Detection and Monitoring of Sulfur Dioxide from Satellite-based UV Sensors

Sulfur dioxide column amounts are retrieved from near-UV spectral radiance data with exceptional precision. The high sensitivity coupled with daily global coverage with unprecedented spatial resolution from Aura/OMI has provided a wealth of new information. Sulfur dioxide is a short-lived constituent of the atmosphere that is produced by volcanoes and from combustion of sulfur-containing fossil fuels. It is oxidized to sulfate aerosols at a rate that depends on altitude. Sulfate aerosols change the reflectance of the atmosphere, making sulfur dioxide an important climate constituent. While fossil fuel burning constitutes a large, broadly distributed source of sulfur dioxide, volcanic eruptions can inject very large sulfur dioxide clouds into the upper atmosphere in a few hours. Explosive eruptions also produce volcanic ash as frothy liquid magma freezes in the atmosphere. Ash clouds are a hazard to aviation but are sometimes difficult to discriminate from other clouds while sulfur dioxide is a unique marker. Volcanic clouds can drift global distances at aircraft cruise altitudes as they are carried by the upper air winds. Thus, satellite observations of sulfur dioxide are invaluable for locating fresh volcanic clouds. A near real-time data production capability has been developed for operational use at NOAA NESDIS where the data are distributed via internet to the Decision Support Systems. The UV algorithms are designed to operate with data from OMI and GOME-2 and future instruments like OMPS. The sensitivity is adequate to monitor pre-eruptive emissions from volcanoes for detection of new activity. In addition, large sources of sulfur dioxide from fossil fuel burning and from smelting of ores are being monitored