sidmon3
Sudden ionospheric distubance (SID) monitor
...Fluctuations in those signal intensities and directions often reflect daytime perturbations of the ionosphere by solar processes, such as solar flares and coronal mass ejections, making VLF receivers useful tools for probing the sun and the earth's ionosphere. For additional general information, see the web page at http://solar-center.stanford.edu/SID/.