Analysis of Saturn’s thermal emission at 2.2-cm wavelength: Spatial distribution of ammonia vapor

Laraia, A.; Ingersoll, Andrew P.; Janssen, M. A.; Gulkis, S.; Oyafuso, Fabiano; Allison, M.

doi:10.1016/j.icarus.2013.06.017

Cited by 28 publications

(30 citation statements)

References 43 publications

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“…In fact, studies with the Very Large Array (VLA) show depleted ammonia with respect to saturation for all four giant planets in the Solar System (de Pater ;Massie 1985;de Pater et al 2001). The same depletion of ammonia is also observed after Saturn's Giant Storm Laraia et al 2013) and in the smaller storm in Saturn's southern hemisphere (Dyudina et al 2007). Li;…”

Section: Interpretation Of Galileo Probe Resultsmentioning

confidence: 84%

Moist Adiabats with Multiple Condensing Species: A New Theory with Application to Giant-Planet Atmospheres

Ingersoll

Oyafuso

2018

Journal of the Atmospheric Sciences

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We derived a new formula for calculating the moist adiabatic temperature profile of an atmosphere consisting of ideal gases with multiple condensing species. This expression unifies various formulas published in the literature and can be generalized to account for chemical reactions. Unlike previous methods, it converges to machine precision independent of mesh size.It accounts for any ratio of condensable vapors to dry gas, from zero to infinity, and for variable heat capacities as a function of temperature. Because the derivation is generic, the new formula is not only applicable to planetary atmosphere in the solar system, but also to hot Jupiters and brown dwarfs in which a variety of alkali metals, silicates and exotic materials condense. We demonstrate that even though the vapors are ideal gases, they interact in their effects on the moist adiabatic lapse rate. Finally, we apply the new thermodynamic model to study the effects of downdrafts on the distribution of minor constituents and thermal profile in the Galileo probe hotspot. We find that the Galileo Probe measurements can be interpreted as a strong downdraft that displaces an air parcel from 1 bar to the 4 bar level. Recently, the Juno spacecraft has made several flybys to Jupiter, and the Microwave Radiometer (MWR) onboard the spacecraft has measured the thermal emission from Jupiter's atmosphere from the cloud top at about 1 bar to a hundred bars. Because the measured absolute brightness temperature is precise to about a few percent, and the limb darkening is precise to one tenth of a percent (Janssen et al. 2016), traditional Jovian thermodynamics -assuming constant heat capacity and small mixing ratios of condensates -needs to be carefully reviewed and refined according to the requirement of the new instrument. Furthermore, numerous exotic exoplanets exhibit the condensation of alkali metals, silicates, irons, etc in their atmospheres (Morley et al. 2012). The traditional moist adiabatic theory for single condensing species deserves a revisit. Several authors have improved the original model of Weidenschilling; Lewis (1973) using different methods and assumptions. For example, Atreya; Romani (1985) considered ammonia solution and chemical reactions forming NH 4 SH, but they assumed a diluted atmosphere, meaning that the mixing ratios of condensable species are small. Pierrehumbert (2010) and Leconte et al.

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Section: Interpretation Of Galileo Probe Resultsmentioning

confidence: 84%

Moist Adiabats with Multiple Condensing Species: A New Theory with Application to Giant-Planet Atmospheres

Ingersoll

Oyafuso

2018

Journal of the Atmospheric Sciences

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“…The warming contributes to the re-evaporation of the condensates (the obscuring white aerosols), and the descent of the dry air in cells is expected to cause further depletion of other tropospheric species -ammonia, phosphine and H 2 S -which decrease in abundance with height, in addition to those that have already been precipitated. This compensating subsidence may explain the observed NH 3 depletion to several bars over much of Jupiter (de Pater et al, 2001;Showman and de Pater, 2005), as well as the observed dearth of NH 3 opacity in the aftermath of Saturn's springtime storm Laraia et al, 2013). After the downdrafts, the remaining atmosphere of the SEB would be unsaturated and stable.…”

Section: Vertical Structure Of Convective Complexesmentioning

confidence: 93%

Moist convection and the 2010–2011 revival of Jupiter’s South Equatorial Belt

Fletcher

Orton

Rogers

et al. 2017

Icarus

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The transformation of Jupiter's South Equatorial Belt (SEB) from its faded, whitened state in 2009-2010(Fletcher et al., 2011b to its normal brown appearance is documented via comparisons of thermal-infrared (5-20 µm) and visible-light imaging between November 2010 and November 2011. The SEB revival consisted of convective eruptions triggered over ∼ 100 days, potentially powered by the latent heat released by the condensation of water. The plumes rise from the water cloud base and ultimately diverge and cool in the stably-stratified upper troposphere. Thermal-IR images from the Very Large Telescope (VLT) were acquired 2 days after the SEB disturbance was first detected as a small white spot by amateur observers on November 9th 2010. Subsequent images over several months revealed the cold, putatively anticyclonic and cloudy plume tops (area 2.5 × 10 6 km 2 ) surrounded by warm, cloud-free conditions at their peripheries due to subsidence. The latent heating was not directly detectable in the 5-20 µm range. The majority of the plumes erupted from a single source near 140 − 160 • W, coincident with the remnant cyclonic circulation of a brown barge that had formed during the fade. The warm remnant of the cyclone could still be observed in IRTF imaging 5 days before the November 9th eruption. Additional plumes erupted from the leading edge of the central disturbance immediately east of the source, which propagated slowly eastwards to encounter the Great Red Spot. The tropospheric plumes were sufficiently vigorous to excite stratospheric thermal waves over the SEB with a 20 − 30 • longitudinal wavelength and 5-6 K temperature contrasts at 5 mbar, showing a direct connection between moist convection and stratospheric wave activity. The subsidence and compressional heating of dry, unsaturated air warmed the troposphere (particularly to the northwest of the central branch of the revival) and removed the aerosols that had been responsible for the fade. Dark, cloud-free lanes west of the plumes were the first to show the colour change, and elongated due to the zonal windshear to form the characteristic 'S-shape' of the revival complex. The aerosol-free air was redistributed and mixed throughout the SEB by the zonal flow, following a westward-moving southern branch and an eastwardmoving northern branch that revived the brown colouration over ∼ 200 days. The transition from the cool conditions of the SEBZ during the fade to the revived SEB caused a 2-4 K rise in 500-mbar temperatures (leaving a particularly warm southern SEB) and a reduction of aerosol opacity by factors of 2-3. Newly-cleared gaps in the upper tropospheric aerosol layer appeared different in filters sensing the ∼ 700-mbar cloud deck and the 2-3 bar cloud deck, suggesting complex vertical structure in the downdrafts. The last stage of the revival was the re-establishment of normal convective activity northwest of the GRS in September 2011, ∼ 840 days after the last occurrence in June 2009. Moist convection may therefore play an important role in controlling th...

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“…Perturbations in the troposphere were much more subdued, although Achterberg et al (2014) reported an increase of about 3 K in the far-IR (20-200 µm, probing the upper troposphere near 400 mbar) thermodynamic temperature at the storm's latitude. In addition, 2.2-cm thermodynamic temperatures measured by the Cassini spacecraft three months into the storm were observed to increase more significantly (from 148 K to 166 K) at the storm latitude, likely due to a strong reduction in the relative humidity of ammonia there (Laraia et al 2013). Although this information is not quite sufficient to quantitatively estimate the change of the disc-averaged continuum thermodynamic temperature at the storm's epoch, it seems clear that if anything, the effect of the storm would be an increase in these continuum temperatures.…”

Section: Saturnmentioning

confidence: 97%

Planckintermediate results

Akrami

Ashdown

Aumont

et al. 2017

A&A

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Measurements of flux density are described for five planets, Mars, Jupiter, Saturn, Uranus, and Neptune, across the six Planck High Frequency Instrument frequency bands (100-857 GHz) and these are then compared with models and existing data. In our analysis, we have also included estimates of the brightness of Jupiter and Saturn at the three frequencies of the Planck Low Frequency Instrument (30, 44, and 70 GHz). The results provide constraints on the intrinsic brightness and the brightness time-variability of these planets. The majority of the planet flux density estimates are limited by systematic errors, but still yield better than 1% measurements in many cases. Applying data from Planck HFI, the Wilkinson Microwave Anisotropy Probe (WMAP), and the Atacama Cosmology Telescope (ACT) to a model that incorporates contributions from Saturn's rings to the planet's total flux density suggests a best fit value for the spectral index of Saturn's ring system of β ring = 2.30 ± 0.03 over the 30-1000 GHz frequency range. Estimates of the polarization amplitude of the planets have also been made in the four bands that have polarizationsensitive detectors (100-353 GHz); this analysis provides a 95 % confidence level upper limit on Mars's polarization of 1.8, 1.7, 1.2, and 1.7 % at 100, 143, 217, and 353 GHz, respectively. The average ratio between the Planck-HFI measurements and the adopted model predictions for all five planets (excluding Jupiter observations for 353 GHz) is 0.997, 0.997, 1.018, and 1.032 for 100, 143, 217, and 353 GHz, respectively. Model predictions for planet thermodynamic temperatures are therefore consistent with the absolute calibration of Planck-HFI detectors at about the three-percent-level. We compare our measurements with published results from recent cosmic microwave background experiments. In particular, we observe that the flux densities measured by Planck HFI and WMAP agree to within 2 %. These results allow experiments operating in the mm-wavelength range to cross-calibrate against Planck and improve models of radiative transport used in planetary science.

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Analysis of Saturn’s thermal emission at 2.2-cm wavelength: Spatial distribution of ammonia vapor

Cited by 28 publications

References 43 publications

Moist Adiabats with Multiple Condensing Species: A New Theory with Application to Giant-Planet Atmospheres

Moist Adiabats with Multiple Condensing Species: A New Theory with Application to Giant-Planet Atmospheres

Moist convection and the 2010–2011 revival of Jupiter’s South Equatorial Belt

Planckintermediate results

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