| Name: | Chitradeep Saha |
| Affiliation: | Center of Excellence in Space Sciences India, IISER Kolkata |
| Conference ID : | ASI2024_518 |
| Title : | Origin of supermodulation in solar magnetic activity |
| Authors : | Chitradeep Saha1, Suprabha Mukhopadhyay1,2, Dibyendu Nandy1,2
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| Authors Affiliation: | 1 Center of Excellence in Space Sciences India, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
2 Department of Physical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India |
| Mode of Presentation: | Oral |
| Abstract Category : | Sun, Solar System, Exoplanets, and Astrobiology |
| Abstract : | Direct sunspot observations and indirect cosmogenic isotope based reconstructions of solar activity exhibit variabilities well beyond the decadal solar cycle timescale – a phenomenon termed as supermodulation. These long-term solar activity proxies point to the existence of quasiperiodic variabilities in solar activity, including the centennial Gleissberg cycle, the 200-year Suess or de Vries cycle, the 2400-year Hallstatt cycle, etc. Whether such long term modulation in the Sun’s magnetic output results from nonlinear mechanisms or stochastic perturbations is a matter of intense debate. Based on multi-millennial scale solar dynamo simulations, we show that long-term modulation in solar activity is only excited in the presence of stochastic fluctuations. Our simulations conclusively demonstrate that invoking nonlinear quenching mechanisms alone – in the absence of any stochastic forcing in the dynamo framework – cannot produce statistically significant and persistent supermodulation in the sunspot cycle. |
