One obvious feature of the solar cycle is its variation from one cycle to another. In this article,
we review the dynamo models for the long-term variations of the solar cycle. By long-term …

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 …

We report progress on the ongoing recalibration of the Wolf sunspot number (SN) and group-
sunspot number (GN) following the release of version 2.0 of SN in 2015. This report …

Abstract Study Analysis Group 21 (SAG21) of NASA's Exoplanet Exploration Program
Analysis Group was organized to study the effect of stellar contamination on space-based …

The Sun is the main energy source to Earth, and understanding its variability is of direct
relevance to climate studies. Measurements of total solar irradiance (TSI) exist since 1978 …

Extreme solar particle events (ESPEs) are rare and the most potent known processes of
solar eruptive activity. During ESPEs, a vast amount of cosmogenic isotopes (CIs) 10Be …

Solar magnetic activity drives the dominant 11-year cyclic variability of different space
environmental indices, but they can be delayed with respect to the original variations due to …

We consider a conventional α–Ω-dynamo model with meridional circulation that exhibits
typical features of the solar dynamo, including a Hale-cycle period of around 20 years and a …

We propose a self-consistent explanation of Rieger-type periodicities, the Schwabe cycle,
and the Suess-de Vries cycle of the solar dynamo in terms of resonances of various wave …

The Sun sporadically produces eruptive events leading to intense fluxes of solar energetic
particles (SEPs) that dramatically disrupt the near-Earth radiation environment. Such events …