Intra-seasonal variations of dust activity over East Asia in spring 2023 and their mechanisms

Dust activity in East Asia has shown multi-scale temporal variations in the past. 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. Several dust storms have occurred over East Asia in spring 2023, which is taken as a good example for us to explore the intra-seasonal variations of dust activity. Based on station observations of dust events, meteorology reanalysis, and satellite observations of surface vegetation cover, here we find that there is much difference in dust storm activity between March and April of 2023 in terms of both the location and intensity. Dust storms mainly occurred in the central and eastern parts of Inner Mongolia and in the central and northern parts of Tarim Basin in March. In contrast, they mainly occurred in the western part of Inner Mongolia, eastern part of Northwest China, and a large region of Tarim Basin. For the regional mean number of dust storm days (N_DS), it is significantly higher than the climatological mean value of 2003–2022 in April but lower for March of 2023. 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 intra-seasonal variations of dust storm activity, although its effect is offset or enhanced by that of soil moisture and vegetation cover to a lesser extent. The shift of wind field 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 500 hPa. Overall these results highlight the intra-seasonal variation of dust activity in spring 2023 in East Asia and the essential role of associated atmospheric circulation in driving this.