Characterization and applications of multi-decadal black carbon observations at a Mediterranean mountain site

Abstract. Long-term observations of black carbon (BC) are essential for assessing the effectiveness of air-quality and climate policies and for understanding the potential feedback of climate change. We present an 18-year dataset (2007–2024) of equivalent black carbon (eBC) mass concentration derived from the aerosol absorption coefficient measured at the Monte Cimone WMO/GAW Global Station (CMN, 2165 m a.s.l.), a key high-altitude observatory in the Mediterranean climate-change hotspot. The dataset is accompanied by detailed description of: i) the infrastructural evolution, including instrumentation and sampling system; ii) the definition of quality assurance protocol and data treatment; iii) the definition of the uncertainties. This documentation provides a comprehensive description and quantification of the data reliability over 18 years of measurements, necessary for the scientific valorisation of the dataset. Applications of the dataset demonstrate: i) a statistically significant decline in eBC concentrations over the last two decades ii) a strong linkage between eBC variability and boundary-layer dynamics when combined with ERA5 reanalysis; iii) a variable agreement with FLEXPART simulations across temporal scales, supporting its use for model evaluation. The dataset, openly available through the ITINERIS HUB, provides one of the longest continuous eBC records in the Mediterranean troposphere and represents a valuable resource for climate studies, trend assessments, and multi-station integration within ACTRIS and GAW.