  The two most intense wildfires of the last decade that took place in Canada
in 2017 and Australia in 2019-2020 were followed by large injections of smoke
in the stratosphere due to pyroconvection. It was discovered by Khaykin et al.
(2020, doi:10.1038/s43247-020-00022-5) and Kablick et al. (2020,
doi:10.1029/2020GL088101) that, after the Australian event, part of this smoke
self-organized as anticyclonic confined vortices that rose in the mid-latitude
stratosphere up to 35 km. Based on CALIOP observations and the ERA5 reanalysis,
this new study analyzes the Canadian case and find, similarly, that a large
plume penetrated the stratosphere by 12 August 2017 and got trapped within a
meso-scale anticyclonic structure which travelled across the Atlantic. It then
broke into three offsprings that could be followed until mid-October performing
three round the world journeys and rising up to 23 km. We analyze the dynamical
structure of the vortices produced by these two wildfires and demonstrate how
they are maintained by the assimilation of data from instruments measuring the
signature of the vortices in the temperature and ozone field. We propose that
these vortices can be seen as bubbles of low absolute potential vorticity and
smoke carried vertically across the stratification from the troposphere inside
the middle stratosphere by their internal heating, against the descending flux
of the Brewer-Dobson circulation.
