Opportunistic validation of sulfur dioxide in the Sarychev Peak volcanic eruption cloud

• Main Authors: T. M. Lopez, S. A. Carn
• Format: Article
• Language: English
• Published: Copernicus Publications 2011-09-01
• Series: Atmospheric Measurement Techniques
• Online Access: http://www.atmos-meas-tech.net/4/1705/2011/amt-4-1705-2011.pdf

We report attempted validation of Ozone Monitoring Instrument (OMI) sulfur dioxide (SO<sub>2</sub>) retrievals in the stratospheric volcanic cloud from Sarychev Peak (Kurile Islands) in June 2009, through opportunistic deployment of a ground-based ultraviolet (UV) spectrometer (FLYSPEC) as the volcanic cloud drifted over central Alaska. The volcanic cloud altitude (~12–14 km) was constrained using coincident CALIPSO lidar observations. By invoking some assumptions about the spatial distribution of SO<sub>2</sub>, we derive averages of FLYSPEC vertical SO<sub>2</sub> columns for comparison with OMI SO<sub>2</sub> measurements. Despite limited data, we find minimum OMI-FLYSPEC differences within measurement uncertainties, which support the validity of the operational OMI SO<sub>2</sub> algorithm. However, our analysis also highlights the challenges involved in comparing datasets representing markedly different spatial and temporal scales. This effort represents the first attempt to validate SO<sub>2</sub> in a stratospheric volcanic cloud using a mobile ground-based instrument, and demonstrates the need for a network of rapidly deployable instruments for validation of space-based volcanic SO<sub>2</sub> measurements.