![Color maps showing statistical uncertainties on the line-of-sight CH3CN Doppler shifts, for four epochs (2016-08-19 to 2022-08-01). Titan’s wireframe grid is shown for each epoch, with the spatial resolution (elliptical beam FWHM) indicated lower left.-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/10/Temporal-Variability.png?fit=1200%2C690&ssl=1)
[astro-ph.EP] Previous ALMA observations have revealed unexpectedly strong and rapid variations in Titan’s high-altitude equatorial zonal winds, which present a challenge to our understanding of this moon’s atmospheric dynamics.
Here we report further measurements of Titan’s zonal wind field at middle atmospheric altitudes ≈200-490 km, based on ALMA observations of spatially and spectrally resolved CH3CN emission between 2016-2023 (corresponding to a solar longitude Ls=81.6∘-156.4∘, spanning Titan’s late southern autumn to late winter).
These observations indicate substantial, ongoing, rapid temporal variability of Titan’s zonal winds, on timescales as short as ≈1 Earth month (0.9∘ in Ls). The strongest variability is at (near-)equatorial latitudes where the zonal winds are fastest (up to 240±26 ms−1), with repeated ∼40 ms−1 fluctuations occurring between Ls=146.0∘-156.4∘.
The observed longer-term trends are qualitatively well-reproduced by two independent, state-of-the-art general circulation models (GCMs), which match the observed decrease in zonal wind speeds over a broad range of latitudes between Ls=81.6∘-146.0∘, followed by a more moderate increase between Ls=146.0∘-156.4∘. The wind speeds at mid-to-high latitudes (∼−45∘ south) are also typically reasonably well reproduced by the GCMs (differing by ≲30%).
However, the equatorial wind speeds are up to a factor of ∼2 faster than model predictions (with the greatest discrepancy around solstice; Ls≈90∘). Rapid temporal variability of the retrieved zonal winds indicates the presence of strong atmospheric instabilities that are not well reproduced by models, suggesting a need for future GCM improvements.
Martin A. Cordiner, Yuan Lian, Juan M. Lora, Nicholas A. Lombardo, Lucy Wright, Jonathon Nosowitz, Richard Cosentino, Nicholas A. Teanby, Conor A. Nixon, Alexander E. Thelen, Claire E. Newman, Steven B. Charnley, Eliot F. Young
Comments: Accepted for publication in PSJ, September 2026
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2610.03635 [astro-ph.EP] (or arXiv:2610.03635v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2610.03635
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Submission history
From: Martin Cordiner PhD
[v1] Fri, 2 Oct 2026 17:25:15 UTC (849 KB)
https://arxiv.org/abs/2610.03635
Astrobiology, exoplanet,
