Seasonal variation of aerosol optical properties in a coastal city of southeast China: Based on one year of measurements

Abstract

Aerosols have a significant impact on both direct and indirect radiative effects and are considered to be one of the largest contributors to the uncertainty in global climate change assessment. In this study, continuous one-year-round in-situ observations of aerosol optical properties were conducted in the southeastern coastal city of Xiamen, China, and the effects of chemical composition on aerosol optical properties were analyzed to assess the environmental and climate effects of aerosols. The scattering coefficient (σsp), absorption coefficient (σap), single scattering albedo (SSA) showed significant seasonal variations. The σsp and σap showed obvious bimodal diurnal patterns, with peaks occurring in the morning peak and evening, while the diurnal patterns of SSA were reversed. The results of the chemical component-based estimation reconstruction of σsp illuminated that OM, NH4NO3, (NH4)2SO4 were the main contributors to the σsp. The concentration weighted trajectory (CWT) method was used to characterize the contributing sources of each chemical component affecting σsp. The main contributing source areas were elucidated and varied slightly with species and season. The wind dependence analysis reflected that σap was mainly influenced by local emissions, while σsp was affected by both local emissions and regional transport. The contribution sources of σsp and σap were investigated using potential source contribution function (PSCF) method. The contributing source of σsp and σap in Xiamen were clarified, and varied slightly with seasonal differences. This study revealed the aerosol optical properties in the southeastern coastal urban areas of China and provided a scientific basis for the estimation of the factors affecting climate change.