Phase lags of solar hemispheric cycles

Abstract

The North-South asymmetry of solar activity is variable in time and strength. We analyse the long-term variation of the phase lags of hemispheric cycles and check a conjectured relationship between these phase lags and the hemispheric cycle strengths. Sunspot data are used from cycles 12-23 in which the separation of northern and southern hemispheres is possible. The centers of mass of the hemispheric cycle profiles were used to study the phase relations and relative strengths of the hemispheric cycles. This approach considers a cycle as a whole and disregards the short-term fluctuations of the cycle time profile. The phase of the hemispheric cycles shows an alternating variation: the northern cycle leads in 4 cycles and follows in 4 cycles. No significant relationship is found between the phase and strength differences of the hemispheric cycles. The period of 4+4 cycles appears to be close to the Gleissberg cycle and may provide a key to its physical background. It may raise a new aspect in the solar dynamo mechanism because it needs a very long memory.

7 pages, 6 figures

References in corpus (3)

• The north-south asymmetry of soft X-ray flare index during solar cycles 21, 22 and 23
• Bypassing Cowling's theorem in axisymmetric fluid dynamos
• Long-term variation in distribution of sunspot groups

Cited by in corpus (11)

• On-line Tools for Solar Data Compiled at the Debrecen Observatory and their Extensions with the Greenwich Sunspot Data
• Hemispheric Coupling: Comparing Dynamo Simulations and Observations
• Origin of the hemispheric asymmetry of solar activity
• Solar-Cycle Characteristics in Kodaikanal Sunspot Area: North--South Asymmetry, Phase Distribution and Gnevyshev Gap
• Long-term Variations in Solar Activity: Predictions for Amplitude and North--South Asymmetry of Solar Cycle 25
• Solar surface rotation: N-S asymmetry and recent speed-up
• Simulation Study of Hemispheric Phase-Asymmetry in the Solar Cycle
• Sunspot Group Development in High Resolution
• North-South Asymmetry in Solar Activity and Solar Cycle Prediction, V: Prediction for the North-South Asymmetry in the Amplitude of Solar Cycle 25
• On the Decay of Sunspot Groups and Their Internal Parts in Detail
• Phase relationships of solar hemispheric toroidal and poloidal cycles