Observations of Volcanic SO2 and HCl from Aura MLS

The Microwave Limb Sounder (MLS) on board the Aura satellite has been taking composition measurements of the Earth's upper troposphere, stratosphere and mesosphere for the past 5 years. During this time period, MLS has observed volcanic emissions from Manam, Anatahan, Soufriere Hills, Okmok, Kasatochi, Redoubt,and Sarychev eruptions. The eruptions from these volcanoes injected SO2 and HCl into the lower stratosphere. MLS makes vertically resolved measurements of these gases and therefore can determine the injection height of these volcanoes. We will provide a survey of the eruptions MLS has observed to date and compare results to SO2 columns seen by the Ozone Monitoring Instrument (OMI), also on the Aura satellite. Aura MLS however, can only make measurements along its orbit track twice daily which limits its usefulness for hazards detection or determining the amount of injected SO2. The utility of these measurements for hazard detection will be greatly enhanced in the next generation MLS instrument envisioned for the third tier decadal survey Global Atmospheric Composition Mission (GACM). The future mission will provide 50 km^2 near global coverage with 4--6 observations per day.