Characterising the electron density fluctuations in the high-latitude ionosphere at Swarm altitude in response to the geomagnetic activity

Abstract

The high−latitude ionosphere is characterised by plasma density irregularities with typical lengths in a wide range of scales (from ~1 m up to ~1000 km). The enhancement of these irregularities caused for instance by severe Space Weather conditions can affect trans−ionos− pheric communications between ground facilities and satellites. For this reason, an accurate characterisation of the dynamic properties of electron density and their variation with the geomagnetic activity level is of particular interest for the Space Weather especially at high latitudes. In this framework, taking advantage of high resolution in situ measurements by the recent ESA−Swarm space mission orbiting in the ionospheric F−layer, we study both the dynamical properties of the electron density and the scaling properties of the electron den− sity fluctuations at high latitudes in the Northern and Southern Hemispheres in response to changes in the geomagnetic activity levels via nonlinear techniques involving the first−order structure functions. Indeed, it has been shown that the turbulent character of the ionos− pheric plasma density plays an important role in the generation and dynamics of ionospheric plasma density irregularities and the study of the scaling properties of the electron density fluctuations permits us to characterise the possible turbulent state of the ionospheric elec− tron density. The obtained results are consistent with the turbulent character of the ionospheric dynamics, and with the presence of dif− ferent turbulent regimes that show a dependence on the geomagnetic activity levels, magnetic latitude and MLT values.

On the 2015 St. Patrick's Storm Turbulent State of the Ionosphere: Hints From the Swarm Mission

“…The increased interest in the ionospheric turbulence phenomena (e.g., De Michelis et al., 2017; Dyrud et al., 2008; Grach et al., 2016; Pécseli, 2016; Spicher et al., 2015) demonstrates the need to better understand these processes and the different ways in which they can influence the ionospheric environment. For instance, the generation and dynamics of ionospheric inhomogeneities and irregularities (see, e.g., Basu et al., 1988; Earle et al., 1989; Giannattasio et al., 2019) can be affected by turbulence processes occurring in the plasma and this means that ionospheric turbulence may play a significant role in the framework of space weather. Indeed, the ionospheric inhomogeneities and irregularities are among the main causes of disturbances in the propagation of electromagnetic signals in the ionosphere and consequently a better understanding of the turbulence will be of help to all those systems, such as the Global Positioning Systems (GPS) and Global Navigation Satellite Systems (GNSS), which are based on the propagation of an electromagnetic signals through the ionosphere.…”

Dynamical complexity in Swarm electron density time series using Block entropy

“…The plasma density in the ionosphere is characterized by multi-scale irregularities that range from a few meters up to thousands of kilometers and which are related to atmospheric as well as magnetospheric conditions [2,3].…”

On Turbulent Features of E × B Plasma Motion in the Auroral Topside Ionosphere: Some Results from CSES-01 Satellite

“…These features provide a strong indication of the non-Gaussian character of the velocity increments (being Γ 4 > 3) that is related to the occurrence of intermittency. Another interesting feature of the trend of Γ 4 is the presence of a local maximum at τ 0.2 s. This timescale is near the one corresponding to the O + ion inertial length, η, assuming a density n O + ∈ [1, 2] • 10 5 cm −3 (this range of values for the oxygen ion density n O + is estimated from electron density n e − [51] assuming quasi-neutrality and that oxygen ions are the more relevant ions at CSES-01 altitude). Indeed, if we consider the Taylor's hypothesis valid, we have τ O + η = η/v s 0.3 s being v s ∼ 7.8 km/s the satellite speed.…”