85 research outputs found
Effects of Solar Active Regions on Meridional Flows
The aim of this paper is to extend our previous study of the solar-cycle
variations of the meridional flows and to investigate their latitudinal and
longitudinal structure in the subphotospheric layer, especially their
variations in magnetic regions. Helioseismology observations indicate that mass
flows around active regions are dominated by inflows into those regions. On
average, those local flows are more important around leading magnetic
polarities of active regions than around the following polarities, and depend
on the evolutionary stage of particular active regions. We present a
statistical study based on MDI/SOHO observations of 1996-2002 and show that
this effect explains a significant part of the cyclic change of meridional
flows in near-equatorial regions, but not at higher latitudes. A different
mechanism driving solar-cycle variations of the meridional flow probably
operates.Comment: 4 pages, 5 figures, accepted for publication in ApJ
Helioseismic Observations of Torsional Oscillations Inside the Sun and Their Potential for Predicting Solar Cycles
The helioseismic analysis of torsional oscillations of the Sun, obtained in 1996-2018 from SOHO (Solar and Heliospheric Observatory) and SDO (Solar Dynamics Observatory), reveals the spatio-temporal dynamics associated with the dynamo process. The data reveal new relationships between the migrating magnetic field patterns observed in synoptic magnetograms and the dynamics of torsional oscillations near the surface and in the interior. In particular, it is found that the evolution of torsional oscillations in the deep convection zone is ahead of the surface magnetic evolution by several years, and that it is related to the extended solar cycle phenomenon previously observed in the solar corona. The data show substantial differences in the torsional oscillation properties between Cycles 23 and 24 indicating fundamental changes in the dynamo regime, and also reveal initiation of Cycle 25. The helioseismology observations of the torsional oscillations open new perspectives for understanding the global dynamo processes inside the Sun, and for predicting the next solar cycle
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