An item in the Jan. 22 K7RA Solar Update mentioned a Sudden Ionospheric Disturbance (SID) last Wednesday after a solar flare. It also provided links to Stanford University Websites that describe SIDs and how to build equipment to monitor them.

The Stanford SOLAR Center Space Weather Monitors Web page has many links describing how to build a SID monitor. The Technical Documents Web page has schematics for a SID monitor.

The circuit is simple: a loop antenna that will work at frequencies in the low kHz range around 24 kHz, an active filter around this frequency, a preamplifier and a detector. SIDs can be detected by monitoring variations in signals from very low frequency transmitters at various locations worldwide. A link to a list of these transmitters [PDF] is available on the Weather Monitor Web page.

The AWESOME monitor provides additional capability, allowing monitoring of interesting very low frequency (VLF) phenomena including sprites and whistlers. "AWESOME" is an acronym for "Atmospheric Weather Electromagnetic System for Observation, Modeling and Education."