Jeremy J. Wesely*, Amy R. Hakola and Gordon R. Brooks
Air Force Weather Agency, 106 Peacekeeper Dr., STE 2N3, Offutt, AFB, NE 68113
(402) 294-1684, DSN: 271-1684 jeremy.wesely@afwa.af.mil
Ben H. Barnum and Nathaniel S. Winstead
Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723-6099
The science behind the Air Force Weather Agency’s (AFWA) Dust Transport Application (DTA) is discussed and the results of an extensive verification of DTA over Africa, central and southwest Asia are presented. DTA ingests AFWA MM5 45km resolution surface wind data, which is used to calculate the surface dust flux based on wind threshold velocity. There are differing threshold velocities based upon the dust particles’ diameter, air and particle density, and soil moisture. DTA also accounts for the vertical transport of dust through the calculation of horizontal divergence and a second parameter that calculates vertical diffusion. In addition, DTA uses a dust source region database that was developed on the basis of land use, topography, the use of Advanced Very High Resolution Radiometer (AVHRR), and Total Ozone
Mapping Spectrometer (TOMS) data.
Verification of DTA began in February of 2002 in 18 sub-regions (based on dust source areas) in
Africa and Central/Southwest Asia. Probability of Detection (POD), False Alarm Ratio (FAR), and Critical
Success Index (CSI) values were calculated for each sub-region. In addition, DTA strengths and limitations were cataloged and provided to forecasters. DTA demonstrated skill at forecasting synoptic scale dust events such as those induced by warm and cold air advection, but was limited in its ability to detect some mesoscale dust events that are generated by convective downdrafts.