| Summary: | Atmospheric aerosols play a significant role in Earth’s energy budget by scattering and absorbing shortwave radiation and influencing cloud properties and lifetimes. The climate impact of aerosols is strongly dependent on their properties yet many aerosol processes, including New Particle Formation (NPF) remain poorly understood. In-situ observations are essential for understanding climate mechanisms in the atmosphere, but their value also relies on a clear understanding of atmospheric transport patterns and the history of the observed air masses. Aerosol measurements are often biased toward the Northern Hemisphere and low-altitude, leaving the Southern Hemisphere and high-altitude areas underrepresented. This thesis focuses on observations from the Chacaltaya Global Atmospheric Watch station (CHC) in the Bolivian Central Andes. This thesis aims to: (1) develop methodologies that integrate high-resolution dispersion transport modelling (DTM) with in-situ aerosol observations; (2) apply these methodologies to gain a detailed understanding of aerosol transport and dynamics at CHC; and (3) demonstrate the validity of these methods across different environments. To achieve this, highly resolved (1 km) regional backward DTM using WRF-FLEXPART are combined with techniques like k-means clustering and inverse modelling to analyse in-situ aerosol measurements from the Bolivian Andes. The broader validity of these techniques is also demonstrated in the Central Arctic. Using DTM source–receptor relationships and k-means clustering, we identified that air masses arriving at CHC are typically a mix of free troposphere (FT, 76%) and boundary layer (BL, 24%) influences, with few periods of purely free-tropospheric air (at night). These findings and methods serve as a foundation for further studies in the region and beyond. Using the airmass history methodology and molecular-level observations, we demonstrate that oxygenated organic molecules detected at CHC likely originate from isoprene emissions in the Amazon Basin BL that ...
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