The solar reflected component in Jupiter's 5‐μm spectra from NIMS/Galileo observations

Drossart, P.; Roos-Serote, M.; Encrenaz, Thérèse; Lellouch, E.; Baines, K. H.; Carlson, R. W.; Kamp, L. W.; Orton, Glenn S.; Calcutt, S. B.; Irwin, Patrick; Taylor, F. W.; Weir, Andrew

doi:10.1029/98je01899

Cited by 16 publications

(11 citation statements)

References 22 publications

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“…The cloud is assumed to extend between 1.3 and 0.7 bar, with uniform density along altitude in this pressure range and zero elsewhere. The lower and upper limits of the cloud are in agreement with the previous results of Giles et al () and Drossart et al (), respectively. During retrieval, the analysis code varies the opacity applying, as a free parameter, a scalar multiplicative factor to this uniform density profile.…”

Section: Methodssupporting

confidence: 92%

On the Spatial Distribution of Minor Species in Jupiter's Troposphere as Inferred From Juno JIRAM Data

et al. 2020

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The spatial distribution of water, ammonia, phosphine, germane, and arsine in the Jupiter's troposphere has been inferred from the Jovian Infrared Auroral Mapper (JIRAM) Juno data. Measurements allow us to retrieve the vertically averaged concentration of gases between~3 and 5 bars from infrared-bright spectra. Results were used to create latitudinal profiles. The water vapor relative humidity varies with latitude from <1% to over 15%. At intermediate latitudes (30-70°) the water vapor maxima are associated with the location of cyclonic belts, as inferred from mean zonal wind profiles (Porco et al., 2003). The high-latitude regions (beyond 60°) are drier in the north (mean relative humidity around 2-3%) than the south, where humidity reaches 15% around the pole. The ammonia volume mixing ratio varies from 1 × 10 −4 to 4 × 10 −4 . A marked minimum exists around 10°N, while data suggest an increase over the equator. The high-latitude regions are different in the two hemispheres, with a gradual increase in the south and more constant values with latitude in the north. The phosphine volume mixing ratio varies from 4 × 10 −7 to 10 × 10 −7 . A marked minimum exists in the North Equatorial Belt. For latitudes poleward 30°S and 30°N, the northern hemisphere appears richer in phosphine, with a decrease toward the pole, while the opposite is observed in the south. JIRAM data indicate an increase of germane volume mixing ratio from 2 × 10 −10 to 8 × 10 −10 from both poles to 15°S, with a depletion centered around the equator. Arsine presents the opposite trend, with maximum values of 6 × 10 −10 at the two poles and minima below 1 × 10 −10 around 20°S.

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Section: Methodssupporting

confidence: 92%

On the Spatial Distribution of Minor Species in Jupiter's Troposphere as Inferred From Juno JIRAM Data

et al. 2020

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“…Again, part of this difference may be due to the fact that we are not necessarily observing identical regions of the planet, but reflected sunlight clearly accounts for a significant part of the dayside radiance from the zones. This flux difference between the nightside and dayside observations of the equatorial zone is consistent with the analysis of Drossart et al (1998), who studied the solar reflected component of Jupiter's 5-μm spectra from Galileo NIMS and found that the minimum flux level was six times greater on the dayside than on the nightside.…”

Section: Reflected Sunlight Analysissupporting

confidence: 74%

Cloud structure and composition of Jupiter’s troposphere from 5-μm Cassini VIMS spectroscopy

Giles

Fletcher

Irwin

2015

Icarus

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Jupiter's tropospheric composition and cloud structure are studied using Cassini VIMS 4.5-5.1 µm thermal emission spectra from the 2000-2001 flyby. We make use of both nadir and limb darkening observations on the planet's nightside, and compare these with dayside observations. Although there is significant spatial variability in the 5-μm brightness temperatures, the shape of the spectra remain very similar across the planet, suggesting the presence of a spectrally-flat, spatially inhomogeneous cloud deck. We find that a simple cloud model consisting of a single, compact cloud is able to reproduce both nightside and dayside spectra, subject to the following constraints: (i) the cloud base is located at pressures of 1.2 bar or lower; (ii) the cloud particles are highly scattering; (iii) the cloud is sufficiently spectrally flat. Using this cloud model, we search for global variability in the cloud opacity and the phosphine deep volume mixing ratio. We find that the vast majority of the 5-μm inhomogeneity can be accounted for by variations in the thickness of the cloud decks, with huge differences between the cloudy zones and the relatively cloud-free belts. The relatively low spectral resolution of VIMS limits reliable retrievals of gaseous species, but some evidence is found for an enhancement in the abundance of phosphine at high latitudes.

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“…However, the model proposed by Carlson et al does appear to apply to Jupiter's zones, at least in the regions marked in Figure 8 as candidates for water clouds. Similarly, models of Galileo/ NIMS spectra of the EQZ by Drossart et al (1998) are probably accurate while models of hot spots that included water clouds (e.g., Nixon et al 2001) will need to be revised.…”

Section: Discussionmentioning

confidence: 99%

“…Evidence for water clouds in Jupiter's zones is also ambiguous. Drossart et al (1998) compared dayside and nightside NIMS spectra of low-flux regions in the EQZ. A saturated H 2 O profile above an opaque water cloud at 5 bars provides a satisfactory fit to these data.…”

Section: Introductionmentioning

confidence: 99%

Jupiter’s Deep Cloud Structure Revealed Using Keck Observations of Spectrally Resolved Line Shapes

Bjoraker

Wong

Pater

et al. 2015

ApJ

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Technique: We present a method to determine the pressure at which significant cloud opacity is present between 2 and 6 bars on Jupiter. We use (a) the strength of a Fraunhofer absorption line in a zone to determine the ratio of reflected sunlight to thermal emission, and (b) pressure-broadened line profiles of deuterated methane (CH 3 D) at 4.66 μm to determine the location of clouds. We use radiative transfer models to constrain the altitude region of both the solar and thermal components of Jupiter's 5 μm spectrum. Results: For nearly all latitudes on Jupiter the thermal component is large enough to constrain the deep cloud structure even when upper clouds are present. We find that hot spots, belts, and high latitudes have broader line profiles than do zones. Radiative transfer models show that hot spots in the North Equatorial Belt and South Equatorial Belt (SEB) typically do not have opaque clouds at pressures greater than 2 bars. The South Tropical Zone (STZ) at 32S has an opaque cloud top between 4 and 5 bars. From thermochemical models this must be a water cloud. We measured the variation of the equivalent width of CH 3 D with latitude for comparison with Jupiter's belt-zone structure. We also constrained the vertical profile of H 2 O in an SEB hot spot and in the STZ. The hot spot is very dry for P < 4.5 bars and then follows the H 2 O profile observed by the Galileo Probe. The STZ has a saturated H 2 O profile above its cloud top between 4 and 5 bars.

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The solar reflected component in Jupiter's 5‐μm spectra from NIMS/Galileo observations

Cited by 16 publications

References 22 publications

On the Spatial Distribution of Minor Species in Jupiter's Troposphere as Inferred From Juno JIRAM Data

On the Spatial Distribution of Minor Species in Jupiter's Troposphere as Inferred From Juno JIRAM Data

Cloud structure and composition of Jupiter’s troposphere from 5-μm Cassini VIMS spectroscopy

Jupiter’s Deep Cloud Structure Revealed Using Keck Observations of Spectrally Resolved Line Shapes

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