Dynamics of cloud features on Uranus

Sromovsky, L. A.; Fry, P. M.

doi:10.1016/j.icarus.2005.07.022

Cited by 71 publications

(84 citation statements)

References 25 publications

(82 reference statements)

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“…This intensity asymmetry is also obvious in the HST-images of Karkoschka (2001) or Rages et al (2004) and in Keck observations obtained with an adaptive optic system (Sromovsky & Fry 2005).…”

Section: Peculiarities For the Meridional Slitmentioning

confidence: 66%

Limb polarization of Uranus and Neptune

Joos¹,

Schmid²

2006

A&A

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Aims. We have detected a strong limb polarization for Uranus and Neptune. With spectropolarimetric observations we characterize the spectral dependence of this limb polarization and explore the diagnostic potential for investigating the distribution and properties of the scattering particles. Methods. We present disk resolved spectropolarimetry of Uranus and Neptune covering the wavelength range from 5300 Å to 9300 Å and compare the spectropolarimetric signal for different limb sections and the center of the planetary disk. As an additional benefit we obtained center to limb disk profiles for the intensity and polarization for various wavelengths. Results. Our data show for both planets a strong linear limb polarization oriented perpendicular to the limb. The polarization at the center of the planetary disks is essentially zero. Overall the limb polarization increases towards shorter wavelengths, and it is further enhanced in the methane absorption bands when compared to adjacent inter band regions. Qualitatively, the polarization signal is very similar for Uranus and Neptune. For Uranus the peak limb polarization of the methane absorption bands reaches a maximum of 3% whereas in the nearby higher albedo regions it peaks at about 2%. The measured polarization for Neptune is significantly lower because the signal is averaged down by the limited spatial resolution of our Neptune data. The disk profiles for Uranus (center to limb profiles) show for the intensity a strong asymmetry between the bright South pole regions and the darker northern latitudes. The asymmetry is particularly strong in the methane bands. We measure a significant limb brightening in the methane bands at the Uranian eastern and western limbs. The intensity asymmetry between North and South and the limb brightening display a tight anti-correlation with the albedo of the selected wavelength interval. From the polarization profiles of Uranus we determine slit integrated polarization values in order to derive intrinsic limb polarization parameters which are corrected for the limited spatial resolution of our data. These parameters are compared with previous imaging polarimetry. Conclusions. The polarimetric measurements of Uranus and Neptune are compatible with expectations for the limb polarization of scattering atmospheres containing substantial layers of particles which scatter radiation similar to Rayleigh scattering. It seems that the limb polarization contains interesting diagnostic information, in particular on the scattering properties of the aerosol particles in the haze layers at high altitudes.

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Section: Peculiarities For the Meridional Slitmentioning

confidence: 66%

Limb polarization of Uranus and Neptune

Joos¹,

Schmid²

2006

A&A

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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.

106

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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“…Considerable progress has been made concerning Earth-based cloud observations of Uranus and Neptune in the infrared as well as visible wavelength region (e.g. Karkoschka 1998;Hammel et al 2001;Roe et al 2001;de Pater et al 2002;Gibbard et al 2003;Sromovsky and Fry 2005;Irwin et al 2007). However, the lightning source might be in the water clouds located at a pressure level of about 40 bar, which is not accessible with these observations (Encrenaz et al 2004).…”

Section: Uranus and Neptunementioning

confidence: 99%

Updated Review of Planetary Atmospheric Electricity

Yair

Fischer

Simões³

et al. 2008

Space Sci Rev

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This paper reviews the progress achieved in planetary atmospheric electricity, with focus on lightning observations by present operational spacecraft, aiming to fill the hiatus from the latest review published by Desch et al. (Rep. Prog. Phys. 65:955-997, 2002). The information is organized according to solid surface bodies (Earth, Venus, Mars and Titan) and gaseous planets (Jupiter, Saturn, Uranus and Neptune), and each section presents the latest results from space-based and ground-based observations as well as laboratory experiments. Finally, we review planned future space missions to Earth and other planets that will address some of the existing gaps in our knowledge.

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Dynamics of cloud features on Uranus

Cited by 71 publications

References 25 publications

Limb polarization of Uranus and Neptune

Limb polarization of Uranus and Neptune

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

Updated Review of Planetary Atmospheric Electricity

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