Solar activity forecast with a dynamo model

By Jie Jiang, Piyali Chatterjee, A. Choudhuri. 2007

193 citations recorded by the source corpus.

Although systematic measurements of the Sun’s polar magnetic field exist only from mid-1970s, other proxies can be used to infer the polar field at earlier times. The observational data indicate a strong correlation between the polar field at a sunspot minimum and the strength of the next cycle, although the strength of the cycle is not correlated well with the polar field produced at its end. This suggests that the Babcock–Leighton mechanism of poloidal field generation from decaying sunspots involves randomness, whereas the other aspects of the dynamo process must be reasonably ordered and deterministic. Only if the magnetic diffusivity within the convection zone is assumed to be high (of order 10 12 cm 2 s 1 ), we can explain the correlation between the polar field at a minimum and the next cycle. We give several independent arguments that the diffusivity must be of this order. In a dynamo model with diffusivity like this, the poloidal field generated at the mid-latitudes is advected toward the poles by the meridional circulation and simultaneously diffuses towards the tachocline, where the toroidal field for the next cycle is produced. To model actual solar cycles with a dynamo model having such high diffusivity, we have to feed the observational data of the poloidal field at the minimum into the theoretical model. We develop a method of doing this in a systematic way. Our model predicts that cycle 24 will be a very weak cycle. Hemispheric asymmetry of solar activity is also calculated with our model and compared with observational data.

Subfields: Astronomy and Astrophysics, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/db30277b7a898dce98e71ccd9a296c56d275f4fe

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Citations in the corpus

DETECTION OF EQUATORWARD MERIDIONAL FLOW AND EVIDENCE OF DOUBLE-CELL MERIDIONAL CIRCULATION INSIDE THE SUN (2013, unknown): “2010; Jiang et al. 2007).”
Exploring the Physical Basis of Solar Cycle Predictions: Flux Transport Dynamics and Persistence of Memory in Advection- versus Diffusion-dominated Solar Convection Zones (2007, background): “Owing to the lack of observations of conditions inside the convection zone, opinions differ as to whether the real solar dynamo is weakly or strongly diffusive (e.g. Dikpati & Gilman 2006; Jiang et al. 2007).”
Solar Dynamo Theory (2014, methodology): “Figure 12 shows a cycle 24 prediction produced by the similar prediction scheme developed by Choudhuri et al. (2007; see also Jiang et al. 2007).”
Sunspot Group Tilt Angles and the Strength of the Solar Cycle (2010, methodology): “A more physicsbased approach is offered by models of the evolution of the Sun’s magnetic field, although recent dynamo computations have given controversial results for cycle 24 (Dikpati & Gilman, 2006; Choudhuri et al., 2007; Jiang et al., 2007).”