Dust Modeling with the USAF's Global Air-Land Weather Exploitation Model (GALWEM)

Lofted dust adversely impacts military activities ranging from aircraft operations to targeting systems to troop movements. This problem is frequently observed in Southwest Asia and in Northern Africa during the spring and summer months when dry conditions are coupled with synoptic forcing and/or convective outflows. To better understand and improve our current NWP ability to simulate atmospheric dust, we perform studies using the Global Air-Land Weather Exploitation Model (GALWEM), the Air Force’s unique instantiation of the United Kingdom Met Office’s Unified Model (UM). This study examines different configurations of GALWEM’s dust lofting scheme by modifying four different parameters. The tunable parameters affect how much dust is lofted, how much forcing is required to loft the dust, dust source regions, and strength of vertical mixing. We present the results of how these configurations compare to our current operational baseline utilizing both objective and subjective verification. In addition, since dust is an active tracer in GALWEM, we also measure overall model performance to help identify potential 2^nd and 3^rd order effects.