Radiative forcing of the stratosphere of Jupiter, Part I: Atmospheric cooling rates from Voyager to Cassini

Zhang, X.; Nixon, C. A.; Shia, R. L.; West, R. A.; Irwin, Patrick; Yelle, R.; Allen, Mark; Yung, Y. L.

doi:10.1016/j.pss.2013.07.005

Cited by 28 publications

(65 citation statements)

References 75 publications

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“…The horizontal advection timescale in our model is about 10 8 s at 100 Pa, comparable to the vertical circulation timescale due to the continuity constraint. This horizontal transport timescale is also similar to that inferred from Voyager and Cassini observations (Nixon et al 2010, Zhang et al 2013a.…”

Section: D Simulations On Fast-rotating Planetssupporting

confidence: 87%

Global-mean Vertical Tracer Mixing in Planetary Atmospheres. I. Theory and Fast-rotating Planets

Zhang

Showman

2018

ApJ

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Most chemistry and cloud formation models for planetary atmospheres adopt a one-dimensional (1D) diffusion approach to approximate the global-mean vertical tracer transport. The physical underpinning of the key parameter in this framework, eddy diffusivity K zz , is usually obscure. Here we analytically and numerically investigate vertical tracer transport in a 3D stratified atmosphere and predict K zz as a function of the large-scale circulation strength, horizontal mixing due to eddies and waves and local tracer sources and sinks. We find that K zz increases with tracer chemical lifetime and circulation strength but decreases with horizontal eddy mixing efficiency. We demarcated three K zz regimes in planetary atmospheres. In the first regime where the tracer lifetime is short compared with the transport timescale and horizontal tracer distribution under chemical equilibrium (χ 0 ) is uniformly distributed across the globe, global-mean vertical tracer mixing behaves diffusively. But the traditional assumption in current 1D models that all chemical species are transported via the same eddy diffusivity generally breaks down. We show that different chemical species in a single atmosphere should in principle have different eddy diffusion profiles. In the second regime where tracer is short-lived but χ 0 is non-uniformly distributed, a significant non-diffusive component might lead to a negative K zz under the diffusive assumption. In the third regime where the tracer is long-lived, global-mean vertical tracer transport is also largely influenced by non-diffusive effects. Numerical simulations of 2D tracer transport on fast-rotating zonally symmetric planets validate our analytical K zz theory over a wide parameter space. Subject headings: planetary atmospheres -eddy mixing -tracer transport -methods: analytical and numerical

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Section: D Simulations On Fast-rotating Planetssupporting

confidence: 87%

Global-mean Vertical Tracer Mixing in Planetary Atmospheres. I. Theory and Fast-rotating Planets

Zhang

Showman

2018

ApJ

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“…These abundances fall within the range of previous studies (see the excellent summary in Fig. 1 of Zhang et al, 2013a). The most radical deviations of the abundance profiles from previous work failed to reproduce the data satisfactorily.…”

Section: Sensitivity To the Hydrocarbon Priorssupporting

confidence: 84%

Mid-infrared mapping of Jupiter’s temperatures, aerosol opacity and chemical distributions with IRTF/TEXES

Fletcher

Greathouse

Orton

et al. 2016

Icarus

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230

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International audienceGlobal maps of Jupiter’s atmospheric temperatures, gaseous composition and aerosol opacity are derived from a programme of 5–20 µm mid-infrared spectroscopic observations using the Texas Echelon Cross Echelle Spectrograph (TEXES) on NASA’s Infrared Telescope Facility (IRTF). Image cubes from December 2014 in eight spectral channels, with spectral resolutions of R ∼2000−12,000−12,000 and spatial resolutions of 2–4° latitude, are inverted to generate 3D maps of tropospheric and stratospheric temperatures, 2D maps of upper tropospheric aerosols, phosphine and ammonia, and 2D maps of stratospheric ethane and acetylene. The results are compared to a re-analysis of Cassini Composite Infrared Spectrometer (CIRS) observations acquired during Cassini’s closest approach to Jupiter in December 2000, demonstrating that this new archive of ground-based mapping spectroscopy can match and surpass the quality of previous investigations, and will permit future studies of Jupiter’s evolving atmosphere. The visibility of cool zones and warm belts varies from channel to channel, suggesting complex vertical variations from the radiatively-controlled upper troposphere to the convective mid-troposphere. We identify mid-infrared signatures of Jupiter’s 5-µm hotspots via simultaneous M, N and Q-band observations, which are interpreted as temperature and ammonia variations in the northern Equatorial Zone and on the edge of the North Equatorial Belt (NEB). Equatorial plumes enriched in NH3 gas are located south-east of NH3-desiccated ‘hotspots’ on the edge of the NEB. Comparison of the hotspot locations in several channels across the 5–20 µm range indicate that these anomalous regions tilt westward with altitude. Aerosols and PH3 are both enriched at the equator but are not co-located with the NH3 plumes. The equatorial temperature minimum and PH3/aerosol maxima have varied in amplitude over time, possibly as a result of periodic equatorial brightenings and the fresh updrafts of disequilibrium material. Temperate mid-latitudes display a correlation between mid-IR aerosol opacity and the white albedo features in visible light (i.e., zones). We find hemispheric asymmetries in the distribution of tropospheric PH3, stratospheric hydrocarbons and the 2D wind field (estimated via the thermal-wind equation) that suggest a differing efficiency of mechanical forcing (e.g., vertical mixing and wave propagation) between the two hemispheres that we argue is driven by dynamics rather than Jupiter’s small seasonal cycle. Jupiter’s stratosphere is notably warmer at northern mid-latitudes than in the south in both 2000 and 2014, although the latter can be largely attributed to strong thermal wave activity near 30°N that dominates the 2014 stratospheric maps and may be responsible for elevated C2H2 in the northern hemisphere. A vertically-variable pattern of temperature and windshear minima and maxima associated with Jupiter’s Quasi Quadrennial Oscillation (QQO) is observed at the equator in both datasets, although the contrasts wer...

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“…Having explored the potentially multi-tiered circulation cells in the upper troposphere and mid-troposphere, we now turn our attention to atmospheric motions above the tropopause. On the Gas Giants, the zonal winds and banded structures persist high into the stratosphere, and are superimposed onto larger interhemispheric circulations, both non-seasonal on Jupiter (Nixon et al 2007;Zhang et al 2013;Melin et al 2018) and seasonal on Saturn (see review by . The temperature and composition of the Gas Giant stratospheres is also modulated by the presence of polar vortices and wave-driven equatorial oscillations.…”

Section: Stratospheric Circulation: Chemical Tracersmentioning

confidence: 99%

Ice Giant Circulation Patterns: Implications for Atmospheric Probes

et al. 2020

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Atmospheric circulation patterns derived from multi-spectral remote sensing can serve as a guide for choosing a suitable entry location for a future in situ probe mission to the Ice Giants. Since the Voyager-2 flybys in the 1980s, three decades of observations from ground- and space-based observatories have generated a picture of Ice Giant circulation that is complex, perplexing, and altogether unlike that seen on the Gas Giants. This review seeks to reconcile the various competing circulation patterns from an observational perspective, accounting for spatially-resolved measurements of: zonal albedo contrasts and banded appearances; cloud-tracked zonal winds; temperature and para-H2 measurements above the condensate clouds; and equator-to-pole contrasts in condensable volatiles (methane, ammonia, and hydrogen sulphide) in the deeper troposphere. These observations identify three distinct latitude domains: an equatorial domain of deep upwelling and upper-tropospheric subsidence, potentially bounded by peaks in the retrograde zonal jet and analogous to Jovian cyclonic belts; a mid-latitude transitional domain of upper-tropospheric upwelling, vigorous cloud activity, analogous to Jovian anticyclonic zones; and a polar domain of strong subsidence, volatile depletion, and small-scale (and potentially seasonally-variable) convective activity. Taken together, the multi-wavelength observations suggest a tiered structure of stacked circulation cells (at least two in the troposphere and one in the stratosphere), potentially separated in the vertical by (i) strong molecular weight gradients associated with cloud condensation, and by (ii) transitions from a thermally-direct circulation regime at depth to a wave- and radiative-driven circulation regime at high altitude. The inferred circulation can be tested in the coming decade by 3D numerical simulations of the atmosphere, and by observations from future world-class facilities. The carrier spacecraft for any probe entry mission must ultimately carry a suite of remote-sensing instruments capable of fully constraining the atmospheric motions at the probe descent location.

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Radiative forcing of the stratosphere of Jupiter, Part I: Atmospheric cooling rates from Voyager to Cassini

Cited by 28 publications

References 75 publications

Global-mean Vertical Tracer Mixing in Planetary Atmospheres. I. Theory and Fast-rotating Planets

Global-mean Vertical Tracer Mixing in Planetary Atmospheres. I. Theory and Fast-rotating Planets

Mid-infrared mapping of Jupiter’s temperatures, aerosol opacity and chemical distributions with IRTF/TEXES

Ice Giant Circulation Patterns: Implications for Atmospheric Probes

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