SATELLITE MEASUREMENTS OF VOLATILE EMISSIONS FROM RECENT NORTH PACIFIC ARC ERUPTIONS

Summer 2008 saw the beginning of a period of elevated volcanic activity in the North Pacific, with major eruptions of Okmok and Kasatochi (Aleutian Islands) in July-August 2008, Redoubt (Alaska) in March 2009, and Sarychev Peak (Kurile Islands) in June 2009. The Kasatochi and Sarychev Peak eruptions were notable for their sulfur dioxide (SO2) emissions, releasing ~1.4 Tg and ~1 Tg (preliminary estimate) of SO2, respectively. Much of this SO2 reached the upper troposphere and stratosphere, producing long-lived SO2 and sulfate aerosol clouds. The Kasatochi SO2 burden was the largest volcanic SO2 emission measured by ultraviolet (UV) satellite remote sensing since 1991, and the largest at high northern latitudes since UV measurements began in 1978. We present observations of these recent eruptions from current satellite sensors providing measurements of volatile and aerosol emissions from explosive volcanic eruptions. These include the Ozone Monitoring Instrument (OMI), Atmospheric Infrared Sounder (AIRS), Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Microwave Limb Sounder (MLS), which are all in NASA's polar-orbiting A-Train satellite constellation. A-Train satellites orbit within ~8 minutes of each other, providing near-coincident measurements from multiple instruments. Combining data from different sensors and platforms improves SO2 loading measurements and provides information on volcanic cloud altitude, which is linked to eruption dynamics. In addition to SO2, hydrogen chloride (HCl) and bromine monoxide (BrO) concentrations can be measured if present above detection limits and (in the case of HCl) injected to sufficient altitude. The 2008 Kasatochi eruption produced the first volcanic cloud containing measurable BrO, with ~100 tons of BrO measured by OMI. No BrO was detected in the Sarychev Peak eruption cloud, despite similarities in magnitude and SO2 loading to the Kasatochi eruption. These eruptions demonstrate the range of volcanic cloud observations now available from satellite instruments, and their potential to further our understanding of volatile emissions and eruption dynamics in volcanic arcs.