Browsing by Author "Borrego, Carlos"
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- Influence of traffic emissions estimation variability on urban air quality modellingPublication . Borrego, Carlos; Tchepel, Oxana; Monteiro, Alexandra; Barros, Nelson; Miranda, Ana IsabelThe main objective of this work is to analyse how uncertainties in emission data of nitrogen oxides (NOx) and volatile organic compounds (VOC), originated from road traffic, influence the model prediction of ozone (O3) concentration fields. Different methods to estimate emissions were applied and results were compared in order to obtain their variability. Based on these data, different emission scenarios were compiled for each pollutant considering the minimum and the maximum values of the estimated emission range. These scenarios were used as input to the MARIV mesoscale modelling system. Simulations have been performed for a summer day in the Northern Region of Portugal. The different approaches to estimate NOx and VOC traffic emissions show a significant variability of absolute values and of their spatial distribution. Comparison of modelling results obtained from the two scenarios presents a dissimilarity of 37% for ozone concentration fields as a response of the system to a variation in the input emission data of 63% for NOx and 59% for VOC. Far beyond all difficulties and approximations, the developed methodology to build up an emission data base shows to be consistent and an useful tool in order to turn applicable an air quality model. Nevertheless, the sensitivity of the model to input data should be considered when it is used as a decision support tool.
- Ozone deposition modelling in a portuguese coastal zonePublication . Valinhas, Maria José; Borrego, Carlos; Barros, Nelson; Carvalho, Ana CristinaThe deposition of pollutants from the atmosphere to ecosystems is the cause of some present environmental problems: acidification, eutrophication and, indirectly, ground level ozone. Related with these issues is the critical loads/levels concept, widely accepted in Europe as basis for pollution control strategies. The knowledge of atmospheric pollutants deposition on ecosystems is needed to setup this methodology. This paper presents the parameterisation done in the deposition module of the system of models MAR IV which is adequate to simulate the transport, dispersion and removal of pollutants, including ozone production for mesoscale application. The ozone surface resistance (Rc) pararneterisation was applied to Lisbon region and the modelk performance was assessed with ozone deposition experimental data observed in the study area during the fieldwork LisbEx 97. The influence of parameterisation became evident with the good fit between modelled results and measured data. Based on an empirical method described by the Stockholm Environmental Institute report a Critical Load map, for non-forested areas, was calculated for Pomgal. The methodology is based on the kind of soil and its buffer capacity to acid compounds, The results show that around 70°/0of the country is in sensitive areas reinforcing the need for the application of this concept.
- Stratozon: o ozono estratosférico na baixa troposfera sobre PortugalPublication . Barros, Nelson; Borrego, Carlos; Fontes, Tânia; Carvalho, Ana CristinaSupported by Science and Technology Foundation, the STRATOZON project is a 2 years national project and is being developed by Fernando Pessoa and Aveiro Universities, in collaboration with the Meteorological Institute and the Environmental Institute. The main scope of STRATOZON project is to justify non-photochemical ozone episodes, and such, episodes that cannot be controlled by local/regional management of its precursors emissions. At the end, it will be produced a document with guidelines to the Environmental Institute about this subject. Financiado pela Fundação para a Ciência e a Tecnologia, o projecto STRATOZON: O ozono estratosférico na baixa troposfera sobre Portugal, é um projecto nacional, que têm duração de 2 anos (2002-2004), e está a ser desenvolvido pela Universidade Fernando Pessoa e pela Universidade de Aveiro, em colaboração com o Instituto de Meteorologia e o Instituto do Ambiente. O projecto STRATOZON tem como objectivo genérico justificar os episódios de ozono de origem não fotoquímica e, como tal, não passíveis de qualquer controlo local/regional de emissões dos seus precursores. No final será feito um documento contendo directrizes para o Instituto do Ambiente sobre esta matéria.
- Urban photochemical pollution in the Iberian Peninsula: Lisbon and Barcelona airshedsPublication . Barros, Nelson; Borrego, Carlos; Toll, Isabel; Soriano, Cecilia; Jiménez, Pedro; Baldasano, José MariaNumerical simulations with photochemical transport models were independently performed for two domains situated in the Iberian Peninsula covering the Lisbon and Barcelona airsheds. Although the days chosen for simulation of the two cities are not the same, the synoptic situations in both cases, known as typical summertime situations, were similar, which allowed the development of typical mesoscale circulations, such as sea breezes and mountain and valley winds dominated by the Azores anticyclone. Emission inventories for the two areas were developed. The O3 concentrations recorded in both cities have a similar level. Nevertheless, Ox values in Barcelona are higher than in Lisbon, which may, at a first glance, indicate an apparently more oxidant atmosphere in Barcelona. Photochemical modeling for the two cities has shown that the behavior of the circulatory patterns in both urban areas is rather different, which mainly has to do with the different strengths of the sea breeze and the topography, inducing an important offshore vertical layered dimension of pollutant transport in Barcelona versus an important inland horizontal transport in Lisbon.
- A winter ozone episode over PortugalPublication . Carvalho, Ana Cristina; Moreira, Nuno; Leitão, Paula; Fontes, Tânia; Barros, Nelson; Borrego, Carlos