Table 1. Hygroscopic growth factors from the literature measured for different aerosol types
Fig. 1
Experimental set-up.
Fig. 2
Chemical speciation of PM10 fraction during winter and spring campaigns expressed in percentages (%).The unaccounted mass fraction refers to the percentage of mass that was not determined by chemical analysis compared to the gravimetric PM10 mass. Mineral fraction was calculated as the sum of Al2O3, SiO2, CO3, Ca, Fe, Mg, K; trace elements as the sum of Li, P, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Cd, Sn, Sb, Cs, Ba, La, Ce, Lu, Hf, Ta, W, Tl, Pb, Bi, Th and U; and POM as OC*1.6.
Fig. 3
Time series of hourly average values of the scattering and absorption coefficients, single-scattering albedo, scattering Ångström exponent and f(RH=85%) during the winter campaign.
Table 2. Statistical summary of the aerosol dry scattering and absorption coefficient, single-scattering albedo, scattering Ångström exponent and scattering enhancement factor at 85% RH during the winter and spring campaigns
Fig. 4
Time series of hourly average values of the scattering and absorption coefficients, single-scattering albedo, scattering Ångström exponent and f(RH=85%) during the spring campaign.
Fig. 5
Diurnal evolution of the scattering and absorption coefficients at 550 nm, scattering enhancement factor at 85% RH and 550 nm, single-scattering albedo at 637 nm and scattering Ångström exponent during the winter (upper panel) and spring (lower panel) campaigns.
Fig. 6
Aerosol light-scattering enhancement factor at 550 nm versus relative humidity during different time periods in the winter (a) and spring (b) campaigns. Each point represents the average f(RH) value in 2% RH size bins.
Table 3. Mean and standard deviation of the dry scattering and absorption coefficients, single-scattering albedo, scattering Ångström exponent and scattering enhancement factor at 85% RH during the humidograms
Fig. 7
Frequency distribution of f(RH=85%) at 550 nm during the winter and spring campaigns. Data for periods where α(dry, 450–700) was above and below 1 and ω0(dry, 637 nm) was above and below 0.6 were extracted and plotted separately.
Fig. 8
Scattering enhancement factor at 85% relative humidity versus the ratio POM/(POM+) for the winter and spring campaigns. The linear fit refers to dust-free conditions.
Fig. 9
Time series of daily a) Ambient relative humidity, b) single-scattering albedo at 550 nm, c) backscatter fraction at 550 nm and d) aerosol forcing efficiency at 550 nm measured with the reference nephelometer and calculated to ambient RH conditions and to RH=85% during the spring campaign.