EGUsphere EGUsphere EGUsphere EGUsphere Copernicus Publications Göttingen, Germany 10.5194/egusphere-2025-2323 Monitoring of Lower Thermospheric Neutral Density Variations Using Meteor Head Echoes Huyghebaert Devin https://orcid.org/0000-0002-4257-4235 1 2 Vierinen Juha 2 1 Gustavsson Björn 2 Latteck Ralph https://orcid.org/0000-0002-0001-7473 1 Renkwitz Toralf https://orcid.org/0000-0002-0739-2655 1 Zecha Marius 1 Stephan Claudia C. https://orcid.org/0000-0001-5736-1948 1 Conte J. Federico https://orcid.org/0000-0002-9247-702X 1 Kastinen Daniel https://orcid.org/0000-0002-6371-1016 3 Kero Johan https://orcid.org/0000-0002-2177-6751 3 Chau Jorge L. 1 Leibniz Institute of Atmospheric Physics, University of Rostock, Germany Department of Physics and Technology, UiT The Arctic University of Norway, Norway Swedish Institute for Space Physics, Sweden 24 06 2025 2025 1 16 Copyright: © 2025 Devin Huyghebaert et al. 2025 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://egusphere.copernicus.org/preprints/2025/egusphere-2025-2323/ The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2025/egusphere-2025-2323/egusphere-2025-2323.pdf

Observations of neutral density in the mesosphere and lower thermosphere (MLT) region of the terrestrial atmosphere are important for understanding lower atmospheric, geomagnetic, and anthropogenic forcing. This study introduces a statistical method for measuring neutral density variations using an extensive dataset of meteor head echoes that were observed using the MAARSY high-power large-aperture (HPLA) mesosphere–stratosphere–troposphere (MST) radar. The method relies on observing the mean geocentric velocity of meteor head echoes as a function of initial detection altitude and day-of-year. The meteor head echo catalog used contains 1.4 million meteor head echoes between 2016–2023. Neutral density variations are observed with a 3 day time and 2 km altitude resolution between 85–115 km. The measurements show variations in neutral density potentially due to geomagnetic and atmospheric events. Variations of 20–40 % are common in the dataset, and agree with the magnitude of atmospheric neutral density fluctuations from an Upper-Atmosphere ICOsahedral Non-hydrostatic (UA-ICON) atmosphere model run.