@article{01f465168e1243f5906d0ccd1df230c7,
title = "Solar inertial modes: Observations, identification, and diagnostic promise",
abstract = "The oscillations of a slowly rotating star have long been classified into spheroidal and toroidal modes. The spheroidal modes include the well-known 5-min acoustic modes used in helioseismology. Here we report observations of the Sun's toroidal modes, for which the restoring force is the Coriolis force and whose periods are on the order of the solar rotation period. By comparing the observations with the normal modes of a differentially rotating spherical shell, we are able to identify many of the observed modes. These are the high-latitude inertial modes, the critical-latitude inertial modes, and the equatorial Rossby modes. In the model, the high-latitude and critical-latitude modes have maximum kinetic energy density at the base of the convection zone, and the high-latitude modes are baroclinically unstable due to the latitudinal entropy gradient. As a first application of inertial-mode helioseismology, we constrain the superadiabaticity and the turbulent viscosity in the deep convection zone.",
keywords = "Sun: general, Sun: helioseismology, Sun: interior, Sun: oscillations, Sun: rotation",
author = "Laurent Gizon and Cameron, {Robert H.} and Yuto Bekki and Birch, {Aaron C.} and Bogart, {Richard S.} and {Sacha Brun}, Allan and Cilia Damiani and Damien Fournier and Laura Hyest and Kiran Jain and B. Lekshmi and Liang, {Zhi Chao} and Bastian Proxauf",
note = "Funding Information: Acknowledgements. Author contributions: this project was initiated and supervised by LG and RHC. The helioseismic ring parameter fits were provided by RSB for HMI and KJ for GONG. BP and Z-CL measured the mode parameters. YB solved the 2D eigenvalue problem. DF and LH solved the 1D eigenvalue problem. LG, RHC and ACB wrote the draft paper. All authors contributed to the final manuscript. We are very grateful to John Leibacher for useful comments. LG thanks the Max Planck Institute for Astrophysics for the opportunity to present a preliminary account of these results at the 2020 Biermann Lectures. The HMI data are courtesy of NASA/SDO and the HMI Science Team. This work utilizes GONG data from the National Solar Observatory (NSO), which is operated by AURA under a cooperative agreement with NSF and with additional financial support from NOAA, NASA, and USAF. This work was supported in part by NASA contract NAS5-02139 to Stanford University. YB is a member of the International Max Planck Research School for Solar System Science at the University of G{\"o}ttingen, and acknowledges partial support from the Japan Student Services Organization (JASSO). We acknowledge support from ERC Synergy Grant WHOLE SUN 810218. LG acknowledges support from NYUAD Institute Grant G1502. LG, DF and BP acknowledge funding by Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through SFB 1456/432680300 Mathematics of Experiment, project C04. The computational resources were provided by the German Data Center for SDO through German Aerospace Center (DLR) grant 50OL1701. LG, ACB, and CD acknowledge support from DLR under PLATO Data Center grant 50OO1501. Publisher Copyright: {\textcopyright} L. Gizon et al. 2021.",
year = "2021",
month = aug,
day = "1",
doi = "10.1051/0004-6361/202141462",
language = "English (US)",
volume = "652",
journal = "Astronomy and Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",
}