Circumpolar transport of a volcanic cloud from Hekla (Iceland)

Abstract

Hekla volcano (Iceland) erupted on 17 August 1980 and emplaced a sulfur dioxide (SO2) cloud into the north polar stratosphere at a maximum altitude of ∼15 km. The SO2 is tracked using satellite data from the ultraviolet (UV) Nimbus‐7 Total Ozone Mapping Spectrometer (N7/TOMS) and the infrared (IR) High‐resolution Infrared Radiation Sounder (HIRS/2) on the NOAA TIROS Operational Vertical Sounder (TOVS) platform. The eruption emitted ∼0.5–0.7 Tg of SO2, which later split into three distinct clouds, one of which circled the North Pole at the perimeter of an atypically persistent Arctic cyclone for six days, impacting airspace on three continents. Separate clouds drifted across eastern Russia, Alaska, and Canada. Maximum SO2 columns derived from TOMS and HIRS/2 accurately define the volcanic cloud's path and fit trajectories produced by the NOAA Hybrid Single‐Particle Lagrangian Integrated Trajectory (HYSPLIT) model, providing confidence in the model. When combined with the SO2 measurements, trajectory altitudes derived from HYSPLIT provide robust estimates of the altitudes of the SO2 clouds (8–15 km), which would be elusive using either the satellite data or the trajectory model in isolation. Near‐coincident, spectrally discrete UV and IR retrievals are compared in the volcanic cloud and indicate good agreement between TOMS and HIRS/2 SO2 columns for pixels with similar viewing geometry. Hekla eruptions, which follow a pattern of early explosive venting of volcanic gases with significant stratospheric injection, could play a role in promoting Arctic ozone loss, depending on the phase of the North Atlantic Oscillation during the eruption.