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arXiv · 2010.13052

Solar east-west flow correlations that persist for months at low latitudes are dominated by active region inflows

Chris S. Hanson·Thomas L. Duvall Jr.·Aaron C. Birch·Laurent Gizon·Katepalli R. Sreenivasan
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Abstract

Context: Giant-cell convection is believed to be an important component of solar dynamics. For example, it is expected to play a crucial role in maintaining the Sun's differential rotation. Aims: We re-examine early reports of giant convective cells detected using correlation analysis of Dopplergrams. We extend this analysis using 19 years of space and ground-based observations of near-surface horizontal flows. Method: Flow maps are derived through local correlation tracking of granules and helioseismic ring-diagram analysis. We compute temporal auto-correlation functions of the east-west flows at fixed latitude. Results: Correlations in the east-west velocity can be clearly seen up to five rotation periods. The signal consists of features with longitudinal wavenumbers up to m=9 at low latitudes. Comparison with magnetic images indicates that these flow features are associated with magnetic activity. The signal is not seen above the noise level during solar minimum. Conclusions: Our results show that the long-term correlations in east-west flows at low latitudes are dominantly due to inflows into active regions and not to giant convective cells.

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Chris S. Hanson, Thomas L. Duvall Jr., Aaron C. Birch, Laurent Gizon, Katepalli R. Sreenivasan. 2020-10-25. Solar east-west flow correlations that persist for months at low latitudes are dominated by active region inflows. https://doi.org/10.1051/0004-6361%2F202039108

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