Pattern Transition of Dust Events over Northern China and Mongolia and Its Modulating Circulation in Spring

抄録

This study examines the pattern transition of dust events identified based on dust RGB images from the Himawari-8 satellite, along with associated key circulations and dynamic features, during spring 2016-2020. The dust RGB images are ordered onto a 4 × 3 topological map according to the spatial similarity of the dust distribution using self-organizing maps. In this topological map, the dust distribution exhibits mainly an eastward displacement or amplification from the Taklimakan Desert to the Gobi Desert. The key circulation triggering the transition of dust pattern is the large-scale tilted ridge from Xinjiang to Siberia. Such a northeast–southwest-oriented ridge conveys cold air into Tibet and causes the near-surface Siberian high extending southward from the Sayan mountains to central China. Consequently, dust intrudes from the Gobi Desert into northern China. In contrast, a zonal “+ − +” wave train in the upper troposphere confines the near-surface high over western Siberia and induces the near-surface cyclogenesis over Mongolia and northern China. As a result, the dust is mainly concentrated over the Taklimakan Desert, with weak influence over Mongolia and northern China.