Australian PyroCb Smoke Generates Synoptic‐Scale Stratospheric Anticyclones

Abstract

Abstract Fires in southeastern Australia produced at least 18 pyrocumulonimbus (pyroCb) between 29 December 2019 and 4 January 2020. The largest plumes from this event exhibited several previously undocumented phenomena in the stratosphere. These include (i) the generation of potential vorticity and anticyclonic circulations from absorptive aerosol heating, (ii) the formation of a vertical temperature anomaly dipole, (iii) the rapid ascent from the lowermost stratosphere (15–16 km) to altitudes above 31 km in less than 2 months, (iv) an unprecedented abundance of H 2 O and CO in the stratosphere, and (v) the displacement of background O 3 and N 2 O from rapid ascent of air from the troposphere and lower stratosphere. Each of these phenomena is traced back to a 5‐day‐old stratospheric plume composed of a massive amount of aerosol and biomass burning gases from a pyroCb outbreak. Until now, there has been no documented evidence that pyroCb plumes can affect stratospheric winds.