| Abstrakt: |
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. Plain Language Summary: Earth's ionosphere, the ionized portion of the upper atmosphere is highly variable due to atmospheric variations and solar activity. Due to disturbances in the ionospheric electric fields and plasma densities, the ionospheric current systems and their presence on ground‐based magnetometers can undergo very complicated changes during space weather events (such as coronal mass ejections (CME), high‐speed solar wind (HSS), Co‐rotating Interaction Regions (CIRs), solar flares, etc.). In this study, a thorough multi‐instrument examination of the ionospheric fluctuations and the accompanying magnetic variations over Indian longitude regions has been done during the several geomagnetic storms between 3 and 20 December 2006 (Solar flare on 5th, CIR induced moderate storm on 6th, following HILDCAA on 7th–8th, and CME induced intense storm on 15th of December in particular). We have also been able to adequately explain the day‐to‐day fluctuations of the ionosphere over India by taking into account the storm‐produced physical events (such as PPEF, DDEF, change in composition, TID, etc.). Key Points: A detailed multi‐instrument study of magnetic and ionospheric variation due to a variety of space weather phenomenon in December 2006 over Indian longitudes is presentedThis study shows the signature of the X9 solar flare of 5 December 2006 on the SYM‐H and ASY‐H indicesThe impact of solar and geomagnetic events on the variation of the Earth's magnetic field due to the ionospheric electric currents is addressed [ABSTRACT FROM AUTHOR] |
