A Combined HYSPLIT-AERONET Approach for Improved Aerosol Source Identification

Accurate identification of aerosol sources remains a major challenge in atmospheric research because optical properties alone often provide ambiguous information regarding aerosol origin and composition. This study proposes an integrated approach that combines aerosol optical observations with air mass trajectory analysis to improve the reliability and physical interpretation of aerosol source classification. The methodology was tested using observations from the AERONET station at Lampedusa (Italy) for the period 2017-2018, a region frequently influenced by Saharan dust outbreaks, European anthropogenic emissions, and marine air masses. The analysis combines Aerosol Optical Depth (AOD), Ångström Exponent (AE), and Single Scattering Albedo (SSA) derived from AERONET with five-day backward air mass trajectories calculated using the HYSPLIT model at receptor heights of 2000 m and 4000 m. Additional meteorological observations and particulate matter chemical composition data support the interpretation of aerosol episodes. Air mass trajectories were grouped into African, European, and Atlantic/Marine transport sectors and subsequently integrated with optical aerosol characteristics to distinguish dust events, anthropogenic pollution, marine aerosols, and mixed aerosol conditions. The combined approach substantially reduces the ambiguity associated with optical-only classification, particularly for intermediate AE values where mixed aerosol types frequently occur. While trajectory analysis identifies the geographical origin of transported air masses, optical observations provide information on aerosol microphysical properties and loading. Their integration results in improved source attribution, enhanced confidence in aerosol classification, and a more physically interpretable description of aerosol transport processes. The proposed methodology demonstrates the benefits of combining transport modelling with optical observations. It provides a robust framework for future aerosol source apportionment studies and climate-related air quality assessments in regions affected by multiple aerosol sources.