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Analysis of the MEsosphere and Lower Ionosphere fall Effect (AMELIE)

The propagation of very low frequency (VLF: 3-30 kHz) radio waves can sense the electron density profile of the lower boundary of the ionosphere. Monitoring the daily variation around noon time shows a high variability during summer time and a smooth variability during winter time. The transition periods (summer-winter, winter-summer) were expected to be similar. However, observations indicate that these transitions are asymmetric. In order to understand this phenomena, a detailed interdisciplinary study addressing mesospheric dynamics and resulting effects on the electron density profile, impacting VLF propagation. We are addressing various aspects of mesospheric dynamics that are of interest for exploring modifications of the vertical electron density profile. To complement the study we use the modified electron density profiles in related VLF wave propagation studies and compare the results with coordinated measurements and model simulations.


To fulfill the aim of this project, the following tasks are being addressed:

  • Quantification of tidal and other wave activities at mesospheric altitudes with radars at middle and high-latitudes over different longitudes between October and November for different years.
  • Correlation estimation of the mesospheric and ionospheric D region features mentioned above, with respect to simultaneous or previous or future lower atmospheric forcing.
  • Evaluation of the derived hypotheses on a possible coupling mechanism, by comparing and investigating atmospheric and ionospheric models in conjunction with global observations and simulations.


The collaboration comprise 19 people from 7 different research organizations

List of Participants from IAP

  • Prof. Dr. J. L. Chau
  • Prof. Dr. F.-J. Lübken*
  • Dr. S. Mani*
  • Dr. L. Macotela*
  • Dr. T. Renkwitz
  • Dr. F. Conte
  • Dr. M. He


Other organizations

  • Institute for Solar-Terrestrial Physics, German Aerospace Center (DLR), Germany
  • University of Rostock, Germany
  • The High Altitude Observatory (HAO) of the National Center for Atmospheric research (NCAR), USA
  • Centro de Rádio Astronomia e Astrofísica Mackenzie (CRAAM), Universidade Presbiteriana Mackenzie, Brazil
  • British Antarctic Survey, UKRI‐NERC, UK
  • Graz University of Technology, Austria


Funding: AMELIE is funded by DLR-SO

Runtime: 2021 – 2024


*Researchers with affiliation from IAP and University of Rostock