Propagation Mechanism of Medium Wave Broadcasting Waves Observed by the Arase Satellite: Hectometric Line Spectra

Kozo Hashimoto, Atsuki Shinbori, Yuichi Otsuka, Fuminori Tsuchiya, Atsushi Kumamoto, Yoshiya Kasahara, Ayako Matsuoka, Isamu Nagano, Yoshizumi Miyoshi, Tatsuhiro Yokoyama

Research output: Contribution to journalArticlepeer-review


A new type of terrestrial line spectra found by the Arase satellite was reported in 2018. These spectra are called “hectometric line spectra (HLS)”. They primarily consist of constant frequency narrowband components at frequencies between 525 kHz and 1,700 kHz, which originate and are sometimes amplified from AM broadcasting waves. In addition to these, other generated emissions are observed. Entrances and the mode conversion of the AM broadcasting waves into the equatorial and low-latitude ionosphere with plasma density depletion called plasma bubbles are observed. Electron density profiles and equatorial plasma bubbles are examined through Global Positioning System (GPS)-Total electron content (TEC) analyses. As a result, the Arase satellite which observed the HLS passed through the TEC depression region near the equatorial ionosphere associated with plasma bubbles. The scenario based on the mode conversion of the L-O mode to the Z mode and vice versa was confirmed with observations and GPS-TEC analyses. Another entrance when foF2 estimated from TEC is lower than 1,000 kHz instead of a plasma bubble is also found. No mode conversion is necessary, then.

Original languageEnglish
Article numbere2021JA029813
JournalJournal of Geophysical Research: Space Physics
Issue number11
Publication statusPublished - 2021 Nov

ASJC Scopus subject areas

  • Space and Planetary Science
  • Geophysics


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