Volcanic ash forecast transport and dispersion (VAFTAD) model

Journal Article · Wed Dec 01 04:00:00 EST 1993 · Weather and Forecasting

DOI:https://doi.org/10.1175/1520-0434(1993)008<0533:VAFTAD>2.0.CO;2· OSTI ID:53447

Heffter, J L; Stunder, B J.B. ^[1]

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1. NOAA Air Resources Laboratory, Silver Spring, MD (United States)

The National Oceanic and Atmospheric Administration (NOAA) Air Resources Laboratory (ARL) has developed a Volcanic Ash Forecast Transport And Dispersion (VAFTAD) model for emergency response use focusing on hazards to aircraft flight operations. The model is run on a workstation at ARL. Meteorological input for the model is automatically downloaded from the NOAA National Meteorological Center (NMC) twice-daily forecast model runs to ARL. Additional input for VAFTAD ragarding the volcanic eruption is supplied by the user guided by monitor prompts. The model calculates transport and dispersion of volcanic ash from an initial ash cloud that has reached its maximum height within 3 h of eruption time. The model assumes that spherical ash particles of diameters ranging from 0.3 to 30 micrometers are distributed throughout the initial cloud with a particle number distribution based on Mount St. Helens and Redoubt Volcano eruptions. Particles are advected horizontally and vertically by the winds and fall according to Stoke`s law with a slip correction. A bivariate-normal distribution is used for horizontally diffusing the cloud and determining ash concentrations. Model output gives maps with symbols representing relative concentrations in three flight layers, and throughout the entire ash cloud, for sequential 6- and 12-h time intervals. A verification program for VAFTAD has been started. Results subjectively comparing model ash cloud forecasts with satellite imagery for three separate 1992 eruptions of Mount Spurr in Alaska have been most encouraging.

• OSTI ID: 53447
• Journal Information: Weather and Forecasting, Journal Name: Weather and Forecasting Journal Issue: 4 Vol. 8; ISSN WEFOE3; ISSN 0882-8156
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
54 ENVIRONMENTAL SCIENCES
AIR POLLUTION
ASHES
ATMOSPHERIC CIRCULATION
COMPUTERIZED SIMULATION
ENVIRONMENTAL TRANSPORT
SLIP FLOW
VOLCANOES