Keren Duer

The vertical structure of Jupiter’s jet streams remains a critical open question for understanding the planet’s atmospheric dynamics and interior. Traditional models often assume an adiabatic density profile, yet recent observations and theory suggest the presence of stable layers, which could significantly alter both the density structure and gravitational signature. We investigate the implications of non-adiabatic stable layers for Jupiter’s gravity field, focusing on how density anomalies from such layers interact with the inferred vertical structure of zonal winds. We construct temperature–pressure profiles including subadiabatic stable layers to derive density profiles consistent with the latest equation of state. The resulting gravitational harmonics are computed, incorporating both static density and wind structure via thermal wind balance, and compared with Juno measurements. By varying the wind decay characteristics, we assess how stable layers constrain the depth and structure of the deep jets. Our results show that shallow, extensive stable layers substantially modify the background density, requiring more rapid decay of zonal winds to satisfy observed gravitational constraints. Introducing stable layers also broadens the range of physically plausible wind solutions, indicating that the vertical structure of the jets is less constrained than suggested by purely adiabatic models. We conclude that stable layers are a critical, yet often overlooked, component in modelling Jupiter’s interior and dynamics. This study highlights a strong degeneracy between the thermodynamic density structure and the vertical wind profile, implying that the jet stream structure cannot be uniquely determined without independent constraints on the planet’s internal stability.

The giant planets exhibit a fundamental contrast in their equatorial circulation: Jupiter and Saturn are characterized by broad eastward equatorial jets, or superrotation, whereas Uranus and Neptune exhibit strong westward equatorial flow, or subrotation. This dichotomy has often been interpreted as evidence for distinct dynamical regimes on the gas and ice giants. However, here we show that these opposing equatorial states may instead arise from a common dynamical mechanism, with the direction of the equatorial jet determined by the way convection, rotation, and eddy momentum transport interact within the planetary interior and atmosphere.Here we present a unified perspective on the formation of super- and sub-rotating equatorial jets across the giant planets. In deep rotating convection models, columnar convective motions can organize angular momentum in a way that produces either eastward or westward equatorial flow. The two outcomes emerge as separate equilibrated branches of the same dynamical system, implying that the transition from superrotation to subrotation may be understood as a bifurcation rather than as a change in the underlying forcing. Importantly, both regimes are maintained by comparable wave and eddy processes, suggesting that the gas and ice giants need not require fundamentally different explanations for their equatorial jets.This picture connects naturally with idealized atmospheric 3D hydrodynamical simulations of the ice giants, which show that Uranus- and Neptune-like subrotation can be sustained when the modeled circulation extends sufficiently deep and allows eddy momentum fluxes to converge angular momentum away from the equator. Taken together, the two approaches suggest a continuous dynamical pathway linking the deep convective interiors of the gas giants with the deep atmospheric circulation of the ice giants. The observed contrast between superrotation and subrotation may therefore reflect different equilibrated states of a shared convective-eddy system, controlled by planetary parameters such as convective forcing, stratification, rotation rate, and effective dynamical depth.This unified framework provides a basis for interpreting the diversity of zonal winds among the giant planets and offers testable predictions for future observations of Uranus and Neptune, where the depth and maintenance of the equatorial jets remain key open questions.

In rapidly rotating planets, convection driven by residual heat from planetary formation is predicted to organize into columnar circulations aligned with the rotation axis. Such motions have long been proposed to play a central role in giant-planet dynamics, including the maintenance of Jupiter's equatorial superrotation and adjacent westward jets, but their expected depth makes them difficult to observe directly. We analyze microwave brightness-temperature measurements from the Juno Microwave Radiometer (MWR), using multiple channels that probe atmospheric layers down to approximately 100 bar in Jupiter's equatorial region. The data reveal coherent hemispheric asymmetries and characteristic spatial scales consistent with expectations from rapidly rotating deep convection. Comparisons with deep convection simulations reproduce similar signatures and support the interpretation. Cross-depth correlations further suggest axially extended, tilted convective structures. Together, these results provide observational constraints on the geometry and spacing of Jupiter's deep convective motions and their connection to the planet's large-scale atmospheric circulation.

The atmospheres of Hot Jupiters (HJs) are strongly shaped by the extreme day-to-night temperature contrasts that drive supersonic jet streams and global-scale circulation patterns. New observational techniques are beginning to provide constraints on both atmospheric wind velocities and planetary deformation, which is expected to be governed primarily by tidal forcing, planetary rotation, and the internal density structure.However, sufficiently strong global-scale winds can redistribute enough mass to produce an additional dynamical deformation that may be comparable to, or even exceed, the contribution from the static interior structure. Here, we investigate this effect by calculating the lowest-order gravitational harmonic, J2, which characterizes the planetary oblateness and, in the linear hydrostatic regime, is related to the degree-2 tidal Love number k22We estimate the contributions to J2 from both the interior structure and the atmospheric jet streams. The dynamical contribution is calculated based on 3D circulation models spanning a broad HJ parameter space. We show that atmospheric mass anomalies associated with strong winds can significantly modify the expected deformation signal and may therefore be detectable with current and upcoming observations of HJs Love numbers.Finally, we compare our predictions with existing measurements of tidal Love numbers for Ultra-HJs and explore the possibility of constraining the deep wind structure of exoplanet atmospheres from deformation measurements.

Jupiter, a rapidly rotating gas giant, features over 20 atmospheric jet streams that penetrate thousands of kilometers into the planet. This work discusses recent progress, identifies key uncertainties regarding the jets’ driving and dissipating mechanisms, and suggests future research avenues.

The equatorial jets observed on the Jovian planets—Jupiter, Saturn, Uranus, and Neptune—exhibit extreme zonal flow patterns, manifesting as either strongly prograde (in the gas giants) or strongly retrograde (in the ice giants). Existing theories have often treated gas giants and ice giants separately, primarily focusing on the differences between deep and shallow dynamics. However, gravity measurements from the Juno spacecraft have revealed that Jupiter's convective envelope may share similarities with those of the ice giants, challenging traditional distinctions between these planetary types and highlighting the potential for a unified explanation.We present results from a convection-driven anelastic General Circulation Model that introduces a unifying mechanism to explain the equatorial jets on all four Jovian planets. In these simulations, the convective dynamics and planetary rotation drive the formation of tilted convection columns that extend cylindrically from the deep interior to the outer atmospheric layers. These columns play a crucial role in shaping zonal wind patterns, with the tilting of the convection columns introducing asymmetries in momentum transport that lead to the bifurcation of the flow into either superrotation (prograde jets) or subrotation (retrograde jets) in the equatorial region.Through a detailed analysis of the convection-driven columnar structures, we demonstrate that the equatorial wave properties and the leading-order momentum balance share remarkable similarities across different planetary types. Our findings comprehensively explain the potential for both equatorial superrotation and subrotation under constant physical conditions, thereby elucidating the diverse zonal wind patterns observed on the Jovian planets and providing deeper insight into the mechanisms driving equatorial jet formation. Furthermore, the Juno Microwave Radiometer (MWR) may provide evidence for such tilted convection structures, underscoring the necessity of a thorough understanding of their dynamical contributions.

The equatorial jets dominating the dynamics of the Jovian planets exhibit two distinct types of zonal flows: strongly eastward in the gas giants (superrotation) and strongly westward in the ice giants (subrotation). Existing theories propose different mechanisms for these patterns, but no single mechanism has successfully explained both. However, the planetary parameters of the four Solar System giant planets suggest that a fundamentally different mechanism is unlikely. In this study, we show that convection-driven columnar structures can account for both eastward and westward equatorial jets, framing the phenomenon as a bifurcation. Consequently, both superrotation and subrotation emerge as stable branches of the same mechanistic solution. Our analysis of these solutions uncovers similarities in the properties of equatorial waves and the leading-order momentum balance. This study suggests that the fundamental dynamics governing equatorial jet formation may be more broadly applicable across the Jovian planets than previously believed, offering a unified explanation for their two distinct zonal wind patterns.

The equatorial jets dominating the dynamics of the Jovian planets exhibit two distinct types of zonal flows: strongly eastward (superrotation) and strongly westward (subrotation). Existing theories propose different mechanisms for these patterns on gas giants and ice giants, but no single mechanism has successfully explained both. However, the planetary parameters of the four Solar System giant planets suggest that a fundamentally different mechanism is unlikely. In this study, we demonstrate that a convection-driven columnar structure can explain the equatorial jets on all four Jovian planets, framing the problem as a bifurcation phenomenon. Consequently, both superrotation and subrotation emerge as stable branches of the same mechanistic solution. Our analysis of these solutions uncovers similarities in the properties of equatorial waves and the leading-order momentum balance. This study reveals that the underlying dynamics of equatorial jet formation are more universally applicable across the Jovian planets than previously thought, providing a unified explanation for their two distinct zonal wind patterns.

Recent measurements from the Juno spacecraft have revived interest in the possible existence of a radiative zone within Jupiter's atmosphere. If such a layer exists, it would create a stably stratified region, estimated to extend up to 2000 km, challenging the traditional view of a predominantly convective envelope associated with the planet’s zonal jet streams, which penetrate approximately 3000 km. In this study, we explore the potential effects of this radiative zone on Jupiter’s jet stream properties and gravity field. Combining gravity measurement constraints with numerical simulations of a shallow atmospheric model representative of Jupiter, we investigate the dynamical implications of a radiative layer. Our analysis evaluates how the presence of this zone could alter atmospheric dynamics, offering new insights into the planet’s internal structure and questioning the hypothesis of a fully convective dynamical layer. Additionally, through gravity data analysis, we assess whether the existence of such a radiative zone is feasible within Jovian conditions. These findings highlight the importance of considering layered atmospheric models in planetary data interpretation. Moreover, the presence of a radiative zone could be a common feature in other planetary systems and exoplanets, underscoring the need for further research into planetary atmospheres and interiors and their broader implications for planetary science.

The equatorial jets observed on the Jovian planets - Jupiter, Saturn, Uranus, and Neptune - exhibit extreme equatorial zonal flow patterns, manifesting as either strongly prograde (in the gas giants) or strongly retrograde (in the ice giants). Existing theories have often treated gas giants and ice giants separately, primarily focusing on the differences between deep and shallow dynamics. However, recent gravity measurements suggest that the convective envelope of Jupiter may be similar to those of the ice giants, challenging the traditional distinctions between these planet types.We present results from a numerical simulation that introduces a mechanism capable of explaining the equatorial jets on the ice giants in a manner analogous to those on the gas giants. In these simulations, as shown theoretically by Busse et al., the convective dynamics and planetary rotation drive the formation of tilted convection columns. These columns, extending cylindrically from the deep interior to the outer atmospheric layers, play a crucial role in shaping the zonal wind patterns. In this study, the tilting of the convection columns introduces asymmetries in momentum transport, leading to a bifurcation of the flow into either superrotation (prograde jets) or subrotation (retrograde jets).Through a detailed analysis of the convection-driven columnar structures, we demonstrate that the equatorial wave properties and the leading-order momentum balance share remarkable similarities between the two types of solutions. Our findings comprehensively explain the potential for both superrotation and subrotation solutions under constant physical conditions, thereby potentially explaining the diverse zonal wind patterns observed on the Jovian planets and providing a deeper understanding of the mechanisms driving equatorial jet formation.