Propagation Teepee: A Possible High‐Frequency (15–30 MHz) Remote Lightning Signature Identified by Citizen Scientists

• Published in: Geophysical research letters 2020-06, Vol.47 (11), p.n/a
• Main Authors: Fung, Shing F., Typinski, David, Flagg, Richard, Ashcraft, Thomas, Greenman, Wes, Higgins, Charles, Brown, James, Dodd, Larry, Reyes, Francisco, Sky, Jim, Thieman, James, Garcia, Leonard
• Format: Article
• Language: English
• Subjects: citizen science; Identification; ionospheric physics; Jupiter; Lightning; Lightning strokes; Radiation; Radiation sources; Radio; Radio emission; radio wave propagation; Scientists; space weather; Storms; User groups
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2020GL087307

A high‐frequency spectral feature is identified in ground‐based spectrograph data at 15–30 MHz. The feature, likely of terrestrial origin, is often recorded by a group of citizen scientists (the Spectrograph User Group) whose main interest is to observe Jupiter's radio emissions. The feature appears as radio band noise enhancement in which the frequency of enhancement increases and then decreases with time, forming a “triangular spectral feature.” The teepee tent shape leads to its name (TP for short). TPs usually have well‐defined leading and trailing edges. While some TPs occur in isolation, they are often seen in groups, distributed either in time or in apex frequency. While most TPs appear diffuse, close‐up views of a few TPs reveal that they actually consist of discrete bursts, highly suggestive of lightning strokes as possible radiation sources. Here, we investigate the possible generation of TPs by ionospheric reflection of radiation from remote lightning storms. Key Points A new radio signature of terrestrial origin is identified The new feature is likely produced by ionospheric reflection of HF waves from lightning storms moving relative to the observing point The new radio signatures may be used to detect remote lightning storms and study the ionosphere