In situ measurements of aerosol optical properties and number size distributions in a coastal region of Norway during the summer of 2008

• Published in: Atmospheric Chemistry and Physics
• Main Authors: S. Mogo, V. E. Cachorro, J. F. Lopez, E. Montilla, B. Torres, E. Rodríguez, Y. Bennouna, A. M. de Frutos
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2012
• Subjects: Physics; QC1-999; Chemistry; QD1-999; Arctic; Norway; Vesterålen; Andøya; Alomar; albedo; International Polar Year; IPY
• Online Access: https://doi.org/10.5194/acp-12-5841-2012; https://doaj.org/article/5e12352b07fb429eaa9a9f493a88dc9c

In situ measurements of aerosol optical properties and particle size distributions were made in the summer of 2008 at the ALOMAR station facility (69°16' N, 16°00' E), located in a rural site in the north of the island of Andøya (Vesterålen archipelago), approximately 300 km north of the Arctic Circle. The extended three-month campaign was part of the POLARCAT Project (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols, and Transport) of the International Polar Year (IPY-2007-2008). Our goal was to characterize the aerosols of this sub-Arctic area, which are frequently transported to the Arctic region. Data from 13 June to 26 August 2008 were available and the statistical data for all instruments were calculated based on the hourly averages. The overall data coverage was approximately 72%. The hourly mean values of the light-scattering coefficient, σ s , and the light-absorption coefficient, σ a , at 550 nm were 5.41 Mm −1 (StD = 3.55 Mm −1 ) and 0.40 Mm −1 (StD = 0.27 Mm −1 ), respectively. The scattering/absorption Ångström exponents, α s,a , were used in a detailed analysis of the variations of the spectral shape of σ s,a . While α s indicates the presence of two particle sizes corresponding to two types of aerosols, α a indicates only one type of absorbing aerosol particle. α a values greater than 1 were not observed. The single-scattering albedo, ω 0 , ranged from 0.62 to 0.99 (mean = 0.91, StD = 0.05), and the relationships between this parameter and the absorption/scattering coefficients and the Ångström exponents are presented. Any absorption value may lead to the lowest values of ω 0 , whereas only the lowest scattering values were observed in the lowest range of ω 0 . For a given absorption value, lower ω 0 were observed for smaller α s . The submicrometer, micrometer and total concentrations of the particles presented hourly mean values of 1277 cm −3 (StD = 1563 cm −3 ), 1 cm −3 (StD = 1 cm −3 ) and 2463 cm −3 (StD = 4251 cm −3 ), respectively, ...