Modeling study on three-dimensional distribution of dust aerosols during a dust storm over the Tarim Basin, Northwest China

Abstract

The air quality model WRF-Chem was employed to simulate a dust storm event in spring, 2015 over the Taklamakan Desert of the Tarim Basin (TB), Northwest China. Based on the reasonable evaluations with the ground observations and CALIPSO satellite data of meteorology and aerosols, the simulation was used to characterize the three-dimensional distribution of dust aerosols for this springtime dust storm over the TB. Under the impact of unique basin topography on a cold frontal system, a large amount of cold air invading the TB in three main tracks of near-surface winds: (1) westerly winds across the Pamirs Plateau, (2) northerly air flows crossing the Tianshan Mountains, and (3) strong northeast winds passing the northeast mouth of TB, building three main dust plumes over the TB for the dust storm process. The strong dust plume swept southwestwards across the basin with dominating over two weak dust plumes, and the mechanical effect of Tibetan Plateau on the dust plumes could determine the surface dust aerosol distribution over the TB. Based on observation and simulation, the extremely thick boundary layer was identified with the height of 3-5 km from the surface over the TB for the vertical distribution of dust aerosols. Dust aerosols were lifted up to 7 km in the free troposphere over the southern TB driven by the northern slope of the Tibetan Plateau. The distribution of dust aerosols in the upper boundary layer at the height of 3-5 km was controlled by the convergences of near-surface air flows over the TB and the obstruction of plateaus and mountains surrounding the TB, building the floating dust layer over the basin. This modeling study depicted the three-dimensional distribution of dust aerosols in a typical dust storm over the TB, Northwest China.