Signatures of Solar Cycle 25 in Subsurface Zonal Flows

Abstract

The pattern of migrating zonal flow bands associated with the solar cycle, known as the torsional oscillation, has been monitored with continuous global helioseismic observations by the Global Oscillations Network Group, together with those made by the Michelson Doppler Imager onboard the Solar and Heliosepheric Observatory and its successor the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory, since 1995, giving us nearly two full solar cycles of observations. We report that the flows now show traces of the mid-latitude acceleration that is expected to become the main equatorward-moving branch of the zonal flow pattern for Cycle 25. Based on the current position of this branch, we speculate that the onset of widespread activity for Cycle 25 is unlikely to be earlier than the middle of 2019.

8 pages, 5 figures, accepted by ApJL 5 July 2018

References in corpus (3)

• Improved Helioseismic Analysis of Medium-l Data from the Michelson Doppler Imager
• The Extended Solar Cycle Tracked High into the Corona
• Parametrizing the time-variation of the "surface term" of stellar p-mode frequencies: application to helioseismic data

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• On the Origin of Solar Torsional Oscillations and Extended Solar Cycle
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• Changes in the solar rotation over two solar cycles
• Application of Synoptic Magnetograms to Global Solar Activity Forecast
• Changes in the near-surface shear layer of the Sun
• Continuous Solar Observations from the Ground -- Assessing Duty Cycle from GONG Observations
• The QBO-type signals in the subsurface flow fields during solar cycles 23 and 24
• Removal Of Active Region Inflows Reveals a Weak Solar Cycle Scale Trend In Near-surface Meridional Flow
• On effects of surface bipolar magnetic regions on the convection zone dynamo
• Predicting frequency changes of global-scale solar Rossby modes due to solar cycle changes in internal rotation
• Evidence of solar-cycle related structural changes in the solar convection zone
• Machine Learning-Based Characterization of Solar p-Mode Frequency Shifts during Solar Cycle 25