Lagrangian atmospheric transport of the smoke plume from the large Australian Wildfire Event of 2019/2020.

The bushfires in Australia during the 2019/2020 season were particularly severe, leading to the creation of a plume of smoke that rose into the Lower Stratosphere and resulted in record levels of smoke concentration.  In early January 2020, the plume disperses into independent transport paths in the stratosphere. Following a Lagrangian approach, we study the three dimensional atmospheric transport in the region at this time to better understand the cause of the splitting, the subsequent transport geometry, and the influence of the plume buoyancy on its movement. Aided by the Finite Time Lyapunov Exponent tool, we identify Lagrangian Coherent Structures (LCS) which simplify the three-dimensional transport description and make possible the characterization of the smoke plume evolution. 

Our numerical modeling results were able to replicate the observed behavior of the smoke plume during the bushfires in Australia, including the splitting of the plume into multiple pathways. In the model, we found parcels trajectories with the same behavior as the observed plume, highlighted the contribution of the passive advection of the plume by the wind versus the buoyancy effect of hot smoke, delineated the plume into regions destined to different fates, and showed that the division of the main path was affected by an eddy.