Long-term solar variability in a hybrid Babcock-Leighton solar dynamo model
The purpose of this study is to shed some light on the long-term behavior of the solar magnetic activity cycle, in particular the physical origins of the extended episodes of strongly suppressed or enhanced activity (so-called Grand Minima and Maxima). The primary questions that are tackled in this thesis are as follows: Is the occurrence of Grand Minima/Maxima a stochastic process? Are they associated with distinct dynamo modes? Is their triggering due to a Poisson-like processes? What are the physical mechanisms that cause these irregular events? How does the dynamo enter and exit from these extreme modes? What is the underlining mechanism that makes Grand Minima cluster? What is the mechanism which is responsible from parity change during these extreme events? Answers to these questions are sought via a modelling approach based on a hybrid Babcock Leighton solar dynamo model. The resulting simulated solar activity time series and the statistics of Grand Minima and Maxima are compared to their counterparts inferred from reconstructions of the past solar activity based on cosmogenic radionuclides. With different combination parameter values within a reasonable range, it is possible to reproduce solar-like long-term behavior in agreement with radionuclide data.
Solar activity Solar dynamo Climat spatial Space climate Grand Minimum/Maximum