High‐latitude E and F region coupling signature: A case study results from rapid‐run ionosonde

Abstract

Rapid-run ionosonde installed in the high-latitude Sodankylä Geophysical Observatory enables us to observe for the first time extraordinary details of E-F region coupling process in high-latitude ionosphere during geomagnetically quiet period. We present an example on 15 August 2009 when a dense, patchy sporadic E layer was detected. Associated with this unstable sporadic E layer, exhibiting in addition an unusual enhancement with a vertical extent of about 10 km, the highly structured F layer plasma was observed with apparent plasma depletions. We examine this event taking into account the presence of mesoscale traveling ionospheric disturbances which can initiate coupling between these two regions and compare the data with current theories.

Sporadic E Layer with a Structure of Double Cusp in the Vertical Sounding Ionogram

“…The examples of phenomena associated with sporadic layers presented in Figures 6 and 7 show that unusual traces on ionograms, similar to those shown in Figure 2, can be con-sidered as a manifestation of the process of the interaction between the E and F layers, including the propagation of atmospheric waves [2,17,[35][36][37][38][39][40][41][42]. Many studies considered the interaction of regions E and F during the propagation of medium-scale traveling ionospheric disturbances (TIDs), as well as the influence of solar thermal tidal motions that cause the appearance of the so-called descending intermediate E s layers [1][2][3][4][5]8,15,19]. A feature of the intermediate E s layers is their appearance at heights between the E and F regions and a further downward movement towards the E region.…”

“…The majority of the information we possess on E s layers was obtained by vertical sounding using ionosondes. Currently, E s layers are being investigated using modern digital ionosondes, lidars, incoherent scatter radars (ISR), very high frequency (VHF) and partial reflection (PR) radars, rocket probes, and signals from GPS and GLONASS navigation satellite systems [1][2][3][4][5][6][7][8][9][10][11][12][13]. Many important characteristics of the E s layers are well understood, but continued research is still important, as these layers can significantly affect the propagation of HF and VHF radio waves and provide radio communications in disturbed ionospheric conditions or when reflections from the F layer are not possible.…”

Periodic oscillations in the high-latitude ionosphere driven by ultralow frequency waves: simultaneous measurements using SuperDARN radars and GNSS-TEC technique

“…The temporal and spatial variations in energetic electron precipitation, which causes the ionization of the lower ionosphere (bottom E and D regions) as recorded by riometers, can generate plasma density disturbances (TEC perturbations) with spatially irregular structures (Spanswick et al, 2005). Furthermore, a polarized electric eld caused by spatial variations in ionospheric conductivity may be applied from the E to the F-region, causing plasma density perturbations in the upper ionosphere (Shalimov and Kozlovsky, 2015). Pilipenko et al (2014) proposed several other generation mechanisms for TEC perturbations associated with ULF waves, including periodic drifts across a lateral gradient of the ionospheric plasma, periodic shifts of the plasma vertical pro le, ion heating, and eld-aligned plasma transport.…”

Statistics of Traveling Ionospheric Disturbances at High Latitudes Using a Rapid‐Run Ionosonde

“…Another electrodynamic processes such as Perkins instability (Hamza, 1999; Perkins, 1973) and the E‐F ionospheric coupling (Cosgrove & Tsunoda, 2004; Garcia et al., 2000; Kelley et al., 2003; Shalimov & Kozlovsky, 2015) have also been proposed. MSTIDs generated due to the electrodynamic instability imply a certain direction of propagation and presence of a polarization electric field.…”