Volcanic ash is a rare but potentially catastrophic hazard to aviation. Encounters with volcanic ash while in flight can result in engine failure from particulate ingestion and viewing obstruction of the cockpit widescreen from etching by the acidic aerosols. Volcanic Ash Advisory Centers (VAAC) were established to monitor the air space in areas prone to eruptions and to issue volcanic ash warnings.



Volcanic ash particles have distinct spectral signatures that can be used to enhance detection through multi-spectral image processing. Sulfur dioxide is also released in high concentrations during eruptions and exhibits a strong infrared absorption band.

In addition to the traditional GOES imager channels used for volcanic ash discrimination, NASA’s MODIS and AIRS instruments aboard the AQUA and TERRA satellites also contain SO₂ absorption channels, which ASAP researchers at the University of Wisconsin CIMSS, lead by Michael Pavolonis, have exploited to enhance volcanic ash detection. These applications have significantly improved upon existing satellite-based multi-spectral techniques (such as VISST) in identifying and tracking ash clouds and estimating their height. The techniques developed by ASAP also reduce the number of false alarms that commonly plague volcanic ash applications by integrating the results from multiple detection algorithms. More satellite channels have been included to provide a more robust detection capability.

ASAP is also working with the USAF to evaluate the efficacy of using geophysical noise, i.e., volcanic eruption detections, from strategic surveillance assets to provide early location and evaluation of volcanic eruptions and ash plumes. This work is being lead by Dr. Earle Williams at the MIT Lincoln Laboratory.

Additional ASAP research is being lead by Dr. Arlin Krueger at the University of Maryland (Baltimore County) to update volcanic ash algorithms previously developed for the Total Ozone Mapping Spectrometer (TOMS) instrument, launched in July 1996, onboard the NASA Earth Probe satellite (TOMS/EP). TOMS is now defunct, and these improved algorithms will exploit the expanded capability of the Ozone Mapping Instrument (OMI) deployed on the NASA AURA satellite. AURA is a chemistry mission that was launched on July 15, 2004 as an integral element of the NASA AQUA train constellation of polar-orbiting satellites.