Ionospheric response to the space weather event of 18 November 2003 -- An investigation

The present study explores the ionospheric effects of the well cited solar flare events (M3.2, M3.9/2N) of 18 November 2003 associated with CMEs. The H{\alpha} observations of these flares (taken with 15 cm Solar Tower Telescope at ARIES, Nainital) have been analysed to see an association of these flare events with the geomagnetic storm occurred on 20 November 2003. The ionospheric data from Puerto Rico (18.5{\deg}N, 67.2{\deg}W), Dyess (32.4{\deg}N, 99.7{\deg}W) and Millstone Hill (42.6{\deg}N, 71.5{\deg}W) together with the disturbance storm time indices (Dst index) variability exhibited a corresponding associations having a delay in the solar wind parameters, triggered by these flare events.