Theoretical study of the low‐ and midlatitude ionospheric electron density enhancement during the October 2003 superstorm: Relative importance of the neutral wind and the electric field

Abstract

[1] During magnetic storms the ionospheric total electron content (TEC) at low-and midlatitudes often shows great enhancements, which may be associated with mechanisms producing midlatitude storm-enhanced density (SED). The TEC enhancements may result from different ionospheric drivers such as electric fields, neutral winds, and neutral composition effects. To study the importance of the ionospheric drivers in producing the TEC enhancement, we perform numerical simulations for the 29-30 October 2003 superstorm period in the American longitude sector ($ À70°W) using the Sheffield University Plasmasphere Ionosphere Model (SUPIM) with values for the neutral wind, temperature, and composition provided by the National Center for Atmospheric Research (NCAR) Thermosphere Ionosphere General Circulation Model (TIEGCM). Various numerical experiments were run to identify the relative importance of the storm-time ionospheric drivers. For carrying out the storm-time SUPIM simulation, the storm-time upward/poleward E Â B drifts are derived from ROCSAT-1 satellite measurements at low and equatorial latitudes and input to SUPIM, while the storm-time neutral wind and composition disturbances are obtained from TIEGCM run. The simulation results presented in this paper, mainly during the evening period, show that the enhanced upward E Â B drifts due to storm-time eastward penetration electric field can expand the low-latitude equatorial ionization anomaly (EIA) to higher latitudes and produce the TEC enhancement. However, by the effect of penetration electric fields alone, the TEC enhancement is less than by combining the storm-generated equatorward neutral winds and the penetration electric fields. Disturbance neutral composition effects decrease the plasma density at higher latitudes and increase it at low and equatorial latitudes. However, the composition effects do not produce a density increase as large as that produced by the neutral-wind and electric-field effects. Our simulations suggest that the storm-generated equatorward neutral winds play an important role in producing the TEC enhancement at low-and midlatitudes, in addition to the eastward penetration electric field.

Response of the equatorial ionosphere at dusk to penetration electric fields during intense magnetic storms

“…We plan to use this framework to develop algorithms for operational systems support for AFRL's global Scintillation Network Decision Aid system [Groves et al, 1997]. It is hoped that these significant findings will also be incorporated in global magnetosphere-ionosphere-thermosphere coupled models currently under development [Maruyama et al, 2005;Huba et al, 2005;Lin et al, 2005].…”

Total electron content responses to HILDCAAs and geomagnetic storms over South America

“…active times and geomagnetic storms lead to large changes in dayside total electron content (TEC) at low and middle latitudes and the physical mechanisms involved in these changes are well understood (Fuller-Rowell et al, 1997;Tsurutani et al, 2004aTsurutani et al, , 2007Tsurutani et al, , 2008aHuba et al, 2005;Lin et al, 2005).…”

Temporal and spatial variations in ionospheric electron density profiles over South Africa during strong magnetic storms

“…Kelley et al (2004) suggested that daytime eastward prompt penetration electric field (PPEF) that produces negative storms in N max and TEC at equatorial latitudes through enhanced plasma fountain (Balan et al, 2009) could also be the main driver of the positive storms at higher latitudes. However, modeling studies later revealed that the PPEF alone is unlikely to produce the positive storms and equatorward neutral winds alone (Balan et al, 2009) or together with PPEF (Lin et al, 2005;Lu et al, 2012) can produce the…”