Co-spatial evolution of photospheric Doppler enhancements and Hα flare ribbons observed during the solar flare of 2003 October 28

Abstract

The active region NOAA (National Oceanic and Atmospheric Administration) AR 10486 which appeared on the solar disc in 2003 October produced a lot of space weather related activity. Here, we report on the co-spatial evolution of the photospheric Doppler enhancements and the chromospheric Hα flare ribbons observed during the 4B/X17.2 class solar flare of 2003 October 28 in this active region. These velocity enhancements exactly match the Hα brightness enhancements in space, and are delayed by approximately 1 min in time. Hα brightness attains a maximum nearly at the same time as the peak seen in light curves in high-energy emission observed by KORONAS (Kuznetsov et al. 2006).