6 documents found, page 1 of 1
Effects of cyclic fluctuations in meridional circulation using a low-order dyna...
Lopes, I; Passos, DWe develop and subsequently explore the solution space of a simple flux transport dynamo model that incorporates a time-dependent large-scale meridional circulation. Based on recent observations, we prescribed an analytical form for the amplitude of this circulation and study its impact in the evolution of the magnetic field. We find that cyclic variations in the amplitude and frequency of the meridional flow a...
Evidence for a long-term variation of the dynamo action responsible for the sol...
Lopes, I; Passos, DBy using the sunspot time series as a proxy, we have made a detailed analysis of the mean solar magnetic field over the last two and half centuries, by means of a reconstruction of its phase space. We find evidence of a long-term trend variation of some of the solar physical processes (over a few decades) that might be responsible for the apparent erratic behaviour of the solar magnetic cycle. The analysis is d...
Solar Variability Induced in a Dynamo Code by Realistic Meridional Circulation ...
Lopes, I; Passos, DIn this work we use an already-published method to infer a variation profile for the solar meridional circulation over the last 250 years. We feed this variation profile into a numerical dynamo code, and we reconstruct a sunspot time series that acts as a proxy for solar cycle activity. We perform three simulations with slightly different parameters, and the results are compared with the observational data. The...
A Low-Order Solar Dynamo Model: Inferred Meridional Circulation Variations Sinc...
Passos, D; Lopes, iIn this work we present the possible variations that the meridional circulation of the Sun might have undergone during the last 250 years. In order to do this, we reduce an α-Ω dynamo to a low-order system that focuses on the time evolution of one of the solar magnetic field components. Afterward we used a method based on the analysis of phase space of the superficial toroidal magnetic field to infer changes in...
On the luminosity evolution of the Sun during the last 7 millennia
Lopes, I; Passos, D; Brandao, SIn order to test the structural evolution changes of the standard solar model, we reconstruct a luminosity curve on a scale of a few millennia. This reconstruction is based on a previously reconstructed data series of the average behavior of the sunspot number. Then we study the model’s response to this luminosity curve for several evolution scenarios. The structural changes seem to be dominated by the dynamics...
Grand Minima Under the Light of a Low Order Dynamo Model
Lopes, I; Passos, DIn this work we use a low order dynamo model and study under which conditions can it reproduce solar grand minima. We begin by building the phase space of a proxy for the toroidal component of the solar magnetic field and we develop a model, derived from mean field dynamo theory, that gives the time evolution of the toroidal field. This model is characterized by a non-linear oscillator whose coefficients retain...