Satellite‐Beacon Ionospheric‐Scintillation Global Model of the Upper Atmosphere (SIGMA) III: Scintillation Simulation Using A Physics‐Based Plasma Model

Abstract

Electromagnetic signals including Global Navigation Satellite Systems (GNSS) signals often experience fluctuations due to ionospheric density structures termed as scintillation. Physical processes contributing to these structures in polar cap regions likely include gradient‐drift instability. GNSS scintillations are frequently observed at high latitudes and are potentially useful diagnostics of how energy from the transient forcing in the cusp or polar cap region cascades, via instabilities, to small scales. This work interfaces a physics‐based plasma model (Geospace Environment Model of Ion‐Neutral Interactions) to a radio wave propagation model (Satellite‐beacon Ionospheric‐scintillation Global Model of the upper Atmosphere) to explore this cascade. In this work, Geospace Environment Model of Ion‐Neutral Interactions‐Satellite‐beacon Ionospheric‐scintillation Global Model of the upper Atmosphere is used to simulate signal propagation through gradient‐drift instability over Resolute Bay for comparison with GNSS observations during a geomagnetic storm presented earlier in this series of papers. Our spectral and multiscale analyses show close agreement for simulated and observed data, suggesting the use of our physics‐based platform for understanding and predicting the effects of ionospheric instabilities on navigation and communication.

Observations and modeling of scintillation in the vicinity of a polar cap patch

“…2022, 12, 27 processes and aeronomical transport that are required to model the generation of ionospheric fluid instabilities, such as GDI and KHI. It has been interfaced with a full three-dimensional (3D) electromagnetic wave forward propagation model (Deshpande et al, 2014), SIGMA (Satellite-beacon Ionospheric-scintillation Global Model of the upper Atmosphere) (Deshpande & Zettergren, 2019;Spicher et al, 2020). SIGMA can simulate the propagation of a radio signal through irregular media in the ionosphere, which comprises effects such as scattering, diffraction, wave refraction, and reflection through an arbitrary density field -including a turbulent plasma simulated by a physics-based model like GEMINI.…”

“…In this work, we use the GEMINI ionospheric model (Zettergren & Snively, 2015;Deshpande & Zettergren, 2019) to simulate instability on an idealized patch with approximate characteristics derived from the RISR observations. A 3D Cartesian grid spanning 90 z 1000, À350 x 350, À25 y 25 (km) is used for this simulation; the y-direction is assumed periodic, and the magnetic field is taken to be in the Àz-direction (northern hemisphere).…”

“…The effects of shearing (Gondarenko & Guzdar, 2006a) and time-dependent forcing (Gondarenko & Guzdar, 2006b) have likewise been shown to impact density and electric field fluctuations arising from the ionosphere turbulence. Deshpande & Zettergren (2019) have coupled a physics-based model of GDI to a radio propagation model and shown that the instability can generate density irregularities that can explain some aspects of polar cap phase scintillation. Collectively these theoretical studies paint a complicated picture of patch evolution and its connection to irregularities and scintillationpatches are highly sensitive to the initial distribution of ionospheric plasma (including large-scale gradients, seeding structures, and altitude profiles), as well as the temporal effects like variable forcing and ion inertia (Deshpande et al, 2021).…”

On the Production of Ionospheric Irregularities Via Kelvin‐Helmholtz Instability Associated with Cusp Flow Channels

“…The GEMINI model (Geospace Environment Model of Ion-Neutral Interactions) is a 3-dimensional (3D) multifluid-electrodynamic model of high latitude ionospheric plasma instabilities (Zettergren et al, 2015). GEMINI includes aeronomical, transport, and electrodynamic processes relevant to the formation of ionospheric fluid instabilities such as GDI and KHI (e.g., Deshpande & Zettergren, 2019). The model comprises a fluid system of equations (Blelly & Schunk, 1993;Schunk, 1977), describing dynamics of the ionospheric plasma, self-consistently coupled to an quasi-electrodynamic treatment of auroral and neutral dynamo currents (Zettergren et al, 2015).…”

“…Recent modelling work was performed to study the effect of GDI on navigation signals (Deshpande & Zettergren, 2019), and here, as we observe inhomogeneous flows near the boundary between a density reservoir and a trough, we focus essentially on the KHI as a primary mechanism. We perform numerical simulations of the KHI and investigate in more detail the plausibility for it to generate density irregularities and associated phase scintillations in the cusp ionosphere.…”