On the Generation of Large Wave Parallel Electric Fields Responsible for Electron Heating in the High-Latitude E Region


Bahcivan, H., & Cosgrove, R. (2010). On the generation of large wave parallel electric fields responsible for electron heating in the high‐latitude E region. Journal of Geophysical Research: Space Physics, 115(A10).


The sources of parallel electric fields (E) to explain E region electron heating measurements made by incoherent scatter radars have not been resolved. This paper considers the effect of electron density gradients parallel to the geomagnetic field (∇n) on the Farley-Buneman instability and the resulting change in wave δE. The dispersion relation including the ∇n effect is derived and solved for a set of wave vectors at marginal stability. It is shown that ∇n with scales of several kilometers enable propagation of 50 m or longer wavelength waves at large angles (up to 5°) from perpendicularity to the geomagnetic field. The fact that kilometric scales of ∇n were previously shown to occur during strong electrojet and that they coincide statistically well with the altitudes of strongest electron heating support the role of these long-wavelength waves in electron heating. Furthermore, unlike the gradient-drift instability, the ∇n effect contributes to the growth of the waves with the proper k sign regardless of the direction of the convection electric field Ec; this makes the ∇n effect eligible as a source of electron heating, resulting in the consistent increase of electron temperature with the magnitude of Ec. Moreover, it is shown that the inclusion of the ∇n effect reduces the discrepancy between the theoretically required perpendicular electric field turbulence (to raise the electron temperature to the measured values) and the in situ rocket measurements.

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