Intra-Seasonal Variations of Dust Activity Over East Asia in Spring 2023 and Their Mechanisms

Abstract

Dust activity in East Asia has shown multi-scale temporal variations in the past, yet the recent surge during 2021-2023 raises great concerns about its mechanisms. Many studies have been devoted to the interannual variations of dust activity, but little attention is paid to its variations at the intra-seasonal scale and our knowledge on this is still limited. In this study, we investigate the anomalies in the atmospheric states and land surface conditions responsible for the occurrence of several dust storms during March and April of 2023. Dust optical depth (DOD) and meteorological factors from reanalysis as well as vegetation cover from satellite observations for March to April 2023 are compared with the climatological mean during 2003-2022. The results show that compared to climatological mean of 2003-2022, DOD is close to the mean value in April but significantly lower in March of 2023. There is a distinct shift in the patterns of DOD anomaly from March to April. Further analysis reveals that the frequency of strong wind is below (above) the climatological mean for March (April) in the Tarim Basin and Gobi Deserts, indicating that wind speed may play a key role in the occurrence of dust activity, although its effect is offset or enhanced by that of soil moisture and vegetation cover. Overall, the intra-seasonal variations of dust activity from March to April can be ascribed to the shift of wind field, which is closely related to the evolution of geopotential height from positive anomaly in March to negative anomaly in April in Mongolia Plateau and southern Central Siberia at 500hPa. These results highlight the intra-seasonal variability of dust activity in spring 2023 in East Asia and the essential role of associated atmospheric circulation in its occurrence.

Keywords: Intra-seasonal variability, Dust activity, East Asia, Atmospheric circulation