Long-term modulation of solar cycles

Abstract

Solar activity has a cyclic nature with the ~11-year Schwabe cycle dominating its variability on the interannual timescale. However, solar cycles are significantly modulated in length, shape and magnitude, from near-spotless grand minima to very active grand maxima. The ~400-year-long direct sunspot-number series is inhomogeneous in quality and too short to study robust parameters of long-term solar variability. The cosmogenic-isotope proxy extends the timescale to twelve millennia and provides crucial observational constraints of the long-term solar dynamo modulation. Here, we present a brief up-to-date overview of the long-term variability of solar activity at centennial--millennial timescales. The occurrence of grand minima and maxima is discussed as well as the existing quasi-periodicities such as centennial Gleissberg, 210-year Suess/de Vries and 2400-year Hallstatt cycles. It is shown that the solar cycles contain an important random component and have no clock-like phase locking implying a lack of long-term memory. A brief yet comprehensive review of the theoretical perspectives to explain the observed features in the framework of the dynamo models is presented, including the nonlinearity and stochastic fluctuations in the dynamo. We keep gaining knowledge of the processes driving solar variability with the new data acquainted and new models developed.

Accepted for Space Science Review

References in corpus (26)

• Exploring the Physical Basis of Solar Cycle Predictions: Flux Transport Dynamics and Persistence of Memory in Advection versus Diffusion Dominated Solar Convection Zones
• The crucial role of surface magnetic fields for the solar dynamo
• Solar Cycle Propagation, Memory, and Prediction: Insights from a Century of Magnetic Proxies
• Effects of the scatter in sunspot group tilt angles on the large-scale magnetic field at the solar surface
• The evolution of the solar wind
• Visualization of the challenges and limitations of the long-term sunspot number record
• Solar cyclic activity over the last millennium reconstructed from annual 14C data
• Importance of Meridional Circulation in Flux Transport Dynamo: The Possibility of a Maunder-like Grand Minimum
• Magnetically controlled stellar differential rotation near the transition from solar to anti-solar profiles
• Solar Cycle Variability Induced by Tilt Angle Scatter in a Babcock--Leighton Solar Dynamo Model
• The Effect of "Rogue" Active Regions on the Solar Cycle
• Level and length of cyclic solar activity during the Maunder minimum as deduced from the active day statistics
• The Waldmeier effect and the flux transport solar dynamo
• Understanding solar cycle variability
• Nonlinear mechanisms that regulate the solar cycle amplitude
• Polar Network Index as a magnetic proxy for the solar cycle studies
• A theoretical study of the build-up of the Sun's polar magnetic field by using a 3D kinematic dynamo model
• Solar activity: intrinsic periodicities beyond 11 years
• Updated sunspot group number reconstruction for 1749-1996 using the active day fraction method
• Sunspot tilt angles revisited: Dependence on the solar cycle strength
• A 3D kinematic Babcock Leighton solar dynamo model sustained by dynamic magnetic buoyancy and flux transport processes
• Modeling a Maunder Minimum
• Latitude Distribution of Sunspots: Analysis Using Sunspot Data and A Dynamo Model
• Role of observable nonlinearities in solar cycle modulation
• Nature of grand minima and maxima from fully non-linear Flux-Transport Dynamos
• No evidence for synchronization of the solar cycle by a "clock"