Measurements of D-Region Electron Densities Utilizing the Partial Reflection Technique

AIAA Journal ◽  
1981 ◽  
Vol 19 (12) ◽  
pp. 1558-1561
Author(s):  
Robert O. Olsen ◽  
David L. Mott
Keyword(s):  
Electron Densities ◽  
Partial Reflection ◽  
D Region

scholarly journals D-region electron density and effective recombination coefficients during twilight – experimental data and modelling during solar proton events

2009 ◽  
Vol 27 (10) ◽  
pp. 3713-3724 ◽  
Author(s):  
A. Osepian ◽  
S. Kirkwood ◽  
P. Dalin ◽  
V. Tereschenko
Keyword(s):  
Electron Density ◽  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Solar Proton ◽  
Radio Waves ◽  
Electron Densities ◽  
Partial Reflection ◽  
D Region ◽  
Density Values ◽  
Solar Proton Events

Abstract. Accurate measurements of electron density in the lower D-region (below 70 km altitude) are rarely made. This applies both with regard to measurements by ground-based facilities and by sounding rockets, and during both quiet conditions and conditions of energetic electron precipitation. Deep penetration into the atmosphere of high-energy solar proton fluxes (during solar proton events, SPE) produces extra ionisation in the whole D-region, including the lower altitudes, which gives favourable conditions for accurate measurements using ground-based facilities. In this study we show that electron densities measured with two ground-based facilities at almost the same latitude but slightly different longitudes, provide a valuable tool for validation of model computations. The two techniques used are incoherent scatter of radio waves (by the EISCAT 224 MHz radar in Tromsø, Norway, 69.6° N, 19.3° E), and partial reflection of radio-waves (by the 2.8 MHz radar near Murmansk, Russia, 69.0° N, 35.7° E). Both radars give accurate electron density values during SPE, from heights 57–60 km and upward with the EISCAT radar and between 55–70 km with the partial reflection technique. Near noon, there is little difference in the solar zenith angle between the two locations and both methods give approximately the same values of electron density at the overlapping heights. During twilight, when the difference in solar zenith angles increases, electron density values diverge. When both radars are in night conditions (solar zenith angle >99°) electron densities at the overlapping altitudes again become equal. We use the joint measurements to validate model computations of the ionospheric parameters f+, λ, αeff and their variations during solar proton events. These parameters are important characteristics of the lower ionosphere structure which cannot be determined by other methods.

Ionization increases associated with the small solar proton events of 5 February 1965 and 16 July 1966

1969 ◽  
Vol 47 (2) ◽  
pp. 131-134 ◽  
Author(s):  
L. W. Hewitt
Keyword(s):  
Lower Ionosphere ◽  
Solar Proton ◽  
Satellite Observations ◽  
Geographic Latitude ◽  
Electron Number ◽  
Partial Reflection ◽  
D Region ◽  
Resolute Bay ◽  
Solar Proton Events

Observations of partial reflections from the ionosphere at vertical incidence at 2.66 MHz have been made at Resolute Bay, geographic latitude 74.7 °N, since September 1963. By measuring the amplitudes of the ordinary and extraordinary backscattered waves information is obtained about electron number densities in the lower ionosphere. The results presented in this paper show that the partial reflection technique is more sensitive than most other ground-based experiments for the detection of D-region ionization increases associated with small solar proton events. Results obtained by the partial reflection experiment during the events of 5 February 1965 and 16 July 1966 are presented and compared with VLF and satellite observations.

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