| Abstract : | The hemispheric asymmetry of the sunspot cycle is a real and robust feature of the Sun. However, its origin is still not well understood in the literature. In our study, we performed nonlinear time series analyses of the sunspot area and number asymmetry to explore the dynamics of the process that produces this asymmetry. We concluded that there is no strange attractor in the data by computing the correlation dimension for the sunspot asymmetry. On computing Higuchi’s dimension for the same data, we further found that the hemispheric asymmetry is largely governed by a stochastic process. However, from the behaviour of the Hurst exponent, we observed that the time series is not completely determined by a memory-less stochastic noise. Rather, we found that there is a long-term persistence which can go beyond two solar cycles. Therefore, our study suggests that the hemispheric asymmetry of the sunspot cycle predominantly originates due to some irregular process in the solar dynamo. The long-term persistence in the solar cycle asymmetry suggests that the solar magnetic field has some memory in the convection zone. |
