Primary Factors and Synoptic Pattern Classification of Mega Asian Dust Storms in Korea

High concentration Asian Dust Storms (ADSs) significantly impact health and economic activities by increasing atmospheric particulate matter. This study aims to understand the mechanisms, migration paths, and activity patterns of ADSs, which are essential for issuing timely warnings and aiding in atmospheric environment research. Using unsupervised learning methods, including the principal component analysis (PCA) and K-means clustering, we analyzed the mega ADS events from 2002 to 2022 based on the ECMWF reanalysis (ERA5) data. We identified key meteorological factors, including geopotential height and temperature at lower levels (800–1000 hPa), and classified synoptic patterns associated to the mega ADSs during the origination stages in the source regions and the peak concentration stages in Korea. Findings highlight that, during the origination stage, enhanced troughs and high temperature at low levels are primary factors affecting atmospheric instability and consequently strong updrafts that lift dust particles, combined with high planetary boundary layer heights, ranging 1400─2950 m, and strong pressure gradients at the source regions. It is further noted that low-level temperature and specific humidity are critical during the peak stages in Korea, with contributions from higher atmospheric levels. Variability in atmospheric conditions among different patterns affects dust concentrations, with certain patterns experiencing sharp declines in humidity leading to peak dust events. Noting also that the mega ADSs occur under specific synoptic patterns classified at both the origination stages and the peak concentration stages in Korea, this comprehensive analysis provides crucial insights into the dynamics and prediction of mega ADSs in Korea.