Changes in the solar rotation over two solar cycles

Abstract

We use helioseismic data from ground and space-based instruments to analyze how solar rotation has changed since the beginning of solar Cycle 23 with emphasis on studying the differences between Cycles 23 and 24. We find that the nature of solar rotation is indeed different for the two cycles. While the changes in the latitudinally independent component follows solar-cycle indices, some of the other components have a more complicated behavior. There is a substantial change in the behavior of the solar zonal flows and their spatial gradients too. While the zonal flows are in general weaker in Cycle 24 than those in Cycle 23, there are clear signs of the emergence of Cycle 25. We have also investigated the properties of the solar tachocline, in particular, its position, width, and the change (or jump) in the rotation rate across it. We find significant temporal variation in the change of the rotation rate across the tachocline. We also find that the changes in solar Cycle 24 were very different from those of Cycle 23. We do not find any statistically significant change in the position or the width of the tachocline.

arXiv commentAccepted for publication in ApJ

References in corpus (14)

• Deeply penetrating banded zonal flows in the solar convection zone
• On-line Tools for Solar Data Compiled at the Debrecen Observatory and their Extensions with the Greenwich Sunspot Data
• An Updated Solar Cycle 25 Prediction with AFT: The Modern Minimum
• Temporal variations of the rotation rate in the solar interior
• Solar internal rotation rate and the latitudinal variation of the tachocline
• Temporal variations of solar rotation rate at high latitudes
• Comparative analysis of Debrecen sunspot catalogues
• Solar rotation rate and its gradients during cycle 23
• Thinning of the Sun's magnetic layer: the peculiar solar minimum could have been predicted
• Improved Helioseismic Analysis of Medium-l Data from the Michelson Doppler Imager
• Signatures of Solar Cycle 25 in Subsurface Zonal Flows
• Revisiting the solar tachocline: Average properties and temporal variations
• Solar Rotation Rate During the Cycle 24 Minimum in Activity
• The Sun in transition? Persistence of near-surface structural changes through Cycle 24

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