Volcanic Ash |
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
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
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.