EarthCARE observes the life cycle of a stratospheric smoke plume

Le résumé fourni par la source

At the end of May 2025, extremely strong wildfires in Canada produced several pyrocumulonimbus clouds which lifted wildfire smoke particles up to the lower stratosphere (> 10 km height). A dense stratospheric smoke plume developed which reached stratospheric aerosol optical depths up to 3.2 which is comparable with a moderate volcanic eruption. EarthCARE’s lidar ATLID captured this event and enabled us to study stratospheric smoke shortly after emission and to track a single smoke plume on its transport way towards Europe.The spaceborne lidar allowed to precisely study the maximum plume height and revealed a lofting of the smoke plume top height from 13.6 km above Canada to 17.4 km above Europe and a further slight ascent during the transport towards Asia. The self-lofting of dense smoke plumes can be explained by the absorption of solar radiation which heats the ambient air and creates buoyancy. The self-lofting is strongest for optically thick smoke plumes close to the source region and gets weaker when the plume is horizontally more spread and thus optically thinner.ATLID detected an enhanced depolarization ratio of 0.26±0.02 which indicates non-spherical smoke particles in the stratosphere. This finding is in line with previous observations of stratospheric smoke layers, but clearly demonstrates a difference to tropospheric observations of Canadian smoke in Europe, which are characterized by a low depolarization ratio and hence a spherical shape (Haarig et al., 2018).The novel high-spectral-resolution lidar (HSRL) capability of ATLID allowed us for the first time to study the evolution of the lidar ratio of a stratospheric smoke layer during long-range transport. Higher values around 70 sr were observed shortly after emission, which decreased during the first days of transport to values of 49±7 sr.As another highlight, EarthCARE observed a significant downmixing of stratospheric smoke at a strong tropopause fold over the Mediterranean and North Africa (Haarig et al., 2025). These observations directly show a pathway of removal of the stratospheric smoke and closes the life cycle from injection to removal. Additionally, the synergistic EarthCARE observations will be used to estimate the radiative impact of this strong stratospheric smoke event.ReferencesHaarig, M., et al. (2018), Depolarization and lidar ratios at 355, 532, and 1064 nm and microphysical properties of aged tropospheric and stratospheric Canadian wildfire smoke. Atmospheric Chemistry and Physics, 18 (16), 11847–11861.Haarig, M. et al. The life cycle of a stratospheric smoke plume as seen from EarthCARE - tracking a plume from Canada to Europe. ESS Open Archive. October 22, 2025.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.