Solar Meridional Flow in the Shallow Interior during the Rising Phase of Cycle 24

Abstract

Solar subsurface zonal and meridional-flow profiles during the rising phase of solar cycle 24 are studied using time-distance helioseismology technique. The faster zonal bands in the torsional-oscillation pattern show strong hemispheric asymmetries and temporal variations in both width and speed. The faster band in the northern hemisphere is located closer to the equator than the band in the southern hemisphere, and migrates past the equator when the magnetic activity in the southern hemisphere is reaching maximum. The meridional-flow speed decreases substantially with the increase of magnetic activity, and the flow profile shows two zonal structures in each hemisphere. The residual meridional flow, after subtracting a mean meridional-flow profile, converges toward the activity belts and shows faster and slower bands like the torsional-oscillation pattern. More interestingly, the meridional-flow speed above latitude 30 degree shows an anti-correlation with the poleward-transporting magnetic flux, slower when the following-polarity flux is transported and faster when the leading-polarity flux is transported. It is expected that this phenomenon slows the process of magnetic cancellation and polarity reversal in the high-latitude areas.

Accepted by ApJ Letters

References in corpus (3)

• Subsurface Meridional Circulation in the Active Belts
• Speed of Meridional Flows and Magnetic Flux Transport on the Sun
• Forecasting the Maxima of Solar Cycle 24 with Coronal Fe XIV Emission

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• Application of Synoptic Magnetograms to Global Solar Activity Forecast
• Optimization of surface flux transport models for the solar polar magnetic field
• Flows around Averaged Solar Active Regions
• Evolution of Subsurface Zonal and Meridional Flows in Solar Cycle 24 from Helioseismological Data
• Probing Subsurface Flows in Active Region NOAA 12192 - Comparison with NOAA 10486
• Probing the Solar Meridional Circulation using Fourier Legendre Decomposition
• Local Helioseismology of Emerging Active Regions: A Case Study
• Time-dependent theory of solar meridional flows