisoning (Pseudo-nitzschia spp.), diarrhetic shellfish poisoning (Dinophysis spp.), and paralytic shellfish poisoning (G. catenatum) were retrieved, from the National Bivalve Mollusk Monitoring System public database. Contemporaneous environmental variables were acquired from satellite remote sensing, model-derived data, and in situ observations, and generalized additive models (GAMs) were used to explore the functional relationships between HABs and environmental variables and identify regionspecific predictors. Pseudo-nitzschia spp. showed a bimodal annual cycle for most coastal production areas, with spring and summer maxima, reflecting the increase in light intensity during the mixed layer shoaling stage, and the later stimulatory effects of upwelling events, with a higher bloom frequency over coastal areas subjected to stronger upwelling intensity. Dinophysis spp. exhibited a unimodal annual cycle, with spring/summer maxima associated with stratified conditions, that typically promote dinoflagellates. Dinophysis spp. blooms were delayed with respect to Pseudo-nitzschia spp. spring blooms, and followed by Pseudo-nitzschia spp. summer blooms, probably reflecting upwelling-relaxation cycles. G. catenatum occurred occasionally, namely in areas more influenced by river discharges, under weaker upwelling. Statistical-empirical models (GAMs) explained 7-8%, and 21− 54% of the variability in Pseudo-nitzschia spp. and Dinophysis spp., respectively. Overall, a set of four easily accessible environmental variables, surface photosynthetically available radiation, mixed layer depth, sea surface temperature, and chlorophyll-a concentration, emerged as the most influential predictors. Additionally, over the coastal production areas along the south coast, river discharges exerted minor negative effects on both HAB groups. Despite evidence supporting the role of upwelling intensity as an environmental driver of Pseudonitzschia spp., it was not identified as a relevant model predictor. Future model developments, such as the inclusion of additional environmental variables, and the implementation of species- and period-specific, and hybrid modelling approaches, may further support HAB operational forecasting and managing over complex coastal domains.info:eu-repo/semantics/publishedVersio

The signature of NAO and EA climate patterns on the vertical structure of the canary current upwelling system

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 of 25 years (1993-2017). The study focuses on the central part of the Canary Current (25-35 degrees N) with persistent upwelling throughout the year, with an annual cycle and the strongest events from June to September. Upwelling is determined using two different approaches: one index is calculated based on temperature differences between the coastal and the offshore area, and the other is calculated based on wind data and the resulting Ekman transport. Different datasets were chosen according to the indices. Stable coastal upwelling can be observed in the study area for the analysed time span, with differences throughout the latitudes. A deepening of the isothermal layer depth and a cooling of temperatures are observed in the vertical structure of coastal waters, representing a deeper mixing of the ocean and the rise of cooler, denser water towards the surface. During years of a positive NAO, corresponding to a strengthening of the Azores High and the Icelandic Low, stronger winds lead to an intensification of the upwelling activity, an enhanced mixing of the upper ocean, and a deeper (shallower) isothermal layer along the coast (offshore). The opposite is observed in years of negative NAO. Both effects are enhanced in years with a coupled, opposite phase of the EA pattern and are mainly visible during winter months, where the effect of both indices is the greatest. The study therefore suggests that upwelling activities are stronger in winters of positive North Atlantic Oscillation coupled with a negative East Atlantic pattern and emphasizes the importance of interactions between the climate patterns and upwelling.LA/P/0101/2020info:eu-repo/semantics/publishedVersio

Acoustic inversion of the cold water filaments off the Southwest coast of Portugal

Cold water filaments have important implications in the biological and chemical exchanges between the coastal and offshore ocean. The Cape São 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 conducted with the objective to complement the sea surface temperature (SST) satellite observation with a full water column characterization. Due to weather and technical conditions during the project sea trial, only CTD measurements in upper layers of the water column were performed. These at sea collected data together with archival data from the NODC database, allowed to establish realistic scenario of the 3D temperature distribution in the area, including deeper water layers. Archival data of temperature profiles suggest the occurrence of other important oceanic phenomena such as the subduction of warm Mediterrenean water, that should also influence the acoustic propagation. With the help of forward acoustic modelling the significance and signature of the individual oceanographic phenomena on the acoustic propagation, regarding different sampling strategies of the area by acoustic means is investigated. These investigations allowed to develop strategies to settle the main problem addressed by this work: invert the cold water filament structure by acoustic means in a complex environment where acoustic propagation is affected also by other important oceanic and bathymetric features. Since, the objective of this work, is to evaluate the ability to perform a 3D characterization of vertical structure of the ocean, a minimal transmit-receive acquisition composed of a suspended source from a ship and a drifting vertical array, is assumed. The spatial structure is obtained by a combination of inversions for ”mean” sound speed/temperature perturbations obtained for source-array cross-sections covering the area of interest. Matched-field and ray tracing based tomography techniques are used in the inversion for the ”mean” perturbations. The planned sampling strategies and necessary acoustic equipment to resolve such oceanic features is discussed having in mind future sea trials.ATOMS - POCTI/MAR/15296/1999; FCT Program POSI - QCA III

Kinematics of surface currents at the northern margin of the Gulf of Cádiz

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 dataset, which is completed with ADCP time series from multiple moorings at five inner-shelf stations and ERAS wind. Off the shelf, the main circulation pattern consists of a slope current, best developed in summer when north-westerlies dominate, in particular at the most exposed western region. Mechanisms other than upwelling must contribute to this flow in order to explain its seasonal persistence. The slope circulation reverses for regional wind events with an east component > 10 m s(-1), approximately. On the shelf, currents are mainly alongshore and balanced. The circulation is generally continuous along the coast, except for weak (< 0.1 m s(-1), broadly) poleward flows. In the latter case, the flow tends to remain equatorward near Cape Santa Maria. In winter, coastal poleward flows often extend over the entire margin and are mainly wind-driven. In summer, these flows generally consist of coastal counter currents (CCCs) with the poleward direction opposed to that of the slope current. The CCCs are associated with significant cyclonic recirculation, strongest to the west, where a transient eddy is shortly observed for weak wind stress. This circulation develops after periods of strong north-westerlies, supporting that CCCs result from the imbalance of a regional alongshore pressure gradient.info:eu-repo/semantics/publishedVersio

Modelos de avaliação integrada para melhorar a qualidade do ar urbano

Currently, air pollution represents one of the main environmental causes of mortality. It is also responsible by cutting lives short, reducing productivity through working days lost across the economy, increasing medical costs, and by considerable economic impacts. Europe's most serious air pollutants in terms of harm to human health are particulate matter, nitrogen dioxide and ground-level ozone. The principal objective of this thesis is to explore the capabilities of Integrated Assessment Modelling tools to cost-efficiently evaluate measures to improve the air quality, and furthermore to develop an urban Integrated Assessment Model (IAM). For this purpose a review of current integrated assessment methodologies to improve air quality, from simple (e.g. scenario approach) to more comprehensive ones (e.g. optimization approach) was done and some application tests were performed. Based on identified advantages of the revised approaches the Integrated Urban Air Pollution Assessment Model (IUAPAM) was designed and evaluated through its application to a selected urban case study (Porto Urban Area) considering different emission scenarios. The developed model is able to reproduce rapidly emission reduction scenarios and to estimate health impacts, making use of Artificial Neural Networks. Moreover, the use of Multi-Criteria Decision Analysis (MCDA) allows including social aspects and ranking air quality measures/scenarios. This research work contributes to a better understanding of the utility of IAM tools that are available to support the air quality decision-making process. IUPAM revealed to be useful to quickly evaluate the effect of local and regional policies focused on air pollution improvementAtualmente a poluição atmosférica representa uma das principais causas ambientais de mortalidade. Ela é ainda responsável pela redução da esperança média de vida, redução da produtividade devido à redução de dias de trabalho, aumento de custos hospitalares, e por impactos económicos consideráveis. Os poluentes mais relevantes em termos de efeitos na saúde humana são o material particulado, o dióxido de azoto e o ozono troposférico. O objetivo principal da presente tese é o desenvolvimento e teste de um Modelo de Avaliação Integrada (MAI) que permita apoiar a seleção custo-eficiente de medidas de melhoria de qualidade do ar em cidades. Com essa finalidade foi efetuada uma revisão das atuais metodologias de avaliação integrada da qualidade do ar, das mais simples (análise de cenário) às mais complexas (abordagem de otimização), e foram efetuados alguns testes de aplicação que permitiram identificar as principais vantagens e limitações de cada abordagem. Foi desenvolvido um Modelo de Avaliação Integrada à Escala Urbana (MAIEU) que ultrapassa algumas das dificuldades das ferramentas existentes e aproveita as suas vantagens. O modelo foi avaliado através da sua aplicação a um caso de estudo urbano (Grande Porto) e a diferentes cenários de emissões. É capaz de reproduzir rapidamente cenários de redução de emissões, e de estimar os seus impactes na saúde, recorrendo a Redes Neuronais Artificiais. Para além disso, o uso de Análise Multicritério permitiu incluir aspetos sociais e criar uma classificação de medidas/cenários de qualidade do ar. Este trabalho contribui para uma melhor compreensão da utilidade dos MAI, disponíveis para apoiar o processo de tomada de decisão. O MAIEU, revelou ser útil para avaliar rapidamente o efeito de políticas regionais e locais focadas na melhoria da poluição atmosférica à escala urbanaPrograma Doutoral em Ciências e Engenharia do Ambient

Erasmus experience between the University of Cadiz (Spain) and the University of Algarve (Portugal)

A mobility program was carried out during the last two years between the Universities of Cadiz (Spain) and Algarve (Portugal) under the EU funded Erasmus+ Mobility for Teaching. The objective of the mobility was twofold: on one hand, it included the strengthening of the existing scientific cooperation between the University of Cadiz (home institution) and the University of Algarve (host institution) in the field of the Gulf of Cadiz Physical Oceanography; on the other hand, it pretended to improve the teaching quality, focusing on both the lecturers and the students. Both institutions have long ties of cooperation that have recently been intensified under the umbrella of the International Campus of Marine Excellence (CeiMar). Specific objectives oriented towards the lecturers included the exchange of teaching experiences among them as well as the comparison of teaching strategies and methodologies between the host and home institutions at the Master level in order to evaluate and enhance the best teaching practices with the aim of improving the students learning process. Specific objectives oriented towards the students included: (1) to provide local students that cannot afford studying a Master degree abroad with a foreign teacher in the discipline that will offer them different added expectations; (2) to teach students different subjects from those taught at the host institution, thus benefitting from new scientific knowledge and experiences. It must be pointed out that the subject taught by the home institution lecturer represents a competence lacking at the host institution, hence complementing the program of the discipline and providing an added value to the Master degree. Informal questionnaires carried out among students by the host institution revealed that they evaluated having a foreign teacher as a very positive experience. In terms of research, collaboration among both institutions is of great importance because they are both located within the same geographic region and hence, they share common interests. The mobility promoted finishing on-going collaborative publications as well as sharing new research experiences, data and knowledge, hence leading to an improvement of the Physical Oceanography state-of-the-art in the Gulf of Cadiz. In fact, two scientific papers on the Gulf of Cadiz circulation system and two on the storm climate along the Gulf of Cadiz and its relation with coastal hazards have been recently published as a direct result of the mobility program.info:eu-repo/semantics/publishedVersio

Inventário nacional de emissões atmosféricas de dioxinas e furanos

Mestrado em Engenharia do AmbienteCom o presente inventário pretende-se fornecer informação relevante sobre as quantidades de dioxinas e furanos que são libertadas em Portugal para a atmosfera, e identificar as maiores fontes emissoras. Pretende-se ainda verificar a existência de uma tendência nas emissões, para isso o inventário abrange o período 2004-2009. A metodologia consistiu na selecção de fontes que possam ser relevantes no contexto nacional, a caracterização dessas fontes, a selecção e a aplicação de factores de emissão adequados para a estimativa das emissões. Foram tidos em conta estudos realizados em Portugal, nomeadamente os que incluíam medições de dioxinas e furanos realizadas em unidades indústrias. O inventário abrange 19 fontes de emissão, tendo-se concluído que 9 são significativas, isto é, apresentam emissões superiores a 1 g I-TEQ/ano. A maior fonte de emissão identificada foi os incêndios florestais, com emissões entre 18 g I-TEQ/ano e 377 g I-TEQ/ano em 2008 e 2005, respectivamente. Estimou-se uma emissão total nacional de dioxinas e furanos entre 56 e 415 g I-TEQ/ano, no período 2004-2009. Excluindo as emissões dos incêndios florestais, as emissões totais são praticamente constantes ao longo dos anos, e rondam as 38 g I-TEQ/ano.The main objective of this work is to develop an emission inventory of dioxins and furans to provide relevant information about the amounts of those compounds that are released into the atmosphere in Portugal, and identify their major sources. Additionally in order to verify the existence of a trend on the emissions, the inventory was extended to cover the period 2004-2009. The methodology consisted on the selection of sources that may be relevant in the national context, the collection of information to characterize this sources, the selection of appropriate emission factors and their application to estimate the emissions. Several studies conducted in Portugal where considered, including the measurements of dioxins and furans performed in some industrial facilities. The inventory covered 19 emission sources, however it was realized that only 9 were relevant, i.e. with emission amounts greater than 1 g I-TEQ/year. The largest emission source is forest fires, with emissions between 18 g I-TEQ/year and 377 g I-TEQ/year in 2008 and 2005, respectively. The total emission of dioxins and furans in Portugal reaches between 56 and 415 g I-TEQ/year, for the period 2004-2009. Excluding the emissions from forest fires, the total emissions maintain constant over the years, and around 38 g I-TEQ/year

Piece‐wise constant cluster modelling of dynamics of upwelling patterns

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. Corresponding clustering algorithms parameters are automatically derived by using the least-squares clustering criterion. The approach has been successfully applied to real-world SST data covering two distinct regions: Portuguese coast and Morocco coast, for 16 years each.LA/P/0101/2020info:eu-repo/semantics/publishedVersio