Interdecadal variations of aerosol and its composition over the Fenwei Plain based on multi-source observations

Abstract

Understanding the variations and potential source of air pollution is essential for implementing targeted mitigation actions. However, the distribution and long-term trends of Aerosol Optical Depth (AOD) and its components over the Fenwei Plain (FWP) have not been thoroughly investigated. Furthermore, the potential source contribution of AOD loading is still unclear. Thus, maximum synthesis and Mann-Kendall trend (MK) test with Sen's Slope methods are employed to reveal the spatiotemporal variation characteristics of AOD over the FWP. The Potential Source Contribution Function (PSCF) model was applied to analyze the potential source contribution of AOD over the FWP. Results demonstrated that the AOD in spatial pattern exhibited consistency with the topography. AOD over the FWP fluctuated annually from 2000 to 2020, with an increase in the previous decade followed by a gradual decline after 2011. There was a significant monthly variation in AOD with higher values in August (0.47±0.21) and lower in November (0.29±0.12). A positive AOD trend was confirmed from 2000 to 2010 yet a negative trend is identified from 2011 to 2020. The sulfate aerosol (AODSU) exhibited an increasing trend over an extended period. Clear-sky radiation shows a negative trend at the surface and the top of the atmosphere (TOA) from 2000 to 2010, which is consistent with the trend in AOD. The AOD in FWP was primarily influenced by local emissions, with contributions from northern and northwestern sources. This research offers an enhanced overarching comprehension of the distribution and regional climate effects of aerosols over the FWP.