Resonant tidal responses in rotating fluid bodies: global modes hidden beneath localized wave beams

Abstract

In rotating stars and planets, excitation of inertial waves in convective envelopes provides an important channel for tidal dissipation, but the dissipation rate due to inertial waves depends erratically on the tidal frequency. Tidal dissipation is significantly enhanced at some frequencies, suggesting possible resonances between the tidal forcing and some eigenmodes. However, the nature of these resonances remains enigmatic owing to the singularity of the eigenvalue problem of inertial waves, and the resonances are often mistakenly attributed to wave attractors in the literature. In this letter, we reveal that resonant tidal responses correspond to inertial modes with large-scale flows hidden beneath localized wave beams. Strong couplings between the tidal forcing and the hidden large-scale flows intensify the localized wave beams emanating from the critical latitudes, leading to enhanced tidal dissipation. This study resolves a long-standing puzzle regarding the frequency-dependence of tidal dissipation due to inertial waves in convective envelopes.

11 pages, 5 figures, Accepted for publication in ApJL

References in corpus (7)

• Tidal dissipation in stars and giant planets
• Resonance locking in giant planets indicated by the rapid orbital expansion of Titan
• Tidal dissipation in evolving low-mass and solar-type stars with predictions for planetary orbital decay
• Tidal Circularization of Binaries by Resonance Locking I: The Importance of the Pre-Main-Sequence
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• The tidal excitation of r modes in a solar type star orbited by a giant planet companion and the effect on orbital evolution I: The aligned case
• Tidal synchronization trapping in stars and planets with convective envelopes
• Tidally driven inertial waves enhance eccentricity damping and spin evolution in planets and stars