- 1Space Environment and Radio Engineering (SERENE) research group, University of Birmingham, School of Engineering, Electrical and Electronic Engineering, Birmingham, United Kingdom of Great Britain – England, Scotland, Wales (a.wood.1@bham.ac.uk)
- 2Science and Technology Facilities Council (STFC) Rutherford Appleton Laboratory, UK
- 3ASTRON – The Netherlands Institute for Radio Astronomy
The Low Frequency Array (LOFAR) is one of the most advanced radio telescopes in the world. When radio waves from a distant astronomical source traverse the ionosphere, structures in this plasma affect the signal. The high temporal resolution available (~10 ms), the range of frequencies observed (10-90 MHz & 110-250 MHz) and the large number of receiving stations (currently 52 across Europe) mean that LOFAR can also observe the effects of the midlatitude and sub-auroral ionosphere at an unprecedented level of detail.
Case studies have shown substructure within a sporadic-E layer (Wood et al., 2024), substructure within a Medium Scale Travelling Ionospheric Disturbance (TID) (Dorrian et al., 2023), a Small Scale TID (Boyde et al., 2022) and symmetric quasi-periodic scintillations (Trigg et al., 2024). The small-scale size of many of these features (kilometres to tens of kilometres) implies a local source. A climatology of observations during daylit hours shows that ionospheric waves primarily propagate in the opposite direction to the prevailing wind, suggesting that the structures observed are the ionospheric manifestation of quasi-upward propagating Atmospheric Gravity Waves (AGWs; Boyde et al., under review).
The recent development of a light version of the LOFAR data means that, for the first time, it is possible to undertake a large statistical study spanning all seasons and local times. Approximately 3,000 hours of observations were used to create this first climatology. It is shown that the ionospheric structures occur most frequently on summer evenings, are not primarily driven by geomagnetic activity and that there are striking similarities to a climatology of lighting strikes. This adds to the body of evidence which suggests that these features are the ionospheric manifestation of AGWs. Such waves substantially affect the global atmospheric circulation and the potential use of LOFAR to better determine the effect of AGWs on the global circulation is discussed.
This work is supported by the Leverhulme Trust under Research Project Grant RPG-2020-140.
References
Boyde, B. et al. (2022). Lensing from small-scale travelling ionospheric disturbances observed using LOFAR, J. Space Weather Space Clim., 12, 34. doi:10.1051/swsc/2022030
Dorrian, G. D. et al. (2023). LOFAR observations of substructure within a traveling ionospheric disturbance at mid-latitude, Space Weather, 21, 2022SW003198. doi:10.1029/2022SW003198
Trigg, H. et al. (2024). Observations of high definition symmetric quasi-periodic scintillations in the mid-latitude ionosphere with LOFAR. J. Geophys. Res., 2023JA032336. doi:10.1029/2023JA032336
Wood, A. G. et al. (2024). Quasi-stationary substructure within a sporadic E layer observed by the Low Frequency Array (LOFAR), J. Space Weather Space Clim. 14, 27. doi:10.1051/swsc/2024024
How to cite: Wood, A., Dorrian, G., Boyde, B., Trigg, R., Fallows, R., and Mevius, M.: Driving The Mid-Latitude Ionosphere from Below: Observations Made Using the International LOFAR Telescope, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4241, https://doi.org/10.5194/egusphere-egu25-4241, 2025.
