title: The solar magnetic activity band interaction and instabilities that shape quasi-periodic variability.
abstract: Solar magnetism displays a host of variational timescales of which the enigmatic 11-year sunspot cycle is most prominent. Recent work has demonstrated that the sunspot cycle can be explained in terms of the intra- and extra-hemispheric interaction between the overlapping activity bands of the 22-year magnetic polarity cycle. Those activity bands appear to be driven by the rotation of the Sun's deep interior. Here we deduce that activity band interaction can qualitatively explain the 'Gnevyshev Gap'—a well-established feature of flare and sunspot occurrence. Strong quasi-annual variability in the number of flares, coronal mass ejections, the radiative and particulate environment of the heliosphere is also observed. We infer that this secondary variability is driven by surges of magnetism from the activity bands. Understanding the formation, interaction and instability of these activity bands will considerably improve forecast capability in space weather and solar activity over a range of timescales.
authors: High Altitude Observatory, National Center for Atmospheric Research, PO Box 3000, Boulder, Colorado 80307, USA.
authors: Scott W
authors: 0000000273691776
authors: SW
authors: McIntosh
authors: Department of Physics, Montana State University, Bozeman, Montana 59717, USA.
authors: Robert J
authors: RJ
authors: Leamon
authors: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80205, USA.
authors: Larisza D
authors: LD
authors: Krista
authors: Lockheed Martin Advanced Technology Center, 3251 Hanover Street, Building 252, Palo Alto, Colorado 94304, USA.
authors: Alan M
authors: AM
authors: Title
authors: Space Sciences Laboratory, University of California, Berkeley, California 94720, USA.
authors: Hugh S
authors: HS
authors: Hudson
authors: Predictive Science Inc., 9990 Mesa Rim Road, Suite 170, San Diego, California 92121, USA.
authors: Pete
authors: P
authors: Riley
authors: Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovation Drive, Boulder, Colorado 80303, USA.
authors: Jerald W
authors: JW
authors: Harder
authors: Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovation Drive, Boulder, Colorado 80303, USA.
authors: Greg
authors: G
authors: Kopp
authors: Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovation Drive, Boulder, Colorado 80303, USA.
authors: Martin
authors: M
authors: Snow
authors: Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovation Drive, Boulder, Colorado 80303, USA.
authors: Thomas N
authors: TN
authors: Woods
authors: 1] Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA [2] Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors: Justin C
authors: JC
authors: Kasper
authors: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA.
authors: Michael L
authors: ML
authors: Stevens
authors: Division of Astronomy and Astrophysics, University of California, Los Angeles, Colorado 90095, USA.
authors: Roger K
authors: RK
authors: Ulrich