Effects of electrojet turbulence on a magnetosphere‐ionosphere simulation of a geomagnetic storm

• Published in: Journal of geophysical research. Space physics 2017-05, Vol.122 (5), p.5008-5027
• Main Authors: Wiltberger, M., Merkin, V., Zhang, B., Toffoletto, F., Oppenheim, M., Wang, W., Lyon, J. G., Liu, J., Dimant, Y., Sitnov, M. I., Stephens, G. K.
• Format: Article
• Language: English
• Subjects: Agreements; Alignment; Computer simulation; Conductance; Convection modes; Coupling (molecular); Defense programs; Electrodynamics; Electrojets; Electron heating; Electron precipitation; Geomagnetism; Heating; Instability; Ionization; Ionosphere; Magnetic fields; Magnetosphere; Magnetosphere-ionosphere coupling; Magnetospheres; Meteorological satellite program; Meteorological satellites; Nonlinearity; Peak pressure; Polar caps; Polarization; Resistance; Satellite observation; Simulation; Solar wind; Stability; Storms; Streams; Turbulence
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1002/2016JA023700

Ionospheric conductance plays an important role in regulating the response of the magnetosphere‐ionosphere system to solar wind driving. Typically, models of magnetosphere‐ionosphere coupling include changes to ionospheric conductance driven by extreme ultraviolet ionization and electron precipitation. This paper shows that effects driven by the Farley‐Buneman instability can also create significant enhancements in the ionospheric conductance, with substantial impacts on geospace. We have implemented a method of including electrojet turbulence (ET) effects into the ionospheric conductance model utilized within geospace simulations. Our particular implementation is tested with simulations of the Lyon‐Fedder‐Mobarry global magnetosphere model coupled with the Rice Convection Model of the inner magnetosphere. We examine the impact of including ET‐modified conductances in a case study of the geomagnetic storm of 17 March 2013. Simulations with ET show a 13% reduction in the cross polar cap potential at the beginning of the storm and up to 20% increases in the Pedersen and Hall conductance. These simulation results show better agreement with Defense Meteorological Satellite Program observations, including capturing features of subauroral polarization streams. The field‐aligned current (FAC) patterns show little differences during the peak of storm and agree well with Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) reconstructions. Typically, the simulated FAC densities are stronger and at slightly higher latitudes than shown by AMPERE. The inner magnetospheric pressures derived from Tsyganenko‐Sitnov empirical magnetic field model show that the inclusion of the ET effects increases the peak pressure and brings the results into better agreement with the empirical model. Key Points A methodology for including anomalous electron heating (AEH) and nonlinear current (NC) enhancement to ionospheric conductance is developed Inclusion of AEH and NC affects reduces the cross polar cap potential and improves agreement with DMSP observations Inclusion of the AEH and NC effects results in higher inner magnetospheric pressures and improves agreement with DST and empirical models