Effect of terrain relief on dust transport over complex terrains in West Asia

This work investigates the impact of orography on dust transport using the multi-scale NMMB/BSC-Dust model. For this purpose, two model simulations at horizontal resolutions of 0.03o x 0.03o (Low-resolution; LR) and 0.3o x 0.3o (High-resolution; HR) are performed and analysed covering two intense dust storms that occurred in West Asia in March 2012. Differences between both simulations emerge when the dust storms reach the south and west Arabian Peninsula where its complex topography affected meteorology and dust fields in many ways. The HR simulation is better than the LR simulation at reproducing the topography and its topographic effects on meteorology, such as developing orographic clouds, wind speed bias reduction under the dust flows (larger than 5 m/s) and more accurate wind directions, as well as on dust fields, such as a more realistic representation of dust channeling/blocking. Consequently, it improves dust forecasts in the vicinity of complex terrains.