Correcting Black Carbon Absorption Measurements with Micro-aethalometer Model 200: Insights from Comparative Analysis

Black carbon (BC) is the strongest visible-light-absorbing aerosol component in the atmosphere, with a significant impact on Earth's radiative budget. Accurate measurement of BC light absorption is crucial for estimating its radiative effect. The micro-aethalometer model 200 (MA200) by AethLabs, USA, offers high-time-resolution measurement of the multi-wavelength absorption coefficient (σ_ab) within 1 s, making it widely used in aerial measurement due to its compact size and light weight. However, the reliability of the measured σ_ab has not been extensively studied in previous research. In this study, we evaluate the performance of MA200 by comparing σ_ab measurements obtained from MA200 with those from the aethalometer model 33 (AE33) by Magee, USA. Our results revealed a significant variation in the determinant coefficient (R²) between σ_ab measurements from MA200 and AE33, depending on the time resolution. The R² increases from 0.1 to 0.5 and further to 0.97 as the time resolution of σ_ab increases from 1 s to 30 s and 60 s, respectively. We recommend a minimum time resolution of 30 s for stable σ_ab measurements using MA200. Moreover, we determine σ_ab from attenuation coefficient (σ_ATN) measured by MA200 as σ_ab = (σ_ATN – σ₀)/C_MA, where σ₀ ranges from – 15.3 Mm^–1 to – 6.4 Mm^–1 and C_MA ranges from 2.65 to 3.21. Correcting the measured σ_ab based on the findings of this study can provide reliable results for estimating the radiative effects of BC.