Journal Highlights

Analysis of pulsations observed during a solar flare

Editor’s Highlight—


Solar flare emission at X-ray and extreme ultraviolet energies cause substantial enhancements in the electron concentration in Earth’s lower ionosphere (about 60-90 km altitude). Flares often show quasi-period emission (QPPs) with periods ranging minutes to tens of minutes. This paper shows, for the first time, that the lower ionosphere responds to these QPPs. The authors measure the incoming solar radiation with satellite data at geostationary altitude. The impact of the QPPs is seen as amplitude variations of Very Low Frequency (24 kHz) signals propagating in the earth-ionosphere wave-guide between the east coast of the USA and the west coast of Europe. These results demonstrate that the lower ionosphere is much more sensitive to small changes in solar flux than previously thought, as shown in this video