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Universidade de Aveiro (2005)

A qualidade do ar e as alterações climáticas em Portugal

Carvalho, Ana Cristina Caldeira da Silva Gouveia

Titre : A qualidade do ar e as alterações climáticas em Portugal

Auteur : Carvalho, Ana Cristina Caldeira da Silva Gouveia

Université de soutenance : Universidade de Aveiro

Grade : Doutoramento em Ciências Aplicadas ao Ambiente 2005

Through their activities human societies have been interfering with the climatic system, proportionally to their growthand development. Within the climatic system, atmosphere composition is extremely dependent on emissions to the atmosphereresulting from human activities. Hence, monitoring greenhouse gases has becomean important task due to their role in the earth-atmosphere radiative budgetand its consequences on the climatic system at a global scale. Although ozone is notconsidered on the Countries Reports to the United Nations Framework Conventionon Climate Change it is a greenhouse gas with strong interactions with climate. The work presented here is based in three main, and interconnected, parts : the first one follows the tendency on ozone and precursors analysis, namely carbonmonoxide and nitric oxides concentrations in time, and how they may be related with local atmospheric thermodynamic vertical structure ; the second one exploresthe stratosphere-troposphere exchanges and their impact on surface ozoneconcentrations ; finally, the last part concerns the analysis of the impact on air quality in the middle of this century for an integrated emission-climate scenario. The results show that surface ozone concentrations are increasing with time overPortugal, although precursors concentrations are diminishing, notably for carbonmonoxide, according to the tendency verified in the Northern Hemisphere by otherauthors. The positive correlations encountered for surface ozone concentrations andatmospheric instability during winter time give indications that dynamical processesresponsible for stratospheric ozone into the troposphere are important overPortugal. The numerical models applied in the case studies have proven tobe a valuable tool to justifie non-photochemical ozone high concentrations at surface. This phenomenon may be enhanced in climate change scenarios. Air quality studies over Portugal in a combined emission-climate scenario for 2050, for meteorological conditions associated with photochemical formation, have shown worst results than in present climate, for ozone and especially for nitrogen dioxide. The aggravation of the well-connected code of the fire weather index with the burned area, the drought code, allow to say that in future climate scenarioatmospheric emissions of the biomass burning may increase. It is the author hope that the work here presented, associated to others in climate change applications, may contribute as valuable information when structuringactivities are planned by decision makers, due to their implications on atmosphericemissions and their consequences on a global and regional scale

Mots clés : Ciências do ambiente ; Qualidade do ar ; Poluição atmosférica ; Ozono atmosférico ; Alterações climáticas


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