A new inversion algorithm for backscatter ionogram and its experimental validation

Abstract

Abstract.Oblique backscatter sounding is a powerful tool for detecting and monitoring the ionosphere continuously at a remote distance. High-frequency (HF) backscatter ionograms provide the amplitudes of backscatter signals with respect to group path or time delay against operating frequency. Application of inversion algorithm to a backscatter ionogram can extract useful information regarding the ionospheric electron density along the propagation paths. The present study proposes a new inversion algorithm on basis of simulated annealing method to acquire the leading edge of sweep-frequency ionogram, which is subsequently validated by ionospheric vertical sounding data. Quantitative comparisons between the vertical sounding measurements and the inversion results obtained from oblique backscatter sounding indicate that the new algorithm enables us to overcome the instability issue that traditional inversion algorithm faces and output reliable information of ionospheric inversion with satisfactory efficiency, thus providing a robust alternative for ionospheric detection based on oblique backscatter ionograms especially when the ionosphere is calm with slow changes.

Comparisons of ionospheric electron density distributions reconstructed by GPS computerized tomography, backscatter ionograms, and vertical ionograms

“…Since the data points collected manually or automatically on the leading edge of BSI can be uncontinuous and nonuniform in the ground distance, the contours of electron density distribution can present a fluctuated and unsmoothed feature, which is not real. However, large‐scale structures can still be caught by BSI inversion [ Zhao et al , ; Zhu et al , ].…”

“…Due to the temporal and spatial focusing effects, the amplitude of the leading edge on the BSI is most prominent. Thus, the leading edge is widely used for backscatter ionogram inversion [ Zhao et al , ].…”

“…Zhao et al . [] and Zhu et al . [] proposed a new inversion algorithm on the basis of simulated annealing (SA) method to avoid the instability issue for which traditional algorithms would induce.…”

“…Among the ionospheric diagnostic facilities, the Global Position System (GPS) and the sky wave ground backscatter radar are two techniques that are commonly applied to reconstruct large-scale ionospheric electron density profiles. Large-scale ionospheric electron density variations can be detected by the GPS computerize ionosphere topography (CIT) technique [Raymund et al, 1990;Kunitsyn and Tereshchenko, 1992;Pryse and Kersley, 1992;Pryse et al, 1993;Bust et al, 1994;Bust and Mitchell, 2008] or by the sky wave backscatter ionogram (BSI) inversion technique [Croft, 1972;Reinisch, 1986;Fridman and Fridman, 1994;Coleman, 1997;Li et al, 2013;Zhao et al, 2014].…”

Design and Application of Wuhan Ionospheric Oblique Backscattering Sounding System with the Addition of an Antenna Array (WIOBSS-AA)

“…The inversion method makes full use of the recorded backscatter ionograms, which are based on the simulated annealing algorithm [ 34 ]. By dividing the leading edge into several groups, this method can extract ionospheric information of different areas along the sounding path and eventually provide useful details of ionospheric parameters [ 35 ].…”