Direct Radiative Effects of Dust Aerosols over Northwest China Revealed by Satellite-Derived Aerosol Three-Dimensional Distribution

Northwest China is recognized as a main source and a major transport channel of dust aerosols in East Asia. With a fragile ecological environment, this region is quite sensitive to global climate change. Based on the satellite-derived aerosol three-dimensional distribution, the direct radiative effects of dust aerosols over Northwest China are evaluated. Aerosols over Northwest China are mainly distributed in the Tarim Basin, Junggar Basin, Gobi Desert, and Loess Plateau. The aerosol extinction coefficients are greater than 0.36 km⁻¹ over the Tarim Basin and 0.16 km⁻¹ over the Gobi Desert and Loess Plateau, decreasing with height. Aerosols over Northwest China are mainly composed of pure dust and polluted dust. These dust aerosols can modify the horizontal temperature gradient, vertical thermodynamic structure, and diurnal temperature range by absorbing and scattering shortwave radiation and emitting longwave radiation. For the column atmosphere, the radiative effect of dust aerosols shows heating effect of approximately 0.3 K day⁻¹ during the daytime and cooling effect of approximately −0.4 K day⁻¹ at night. In the vertical direction, dust aerosols can heat up the lower atmosphere (0.5–1.5 K day⁻¹) and cool down the upper atmosphere (about −1.0 K day⁻¹) during the daytime, while they cool down the lower atmosphere (−3 to −1.5 K day⁻¹) and heat up the upper atmosphere (1–1.5 K day⁻¹) at night. There are also significant lateral and vertical variations in the dust radiative effects corresponding to their spatial distributions. This study provides some scientific basis for reducing uncertainty in the investigation of aerosol radiative effects and provides observation evidence for simulation studies.