Solar east-west flow correlations that persist for months at low latitudes are dominated by active region inflows
| Autor: | Hanson, Chris S., Duvall Jr., Thomas L., Birch, Aaron C., Gizon, Laurent, Sreenivasan, Katepalli R. |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | A&A 644, A103 (2020) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/202039108 |
| Popis: | 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. Comment: 9 pages, 10 figures, accepted into A&A |
| Databáze: | arXiv |
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