Abstract:

The northwestern Chinese deserts, with Taklimakan Desert as its main body, is one of important sources of the Asian airborne dust. Using the NCAR Community Climate Model (CCM3) coupled with a mineral Dust Entrainment and Deposition model (DEAD), we study effects of land-cover change in desert regions of northwestern China on the airborne dust over East Asia. The emission and contribution of the northwestern deserts to the Asian airborne dust are simulated and analyzed through two groups of numerical experiments with changed land-cover types in desert and semi-desert regions of the northwestern China. The main results can be concluded as the following: The dust emission and airborne dust are closely related to land-cover conditions. Land melioration, such as a change in the land surface type from desert or semi-desert to grassland, restrains the dust emission significantly. The influence of the northwestern deserts on the airborne dust is usually overcastted to the northern China and even to Mongolia. Without Taklimakan Desert, the total emission and deposition fluxes would decrease by up to 50% over the northern China. The emission fluxes of the second and third diameters (1.0-2.5 μm and 2.5-5.0 μm), which account for 76% of the total emission flux, significantly decrease in the no-desert experiment. The dust from the northwestern desert and semi-desert regions can influence the air quality of North China and Northeast China, and even Japan and Korea, through the transport of the atmospheric general circulation.

Key words: CCM3-DEAD, surface types, airborne dust