Low latitude Ionospheric response to the recent super storm of 17 March 2015: Modeling perspectives and recent findings

Abstract:

In this paper, simulation of low latitude ionospheric response to the recent super geomagnetic storm of 17 March 2015 at Indian longitude, utilizing SAMI2 codes by incorporating Doppler EXB drift, relevant to the storm period, is being presented. Intense enhancement in the EXB drift of 60 to 70 m/s over magnetic equator was observed in the evening hours of 17 March due to the prompt penetration of the high latitude electric field. This remarkable intensification of EXB drift transported the F layer to beyond 550 km altitude, quite unusual in the Indian sector. Model EXB drift in the day time during the recovery phase of the super storm was slightly westward, unlike the eastward EXB drift during the quiet day. This has been found to be linked with the disturbance dynamo during the recovery phase. SAMI2 model, utilizing the Doppler EXB drift during the evening hours and model EXB drift during the rest of the period, could simulate the intense F layer height rise and latitudinal expansion of EIA during storm main phase. Equator ward disturbance thermospheric winds during the recovery phase have also been incorporated in the simulation. Simulation results also indicated a complete suppression of the equatorial ionization anomaly (EIA) during the recovery phase, linked with the westward disturbance dynamo electric field. Model simulations indicate the role of the disturbance neutral winds during the recovery phase in enhancing the plasma density, however, the development of the EIA has been found to be controlled by the zonal electric field. The model results have been compared with the ground observations of the total electron content (TEC). TEC map over the Indian region shows a remarkable suppression of the EIA during the recovery phase of the geomagnetic storm. Peculiarities of this super storm will also be discussed in the light of the current understanding of the space weather impact on the low latitude ionosphere.