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Ionospheric E region remote sensing with ELF radio atmospherics
Author(s) -
Cummer Steven A.,
Inan Umran S.
Publication year - 2000
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/2000rs002335
Subject(s) - atmospherics , ionosphere , remote sensing , earth–ionosphere waveguide , attenuation , extremely low frequency , reflection (computer programming) , radio wave , lightning (connector) , schumann resonances , geology , physics , ionospheric absorption , geophysics , meteorology , optics , electromagnetic field , computer science , power (physics) , quantum mechanics , programming language
Radio remote sensing of the ionospheric E region can be difficult, particularly in the nighttime E region valley which lies between two regions of higher electron density. We show that extremely low frequency (ELF) electromagnetic waves launched from below penetrate this region because of their low attenuation and can be reflected from both the D region and the top of the E region valley. This double reflection, also caused by sporadic E layers, produces a measurable effect on the subionospheric propagation of ELF waves, which we demonstrate with numerical Earth‐ionosphere waveguide simulations. This sensitivity opens the possibility of remotely sensing the E region and detecting sporadic E layers with broadband ELF propagation measurements using lightning discharges as the source. From nighttime observations of ELF lightning radiation over the same propagation path on different days, we extract E region electron density profiles that show significant variability not only from day to day but over the course of a single night. This technique is inherently a path‐integrated measurement, enabling tomographic large‐scale ionospheric remote sensing with multiple sources and receivers.