Browsing by Author "Hayakawa, M."
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Automatic Method for Monitoring the Lower Ionosphere and Lightning Location by Tweek-Atmospherics(Університет прикладних наук Інхолланд, Голландія, 2018) Shvets, Аleksandr V.; Krivonos, Alexey P.; Serdiuk, Tetiana M.; Hayakawa, M.ENG: A new real-time technique is proposed for automatic identification of tweek atmospherics, distance finding to lightning and estimating the effective heights of the lower ionosphere for the fundamental and higher order modes of the Earth-ionosphere waveguide. Effectiveness of the technique is demonstrated with the experimental records of atmospherics. Application of a clustering algorithm allowed us to reveal different patterns of variations of the lower ionosphere effective height along different propagations paths. The distance finding accuracy of our tweek method had been roughly estimated by a comparison with independent data from the Blitzortung.org lightning location network to be less than 100 km with standard deviation less than 200 km in the range of distances from 500 to 1400 km.Item Estimating the Lower Ionosphere Height and Lightning Location Using Multimode "Tweek" Atmospherics(Elsevier, 2014) Shvets, Аleksandr V.; Serdiuk, Tetiana M.; Gorishnyaya, Y. V.; Hobara, Y.; Hayakawa, M.EN: There is proposed a new method of estimating the effective ionospheric height of the Earth-ionosphere waveguide and the propagation distance of tweek-atmospherics. It is based on the compensation of waveguide frequency dispersion of a tweek signal, which enables us to improve the accuracy of deducing the cutoff frequencies, especially in the presence of noise. An approach to solve the inverse problem is suggested that reduces the task of finding both the source range and the waveguide cutoff frequencies by using the multimode characteristics of tweeks to an issue of one-dimensional optimization. Based on the numerical modeling of multimode tweek-atmospherics in the Earth-ionosphere waveguide with exponential vertical conductivity profile of the lower ionosphere, it was shown that the accuracy of estimating the effective waveguide height by the new method is good as about 100-400. m for the first and higher order modes. It then allows us to estimate the parameters of vertical conductivity profile of the lower ionosphere for a wide range of source distances from a few hundred to a few thousand kilometers, as long as two or more tweek harmonics can be detected. Preliminary analysis of experimental tweek records show a decrease of the effective height with increasing the mode number, and the scale height of the exponential vertical conductivity profile for the isotropic lower ionosphere model is estimated to be in a range of 0.4-2.5. km. © 2013 .Item A Technique for Automatic Monitoring the Lower Ionosphere and Lightning Location by Tweekatmospherics(Guwahati: IJEAR Department of Physics Gauhati University, 2017) Shvets, Аleksandr V.; Krivonos, A. P.; Serdiuk, Tetiana M.; Hayakawa, M.ENG: A new real-time technique is proposed for automatc identification of tweek atmospherics, distance finding to lightning and estimating the effective heights of the lower ionosphere for the fundamental and higher order modes of the Earth-ionosphere waveguide. Effectiveness of the technique is demonstrated with the experimental records of atmospherics. Application of a clustering algorithm allowed us to reveal different patterns of variations of the lower ionosphere effective height along different propagations paths. The distance finding accuracy of our tweek method had been roughly estimated by a comparison with independent data from the Blitzortung.org lightning location network to be less than 100 km with standard deviation less than 200 km in the range of distances from 500 to 1400 km.