Large-scale traveling ionospheric disturbances impactingequatorial ionization anomaly development in the local morninghours of the Halloween Superstorms on 29-30 October 2003

摘要

This study investigates the development of EIA-like features during the HalloweenSuperstorms. These features are similar to a well-developed equatorial ionosphericanomaly (EIA) and therefore suggest superfountain effects. We tracked EIA-likefeatures in the early-morning sector of 29-30 October 2003 and at around midday on30 October. Their plasma environment was studied with field-aligned plasma density,vertical plasma drift, electron temperature, and vertical plasma flow profiles. Coupledthermosphere-ionosphere plasmasphere (CTIP) simulations reproduced storm-generatedequatorward wind surges. When these EIA-like features appeared early morning on29-30 October, there was no forward fountain circulation; only large-scale travelingionospheric disturbances (TIDs) and strong equatorward winds were present. Theseprovide observational evidence that large-scale TIDs created large plasma depletionsover the dip equator and with the aid of equatorward winds some large enhancementsat -30°N (geomagnetic), resulting in the development of early-morning EIA-likefeatures. We identified TID signatures in the equatorial and midlatitude ionosonde andmagnetometer data, and studied EIA-like features at around midday on 30 Octoberutilizing non-field-aligned TOPEX TEC (2000 UT) and published CHAMP TEC (2030 UT; 2200 UT) line plots. According to our analysis, the EIA-like features seen inthe TEC data were created by large-scale TIDs at 2000 and 2030 UT and by the combinedeffects of large-scale TIDs and forward superfountain at 2200 UT. CTIP simulationsdemonstrate the crucial role of the neutral winds' mechanical or direct effects in thedevelopment of high plasma densities at low midlatitudes.