A Numerical Investigation of the Berg Feature on Uranus as a Vortex-Driven System

LeBeau, Raymond P.; Farmer, Kevin C.; Sankar, Ramanakumar; Hadland, Nathan; Palotai, Csaba

doi:10.3390/atmos11010052

Cited by 4 publications

(2 citation statements)

References 15 publications

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“…In addition to β , any PV gradient in the background of a cyclone (e.g., by a jet or a nearby cyclone) can similarly influence its motion (Chan & Law, 1995; Shin et al., 2006; Rivière et al., 2012). For example, the PV gradient due to the zonal mean wind shear and β was shown, using full 3D models, to drive the meridional motion of large vortices on Uranus (LeBeau et al., 2020) and Neptune (LeBeau & Dowling, 1998). It was recently found that latitude ∼84°, where the CPCs are observed at both poles of Jupiter, is the latitude where the beta‐drift is balanced by an equivalent vorticity‐gradient force, in which the source of the PV gradient field is the PC instead of the planetary β (Gavriel & Kaspi, 2021).…”

Section: Introductionmentioning

confidence: 99%

The Oscillatory Motion of Jupiter's Polar Cyclones Results From Vorticity Dynamics

Gavriel

Kaspi

2022

Geophysical Research Letters

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The poles of Jupiter were observed in detail for the first time by the Juno spacecraft in 2016 (Bolton et al., 2017). In contrast with the polar regions of Saturn, which are inhabited by a single polar cyclone (PC) (Baines et al., 2009;Sánchez-Lavega et al., 2006), Jupiter's PCs are surrounded by a ring of stable circumpolar cyclones (CPCs) (Adriani et al., 2018;Orton et al., 2017). There are eight CPCs at the north pole and five at the south (Figure 1), each with a diameter of roughly 5,000 km and velocities reaching 100 ms −1 (Adriani et al., 2020;Grassi et al., 2018). Such cyclones can be generated by moist convection (O'Neill et al., 2015(O'Neill et al., , 2016, where 2D inverse energy cascade in the turbulent polar regions brings the kinetic energy from the convective scale up to the horizontal scale of the cyclones (Moriconi et al., 2020;. These regions are bounded by prograde jets at around latitudes 65°N∖S (Rogers et al., 2017(Rogers et al., , 2022, which may act as a separating barrier. In contrast with the Great Red Spot, which is centered around latitude 20°S and has a shallow depth (less than 500 km, Parisi et al. ( 2021)) relative to the deep surrounding jets (∼3,000 km, Kaspi et al. ( 2018)), the polar cyclones, subject to the Taylor-Proudman theorem (Vallis, 2017) with a vertical axis parallel to the planetary rotation axis and a smaller Rossby number, potentially extend deeper, suggesting a 2D dynamical regime.The beta-drift is a force that results from a dipole of vorticity (usually termed "beta-gyres," Sutyrin and Flierl (1994)) that is induced by an interaction between the tangential velocity of a cyclone and a gradient of potential vorticity (PV) that is present in the background of the cyclone (Chan, 2005;Gavriel & Kaspi, 2021;Rossby, 1948). This force creates a poleward drift on cyclones and an equatorward drift on anticyclones when only the planetary vorticity gradient (β) is considered (Chan, 2005;Franklin et al., 1996;Merlis & Held, 2019). Beta-drift is a known contributor to the poleward motion of Earth's tropical cyclones (Zhao et al., 2009), and was shown in shallow-water (SW) models to result in cyclones merging into a PC in settings characterizing gas-giants such as Jupiter and Saturn (

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Section: Introductionmentioning

confidence: 99%

The Oscillatory Motion of Jupiter's Polar Cyclones Results From Vorticity Dynamics

Gavriel

Kaspi

2022

Geophysical Research Letters

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“… 2019a ; LeBeau et al. 2020 ), but no vortex rotation was directly resolved, and dramatic brightening events were interpreted as potential convective outbursts related to the feature (de Pater et al. 2011 ).…”

Section: Spatial Variation In the Uranus Atmospherementioning

confidence: 99%

Multiple Probe Measurements at Uranus Motivated by Spatial Variability

Wong,

Rowe-Gurney,

Markham

et al. 2024

Space Sci Rev

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A major motivation for multiple atmospheric probe measurements at Uranus is the understanding of dynamic processes that create and maintain spatial variation in thermal structure, composition, and horizontal winds. But origin questions—regarding the planet’s formation and evolution, and conditions in the protoplanetary disk—are also major science drivers for multiprobe exploration. Spatial variation in thermal structure reveals how the atmosphere transports heat from the interior, and measuring compositional variability in the atmosphere is key to ultimately gaining an understanding of the bulk abundances of several heavy elements. We review the current knowledge of spatial variability in Uranus’ atmosphere, and we outline how multiple probe exploration would advance our understanding of this variability. The other giant planets are discussed, both to connect multiprobe exploration of those atmospheres to open questions at Uranus, and to demonstrate how multiprobe exploration of Uranus itself is motivated by lessons learned about the spatial variation at Jupiter, Saturn, and Neptune. We outline the measurements of highest value from miniature secondary probes (which would complement more detailed investigation by a larger flagship probe), and present the path toward overcoming current challenges and uncertainties in areas including mission design, cost, trajectory, instrument maturity, power, and timeline.

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