Description
The Low Frequency Array (LOFAR) is designed to observe the early universe at radio wavelengths. When radio waves from a distant astronomical source traverse the ionosphere, structures in the plasma affect the signal. The high temporal resolution available (~10 ms), the large range of frequencies observed (10-80 MHz & 120-240 MHz) and the large number of receiving stations (currently 52 across Europe) mean that LOFAR can observe the effects of the midlatitude ionosphere in an unprecedented level of detail.The observational programme LT16_002 began in September 2021 and observations from the first 15 months of this programme are used to investigate ionospheric structures. A variety of patterns in the received signal intensity have been observed, other structures appear to be previously unreported. Collectively, we refer to these structures as Radio Alteration Features (RAFs).
In order to investigate the occurrence and origin of RAFs, 1092 hours of observations from LT16_002 were analysed. RAFs were observed in 382 hours of observations. RAFs are primarily a night-time phenomenon and are more common in summer. They do not appear to have a statistically-significant relationship to geomagnetic activity as measured by a variety of geomagnetic indices, but there is some evidence that they are more common during times of enhanced solar activity or when a CME encounters the Earth.
Work on a measure of the strength of the RAFs is underway using the amplitude scintillation index S4. New observations from LT16_002 mean that the database is continually expanding. Comparisons of the climatology of RAFs to the climatology of other features, such as TIDs, is planned to give an insight into the driving processes. The latest developments in this work will be reported.
| Period | Apr 2023 |
|---|---|
| Event title | Magnetosphere Ionosphere and Solar-Terrestrial Physics (MIST) meeting |
| Event type | Conference |
| Location | Birmingham, United KingdomShow on map |
| Degree of Recognition | National |