Terrain effects of the Tibetan Plateau on dust aerosol distribution over the Tarim Basin, China

Abstract

Dust events are frequent in the Tarim Basin because of its underlying desert surface; moreover, meteorological conditions under the influence of the surrounding high terrains, especially the Tibetan Plateau, may also trigger dust events. However, the terrain effect of the Tibetan Plateau on the dust aerosol distribution over the Tarim Basin remains unclear. This study aimed to investigate the impact of the Tibetan Plateau terrain on the dust aerosol variations in three dust events over the Tarim Basin using the Weather Research and Forecasting Chemistry model. With decreasing altitude of the Tibetan Plateau, dust concentration (DC) decreased in the upper layers and increased in the low layers. The DC within the entire atmospheric layers increased by 8.52%, 24.03%, and 43.05% on average during three dust events at Tibetan Plateau altitudes of 3000 m, 2000 m, and 1000 m, respectively, thereby indicating that the DC in the lower layers increasingly dominated the entire atmospheric layers as the Tibetan Plateau altitude decreased. Low-elevation terrain enhanced the planetary boundary layer height, near-surface wind speed, and surface air temperature, but weakened atmospheric stratification stability, all of which are beneficial for strengthening dust emissions and vertical mixing in the lower layers of the Tarim Basin. Furthermore, a decrease in the Tibetan Plateau altitude led to forming a vertical circulation, with the south to rise and the north to sink over the Tarim Basin. Meteorological field and vertical circulation could adequately explain the changes in the distribution of dust aerosols over the Tarim Basin. Overall, this study enhances our understanding of the effect of the Tibetan Plateau terrain on changes in the dust aerosol in the Tarim Basin and surrounding central Asian regions.