Morning dust events observed around Thaumasia Plateau in the southern hemisphere of Mars

We investigated the local-time dependence of dust event formation around Thaumasia Plateau of Mars using 3,298 images acquired by the Emirates eXploration Imager (EXI) from L s = 7° in MY 36 to L s = 43° in MY 37. Through visual inspection of paired images separated by several hours, we determined formation times for small-scale dust events and distinguished them from water ice clouds using 320 nm water ice optical depth retrievals. Dust events occurred throughout the year but exhibited clear seasonal differences in their preferred formation times. During the southern winter, dust events were more likely to form in the afternoon, whereas during the southern spring and summer, several events initiated in the morning, particularly within the mountain ranges surrounding the plateau. Accounting for seasonal variations in observation opportunities, we found that morning dust lifting dominates in the southern spring and summer, while afternoon formation dominates in the southern winter. These results suggest that different mechanisms operate seasonally: morning events may be associated with the breakdown of nocturnal low‑level jets, while topographically driven slope winds also likely enhance dust lifting in the plateau. This study highlights the unique capability of the non-sun-synchronous EMM orbit to constrain Martian dust storm formation timing.