Link between hemispheric coronal rotational asymmetry and solar activity using STEREO-A observations

To date, it was mysterious whether the solar rotational parameters have a link to the solar activity indicators. To resolve this problem we have carried out a detailed study on the relationship between hemispheric asymmetry in solar coronal rotation and solar activity indicators for solar cycle 24. For this purpose, we applied flux modulation method on solar full disk (SFD) images at 30.4, 19.5 and 28.4 nm recorded by STEREO-A instrument during the period from 2008 to 2018 covering 24^th solar cycle. Our investigation shows that rotational asymmetry is highest during solar maximum period (from 2011 to 2014) and decreases during the ascending and descending phases of the solar cycle. Our analysis further reveals that hemispheric rotational asymmetry leads the sunspot numbers by ∼ 18 months. This clearly indicates that rotational asymmetry may play a key role in the formation of sunspots in conjunction with the differential rotation of the Sun.