Dear colleagues, As the AGU Fall Meeting is around the corner, this means that it is also EGU abstract submission season! The EGU General Assembly will take place as a hybrid conference (in Vienna, Austria and online) on 23–28 April 2023. We would like to draw your attention to Session ST3.6: Ionosphere – upper atmosphere physics with ground-based instrumentation <https://meetingorganizer.copernicus.org/EGU23/session/46384>. The session description can be found at the bottom of this e-mail. Please note that the abstract submission deadline for EGU23 is on *Tuesday, 10 January 2023 at 13:00 CEST*. Guidelines on the abstract submission process can be found on this page <https://egu23.eu/programme/how_to_submit.html>. Please do not hesitate to forward this announcement to your colleagues who make use of ground-based instrument data in their studies of upper atmospheric and ionospheric processes. We are looking forward to your contributions and to seeing you at EGU23! Best regards, The EGU ST3.6 session convening team: Veronika Haberle, Maxime Grandin, Jia Jia, and Frederic Pitout *************************************************************** ST3.6 EDI <https://www.egu.eu/news/689/egu-announces-new-edi-logo-for-the-2021-general-assembly/> *Ionosphere – upper atmosphere physics with ground-based instrumentation* Convener: Veronika HaberleECS<https://meetingorganizer.copernicus.org/EGU23/session/46384#&… Co-conveners: Maxime GrandinECS<https://meetingorganizer.copernicus.org/EGU23/session/46384#&… JiaECS<https://meetingorganizer.copernicus.org/EGU23/session/46384#>,… Pitout<https://meetingorganizer.copernicus.org/EGU23/session/46384#> Abstract submission <https://meetingorganizer.copernicus.org/EGU23/abstractsubmission/46384> The Earth’s upper atmosphere and ionosphere are subject to significant variability associated with solar forcing. While in situ observations of the ionosphere-upper atmosphere are only possible with spacecraft and sounding rockets, a wealth of information is obtained thanks to remote sensing techniques using ground-based instruments. For instance, ground-based magnetometers, used in dense networks, routinely enable the derivation of ionospheric currents and geomagnetic indices. Optical instruments not only provide measurements of auroral and airglow emissions, but are also used to observe upper atmospheric winds and temperatures, e.g. in the thermosphere and mesosphere. Such parameters can also be measured with radars, spanning a wide range of active (ionosondes, meteor radars, coherent and incoherent scatter radars, VLF transmitters, Lidars) and passive (riometers, VLF receivers) systems. Combining ground-based observations from various instruments enables the development of novel data analysis methodologies which in turn enhance our understanding of the underlying physics of space weather and ionosphere-upper atmosphere processes. This includes the study of densities, temperatures and composition of the ionosphere–upper atmosphere, monitoring of its dynamics and chemistry, and measuring of fluxes from precipitating particles and current systems. In this session, we invite contributions featuring the use of ground-based instruments in studies of the ionosphere–upper atmosphere system across all latitudes and of space weather and ionospheric–atmospheric physics processes of various time and spatial scales.