Abstract:
This paper highlights the impact of intense solar events over India during 3–20 December
2006. Ionospheric effects of a major solar flare (X9) on December 5 (10:35 UT) have been investigated by
using dayside and nightside magnetometer data, dayside ionosondes, and dayside GPS vTEC observations.
On the next day, a stream of fast solar wind hits the magnetosphere, causing a HILDCAA (High Intensity
Long Duration Continuous Auroral Activity) preceded by moderate geomagnetic storm. The origin and
characteristics of a positive ionospheric storm which occurred over Tirunelveli (TIR, geomagnetic latitude:
−0.18°N) in the recovery phase of storm due to simultaneous presence of enhanced O/N2 and WEJ or weakened
EEJ during the HILDCAA (7th and 8th of December) is investigated. Subsequently, on December 14, the
most powerful CME since the Halloween event impacts the Earth, and three SSCs are recorded on December
14, 16, and 18. The variability of the ionosphere over the Indian longitude sector due to these intense space
weather fluctuations is presented by utilizing the magnetometers, ionosonde, GPS vTEC, and satellite-based
observations in the same region. This study reports the influence of prompt penetration of the magnetospheric
convection electric field and the disturbance dynamo on several key ionospheric and magnetic parameters
within the Indian longitude sector.
