Rapid chemical evolution of tropospheric volcanic emissions from Redoubt Volcano, Alaska, based on observations of ozone and halogen-containing gases

► 1st observations of Br and I degassing from an Alaskan volcano ► 1st observations of ozone evolution in a volcanic plume ► 1st direct spatial comparison of numerical model and observed ozone evolution in a volcanic plume ► In-plume ozone anomalies can result from ambient ozone variations and Br chemistry. ► Volcanic degassing in Alaska can release reactive halogens to the troposphere.