As part of a global network of centers with volcanic ash expertise, the Washington Volcanic Ash Advisory Center (VAAC) is a joint National Weather Service (NWS) and National Environmental Satellite, Data and Information Service (NESDIS) center that monitors volcanic activity. Acting under International Civil Aviation Organization mandate, the Washington VAAC issues products to advise the aviation community about volcanic ash in the atmosphere, and provides Meteorological Watch Offices and Area Control Centers with information to help them prepare their volcanic ash Significant Meteorological information bulletins (SIGMETs). The NESDIS Satellite Analysis Branch (SAB) observes ash from recent volcanic eruptions in satellite imagery, relying on visible, longwave infrared, and multispectral GOES imagery, and to a lesser extent, shortwave infrared GOES imagery, visible POES imagery, and sulfur dioxide data from NASA’s Earth Probe Total Ozone Mapping Spectrometer (TOMS) mission. SAB augments its satellite analysis with numerous other data sources including pilot reports, surface observations and SIGMETs, as well as information from volcano observatories, the Smithsonian Institution’s Global Volcanism Program, and the United States Geological Survey. SAB then issues Volcanic Ash Advisory Statements (VAAS) that advise users about the current location, height, properties, and movement of volcanic ash. VAASs are available on the World Area Forecast Satellite Broadcast System (WAFs), FAA circuits (AFTN), Global Telecommunications System (GTS), Family of Services, and at Internet address www.ssd.noaa.gov/SSD/ML/vaacmsgs.html. When possible, the Internet site also contains a map showing the graphical location and extent of the ash.
While SAB issues a VAAS to depict current ash location, the National Weather Service National Centers for Environmental Prediction (NCEP) issues a Volcanic Ash Forecast Transport and Dispersion (VAFTAD) model to predict the future ash trajectory. The VAFTAD, created by the NOAA Air Resources Laboratory, uses the NWS regional (ETA) or global (AVN) forecast model data to provide a forecast of ash location 12, 24, 36 and 48 hours after an eruption for low, middle and high aviation flight levels. NWS disseminated VAFTADs are available on WAFs and facsimile circuits (such as Alaska Fax and Honolulu Fax). VAFTADs can also be run interactively by the user on the World Wide Web at www.arl.noaa.gov/ready/runvaftad.html.
In the last two years, hundreds of VAASs and VAFTADs have been issued for threatening activity from over 30 volcanoes, but Popocatepetl (the dangerous volcano near Mexico City), Soufriere Hills (the recently persistent Caribbean volcano) and Pacaya (a Guatemalan volcano) have dominated recent support efforts.
The 8th Conference on Aviation, Range, and Aerospace Meteorology