On Predicting the Solar Cycle using Mean-Field Models

Abstract

We discuss the difficulties of predicting the solar cycle using mean-field models. Here we argue that these difficulties arise owing to the significant modulation of the solar activity cycle, and that this modulation arises owing to either stochastic or deterministic processes. We analyse the implications for predictability in both of these situations by considering two separate solar dynamo models. The first model represents a stochastically-perturbed flux transport dynamo. Here even very weak stochastic perturbations can give rise to significant modulation in the activity cycle. This modulation leads to a loss of predictability. In the second model, we neglect stochastic effects and assume that generation of magnetic field in the Sun can be described by a fully deterministic nonlinear mean-field model -- this is a best case scenario for prediction. We designate the output from this deterministic model (with parameters chosen to produce chaotically modulated cycles) as a target timeseries that subsequent deterministic mean-field models are required to predict. Long-term prediction is impossible even if a model that is correct in all details is utilised in the prediction. Furthermore, we show that even short-term prediction is impossible if there is a small discrepancy in the input parameters from the fiducial model. This is the case even if the predicting model has been tuned to reproduce the output of previous cycles. Given the inherent uncertainties in determining the transport coefficients and nonlinear responses for mean-field models, we argue that this makes predicting the solar cycle using the output from such models impossible.

22 Pages, 5 Figures, Preprint accepted for publication in ApJ

References in corpus (2)

• Astrophysical magnetic fields and nonlinear dynamo theory
• The case for a distributed solar dynamo shaped by near-surface shear

Cited by in corpus (23)

• The Solar Cycle
• Solar cycle prediction
• Solar activity forecast with a dynamo model
• Exploring the Physical Basis of Solar Cycle Predictions: Flux Transport Dynamics and Persistence of Memory in Advection versus Diffusion Dominated Solar Convection Zones
• Prediction of the strength and timing of sunspot cycle 25 reveal decadal-scale space environmental conditions
• Dynamo theories
• Multiple and changing cycles of active stars II. Results
• Progress in Solar Cycle Predictions: Sunspot Cycles 24-25 in Perspective
• A History of Solar Activity over Millennia
• The Hemispheric Asymmetry of Solar Activity During the Twentieth Century and the Solar Dynamo
• Multiple and changing cycles of active stars I. Methods of analysis and application to the solar cycles
• A Stochastically Forced Time Delay Solar Dynamo Model: Self-Consistent Recovery from a Maunder-like Grand Minimum Necessitates a Mean-Field Alpha Effect
• Physical Models for Solar Cycle Predictions
• Turbulent processes and mean-field dynamo
• The dynamics of Wolf numbers based on nonlinear dynamo with magnetic helicity: comparisons with observations
• Variational estimation of the large scale time dependent meridional circulation in the Sun: proofs of concept with a solar mean field dynamo model
• Are solar cycles predictable?
• Hall current effects in mean-field dynamo theory
• Nonlinear mean-field dynamo and prediction of solar activity
• Zonal harmonics of solar magnetic field for solar cycle forecast
• Forecasting the solar cycle using variational data assimilation: validation on cycles 22 to 25
• Long-term Pulses of Dynamic Coupling between Solar Hemispheres
• Modulated cycles in an illustrative solar dynamo model with competing alpha effects