Principal Investigator (PI): Nickolay Krotkov, NASA's Goddard Space Flight Center

Sulfur dioxide (SO2) is a short-lived gas primarily produced by volcanoes, power plants, refineries, metal smelting, and burning of fossil fuels. Where SO2 remains near Earth's surface, it is toxic, causes acid rain, and degrades air quality. Where SO2 is lofted into the free troposphere, it forms aerosols that can alter cloud reflectivity and precipitation. In the stratosphere, volcanic SO2 forms sulfate aerosols that can result in climate change.

The Global Sulfur Dioxide Monitoring Group has a unique multiyear experience in detecting, tracking, and measuring volcanic eruptions and degassing and anthropogenic pollution from space. Our group primarily uses UV satellite data from the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite and the Total Ozone Mapping Spectrometer (TOMS) on multiple satellites. However, our TOMS volcanic SO2 data as well as the most accurate off-line OMI SO2 retrievals are not yet publicly available.

We propose to create and archive a long-term consistent SO2 Earth System Data Records (ESDRs) combining measurements from backscatter Ultraviolet (BUV), thermal infrared (IR), and microwave (MW) instruments on multiple satellites. Our approach is applying our unique in-flight calibration techniques and our mature validated SO2 algorithm to obtain the best measurement-based ESDR of volcanic and anthropogenic SO2 masses and emissions, including SO2 height information. The UV data will be complemented with IR and MW data to extend coverage at night and during high-latitude winter months. The ESDR will contain quality assessments that would enable users to judge the reliability and precision of the data. The ESDR will be available on our product-oriented public web site.

The proposed combined SO2 record will produce the best estimates of the volcanic and anthropogenic contribution to global atmospheric SO2 concentrations. Such measurements are essential given the growing concern over the response of Earth to anthropogenically-forced climate change, effectiveness of air quality regulations, and intercontinental transport of air pollution. Since SO2 is the major precursor of sulfate aerosol, which impacts climate and air quality, SO2 measurements will contribute to a better understanding of the sulfate aerosol distributions and its atmospheric impact.

Visit the Global Sulfur Dioxide Monitoring site

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