Day to night shift in reflection height of VLF radio waves derived from IRI model electron density models

• Published in: Studia geophysica et geodaetica Vol. 67; no. 3-4; pp. 183 - 194
• Main Authors: Madhavilatha, Tirumalaraju, Naidu, Pyla Peddi, Devi, Malladi Indira
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.10.2023; Springer Nature B.V
• Subjects: Accuracy; Atmospheric Sciences; D region; Density profiles; Diurnal; Earth and Environmental Science; Earth Sciences; Electron density; Electron density profiles; Geophysics/Geodesy; Height; Ionosphere; Modelling; Night shifts; Nighttime; Phase measurement; Radio wave propagation; Radio waves; Reflection; Structural Geology; Very Low Frequencies; VLF radio waves; VLF waves; Wave propagation; Waveguides; ionosphere; VLF radio wave propagation; IRI models
• ISSN: 0039-3169; 1573-1626
• DOI: 10.1007/s11200-022-0959-6

The Very Low Frequency (VLF) radio wave propagation characteristics play a very important role in understanding the behaviour of the D-region. The earth-ionosphere wave guide theory has been used to evaluate the reflection height of VLF radio waves using the electron density profiles obtained from the International Reference Ionosphere (IRI) 2012 and 2016 models. For calculating the conductivity parameter, two different collision frequency models have been used. The diurnal shift in reflection height of 16-kHz VLF waves is evaluated for the midpoint of Visakhapatnam-Rugby path using the two IRI models and the results are compared with those values derived from VLF phase measurements made at Visakhapatnam. The theoretically evaluated values using the FT-2001 option for the D-region electron density profile in the IRI-2012 and IRI–2016 models are in good agreement with those obtained from phase measurements, especially in summer. The day to night shift in reflection height obtained using exponential collision critical frequency model are in good agreement with those derived from VLF phase measurements. The diurnal shift in reflection height of VLF radio waves during winter months derived from IRI models are much lower than those obtained from measurements.