Temporal Variability of Titan's Middle-Atmospheric Zonal Winds from Southern Fall to Late Winter (2016-2023)

Abstract

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 L_s=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 L_s). 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 L_s=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 L_s=81.6^∘-146.0^∘, followed by a more moderate increase between L_s=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; L_s≈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.

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BibTeX RIS

BibTeX

@misc{cordiner2026temporal,
  title = {{Temporal Variability of Titan's Middle-Atmospheric Zonal Winds from Southern Fall to Late Winter (2016-2023)}},
  author = {Martin A. Cordiner and Yuan Lian and Juan M. Lora and Nicholas A. Lombardo and Lucy Wright and Jonathon Nosowitz and Richard Cosentino and Nicholas A. Teanby and Conor A. Nixon and Alexander E. Thelen and Claire E. Newman and Steven B. Charnley and Eliot F. Young},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.03635},
  eprint = {2610.03635},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.03635},
  note = {CC BY-NC-ND 4.0},
}

RIS

TY  - UNPB
TI  - Temporal Variability of Titan's Middle-Atmospheric Zonal Winds from Southern Fall to Late Winter (2016-2023)
AU  - Martin A. Cordiner
AU  - Yuan Lian
AU  - Juan M. Lora
AU  - Nicholas A. Lombardo
AU  - Lucy Wright
AU  - Jonathon Nosowitz
AU  - Richard Cosentino
AU  - Nicholas A. Teanby
AU  - Conor A. Nixon
AU  - Alexander E. Thelen
AU  - Claire E. Newman
AU  - Steven B. Charnley
AU  - Eliot F. Young
PY  - 2026
DA  - 2026/10/02
PB  - arXiv
DO  - 10.48550/arxiv.2610.03635
UR  - https://arxiv.org/abs/2610.03635
AB  - 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 CH_3CN emission between 2016-2023 (corresponding to a solar longitude L_s=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 L_s). 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 L_s=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 L_s=81.6^∘-146.0^∘, followed by a more moderate increase between L_s=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; L_s≈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.
ER  -

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