Three Pathways of Eastward Transport of North African Dust: Synoptic Patterns and Impacts on Air Quality in China

Abstract. The long-range eastward transport of North African dust substantially influences China's climate, environment, and human health. However, the circulation mechanisms that modulate its pathway variability and downstream impacts remain poorly understood. In this study, we investigated the synoptic patterns along three distinct eastward transport pathways of North African dust and their impacts on air quality in China using reanalysis and observations. Results show that seasonal variations in dust activity and the position of the westerly belt govern the eastward transport of North African dust, with transport peaking in April and spring accounting for 56.3 % of the annual dust mass potentially available for eastward transport. Among the three transport pathways, the northern pathway transports dust northward into Europe, followed by eastward advection through the mid- and high-latitude westerlies following pre-trough uplift. In contrast, the middle pathway features Mediterranean uplift and northeastward deflection. Mid-latitude westerly transport is modulated by western Mediterranean cyclonic activity, a southward-extending trough, and the blocking and splitting effects of the European high-pressure system. The southern pathway transports dust eastward along lower latitudes and around the southern Tibetan Plateau toward southern China. This pathway is guided by southward displaced lower-latitude westerlies, the European cold trough, and Himalayan topographic deflection. These dust plumes produce maximum PM_2.5 anomalies of 54.1–202.4 μgm^-3 decreasing from north to south across China. These findings may support early warnings of the eastward transport of North African dust to East Asia—an overlooked issue that is becoming increasingly critical as aerosol levels decline in China.