The spatial distribution of quasi-biennial oscillations in the high-latitude solar activity

Abstract

Quasi-biennial oscillations (QBOs) are considered as a fundamental mode of solar magnetic activity at low latitudes ($\le 50^{\circ }$). However, the evolutionary aspect and the hemispheric distribution of solar QBOs at high latitudes ($\ge 60^{\circ }$) are rarely studied. Here, a relatively novel time-frequency analysis technique, named the synchrosqueezed wavelet transform, is applied to extract the main components of the polar faculae in the northern and southern hemispheres for the time interval from August 1951 to December 1998. It is found as the following: (1) Apart from the 22-year Hale cycle, the 17-year extended activity cycle, and the 11-year Schwabe cycle, the QBOs have been estimated as a prominent timescale of solar magnetic activity at high latitudes; (2) the QBOs of the polar faculae are coherent in the two hemispheres, but the temporal (phase) and the spatial (amplitude) variations of solar QBOs occur unevenly on both hemispheres; and (3) for the 11-year period mode, the northern hemisphere begins three months earlier than that in the southern one. Moreover, the spatial and temporal distributions of the hemispheric QBOs differ from those of the 11-year Schwabe cycle mode in the two hemispheres. Our findings could be helpful to improve our knowledge on the physical origin of the spatial distribution of solar QBOs at high latitudes, and could also provide more constraints on solar dynamo models introduced to characterize the different components of the solar magnetic activity cycle.

MNRAS

References in corpus (9)

• The solar magnetic field
• Magnetic Flux Transport at the Solar Surface
• Hemispheric Coupling: Comparing Dynamo Simulations and Observations
• North-south asymmetry in Rieger-type periodicity during solar cycles 19-23
• Understanding solar cycle variability
• Solar cycle indices from the photosphere to the corona: measurements and underlying physics
• Nonlinear dynamo models using quasi-biennial oscillations constrained by sunspot area data
• Search for Short-Term Periodicities in the Sun's Surface Rotation: A Revisit
• Short-Term Variations in the Equatorial Rotation Rate of Sunspot Groups

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• The QBO-type signals in the subsurface flow fields during solar cycles 23 and 24
• The Temporal and Spatial Behaviors of CME Occurrence Rate at Different Latitudes
• Hemispheric Distribution of Solar Active Regions During Solar Cycles 23-25
• Hemispheric asymmetry in the sunspot cycle as a nonextensive phenomenon