Determining the Aethalometer multiple scattering enhancement factor C from the filter loading parameter

• DOI: 10.1016/j.scitotenv.2024.170221
• Publication Date: 2024-01-25T12:10:26Z
• Authors: L. Ferrero; N. Losi; M. Rigler; A. Gregorič; C. Colombi; L. D'Angelo; E. Cuccia; A.M. Cefalì; I. Gini; A. Doldi; S. Cerri; P. Maroni; D. Cipriano; P. Markuszewski; E. Bolzacchini
• Keywords: Aethalometer; Single-scattering albedo; Albedo (alchemy)

Light-absorbing aerosols heat the atmosphere; an accurate quantification of their absorption coefficient is mandatory. However, standard reference instruments (CAPS, MAAP, PAX, PTAAM) are not always available at each measuring site around world. By integrating all previous published studies concerning Aethalometers, AE33 filter loading parameter, provided by dual-spot algorithm, were used to determine multiple scattering enhancement factor from Aethalometer itself (hereinafter CAE) on yearly and a monthly basis. The method was developed in Milan, where measurements compared with MAAP data; comparison showed good agreement terms equivalent black carbon (R2 = 0.93; slope 1.02 negligible intercept 0.12 μg m−3) leading experimental 2.51 ± 0.04 CMAAP). On time base CAE values obtained using new approach 2.52 0.01, corresponding one (CMAAP). Considering seasonal behavior, higher CMAAP computed found summer (2.83 0.12) whereas, lower ones winter/early-spring (2.37 0.03), single albedo behavior Po Valley. Overall, between root mean squared error (RMSE) just 0.038 prediction, characterized close 1 (1.001 0.178), (−0.002 0.455) high degree correlation 0.955). From environmental point view, application dynamic (space/time) determination increases accuracy aerosol heating rate (compared applying fixed C value) up 16 % solely 114 when applied Arctic 80°N.