  In this article, we report an evidence of very high and statistically
significant relationship between hemispheric asymmetry in solar coronal
rotation rate and solar activity. Our approach is based on cross correlation of
hemispheric asymmetry index (AI) in rotation rate with annual solar activity
indicators. To obtain hemispheric asymmetry in solar rotation rate, we use
solar full disc (SFD) images at 30.4 nm, 19.5 nm, and 28.4 nm wavelengths for
24th Solar Cycle i.e., for the period from 2008 to 2018, as recorded by the
Solar Terrestrial Relations Observatory (STEREO) space mission. Our analysis
shows that hemispheric asymmetry in rotation rate is high during the solar
maxima from 2011 to 2014. On the other hand, hemispheric asymmetry drops
gradually on both sides (i.e., from 2008 to 2011 and from 2014 to 2018). The
results show that asymmetry index (AI) leads sunspot numbers by ~1.56 years.
This gives a clear indication that hemispheric asymmetry triggers the formation
of sunspots working together with the differential rotation of the Sun.
