Issue |
A&A
Volume 640, August 2020
|
|
---|---|---|
Article Number | L10 | |
Number of page(s) | 8 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/202038539 | |
Published online | 04 August 2020 |
Letter to the Editor
Predicting frequency changes of global-scale solar Rossby modes due to solar cycle changes in internal rotation
1
Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
e-mail: crgoddard10@gmail.com, gizon@mps.mpg.de
2
Institut für Astrophysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
3
Center for Space Science, NYUAD Institute, New York University Abu Dhabi, Abu Dhabi, UAE
Received:
30
May
2020
Accepted:
13
July
2020
Context. Large-scale equatorial Rossby modes have been observed on the Sun over the last two solar cycles.
Aims. We investigate the impact of the time-varying zonal flows on the frequencies of Rossby modes.
Methods. A first-order perturbation theory approach is used to obtain an expression for the expected shift in the mode frequencies due to perturbations in the internal rotation rate.
Results. Using the time-varying rotation from helioseismic inversions we predict the changes in Rossby mode frequencies with azimuthal orders from m = 1 to m = 15 over the last two solar cycles. The peak-to-peak frequency change is less than 1 nHz for the m = 1 mode, grows with m, and reaches 25 nHz for m = 15.
Conclusions. Given the observational uncertainties on mode frequencies due to the finite mode lifetimes, we find that the predicted frequency shifts are near the limit of detectability.
Key words: Sun: rotation / waves / Sun: oscillations / Sun: interior / Sun: activity / hydrodynamics
© C. R. Goddard et al. 2020
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Open Access funding provided by Max Planck Society.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.