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[1] Numerous radar observations demonstrate anomalously strong electron heating in polar electrojets during magnetic storms. The effect often correlates with the onset of the Farley-Buneman instability caused by strong convection electric field. Anomalous heating of electrons is usually attributed to turbulent electric fields developing in the E region due to that instability. We propose a theoretical model of the effect based on heuristic assumptions on nonlinearly saturated turbulence and equations of the electron and ion energy budget. The model has been quantitatively tested in the companion paper by Milikh and Dimant [2003]. Good agreement with observations supports the implied physical mechanism.

[1] A numerical model of electron energization in the high-latitude electrojet due to Farley-Buneman instability is presented. The model is based on a set of coupled equations describing the energy balance of electrons and ions combined with a heuristic model of the turbulent electric field, obtained in the companion paper. The electron-neutral collision frequency and cooling rate used in the equations, which are affected by non-Maxwellian deviations of the electron energy distribution, are calculated by a special kinetic code. A good agreement of the model results with the existing observations supports the physical ideas underlying the model.

Abstract. Currents flowing in the Earth's ionospheric electrojets often develop Farley-Buneman (FB) streaming instabilities and become turbulent. The resulting electron density irregularities cause these regions to readily scatter VHF and UHF radar signals. Many of the observed characteristics of these radar measurements result from the nonlinear behavior of this plasma. This paper describes a set of high-resolution, 2-D, fully kinetic simulations of electric field driven turbulence in the electrojet. These show the saturated amplitude of the waves; coupling between linearly growing modes and damped modes; the evolution of the system from dominance by shorter (1 m-5 m) to longer (10 m-200 m) wavelength modes; and the propagation of the dominant modes at phase velocities that lie below the linearly predicted phase velocity and close to but slightly above the acoustic velocity. These simulations reproduce many of the observational characteristics of type 1 waves. They provide information useful in accurately modeling FB turbulence and demonstrate the significant progress we have made in simulating the electrojet.

[1] Global magnetospheric MHD codes using ionospheric conductances based on laminar models systematically overestimate the cross-polar cap potential during storm time by up to a factor of 2. At these times, strong DC electric fields penetrate to the E region and drive plasma instabilities that create turbulence. This plasma density turbulence induces nonlinear currents, while associated electrostatic field fluctuations result in strong anomalous electron heating. These two effects will increase the global ionospheric conductance. On the basis of the theory of nonlinear currents developed by Dimant and Oppenheim [2011], this paper derives the correction factors describing turbulent conductivities and calculates turbulent frictional heating rates. Estimates show that during strong geomagnetic storms the inclusion of anomalous conductivity can double the total Pedersen conductance. This may help explain the overestimation of the cross-polar cap potentials by existing MHD codes. The turbulent conductivities and frictional heating presented in this paper should be included in global magnetospheric codes developed for predictive modeling of space weather.Citation: Dimant, Y. S., and M. M. Oppenheim (2011), Magnetosphere-ionosphere coupling through E region turbulence: 2. Anomalous conductivities and frictional heating,