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

Abstract

The recent Chinese Seismo-Electromagnetic Satellite (CSES-01) provides a good opportunity to investigate some features of plasma properties and its motion in the topside ionosphere. Using simultaneous measurements from the electric field detector and the magnetometers onboard CSES-01, we investigate some properties of the plasma E × B drift velocity for a case study during a crossing of the Southern auroral region in the topside ionosphere. In detail, we analyze the spectral and scaling features of the plasma drift velocity and provide evidence of the turbulent character of the E × B drift. Our results provide an evidence of the occurrence of 2D E × B intermittent convective turbulence for the plasma motion in the topside ionospheric F2 auroral region at scales from tens of meters to tens of kilometers. The intermittent character of the observed turbulence suggests that the macro-scale intermittent structure is isomorphic with a quasi-1D fractal structure, as happens, for example, in the case of a filamentary or thin-tube-like structure. Furthermore, in the analyzed range of scales we found that both magnetohydrodynamic and kinetic processes may affect the plasma dynamics at spatial scales below 2 km. The results are discussed and compared with previous results reported in the literature.

Modeling Turbulent Fluctuations in High-Latitude Ionospheric Plasma Using Electric Field CSES-01 Observations

“…In the last twenty years, the availability of high-quality magnetic field and plasma density measurements from several rockets and space missions, such as, for instance, the ESA-Swarm mission, as well as ground-based observations, allowed researchers to better characterize the scaling and spectral features of magnetic field and plasma parameters. As a result of these recent studies, the intermittent character of the ionospheric magnetic and electric field fluctuations has been clearly demonstrated [11][12][13]15,17,18,[21][22][23][24][25][26][27][28][29].…”

“…Assuming that there is a linear correspondence between frequencies and wavenumbers, i.e., supposing Taylor's hypothesis to be valid, k = f /v s where v s 7.8 km/s is the satellite velocity, the selected time interval corresponds to the explored scales between ∼ 390 m and ∼ 3900 m. The validity of Taylor's hypothesis stands on the assumption that transit time is faster than the evolution time of the electric field at the investigated time scale. This corresponds to the assumption that the observed temporal fluctuations are principally due to Doppler-shifted and stationary spatial variations (see, e.g., [17][18][19]42] and references therein).…”

“…where N is a normalization factor. There is still a dependence upon the time scale τ in Equation (18), which is due to the scale dependence of the drift and diffusion coefficients. This allows us to interpret the steady-state solution for a given τ as a local assumption of stationarity in the proximity of the scale τ.…”

“…In the topside F layer of the high-latitude ionosphere, where significant magnetic and electric field variations have been recorded, the range of scale where turbulence is relevant varies from a few meters up to over 1000 km [5]. Moreover, recent studies have shown that scale-invariance and intermittency are features of high-latitude magnetic and electric field fluctuations as well as plasma density variations and E × B drift velocity [6,[11][12][13][14][15][16][17][18]. The emergence of broadband ELF electric field fluctuations and turbulent magnetic field fluctuations have been explained by a variety of physical mechanisms, such as the occurrence of strong shear flows, particle precipitation, and sporadic fast interactions between localized coherent plasma structures (e.g., spatial irregularities, density depletion, convective structures, electron and ion holes, etc.)…”

Ionosphere Monitoring with Remote Sensing

“…At both high and low latitudes, variations in vertical plasma velocity drift plays a key role in the generation of irregularities [54][55][56]. In light of this, Consolini et al [57] used electric and magnetic field measurements provided by the Chinese Seismo-Electromagnetic Satellite (CSES-01) to investigate the properties of the plasma ExB drift velocity during a crossing of the Southern auroral F region. Specifically, they analysed the spectral and scaling features of velocity fluctuations and pointed out the turbulent nature of the drift.…”