Journal article
The rotational and divergent components of atmospheric circulation on tidally locked planets
- Abstract:
- Tidally locked exoplanets likely host global atmospheric circulations with a superrotating equatorial jet, planetary-scale stationary waves, and thermally driven overturning circulation. In this work, we show that each of these features can be separated from the total circulation by using a Helmholtz decomposition, which splits the circulation into rotational (divergence-free) and divergent (vorticity-free) components. This technique is applied to the simulated circulation of a terrestrial planet and a gaseous hot Jupiter. For both planets, the rotational component comprises the equatorial jet and stationary waves, and the divergent component contains the overturning circulation. Separating out each component allows us to evaluate their spatial structure and relative contribution to the total flow. In contrast with previous work, we show that divergent velocities are not negligible when compared with rotational velocities and that divergent, overturning circulation takes the form of a single, roughly isotropic cell that ascends on the day side and descends on the night side. These conclusions are drawn for both the terrestrial case and the hot Jupiter. To illustrate the utility of the Helmholtz decomposition for studying atmospheric processes, we compute the contribution of each of the circulation components to heat transport from day side to night side. Surprisingly, we find that the divergent circulation dominates day–night heat transport in the terrestrial case and accounts for around half of the heat transport for the hot Jupiter. The relative contributions of the rotational and divergent components to day–night heat transport are likely sensitive to multiple planetary parameters and atmospheric processes and merit further study.
- Publication status:
- Published
- Peer review status:
- Peer reviewed
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- Files:
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(Preview, Accepted manuscript, 2.0MB, Terms of use)
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- Publisher copy:
- 10.1073/pnas.2022705118
Authors
- Publisher:
- National Academy of Sciences
- Journal:
- Proceedings of the National Academy of Sciences More from this journal
- Volume:
- 118
- Issue:
- 13
- Article number:
- e2022705118
- Publication date:
- 2021-03-22
- Acceptance date:
- 2021-02-18
- DOI:
- EISSN:
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1091-6490
- ISSN:
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0027-8424
- Language:
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English
- Keywords:
- Pubs id:
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1169616
- Local pid:
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pubs:1169616
- Deposit date:
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2021-04-01
Terms of use
- Copyright holder:
- Hammond and Lewis
- Copyright date:
- 2021
- Rights statement:
- ©2021 The authors. Material published by the PNAS under an exclusive license.
- Notes:
- This is the accepted manuscript version of the article. The final version is available from NAS at: 10.1073/pnas.2022705118
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