Abstract
Abstract. Understanding of aerosol sources that affect climate is an ongoing problem facing scientists as well as policymakers. The role of aerosols in local climate variability depends on a balance between light absorbing and scattering particles as well as on variability of environmental conditions. In this paper we investigate variability of aerosol content (both absorbing and scattering ultraviolet radiation) over continental Portugal in connection with aerosol sources (volcanic eruptions, dust events, wildfires and anthropogenic pollution). The effect of the aerosol on the climate is studied analyzing their contribution to variations of temperature, pressure, sunshine duration and precipitation over Portuguese regions. The present analysis is based on a developed modern multiple regression technique allowing us to build the statistical correlation models to determine both the main local aerosol sources and aerosol's influence on the climate of continental Portugal during 1978–1993. The analysis allows us to conclude that the main sources driving the variations of the aerosol content over studied locations are wildfires, mineral dust intrusions and anthropogenic pollution. The relations between the aerosol content variations and the atmospheric parameters depend on the level of urbanization of the studied region, the type of aerosol and the season. The most significant finding is the decrease of the daily maximum temperature (and diurnal temperature range) related to the decrease of sunshine duration observed during the summer periods of increased content of the absorbing aerosols in the atmosphere.
Highlights
Aerosol particles scatter and absorb solar and terrestrial radiations depending on their microphysical and optical characteristics
The multiple regression models (MRM) for the aerosol index (AI) series (Fig. 3a, d, g, j) are well correlated with the original series for both locations and explain 33–55 % of the AI variations. These results show that the Saharan dust events (SDEs), the wildfires and possibly the volcanic eruptions significantly affect the aerosol content over the lowpopulated location (ID 288), while the anthropogenic polluwww.atmos-chem-phys.net/15/6407/2015/
To study further the role played by the aerosols in the climatic variations of this region, we constructed multiple regression models that explain sunshine duration variations depending on the following parameters: precipitation and pressure, and AIpos and AIneg
Summary
Aerosol particles scatter and absorb solar and terrestrial radiations depending on their microphysical and optical characteristics. These periods start mainly in 2002 when the facilities allowing for the in situ measurements of many aerosol parameters were established at the Évora Geophysics Centre Observatory, (38.57◦ N, 7.91◦ W; 293 m a.s.l.) – see, e.g., Pereira et al (2011, 2012) These studies showed the strong dependence of the local aerosol content and its composition both on anthropogenic and natural sources. The present paper is dedicated to understanding the local and global aerosol sources and the effect of the local aerosol content in climate variations of the continental Portuguese region for the time period 1978–1993. Part 2 of the Supplement presents the correlation analysis between the sunshine duration series and other meteorological parameters
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