Compressible convection in the deep atmospheres of giant planets

Jones, C. A.; Kuzanyan, K. M.

doi:10.1016/j.icarus.2009.05.022

Cited by 110 publications

(132 citation statements)

References 47 publications

Supporting

Mentioning

123

Contrasting

Order By: Relevance

“…Zonal jet formation then occurs even in the presence of bottom boundary friction, in sharp contrast to the results of overly viscous 3D simulations in which the mid-to highlatitude jets are damped out 5,30 . We further claim that dissipation is an essential ingredient for jet equilibration 15 .…”

contrasting

confidence: 56%

A laboratory model for deep-seated jets on the gas giants

et al. 2017

View full text Add to dashboard Cite

The strong east-west jet flows on the gas giants, Jupiter Azimuthally directed (that is, zonal, east-west) jet flows are one of the dominant characteristics in the surficial cloud features observed on the gas giants, Jupiter and Saturn. An essential question of planetary dynamics and structure is whether these jet motions exist only within the shallow troposphere or extend through the molecular envelope that exists above the deeper dynamo region 3 . Determining the depth of these atmospheric jets is one of the prime directives of the NASA (National Aeronautics and Space Administration) Juno mission, which entered into low-altitude Jovian orbit in August 2016 4 . Despite the long-lived scientific interest in these flows, dominant multiple jets have been problematic in fully three-dimensional (3D) numerical models of convection. In particular, multiple banded flows are not found in the most recent, high-resolution models that couple the molecular envelope to the deeper dynamo region. In these models, magnetic dissipation damps the higher-latitude deep jets out of existence [5][6][7] . Similarly, dissipation has also proved overly important in laboratory experiments carried out to date. Laboratory approaches were analysed in the framework of the shallow-layer model and strong viscous damping by the container boundaries only allows for the formation of weak zonal jets with tenuous instantaneous signatures [8][9][10][11][12][13][14] . Thus, it has yet to be demonstrated, as proposed for the gas giant planets 15 , that deep zonally dominant jet flows can exist in the presence of boundary dissipation.We have developed a new laboratory experimental device that is capable of generating strong zonal jets despite viscous friction on the boundaries (Fig. 1a). The working fluid is water, contained in a 1.37-m-high by 1-m-diameter cylindrical tank. The depth of the fluid layer is h o = 50 cm at rest, and the tank's rotation rate is Ω = 7.85 rad s −1 (75 revolutions per minute). Once equilibrated at Ω, the water's free surface takes the shape of a paraboloid, with the fluid layer depth ranging from h min 20 cm on the axis of rotation to h max 90 cm at the tank's outer radius. This rotating surface shape is analogous to the large-scale curvature of a deep spherical planetary fluid layer 16,17 . In addition, the rotation provides strong Coriolis forces, as exist in planetary settings. Once solid body rotation is reached, a submersible pump situated at the base of the tank is turned on, and small-scale turbulence is injected at the base of the fluid layer. The pump continuously circulates water through a lattice of 32 outlets (4 mm diameter) and 32 inlets (2 mm diameter) arranged on a flat base plate without any axisymmetric features (see the injection pattern in Supplementary Fig. 1a). Typical root-mean-square (r.m.s.) fluctuating velocities are in the range u r.m.s. 1-5 cm s −1 . This small-scale turbulence is analogous to the convective turbulence that exists in deep planetary interiors 18,19 and constitutes an appropriate s...

show abstract

contrasting

confidence: 56%

A laboratory model for deep-seated jets on the gas giants

et al. 2017

View full text Add to dashboard Cite

show abstract

“…The basic approach pioneered by Gilman and Glatzmaier has continued to flourish in the past few decades, and several codes in wide use today borrow at some level from this legacy: e.g., the Anelastic Spherical Harmonic (ASH) code (Clune et al 1999;Miesch et al 2000;Brun et al 2004) was developed within Juri Toomre's group at Colorado and has been used for dozens of papers on stellar convection; the Magic code (Wicht 2002;, used more widely in the planetary dynamo community, also descends from a version of the Glatzmaier code. A few other anelastic codes were developed independently (e.g., the Leeds code, see Jones and Kuzanyan 2009), and adopt distinct numerical methods, but follow a similar model. The recently-developed Rayleigh code (described in Featherstone and Hindman 2016a) also adopts the same basic principles as these earlier code, and is (as of this writing) planned for public release in 2017.…”

Section: Historical Survey Of Simulations and Codesmentioning

confidence: 99%

Magnetism, dynamo action and the solar-stellar connection

Brun

Browning

2017

Living Rev Sol Phys

252

182

View full text Add to dashboard Cite

The Sun and other stars are magnetic: magnetism pervades their interiors and affects their evolution in a variety of ways. In the Sun, both the fields themselves and their influence on other phenomena can be uncovered in exquisite detail, but these observations sample only a moment in a single star's life. By turning to observations of other stars, and to theory and simulation, we may infer other aspects of the magnetism-e.g., its dependence on stellar age, mass, or rotation rate-that would be invisible from close study of the Sun alone. Here, we review observations and theory of magnetism in the Sun and other stars, with a partial focus on the "Solar-stellar connection": i.e., ways in which studies of other stars have influenced our understanding of the Sun and vice versa. We briefly review techniques by which magnetic fields can be measured (or their presence otherwise inferred) in stars, and then highlight some key observational findings uncovered by such measurements, focusing (in many cases) on those that offer particularly direct constraints on theories of how the fields are built and maintained. We turn then to a discussion of how the fields arise in different objects: first, we summarize some essential elements of convection and dynamo theory, including a very brief discussion of mean-field theory and related concepts. Next we turn to simulations of convection and magnetism in stellar interiors, highlighting both some peculiarities of field generation in different types of stars and some unifying physical processes that likely influence dynamo action in general. We conclude with a brief

show abstract

“…(2) The higher diffusivity in the numerical experiment can affect the spatial scales of convection and magnetic structures. (Jones & Kuzanyan 2009) showed that the size of convective cells may scale with E 1/3 k , where E k is the Ekman number that evaluates the ratio of viscous forces to Coriolis forces. (3) Global 3D simulations likely overestimate the convective Rossby number of the convection zone (e.g., Featherstone & Hindman 2016), which leads to enhanced convective velocity power on large scales.…”

Section: Rescaling the Data Extracted From The Dynamo Simulationmentioning

confidence: 99%

Emergence of Magnetic Flux Generated in a Solar Convective Dynamo. I. The Formation of Sunspots and Active Regions, and The Origin of Their Asymmetries

Chen

Rempel

Fan

2017

ApJ

View full text Add to dashboard Cite

We present a realistic numerical model of sunspot and active region formation based on the emergence of flux bundles generated in a solar convective dynamo. To this end we use the magnetic and velocity fields in a horizontal layer near the top boundary of the solar convective dynamo simulation to drive realistic radiative-magnetohydrodynamic simulations of the upper most layers of the convection zone. The main results are: (1) The emerging flux bundles rise with the mean speed of convective upflows, and fragment into small-scale magnetic elements that further rise to the photosphere, where bipolar sunspot pairs are formed through the coalescence of the small-scale magnetic elements. (2) Filamentary penumbral structures form when the sunspot is still growing through ongoing flux emergence. In contrast to the classical Evershed effect, the inflow seems to prevail over the outflow in a large part of the penumbra. (3) A well formed sunspot is a mostly monolithic magnetic structures that is anchored in a persistent deep-seated downdraft lane. The flow field outside the spot shows a giant vortex ring that comprises of an inflow below 15 Mm depth and an outflow above 15 Mm depth. (4) The sunspots successfully reproduce the fundamental properties of the observed solar active regions, including the more coherent leading spots with a stronger field strength, and the correct tilts of bipolar sunspot pairs. These asymmetries can be linked to the intrinsic asymmetries in the magnetic and flow fields adapted from the convective dynamo simulation.

show abstract

Compressible convection in the deep atmospheres of giant planets

Cited by 110 publications

References 47 publications

A laboratory model for deep-seated jets on the gas giants

A laboratory model for deep-seated jets on the gas giants

Magnetism, dynamo action and the solar-stellar connection

Emergence of Magnetic Flux Generated in a Solar Convective Dynamo. I. The Formation of Sunspots and Active Regions, and The Origin of Their Asymmetries

Contact Info

Product

Resources

About