Synchronization in Sunspot Indices in the Two Hemispheres

Historical sunspot records were analyzed by means of nonlinear tools to find synchronization phenomena at different time scales on the Sun. Using cross-recurrence plots it is shown that the north – south sunspot synchronization demonstrates a set of distinct periodic oscillations – 43.29, 18.52, and 7.63 years. Also we have traced the sunspot synchronization on shorter time scales. Very rare and episodic synchronization within half of the Carrington rotation rate was detected. By using the empirical mode decomposition technique the north – south sunspot time series were decomposed into intrinsic oscillatory modes. To determine which modes of the signal are responsible for synchronization we separated them into high- and low-frequency parts. It is shown that phase synchronization is detected only in the low-frequency modes. The high-frequency component demonstrates noisy behavior with amplitude synchronization and strong phase mixing.     

Secular Variations of a Shift of the Heliospheric Current Sheet

Geomagnetism and Aeronomy - The shift of the heliospheric current sheet (HCS) can be judged by the correlation between polarities of the interplanetary magnetic field (IMF) observed near the Earth....     

Solar Cycle Signal in Geomagnetic Activity and Climate

Historical geomagnetic and climate records were analyzed to study long-term trends and relationships with solar activity. Wavelet technique and recurrence plot analysis are applied to the data to find their coherence and similarities at different times and time-scales. It is shown that the solar cycle signal is more pronounced in climatic data during the last 60 years.     

Impulse-like behavior of the sunspot activity

Gnevyshev’s hypothesis of time space organization of sunspot activity over the solar surface like impulses is considered. Using numerical simulation it was shown that complex solar cycle shape can be explained by distribution of impulses in the northern and southern hemispheres. For long solar cycles, impulses at higher latitudes breaking Sp?rer’s law were found. Comparison of the time-latitude diagrams of solar magnetic fields and impulses has shown that each wave of new polarity to the poles is accompanied by impulse of sunspot activity.     

Forecast of solar wind parameters according to STOP magnetograph observations

Geomagnetism and Aeronomy - The paper discusses the results of the forecast of solar wind parameters at a distance of 1 AU made according to observations made by the STOP telescope magnetograph...     

The Maunder minimum as a secular minimum with non-stopped Sunspot cyclicity

One of the most enigmatic features of the solar history is the Maunder minimum (1645–1715). We compare the scatter of amplitudes of the 11-year cycles, according to the new Sunspot Number and Sunspot Group series version 2.0, along with scenario of the Maunder minimum as a period with non-stopped cyclicity. We demonstrate that both amplitude and duration of cycles after the Gleissberg and Maunder minima are similar. Moreover, times of minima and maxima of cycles in the course the Maunder minimum coincide with those during the Gleissberg one, indicating a secular variation. Usefulness of the proxy data within the Maunder minimum is discussed. The scatter of amplitudes and duration of the Schwabe cycles in the past is argued to be comparable with those in the modern epoch.     

Spatiotemporal sunspot impulses and reversal of the polar magnetic field on the sun

The spatiotemporal organization of sunspots in the form of activity impulses (according to Gnevyshev’s terminology) is considered as a source of poleward magnetic surges of new polarity. Polar fields in the northern and southern hemispheres have been reconstructed from 1875 to 2012. An increase in the tilt angle of magnetic bipoles with latitude is a crucial parameter in the proposed model to reverse the polar field on the Sun. The role of the surface meridional flow forming magnetic surges of new and old polarities is discussed. It is shown that the velocity and the latitudinal profile of the flow influence the modeled polar field.