| 30 Apr 2026
Meteoroids as a source of metal ion clouds in Earth’s upper thermosphere
Abstract. Advances in lidar technology have enabled the detection of Metal Ion Clouds (MICs) at altitudes between 120–300 km in the Earth’s thermosphere. Observations from a Ca+ lidar in Beijing, China, reveal that these MICs are characterized by tightly packed, stripe-like structures that span extensive areas, covering hundreds to thousands of square kilometers. Some of these stripes extend downward to the Main Metal Layer (MML) around 100 km, and some clouds descend with tidal winds and merge into the underlying MML. While arriving the altitudes of Mesosphere and Low-Thermosphere (MLT), they lead to an increase in Sporadic-E (Es) layer density, and even trigger the formation of a new Es layer. The metal ions in the upper thermosphere will eventually sink into the MML and significantly affect its density variations. The striped structure of MICs and their direct effects on Es and MML suggest they originate from meteoroid trails, challenging traditional views on meteoric input.
Competing interests: The contact author has declared that none of the authors has any competing interests.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
