Fluid Dynamics of Polar Vortices on Earth, Mars, and Titan

Waugh, D. W.

doi:10.1146/annurev-fluid-120720-032208

Cited by 6 publications

(6 citation statements)

References 133 publications

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“…A caveat is the non‐divergent barotropic form of the models. Subsequent instability studies, including consideration of other planetary atmospheres and undertaken with a hierarchy of models (Seviour et al., 2017; Mitchell et al., 2021; Waugh, 2023; and references therein), have both underscored and extended these results.…”

Section: Discussionmentioning

confidence: 94%

“…Planets with significant atmospheres, and also Titan, Saturn's moon, possess a circumpolar vortex (Mitchell et al., 2021; D. M. Waugh, 2023). Despite the differences in the external parameters and the internal physical processes of these planetary systems, vortex‐like features are present on Jupiter, Saturn and Titan.…”

Section: Discussionmentioning

confidence: 99%

“…Planets with significant atmospheres, and also Titan, Saturn's moon, possess a circumpolar vortex (Mitchell et al, 2021;D. M. Waugh, 2023).…”

Section: Counterpart Structuresmentioning

confidence: 99%

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Cyclone‐Like Features Within the Stratospheric Polar‐Night Vortex

Davies,

Sprenger

2024

Geophysical Research Letters

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Distinctive synoptic‐scale (∼1,500 km) flow features are identified within the core of the stratospheric polar‐night vortex at stratopause altitudes (∼50 km). Typically they comprise a train or a complex pattern of transient vortices, each characterized by enhanced values of potential vorticity (PV) and relative vorticity but with a weaker thermal signal. In the MERRA‐2 (and two other) reanalysis fields these cyclone‐like features persist for several days, occur episodically, and form essentially within the core of the polar‐night vortex itself. Their origin is plausibly linked to a form of barotropic instability associated with a radiatively‐induced annular ring of enhanced PV. Moreover, their ubiquity and dynamics carries possible implications for: ‐ the structure of the larger‐scale polar vortex and its preconditioning ahead of a Sudden Stratospheric Warming event; the distribution of trace‐constituents within the core; and the features representation in extended range/seasonal prediction and climate models.

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Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

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Cyclone‐Like Features Within the Stratospheric Polar‐Night Vortex

Davies,

Sprenger

2024

Geophysical Research Letters

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“…From mid autumn through mid winter, the polar jet weakens and descends after its initial rapid formation around equinox (see Figure 1a). At this time, the jet is approaching its mid winter weakened state, which persists for about half a season (Shultis et al., 2022), a phenomenon that has been predicted to exist in the atmospheres of many slowly rotating planets (Guendelman et al., 2022; Waugh, 2023).…”

Section: Resultsmentioning

confidence: 99%

The Heat and Momentum Budgets of Titan's Middle Atmosphere

Lombardo,

Lora

2023

JGR Planets

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The thermal and dynamical structure of Titan's middle atmosphere (the stratosphere and mesosphere) has been observed to evolve over seasonal timescales. Measurements from the Composite Infrared Spectrometer on the Cassini spacecraft indicated the presence of a westerly jet with the strongest winds exceeding 200 m s−1 near the autumn and spring poles. The strength of the winds varied substantially with latitude and altitude, and weakened throughout most of winter. The strong winds also served to trap short‐lived trace molecules near the winter pole, leading to a chemically enriched environment. Here, to better understand the evolution of the middle atmosphere jet, we quantify the heat and zonal momentum budgets in Titan's stratosphere and mesosphere over the course of a Titan year using a three‐dimensional general circulation model. We confirm that the dominant heating balance is between the net radiative and adiabatic heating rates, and also show that the convergence of sensible heat by the atmospheric flow is important at low stratospheric altitudes above the winter pole. We show that the polar jet is maintained by the convergence of zonal momentum by the mean meridional flow, while the low‐latitude winds are maintained by an up‐gradient transport of momentum by eddies that occur on time scales of less than one Titan day. The heat and momentum budgets we determine here will be useful in constraining the factors controlling the evolution of Titan's middle atmosphere over the coming decades.

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“…To date, a number of observation and simulation strategies have been utilized to study the Mars polar atmosphere, especially the winter polar vortices, with varying degrees of success (e.g., Benson et al., 2011; Guzewich et al., 2016; Mitchell et al., 2015; Waugh et al., 2016). Additionally, comparative studies have been conducted across various terrestrial bodies with atmospheres in the Solar System (Guendelman et al., 2022; Waugh, 2022). Among the challenges encountered in the study of the polar region of Mars are strong gradients in temperature, dust, wind and water fields at all levels from the surface through the middle atmosphere (∼60 km), complex wave activity, and condensation of the primary atmospheric constituent CO 2 in the polar atmosphere and deposition on the polar cap.…”

Section: Introductionmentioning

confidence: 99%

Water Transport in the Mars Northern Winter Polar Atmosphere: Observations and Simulations

Gillespie,

McCleese,

Kleinböhl

et al. 2024

JGR Planets

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This study involving both observations and simulations furthers our understanding of water transport in the Martian northern polar region, a critical component of the global water cycle, and explores strengths and weaknesses in simulations of the polar atmosphere. Observations of the northern polar winter by the Mars Climate Sounder (MCS) onboard the Mars Reconnaissance Orbiter show extensive water ice clouds over the polar ice cap throughout the 300–3 Pa (∼10–50 km) vertical column within the vortex during the entire winter season. The observations also indicate that the vortex evolves throughout its depth on a broad range of timescales, from sub‐diurnal to seasonal. Time sequences of these data together with results from a Mars global circulation model and Ensemble Mars Atmosphere Reanalysis System reanalysis (EMARS) are used to study the evolution of the winter polar atmosphere and to examine dynamic mechanisms for transporting water across the vortex boundary. Model simulations and reanalysis show a similar temperature structure to observations, although they struggle to reproduce some of the detailed features such as the extent of polar warming above the vortex and the magnitude of the temperature minima inside the vortex. The free run simulation also fails to capture the vertically distributed water ice cloud due to a general absence of transport across the vortex boundary. EMARS results, with assimilated MCS temperatures, show a greater amount of water entering the vortex at pressures below 200 Pa, leading to a more vertically extended cloud within the vortex and improving agreement with observations.

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Fluid Dynamics of Polar Vortices on Earth, Mars, and Titan

Cited by 6 publications

References 133 publications

Cyclone‐Like Features Within the Stratospheric Polar‐Night Vortex

Cyclone‐Like Features Within the Stratospheric Polar‐Night Vortex

The Heat and Momentum Budgets of Titan's Middle Atmosphere

Water Transport in the Mars Northern Winter Polar Atmosphere: Observations and Simulations

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