Uranus in 2003: Zonal winds, banded structure, and discrete features

Hammel, Heidi B.; Pater, Imke de; Gibbard, S. G.; Lockwood, G. W.; Rages, K.

doi:10.1016/j.icarus.2004.11.012

Cited by 58 publications

(69 citation statements)

References 31 publications

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“…Summarizing, let us emphasize that the existing opinion that the equatorial jets produced in barotropic simulations are always directed westward is fallacious although a certain preference to the formation of westward jets has been noticeable. Note also that the simulated equatorial jets are not necessarily symmetric with respect to the equator; this fact has been addressed in some discussions of the circulation on Uranus (Karkoschka, 1998;Hammel et al, 2001Hammel et al, , 2005Sromovsky and Fry, 2005).…”

Section: Equatorial Jetsmentioning

confidence: 97%

Anisotropic turbulence and zonal jets in rotating flows with a β-effect

Galperin

Sukoriansky

Dikovskaya

et al. 2006

Nonlin. Processes Geophys.

108

107

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Abstract. Numerical studies of small-scale forced, twodimensional turbulent flows on the surface of a rotating sphere have revealed strong large-scale anisotropization that culminates in the emergence of quasi-steady sets of alternating zonal jets, or zonation. The kinetic energy spectrum of such flows also becomes strongly anisotropic. For the zonal modes, a steep spectral distribution, E(n)=C Z ( /R) 2 n −5 , is established, where C Z =O(1) is a non-dimensional coefficient, is the angular velocity, and R is the radius of the sphere, respectively. For other, non-zonal modes, the classical, Kolmogorov-Batchelor-Kraichnan, − 5 3 spectral law is preserved. This flow regime, referred to as a zonostrophic regime, appears to have wide applicability to large-scale planetary and terrestrial circulations as long as those are characterized by strong rotation, vertically stable stratification and small Burger numbers. The well-known manifestations of this regime are the banded disks of the outer planets of our Solar System. Relatively less known examples are systems of narrow, subsurface, alternating zonal jets throughout all major oceans discovered in state-of-the-art, eddy-permitting simulations of the general oceanic circulation. Furthermore, laboratory experiments recently conducted using the Coriolis turntable have basically confirmed that the lateral gradient of "planetary vorticity" (emulated via the topographic β-effect) is the primary cause of the zonation and that the latter is entwined with the development of the strongly anisotropic kinetic energy spectrum that tends to attain the same zonal and non-zonal distributions, −5 and − 5 3 , respectively, in both the slope and the magnitude, as the corresponding spectra in other environmental conditions. The non-dimensional coCorrespondence to: B. Galperin (bgalperin@marine.usf.edu) efficient C Z in the −5 spectral law appears to be invariant, C Z 0.5, in a variety of simulated and natural flows.This paper provides a brief review of the zonostrophic regime. The review includes the discussion of the physical nature, basic mechanisms, scaling laws and universality of this regime. A parameter range conducive to its establishment is identified, and collation of laboratory and naturally occurring flows is presented through which the zonostrophic regime manifests itself in the real world.

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Section: Equatorial Jetsmentioning

confidence: 97%

Anisotropic turbulence and zonal jets in rotating flows with a β-effect

Galperin

Sukoriansky

Dikovskaya

et al. 2006

Nonlin. Processes Geophys.

108

107

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“…There are also features near the equator, at latitudes where such activity has never been detected before. The dynamics and wind velocity profiles of these features are the subject of a paper by Hammel et al (2004).…”

Section: Observationsmentioning

confidence: 99%

Near-infrared adaptive optics imaging of the satellites and individual rings of Uranus

Gibbard¹,

Pater²,

Hammel³

2005

Icarus

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We present the first Earth-based images of several of the individual faint rings of Uranus, as observed with the adaptive optics system on the W.M. Keck II telescope on four consecutive days in October 2003. We derive reflectivities based on multiple measurements of 8 minor moons of Uranus as well as Ariel and Miranda in filters centered at wavelengths of 1.25(J), 1.63(H), and 2.1(Kp) µm. These observations have a phase angle of 1.84 • -1.96 • . We find that the small satellites are somewhat less bright than in observations made by the HST at smaller phase angles, confirming an opposition surge effect. We calculate albedoes for the ring groups and for each ring separately. We find that the ring particles, as well as the particles in the three other ring groups, have albedoes near 0.043 at these phase angles. The equivalent depths of some of the individual rings are different than predicted based upon ring widths from occultation measurements (assuming a constant particle ring brightness); in particular the γ ring is fainter and the η ring brighter than expected. Our results indicate that q, the ratio of ring intensity at apoapse vs. periapse, is close to 3.2 ± 0.16. This agrees well with a model that has a filling factor for the ring of 0.06 (Karkoschka, 2001, Icarus 151, 78-83). We also determine values of the north to south brightness ratio for the individual rings and find that in most cases they are close to unity.

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“…Patterns of zonal winds of ice giants as revealed by available data are also noteworthy for their lack of coherence (variation of absolute values, high dispersions and differences in results from different spectral bands) once compared to the Jupiter and Saturn cases (see Hammel et al, 2001, Hammel et al, 2005 for Uranus, Sromovsky et al, 1993 andFitzpatrick et al, 2014 for Neptune). The assessment of the relative role of different phenomena (such as vertical wind shear, transient clouds due to dynamically driven sublimation and condensation, temporal variations on different time scales) will highly benefit from the long-term, high spatial resolution monitoring.…”

Section: Atmospheres Of Uranus and Neptunementioning

confidence: 94%

The comparative exploration of the ice giant planets with twin spacecraft: Unveiling the history of our Solar System

Turrini

Politi

Peron

et al. 2014

Planetary and Space Science

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In the course of the selection of the scientific themes for the second and third L-class missions of the Cosmic Vision 2015-2025 program of the European Space Agency, the exploration of the ice giant planets Uranus and Neptune was defined "a timely milestone, fully appropriate for an L class mission". Among the proposed scientific themes, we presented the scientific case of exploring both planets and their satellites in the framework of a single L-class mission and proposed a mission scenario that could allow to achieve this result. In this work we present an updated and more complete discussion of the scientific rationale and of the mission concept for a comparative exploration of the ice giant planets Uranus and Neptune and of their satellite systems with twin spacecraft. The first goal of comparatively studying these two similar yet extremely different systems is to shed new light on the ancient past of the Solar System and on the processes that shaped its formation and evolution. This, in turn, would reveal whether the Solar System and the very diverse extrasolar systems discovered so far all share a common origin or if different environments and mechanisms were responsible for their formation. A space mission to the ice giants would also open up the possibility to use Uranus and Neptune as templates in the study of one of the most abundant type of extrasolar planets in the galaxy. Finally, such a mission would allow a detailed study of the interplanetary and gravitational environments at a range of distances from the Sun poorly covered by direct exploration, improving the constraints on the fundamental theories of gravitation and on the behaviour of the solar wind and the interplanetary magnetic field.

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Uranus in 2003: Zonal winds, banded structure, and discrete features

Cited by 58 publications

References 31 publications

Anisotropic turbulence and zonal jets in rotating flows with a β-effect

Anisotropic turbulence and zonal jets in rotating flows with a β-effect

Near-infrared adaptive optics imaging of the satellites and individual rings of Uranus

The comparative exploration of the ice giant planets with twin spacecraft: Unveiling the history of our Solar System

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