Self-lofting and dynamical confinement of the Raikoke volcanic plume.
Résumé
Recent research has provided evidence of the self-lofting capacity of smoke aerosols in the
stratosphere and their self-confinement by persistent anticyclones (Smoke-Charged Vortices, SCV),
prolonging the atmospheric residence time and radiative effects of wildfire emissions. By contrast,
the volcanic aerosols - composed mostly of non-absorptive sulphuric acid droplets – were never
reported to be subject of dynamical confinement. In this study, we use high-resolution satellite
observations from various satellite instruments (TROPOMI, ALADIN, CALIPSO, OMPS-LP and
EUMETSAT GNSS-RO) together with high-resolution ECMWF ERA5 reanalysis and meteorological
radiosoundings to show that the eruption of Raikoke volcano in June 2019 produced a long-lived
stratospheric anticyclone termed Vorticized Volcanic Plume (VVP). The primary VVP structure
contained 24% of the total erupted mass of sulphur dioxide, circumnavigated the globe three
times, and ascended diabatically by more than 13 km in three months through radiative heating of
the confined aerosol plume. We argue that persistent anticyclonic formations act to maintain the
volcanic plumes at high concentration thereby providing a high degree of radiative heating and
upward thrust to volcanic plumes.
The mechanism of dynamical confinement has important implications for the planetary-scale
transport of volcanic emissions, their stratospheric residence time, and atmospheric radiation
balance. It also provides a challenge or “out of sample test” for weather and climate models that
should be capable of reproducing such dynamical structures