Minimizing light absorption measurement artifacts of the Aethalometer: evaluation of five correction algorithms

TLDR

The aerosol light absorption coefficient is key to atmospheric radiation budgets, yet Aethalometer measurements are systematically too high compared to reference methods, prompting the development of four correction algorithms. The study develops a new correction scheme that incorporates aerosol optical properties into the Aethalometer measurements. The new correction scheme was evaluated on six diverse aerosol datasets, including multi‑wavelength and white‑light AE, and compared against a Multi‑Angle Absorption Photometer over periods ranging from six months to five years. The study analyzes how each correction alters wavelength dependence, assesses performance limits, and provides recommendations for optimal use. Abstract.

Abstract

Abstract. The aerosol light absorption coefficient is an essential parameter involved in atmospheric radiation budget calculations. The Aethalometer (AE) has the great advantage of measuring the aerosol light absorption coefficient at several wavelengths, but the derived absorption coefficients are systematically too high when compared to reference methods. Up to now, four different correction algorithms of the AE absorption coefficients have been proposed by several authors. A new correction scheme based on these previously published methods has been developed, which accounts for the optical properties of the aerosol particles embedded in the filter. All the corrections have been tested on six datasets representing different aerosol types and loadings and include multi-wavelength AE and white-light AE. All the corrections have also been evaluated through comparison with a Multi-Angle Absorption Photometer (MAAP) for four datasets lasting between 6 months and five years. The modification of the wavelength dependence by the different corrections is analyzed in detail. The performances and the limits of all AE corrections are determined and recommendations are given.