Sun, Space Weather, and Solar-Stellar Connection

Periodicity in the Ratio of Sunspot Number to the Sunspot-group Area

Not scheduled

3m

Poster

Speaker

Dr Manjunath Hegde (Indian Institute of Astrophysics)

Description

The solar dynamo, believed to operate near the base of the convection
zone (BCZ), generates the magnetic fields responsible for solar activity and
solar cycles. Magnetic structures (flux tubes) formed near BCZ rise through
the convection zone, potentially fragmenting/branching into smaller
structures. These structures emerge as sunspots or active regions/sunspot groups
on the Sun's surface. This process vary with time and latitude, depending on the
solar cycle phase and other timescales. In this study, we analyze sunspot data from
Kodaikanal Observatory (1904-2017) to examine variations in the ratio of the 13-month
smoothed international sunspot number (SN) to the average sunspot group area (A).
A large/small SN/A may imply the fragmentation process is less/more. We apply
fast Fourier transform (FFT) and Morlet wavelet analysis to study periodicities
in the SN/A ratio. We find besides ~11-year periodicity, ~67, 63, 60, 45 year
periodicities in SN/A. These results, combined with variations in other solar activity
indices, help deepen our understanding of solar variability and the underlying
processes driving magnetic field evolution.