A Long‐Term Study of Mars Mesospheric Clouds Seen at Twilight Based on Mars Express VMC Images

We present the first systematic study of clouds observed during twilight on Mars. analyze images obtained by Visual Monitoring Camera Mars Express between 2007 and 2020. Using an automated retrieval algorithm, we found 407 cases at twilight, in which geometry observations allows to derive minimum altitude, revealing that many these are mesosphere (above 40 km up 90 km). The majority mesospheric were detected mid-latitudes local autumn winter, a new trend only hinted previous studies. In particular, find massive concentration southern Terra Cimmeria Aonia, region where high altitude events have been previously observed. propose there is unknown mechanism regions enhances probability host around winter solstice.