DCA - Comunicações a Conferências / ConferenceItem
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- 7Be as a tracer on the investigation of upper tropospheric dispersion of Saharan dust during the mid-winter 2000 storm events (Azores).Publication . Rodrigues, A. F.; Holmes, Charles; Pio, Casimiro; Marot, Marci; Fialho, Paulo7Be is a nuclide that acts like a tracer of input from the stratosphere and upper troposphere, where it is produced by spallation processes of light atmospheric nuclei such as nitrogen 14, oxygen 16 and carbon 12, with protons and neutrons (Zanis et al. 2000). By measuring the activity of beryllium isotopes attached to submicrometer aerosol particles, information on the mechanisms of exchange between the stratosphere and troposphere is obtained. […].
- Aerosol Measurements in the Free Troposphere at the North Atlantic Pico Mountain Observatory in the Azores.Publication . Mazzoleni, Claudio; Fialho, Paulo; Gorkowski, Kyle; Owen, Robert; Dziobak, Michael P.; Hueber, Jacques; Dzepina, Katja; Kramer, Louisa; Olsen, Seth C.; Kumar, Sumit; Helmig, DetlevPico is a small island (447 km2) in the archipelago of the Azores, Portugal, in the North Atlantic Ocean. The island has a very steep inactive volcano. An atmospheric monitoring station (Pico Mountain Observatory) was established close to the summit of the volcano by the late Dr. Richard Honrath and colleagues in 2001. The station, far from persistent local sources, is located near the northern cliff of the summit caldera at an altitude of 2225 meters. The station altitude is typically well above the boundary layer during summertime, when average marine boundary-layer heights are below 1200 meters and rarely exceed 1300 meters. Air masses reaching the station are often transported from North America and seldom from Europe or North Africa. The station’s uniqueness and significance lie in its location that allows study of the transport and evolution of gases and aerosols from North America in the free troposphere. Until recently, the focus was on the measurement and analysis of trace gases (ozone, carbon monoxide, non-methane hydrocarbons, nitrogen oxides) and light-absorbing aerosol (black carbon and iron oxide). Aerosol light attenuation has been measured at the site since 2001 using a seven-wavelengths aethalometer. An optical particle sizer was installed at the site in 2010 and has been running in parallel to the aethalometer for two seasons. A three-wavelength nephelometer, to measure the aerosol total- and back-scattering, and aerosol samplers for morphological and chemical analysis will be installed at the site in 2012. Our goal is to enhance the observatory monitoring capabilities for aerosol research. The objectives of this new research program are to: (a) assess background as well as specific event tropospheric aerosol properties, (b) compare aerosol and gases measurements with model outputs, and (c) use the data collected to provide satellite validation. This research is anticipated to enhance our understanding of the interactions between tropospheric aerosols, clouds, and climate by allowing, for example, the analysis of North American outflows and seasonal changes, the assessment of different source regions, the estimation of aerosol radiative forcing above marine clouds and in clear sky, and the study of the relative contribution of anthropogenic versus biomass burning emissions. In this poster we present a preliminary analysis of the black carbon and aerosol size data in conjunction with retroplume model analysis.
- Aerosol Optical Depth measurements in the Azores.Publication . Carvalho, Fernanda; Henriques, Diamantino; Fialho, PauloA preliminary analysis of AOD results from sun-photometer measurements collected at Jose Agostinho Observatory at Angra do Heroísmo (Terceira Island, the Azores) was presented. The observational period ranges from August 2004 to December 2007, using a SP02 sun-photometer at wavelengths 412, 500, 675, and 862 nm, coupled to a 2AXP sun-tracker. The sampling interval is 5 s and data is filtered for cloud contamination in a time window of 10 minutes. Most AOD 500 nm values are below 0.3, showing a small variation during the day; frequency distribution shows a typical right skew distribution. Alpha and beta Angstrom coefficients were also computed and analyzed in the same way. Alpha values are generally positive and lower than 4, while beta values are below 1.5. AOD results from the AERONET station at Horta Observatory (Faial Island, the Azores) were also used and compared with Angra data. AOD and Angstrom coefficients were also analyzed with wind results from the automatic weather station located at both observatories. Results show different wind distributions due to different exposures; however, systematic higher AOD values are found at Horta. The proximity of the two sites indicates that these differences are more likely due to different instruments and processing methods used.
- Aerosol optical properties at Santiago Island, Cape Verde.Publication . Cerqueira, Mário; Pio, Casimiro; Fialho, Paulo; Cardoso, João; Nunes, Teresa; Almeida, S. M.> huge amounts of mineral dust are emitted every year from the Sahara desert to the atmosphere; > optical parameters of mineral aerosols determine the direct interaction of solar and terrestrial radiation in the atmosphere through scattering and absorption; > mineral dust has a great impact on cloud formation leading to additional indirect radiation effects; > The dense haze from dust events is also known to affect visibility.
- Amostragem de partículas em suspensão na atmosfera do Atlântico Norte.Publication . Rodrigues, A. F.; Fialho, Paulo; Pio, CasimiroOs aerossóis têm géneses e composições muito diferenciadas. Estes têm origem nas emissões naturais (por exemplo o spray marinho e as emissões vulcânicas) ou antropogénicas (por exemplo os processos de combustão). A caracterização física e química dos aerossóis é importante para compreender a relação entre: a sua origem; os mecanismos de transporte difusivo das massas de ar atmosférico; os processos de nucleação associados à formação de nuvens; e os mecanismos de transformação química. O Arquipélago dos Açores localizado numa zona remota (longe das emissões poluentes do continente Europeu e Americano e com emissões locais desprezáveis), é o local ideal para a caracterização física e química das massas de ar que o atravessam. A sua atmosfera "limpa" permite o estudo do transporte a longas distâncias de poluentes entre os continentes americano e europeu. Neste contexto efectuou-se a caracterização física do aerossol, recorrendo a um colector de partículas de grande volume (High-Volume - figura 1) com uma cabeça de pré-selecção de 10 μm. Os aerossóis foram separados em duas fracções, uma fina (diâmetros inferiores a 10 μm) essencialmente associada a contribuições antropogénicas, e outra grosseira (diâmetros entre 0,95 μm e 10 μm) maioritariamente relacionada com contribuições naturais. A massa de aerossol amostrada é determinada pela pesagem dos filtros onde este é recolhido, conjuntamente são efectuadas medidas de caudal volúmico e tempo de amostragem.
- Análise comparativa da importância dos vários agentes de polinização na cultura do morangueiroPublication . Albano, Sílvia; Salvado, Eva; Borges, Paulo A. V.; Mexia, AntónioA maioria das cultivares modernas de morangueiro possuem flores hermafroditas auto-férteis cuja polinização está dependente da acção combinada de vários agentes, nomeadamente o vento, a gravidade e os insectos polinizadores. A contribuição relativa de cada um destes agentes de polinização é variável consoante as cultivares envolvidas e o ambiente em que está inserida a cultura (estufai ar-livre). Com o objectivo de avaliar a importância dos vários agentes de polinização, na cultivar Camarosa, em condições de ar-livre, foram introduzidas várias colmeias num campo localizado na região do Ribatejo (Almeirim), no início da floração do ano de 2004. A metodologia utilizada consistiu na realização de experiências de polinização controlada a flores primárias da cultura, tendo sido definidos um total de seis modalidades: 1- Flores não embolsadas (Controlo); 2- Flores emasculadas, não embolsadas; 3- Flores embolsadas em tule; 4- Flores emasculadas, embolsadas em tule; 5- Flores embolsadas em celofane; 6- Flores polinizadas manualmente, embolsadas em celofane. Para cada modalidade foram analisados os seguintes parâmetros: peso e dimensões (diâmetros e altura) dos frutos, percentagem de vingamento e percentagem de frutos deformados. As modalidades com flores expostas às visitas dos insectos originaram frutos de maior peso e maiores dimensões e menor percentagem de frutos deformados. Em relação ao vento, os resultados apontam para a sua relevância, sobretudo na promoção da auto-polinização na flor do morangueiro.
- Applications of the hard sphere DeSantis equation of state to the estimation of the density of compressed alternative refrigerants.Publication . Fialho, Paulo; Nieto de Castro, Carlos A.The density of liquid refrigerants is very important for the design of compression cycles in the refrigeration and air conditioning industries. The increasing concern with the environmental protection leads the governments to legislate in order to banish in the short term the use of the CFC's and in the long run the HCFC's. Considering those decisions, the industries need to find new replacements for those compounds, and suitable substitutes seam to be HFC's, fluorinated ethers, their mixtures and mixtures with small quantities of HCFC's. The only problem in using those alternative refrigerants is the lack of knowledge about their properties. Among them, the density is one of the most important. It is the propose of this paper to show the use of a model that allows the user to estimate the liquid density for the refrigerants. The uncertainty of this model is of ± 2.0 % for reduced values of temperature less then 0.95 and reduced values of density less then 1.0. This model needs the information for the critical parameters and the pressure of the saturated liquid-vapour line. The Hard-Sphere DeSantis equation of state Ref. /1/ is use to give physical support to the model. The corrections to the attractive and repulsive part, a and b, have been calculated from a few experimental pure refrigerants Ref. /1/ (HCFC 152a, HCFC 22, HCFC 142b, HCFC 123, HCFC 114).
- An approach to evaluate aerosol optical depth at marine boundary layer : the Pico-Graciosa measurement platformPublication . Henriques, Diamantino; Carvalho, Fernanda; Fialho, PauloAerosols are an important constituent of the atmospheric boundary layer. Aerosol particles provide surfaces for heterogeneous chemical processes, they also act as a condensation sink for atmospheric trace species. In the marineatmosphere originate from a variety of production and transformation processes that includes sea spray aerosol produced at the sea surface through the interactions between wind and surface waves (Liss and Johnson, 2013).
- Assessment of air quality on basis of particle matter (PM) measurement in the North Atlantic.Publication . Barata, Filipe; Fialho, Paulo; Pio, CasimiroThe European thematic strategy on air pollution and the accompanying proposal to revise the ambient air quality directive (1999/30/EC) would, for the first time, introduce controls on human expose to PM2.5 to complement the existing limits on coarse particulate matter (PM10) (EC, 2005).
- Avaliação do valor nutritivo e Identificação dos fitoestrogénios produzidos pelasplantas Pittosporum undulatum Vent., 1800 e Hedychium gardnerianum Ker-Gawler, 1828Publication . Nunes, Hélder Patrício Barcelos; Borba, Alfredo Emílio Silveira de; Silva, Joaquim Fernando Moreira daO Pittosporum undulatum Vent., 1800 e o Hedychium gardnerianum Ker-Gawler, 1828, conhecidas vulgarmente por faia e por conteira, são duas plantas invasoras dos Açores que, em períodos de maior escassez alimentar, são fornecidas aos ruminantes como alimentos volumosos, contudo pensa-se que seu fornecimento aos animais possa estar diretamente associado aos abortos verificados em algumas explorações dos Açores. Estas plantas poderão, por esse motivo, conter diversos metabólitos secundários, mais concretamente fitoestrogénios, que poderão influenciar a atividade sexual dos animais quando alimentados com estas plantas. Este estudo tem como objetivo avaliar o valor nutritivo e quantificar os diferentes tipos de fito-estrogénios presentes nestas plantas. […].