Aerossóis atmosféricos no Bioma Caatinga: distribuição, higroscopicidade e formação de novas partículas

Abstract

Aerosols affect climate in different ways through their interactions with radiation and clouds, and by absorbing and scattering solar radiation. The overall effect of these interactions modifies the planetary albedo and, consequently, the terrestrial radiative balance, resulting in warming as the albedo increases and more radiation is absorbed. This study aims to reduce uncertainties about aerosol populations, black carbon concentrations, cloud condensation nuclei and new particle formation, measured in the Caatinga region in the interior of the state of Ceará, where there are few studies focused on the study of aerosols in this biome. However, this study brings unprecedented contributions regarding aerosol concentrations as well as the definition of hygroscopicity and new particle formation. The objective of this study will be to evaluate aerosols regarding black carbon (BC) concentration, cloud condensation nuclei (CNN), hygroscopicity (κ) and new particle formation (NPF): the campaigns were carried out in the Caatinga biome and in urban areas, respectively. The first stage of this work consisted of aerosol measurements. Three field campaigns (~10 days each) have been carried out to collect aerosols in the Caatinga and urban areas using a mobile scanning particle size spectrometer, a multispectral black carbon monitor (BC 1054) and a cloud condensation nuclei counter (CCNC). The analyses carried out in the Caatinga and urban areas were on the concentrations by size of the aerosols, especially black carbon and its hygroscopicity (κ). In general, the concentration of aerosols in the Caatinga and urban areas are different, with much higher concentrations in the urban areas. On the other hand, the hygroscopicity (κ) for the Caatinga and urban areas were the same, with κ equal to 0.19. These aerosols are less hygroscopic than continental aerosols observed in Europe (κ = 0.36) and than the global continental average (κ = 0.27). Regarding the formation of new particles, 45% of the days analyzed were identified, the events of formation of new particles were evaluated and it was concluded that 70% of the days analyzed had NPF, either class I or class II.