Propagation characteristics of very low latitude whistlers by three-dimensional ray tracing

✍ Scribed by Kenji Ohta; Yasuhiro Nishimura; Tomomi Kitagawa; Masashi Hayakawa

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 290 KB
• Volume: 81
• Category: Article
• ISSN: 8756-6621
• DOI: 10.1002/(sici)1520-6424(199806)81:6<42::aid-ecja5>3.0.co;2-7

✦ Synopsis

In magnetosphere propagation of very low latitude whistlers occurs at geomagnetic latitudes around 10 degrees, both duct propagation and nonduct propagation are conjectured as propagation mechanisms. The conjecture for nonduct propagation is based on the fact that the enhancement factor that is needed in duct propagation, reaches several hundred percent at very low latitudes and thus duct propagation is hardly conceivable. The conjecture for the duct propagation is mostly based on observation of echo train whistlers, that must be generated by reverberating propagation along the same path. From this perspective, the possibility of echo train whistler generation by nonduct propagation is investigated using three-dimensional ray tracing based on the night electron density model and the IGRF magnetic field model for very low latitudes. We show that echo train whistlers can be generated by considering not only vertical emission but also conical emission angle within a 3° emission angle to the ionosphere. It is also shown that nonduct propagation can be transmitted downward through the ionosphere over a wide frequency range and that the point of downward transmission through the ionosphere depends less on the frequency.