Ionospheric irregularities and scintillations: a direct comparison of in situ density observations with ground-based L-band receivers

Abstract

Ionospheric irregularities can affect satellite communication and navigation by causing scintillations of radio signals. The scintillations are routinely measured using ground-based networks of receivers. This study presents observations of ionospheric irregularities by Langmuir probes on the Swarm satellites. They are compared with amplitude scintillation events recorded by the Global Positioning System-Scintillation Network and Decision Aid (GPS-SCINDA) receiver installed in Mbarara (Lat: $$0.6^{\circ }\hbox {S}$$ 0 . 6 ∘ S , Lon: $$30.8^{\circ }\hbox {E}$$ 30 . 8 ∘ E , Mag. lat: $$10.2^{\circ }\hbox {S}$$ 10 . 2 ∘ S ). The study covers the years from 2014 to 2018 when both data sets were available. It was found that the ground-based amplitude scintillations were enhanced when Swarm registered ionospheric irregularities for a large number of passes. The number of matching observations was greater for Swarm A and C which orbited at lower altitudes compared to Swarm B. However, some counterexamples, i.e., cases when in situ electron density fluctuations were not associated with any observed L-band amplitude scintillation and vice versa, were also found. Therefore, mismatches between observed irregularity structures and scintillations can occur just over a few minutes and within distances of a few tens of kilometers. The amplitude scintillation strength, characterized by the S4 index was estimated from the electron density data using the well-known phase screen model for weak scattering. The derived amplitude scintillation was on average lower for Swarm B than for A and C and less in accordance with the observed range. Irregularities at an altitude of about 450 km contribute strongly to scintillations in the L-band, while irregularities at about 510-km altitude contribute significantly less. We infer that in situ density fluctuations observed on passes over or near Mbarara may be used to indicate the risk that ionospheric radio wave scintillations occur at that site.

Turbulence Signatures in High‐Latitude Ionospheric Scintillation

“…In the linear range, the corresponding spatial scales are given by l τ ∼ V eff τ. Given the characteristic values of the linear range, and a typical value of V eff in the range of 100-200 m/s, we find l τ ∼ 10-160 m, which is of the same order of magnitude or slightly smaller than the diffraction Fresnel scale associated with a scattering layer located at ionospheric region heights (Aol et al, 2020;Yeh & Liu, 1982). These results pinpoint the importance of the role played by ionospheric Fresnel-scale structures in the generation of scintillation.…”

Properties of Whistler Waves’ Ducting in Plasmas With Systems of Small‐Scale Density Depletions

“…The DEMETER satellite, whose results stimulated this study, provided a spatial resolution of density irregularities of about 10 km. SWARM satellite instruments allow direct measurements of ionospheric plasma disturbances with scales down to 500 m (Aol et al, 2020a(Aol et al, , 2020b. Detection of subhectometer-scale irregularities by a low-orbit satellite requires the use of density probes with microsecond time resolution.…”

Ionospheric Total Electron Content and Scintillation Variations over Uzbekistan and China GPS stations during the Annular Solar Eclipse on 21 June 2020

“…Scintillations are routinely measured using ground-based networks of receivers. For example, a discussion of ionospheric disturbance observations by Langmuir probes on Swarm satellites is published in the paper [49].…”