Supergranular-scale solar convection not explained by mixing-length theory
Hanson CS, Das SB, Mani P, Hanasoge S, Sreenivasan KR. 2024. Supergranular-scale solar convection not explained by mixing-length theory. Nature Astronomy.
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Journal Article
| Epub ahead of print
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Author
Hanson, Chris S.;
Das, Srijan BISTA;
Mani, Prasad;
Hanasoge, Shravan;
Sreenivasan, Katepalli R.
Department
Abstract
Supergranules, which are solar flow features with a lateral scale of 30,000–40,000 km and a lifetime of ~24 h, form a prominent component of the Sun’s convective spectrum. However, their internal flows, which can be probed only by helioseismology, are not well understood. We analyse dopplergrams recorded by the Solar Dynamics Observatory satellite to identify and characterize ~23,000 supergranules. We find that the vertical flows peak at a depth of ~10,000 km, and remain invariant over the full range of lateral supergranular scales, contrary to numerical predictions. We also infer that, within the local seismic resolution (≳5,000 km), downflows are ~40% weaker than upflows, indicating an apparent mass-flux imbalance. This may imply that the descending flows also comprise plumes, which maintain the mass balance but are simply too small to be detected by seismic waves. These results challenge the widely used mixing-length description of solar convection.
Publishing Year
Date Published
2024-06-25
Journal Title
Nature Astronomy
Publisher
Springer Nature
Acknowledgement
We thank F. J. Simons for the codes for computing Slepian functions,
M. Rempel and R. Cameron for their insights into solar convection, J.
W. Lord for the numerical simulations and J. Naranjo for his help with
the NYUAD NetDRMS system. This research was carried out with the
High Performance Computing resources at NYUAD. The datasets were
prepared in the data centre at the Center for Space Science of NYUAD.
This research is based upon work supported by Tamkeen under the
NYUAD Research Institute (Grant Nos G1502 and CASS to C.S.H,
S.H. and K.R.S.). S.H. acknowledges funding from the Department
of Atomic Energy, India. K.R.S. and S.H. acknowledge support from
the Ofice of Sponsored Research of King Abdullah University of
Science and Technology (Award No. OSR-CRG2020-4342). S.B.D.
acknowledges funding from the Elisabeth H. and F. A. Dahlen Award
2022 by the Department of Geosciences, Princeton University. S.B.D.
also acknowledges funding from the European Union’s Horizon 2020
research and innovation programme under a Marie Skłodowska-Curie
grant (Grant Agreement No. 101034413). Some data products were
processed and downloaded from the German Data Center for SDO,
which is funded by the German Aerospace Center (DLR Grant No.
500L1701).
eISSN
IST-REx-ID
Cite this
Hanson CS, Das SB, Mani P, Hanasoge S, Sreenivasan KR. Supergranular-scale solar convection not explained by mixing-length theory. Nature Astronomy. 2024. doi:10.1038/s41550-024-02304-w
Hanson, C. S., Das, S. B., Mani, P., Hanasoge, S., & Sreenivasan, K. R. (2024). Supergranular-scale solar convection not explained by mixing-length theory. Nature Astronomy. Springer Nature. https://doi.org/10.1038/s41550-024-02304-w
Hanson, Chris S., Srijan B Das, Prasad Mani, Shravan Hanasoge, and Katepalli R. Sreenivasan. “Supergranular-Scale Solar Convection Not Explained by Mixing-Length Theory.” Nature Astronomy. Springer Nature, 2024. https://doi.org/10.1038/s41550-024-02304-w.
C. S. Hanson, S. B. Das, P. Mani, S. Hanasoge, and K. R. Sreenivasan, “Supergranular-scale solar convection not explained by mixing-length theory,” Nature Astronomy. Springer Nature, 2024.
Hanson CS, Das SB, Mani P, Hanasoge S, Sreenivasan KR. 2024. Supergranular-scale solar convection not explained by mixing-length theory. Nature Astronomy.
Hanson, Chris S., et al. “Supergranular-Scale Solar Convection Not Explained by Mixing-Length Theory.” Nature Astronomy, Springer Nature, 2024, doi:10.1038/s41550-024-02304-w.
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