At the Edge of the World: Particle Dispersion in the Atmospheric Boundary Layer over Ushuaia

Understanding the individual and relative motion of particles is fundamental to characterizing transport processes in complex flows. While large-scale transport in the atmosphere is relatively well understood and measured by monitoring stations and satellite observations, our knowledge of the smaller scales, particularly at scales below  50 km within the atmospheric boundary layer (ABL), remains limited. In this region, a wide range of processes involving particles originating from the ground take place, including the dispersion of gases and aerosols, smoke from fires and wind-blown particulate matter such as dust and pollen.
A central open question concerns how pairs of particles separate from each other in realistic, non-stationary ABL conditions, where turbulence, shear, and surface forcing coexist across a broad range of scales. Most in-situ studies have focused on mid-latitude environments and on relatively large spatial and temporal scales, often tracking particle motion over several days, whereas the Global South remains comparatively unexplored. Yet, these regions host  dynamically rich regimes that provide a natural stress test for transport theories developed under more idealized conditions.
Here we present an in-situ study of pair dispersion in the ABL over Ushuaia, Argentina, based on Lagrangian measurements extending from the surface up to approximately 3 km above ground level. We launch up to 10 simultaneous small, lightweight, and biodegradable balloons into the atmosphere and track them for up to two hours using commercial radiosondes. This work aims to provide new observational insight on relative dispersion at small scales in a complex ABL setting and to contribute to a more physically grounded understanding of atmospheric transport.