Persisting volcanic ash particles impact stratospheric SO2 lifetime and aerosol optical properties

After the Mt. Kelut eruption in 2014, stratospheric ash-rich aerosols were observed for months.

Here we show that the persistence of super-micron ash is consistent with a density near 0.5 g cm⁻3, close to pumice. Ash-rich particles dominate the volcanic cloud optical properties for the first 60 days. We also find that the initial SO2 lifetime is determined by SO2 uptake on ash, rather than by reaction with OH as commonly assumed.