FCT (DCEA) - Capítulos de Livros em Editoras Internacionais
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Browsing FCT (DCEA) - Capítulos de Livros em Editoras Internacionais by Author "Carvalho, Ana Cristina"
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- Learning from 24 years of ozone data in PortugalPublication . Barros, Nelson; Silva, M.P.; Fontes, Tânia; Manso, M. Conceição; Carvalho, Ana CristinaOzone (O3) is a secondary pollutant mainly produced in the troposphere by photochemical reactions with high impact on human health. In this work hourly average O3 concentrations from the Portuguese air quality network collected during 24 years (1988–2011) were analysed. The background time series were assessed by environment type (urban, suburban and rural) and considering several criteria: the annual mean O3 concentration, the Directive 2008/50/EC O3 long-term objective and the 2005 WHO Guideline for protection of human health and, finally, the hourly information threshold exceedances. The trend of annual mean O3 concentration data and the maximum daily eight-hour mean ozone concentration data were both annually compared using an one-way ANOVA followed by a Tamhane post-hoc comparison test. In both series, although of an instable trend, a tendency for an increase of the mean O3 concentrations was found. On the other hand, after 2006, for all stations types, the normalized number of exceedances for public O3 information are significantly decreasing (p<0.05). In this paper, the O3 trend will be analyzed and discussed, contributing to improve knowledge of long time series of O3 concentrations in Portugal.
- 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.