Work

Transport of volcanic aerosol from the Raikoke eruption in 2019 through the Northern Hemisphere

Year: 2026

Type: article

Abstract: . Volcanic injections into the upper troposphere–lower stratosphere (UTLS) affect climate by altering Earth's radiation budget and atmospheric chemistry. However, the pathways by which mid-latitude eruptions spread globally remain poorly understood. We combine nighttime Compact Optical Backscatter Aerosol Detector (COBALD) profiles over Lhasa with ERA5-driven Chemical Lagrangian Model of the Stratosphere (CLaMS) backward trajectories and global three-dimensional SO2-based tracer simulations. With this integrated framework, we track the Raikoke plume (21–22 June 2019; VEI 4) as it evolved within the mature Asian Summer Monsoon Anticyclone (ASMA). Balloon-borne measurements capture the plume’s arrival, vertical spreading, and dilution by ASMA-interior air. Trajectories reveal two principal pathways from distinct Raikoke plumes: (i) an upper-level branch within the summertime stratospheric easterly flow (~460–490 K) carrying the trailing filament of the vorticized volcanic plume (VVP), and (ii) a lower-level branch within the subtropical westerly jet (~390–430 K) carrying the main plume. Although the ASMA can act as a transport barrier at certain potential-temperature levels, it admits in-mixing along jet-aligned filaments and redistributes aerosols internally. SO2-based tracer simulations are sensitive to how parameterized small-scale mixing is represented in CLaMS, underscoring the need to adjust subgrid-scale mixing parameterizations when model resolution changes (here, from ERA-Interim to ERA5 reanalyses). Independent Portable Optical Particle Spectrometer (POPS) profiles over Boulder (USA) confirm the plume’s timing and altitude, providing out-of-region validation. Sensitivity to injection level indicates an additional ~4–5 km of uplift from aerosol-radiative lofting.

Source: Atmospheric chemistry and physics

DOI: 10.5194/acp-26-4749-2026