Abstract:
Solar flares and coronal mass ejections (CMEs) are two very important active events from Sun.
Inspite of several theoretical and statistical analyses, the relation between solar flares and CMEs is so far
not well established, and strong opinions and arguments still continue. Statistical approaches use a lot of data
available from many measurements by space and ground instruments. They try to map the measured parameters
of one event to that of another event and try to establish the relation between them. Halo CMEs are a kind of
special CMEs in the sense that they are directed towards Earth and hence can influence Earth’s atmosphere.
For a scientist interested in Sun–Earth interactions and the effect on Earth’s atmosphere, study of Halo CMEs
is extremely important. In this paper the relation between solar flares and Halo CMEs is studied. The data sets
used are for the period from October 2006 to March 2017. For the first time, the Halo CMEs are categorized
into four different groups based on the relative time of occurrence with respect to the flares and the relation
between the flare and Halo CME parameters is studied. It is shown that: (a) there is a good correlation between
certain flare parameters (like flare flux and peak intensity) and CME parameters (like kinetic energy, linear
speed, and mass) especially when the Halo CME occurs during the flare; (b) For the same set of CMEs, the
correlation is poor with flare duration; and (c) For CMEs before or after the flare, the correlation is lesser than
the CMEs occurring during the flare.
