Using Horizontal Transport Characteristics to Infer an Emission Height Timeseries of Volcanic SO2

Characterizing the emission height of sulfur dioxide (SO2) from volcanic eruptions yields information about the strength of volcanic activity, and is crucial for the assessment of possible climate impacts and for validation of satellite retrievals of SO2. Sensors such as the Ozone Monitoring Instrument (OMI) on the polar-orbiting Aura satellite provides accurate maps of the spatial distribution of volcanic SO2, but provide limited information on its vertical distribution. The goal of the work presented here is to explore the possibility of using a trajectory model to reconstruct both the temporal activity and injection altitude of a volcanic source from OMI column measurements of SO2 observed far from the volcano. Statistical analyses based on the distance of closest approach to the volcano of back trajectories initialized at the measurements are compared to an optimal reconstruction based on forward trajectories. The inferred altitude of the SO2 cloud is verified using the altitude of derived sulfate aerosol detected in aerosol backscatter vertical profiles form the CALIPSO instrument.