Comparison of Intensity, Duration, and Transport of the Heavy Asian Dust Case in March 2021 over East Asia

Abstract A severe Asian dust episode occurred over East Asia from 25 March to 2 April 2021. Using hourly PM 10 concentrations and aerosol/dust lidar products (dust extinction coefficient and dust optical depth, DOD) from Mongolia, the Korean Peninsula, and Japan, we investigated dust intensity, duration, and plume height/vertical distribution from source to downwind regions. Asian dust was emitted over the Gobi Desert and the Inner Mongolian Plateau on 26–27 March under strong winds enhanced by baroclinic instability. The Asian dust was transported southeastward across central China and subsequently advected eastward via the Shandong and Liaodong Peninsulas and the Bohai Bay, reaching the Korean Peninsula on 28 March and Japan during 29–31 March. Peak hourly PM 10 decreased markedly downwind, from 5183 μg m −3 at Erdene (Mongolia) to 3318 μg m −3 at Hohhot (China), 1491 μg m −3 at Heuksan-do (South Korea), and 211 μg m −3 at Rishiri (Japan). Despite this decrease, PM 10 exceeded Korea’s PM 10 advisory criterion (≥ 150 μg m −3 ) for ~ 40 h in South Korea and for 8 h in Japan. PM 10 in South Korea also exceeded the Korea Meteorological Administration’s Asian dust warning criterion (≥ 800 μg m −3 ), leading to dust warnings on 28 and 29 March. The long duration resulted from a persistent 500-hPa trough and quasi-stationary cyclone over Manchuria, sustaining 850-hPa baroclinicity and continuous downstream transport. Lidar observations indicated that dense dust was confined below ~ 0.5 km near the source, whereas an elevated plume at 1–2 km dominated transboundary transport over South Korea and Japan, with maximum DODs of 0.67 in Seoul and 1.5 in Matsue. Overall, vigorous updrafts over the source region triggered substantial emissions, and the dust plume was transported by northwesterly flow primarily at 1–2 km altitude, contributing to very high near-surface particle concentrations in downwind regions. Graphical abstract