Skip to content


  • Article
  • Open Access

Equivalent electron densities at reflection heights of tweek atmospherics in the low-middle latitude D-region ionosphere

Earth, Planets and Space201455:BF03352469

  • Received: 1 May 2003
  • Accepted: 7 November 2003
  • Published:


Tweek atmospherics are ELF/VLF pulse signals with frequency dispersion characteristics that originate from lightning discharges and propagate in the Earth-ionosphere waveguide mode over long distances. In this paper, we estimate equivalent nighttime electron densities at reflection heights in D-region ionosphere at low-middle latitudes by accurately reading the first-order mode cut-off frequency of tweek atmospherics. The estimation method was applied to tweek atmospherics received simultaneously at Moshiri and Kagoshima in Japan. Equivalent electron densities ranged from 20—28 el./cm3 at ionospheric reflection heights of 80—85 km. Comparing our estimates with electron density profiles obtained from the IRI-95 model, MF radar measurements, and rocket experiments revealed almost consistent results for the lower part of the D-region ionosphere. The tweek method has the unique advantage of enabling reflection-height (equivalent electron densities) monitoring over a wide area of several thousand kilometers.

Key words

  • Tweek atmospherics
  • cut-off frequency
  • equivalent electron densities (reflection heights)