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NASA NTRS2011

The 2010-2011 Revival of Jupiter's South Equatorial Belt: Perturbations of Temperatures, Clouds and Composition from Infrared Observations

On 2010 November 9, a perturbation appeared in Jupiter's South Equatorial Belt (SEB), which began a classical "revival" of the SEB, returning the entire axisymmetric region to its normal dark color from its anomalous, light, "faded" state. The early revival is marked by strong upwelling gas at the outbreak location, to the west of which appear alternating clear and cloudy regions. Clear regions are correlated with dark clouds near the outbreak and in a southern retrograding branch but less so in a northern prograding branch. A 5-micrometer image from 2010 March 1 shows much of the SEB closer to a pre-faded state.

atmosphere↗
NASA NTRS1993

A study of the time variability of Jupiter's atmospheric structure

Aspects of the time-variable nature of the Jovian atmosphere are addressed using high-resolution photometrically calibrated multicolored imaging data obtained over two Jovian apparitions. During the period of observations, Jupiter's South Equatorial Belts (SEB) underwent a drastic brightening and its Equatorial Zone gradually darkened throughout the period. Based on the data, vertically inhomogeneous atmospheric structure models are constructed and used to make direct quantitative comparisons between different latitudinal regions and different epochs. The drastic brightening of the SEB is explained by an increase in both the optical thickness and the single-scattering albedo of the upper tropospheric cloud.

Kuehn, D. M.↗
NASA NTRS1993

Jupiter

N/A.

Jupiter South Equatorial Belt (SEB)↗
NASA NTRS1994

A change of upper cloud structure in Jupiter's South Equatorial Belt during the 1989-1990 event

We have analyzed two data sets of Jupiter's limb darkening taken before (March 1990) and after (March 1991) a South Equatorial Belt (SEB) disturbance. The vertical aerosol structure has been determined for the SEB, the Equatorial Zone (EZ), and the North Equatorial Belt (NEB). We find that all regions can be well represented with a two-cloud layer model, with slightly higher NH3-cloud top altitude in the EZ than in the two belts. The cloud single-scattering albedos tilda-omega(sub cl) (determined within plus or minus 0.003) show little difference in the EZ (from 0.9956 to 0.9952) and the NEB (from 0.9925 to 0.9926) during a 1-year period, while a relatively larger decrease is found in the SEB from 0.9975 to 0.9957, indicating the recovery of the belt through the disturbance. The NH3-cloud top altitude in the SEB shows the most prominent change, lower in 1990 and higher in 1991. We suggest that the brightening and the darkening of the SEB may originate not only from the changes of tilda-omega(sub cl) but also from changes of the ammonia condensation level in the atmosphere, probably due to a decrease of the tropospheric temperature and/or an increase of the ammonia vapor.

Satoh, Takehiko↗
NASA NTRS1986

The abundance and distribution of water vapor in Jupiter's atmosphere

The atmospheric transmission window between 1800 and 2250/cm in Jupiter's atmosphere was observed from the Kuiper Airborne Observatory and by the IR spectrometer (IRIS) on Voyager. The vertical distribution of H2O was derived for the 1-6 bar portion of Jupiter's troposphere. The spatial variation of H2O was measured using IRIS spectra of the Hot Spots in the North and South Equatorial Belts (NEB, SEB) and the Equatorial Zone and for an average of the North and South Tropical Zones. The H2O column abundance above the 4 bar level is the same in the zones as in the SEB Hot Spots, about 20 cm amagats. The NEB Hot Spots are desiccated by a factor of 3 with respect to the rest of Jupiter. For an average between -40 and +40 deg latitude, the H2O mole fraction, qH2O, is saturated for P less than 2 bars, qH2O = 4 millionths in the 2-4 bar range, and it increases to 3/100,000 at 6 bars. A similar vertical profile applies to the spatially resolved zone and belt spectra, except that H2O falls off more rapidly at P less than 4 bars in the NEB Hot Spots. A massive H2O cloud at 5 bars, T = 273 K is inconsistent with the observations. Instead, a thin H2O ice cloud would form at 2 bars, T = 200 K. The O/H ratio in Jupiter, inferred from H2O measurements in both belts and zones at 6 bars, is depleted by a factor of 50 with respect to the sun.

Bjoraker, Gordon L.↗
NASA NTRS1979

Spatially resolved methane band photometry of Jupiter. I - Absolute reflectivity and center-to-limb variations in the 6190-, 7250-, and 8900-A bands. II - Analysis of the south equatorial belt and south tropical zone reflectivity

Spatially resolved measurements of the absolute reflectivity and center to limb variations of Jupiter in the 6190, 7250 and 8900 A methane bands and nearby continuum regions are presented and analyzed for the south equatorial belts (SEBs) and south tropical zone (STrZ). It is found that the polar hoods, equatorial zone, Red Spot and north tropical zone have highest methane reflectivities, with the temperate zones and polar regions having low reflectivity and the STrZ and SEBs having intermediate values. The data on the SEB and STrZ are analyzed in terms of diffuse reflecting-scattering and two-cloud models of the vertical distribution of aerosols in the Jovian atmosphere. To fit observations, the STrZ cloud top must have between 0.55 and 0.43 bar total pressure and optical depth between 1.5 and 2.5. The reflecting-scattering models are not suitable for the SEBs. The SEB upper cloud is deeper, cloud thickness is less and the lower cloud is deeper than in the STrZ. A forward scattering haze layer accounts for limb darkening in the continuum.

West, R. A.↗
NASA NTRS1986

The abundance and distribution of water vapor in Jupiter's atmosphere

The atmospheric transmission window between 1800 and 2250 cm(-1) in Jupiter's atmosphere was observed from the Kuiper Airborne Observatory (KAO) and by the infrared spectrometer (IRIS) on Voyager. The vertical distribution of H2O was derived for the 1 to 6 bar portion of Jupiter's troposphere. The spatial variation of H2O was measured using IRIS spectra of the Hot Spots in the North and South Equatorial Belts, the Equatorial Zone, and for an average of the North and South Tropical Zones. The H2O column abundance above the 4 bar level is the same in the zones as in the SEB Hot Spots, about 20 cm-amagat. The NEB Hot Spots are desiccated by a factor of 3 with respect to the rest of Jupiter. For an average between -40 to 40 deg latitude, the H2O mole fraction, qH2O, is saturated for P less than 2 bars, qH2O = 4x10 to the -6 in the 2 to 4 bar range and it increases to 3x10 to the -5 at 6 bars. A similar vertical profile applies to the spatially resolved zone and belt spectra, except that H2O falls off more rapidly at P less than 4 bars in the NEB Hot Spots. The massive H2O cloud at 5 bars, T = 273 K, proposed in solar composition models, is inconsistent with the observations. Instead, a thin H2O ice cloud would form at 2 bars, T = 200 K. The O/H ratio in Jupiter, inferred from H2O measurements in both belts and zones at 6 bars, is depleted by a factor of 50 with respect to the Sun. The implications for the origin of Jupiter of globally depleted O/H, but enhanced C/H and N/H, are discussed.

Bjoraker, Gordon L.↗
NASA NTRS1986

Water vapor in Jupiter's atmosphere

High spectral resolution observations of Jupiter at 2.7 and 5 microns acquired from the Kuiper Airborne Observatory were used to infer the vertical distribution of H2O between 0.7 and 6 bars. The H2O mole fraction, qH2O, is saturated for P<2 bars, qH2O = 4x.000001 in the 2 to 4 bar range and it increases to 3x.00001 at 6 bars where T = 288 K. The base of the 5 micron line formation region is determined by pressure-induced H2 opacity. At this deepest accessible level, the O/H ratio in Jupiter is depleted by a factor of 50 with respect to the solar atmosphere. High spatial resolution Voyager IRIS spectra of Jupiter's North Tropical Zone, Equatorial Zone, and Hot Spots in the North and South Equatorial Belt were analyzed to determine the spatial variation of H2O across the planet. The column abundance of H2O above the 4 bar level is the same in the zones as in the SEB Hot Spots, about 20 cm-amgt. A cloud model for Jupiter's belts and zones was developed in order to fit the IRIS 5 micron spectra. An absorbing cloud located at 2 bars whose 5 micron optical thickness varies between 1 in the Hot Spots and 4 in the coldest zones satisfactorily matches the IRIS data.

Bjoraker, G. L.↗
NASA NTRS1973

Initial development of the June 1971 south equatorial belt disturbance on Jupiter

Photographs taken with the Catalina 61-inch reflector from June 21 through July 10, 1971 have permitted study and measurement of early developments of a major South Equatorial Belt (SEB) disturbance. High resolution photographs of the disturbance were obtained on seven nights during the 19-day interval. The first photograph at 04:38 UT on June 21 recorded the initial outbreak at 79.5 deg longitude (System 2), and -14 deg Zenographic latitude. From this point, dark spots moved along the SEBs towards increasing longitude. The preceding white spot had an initial period of 9h54m32.5 tor-3.5s, and retrograding dark spots on the SEBs a mean period of 9h58m30s.5 tor- 7s. The feature from which all the spots emerged had a rotation period of 9h55m29s tor- 2.5s, and is close to the System 3 radio period of 9h55m29.73s tor- 0.04s derived by Carr.

Minton, R. B.↗
NASA NTRS2012

Assessing the Time Variability of Jupiter's Tropospheric Properties from 1996 to 2011

We acquired and analyzed mid-infrared images of Jupiter's disk at selected wavelengths from NASA's Infrared Telescope Facility (IRTF) from 1996 to 2011, including a period of large-scale changes of cloud color and albedo. We derived the 100-300 mbar temperature structure, together with tracers of vertical motion: the thickness of a 600- mbar cloud layer, the 300-mbar abundance of the condensable gas NH3, and the 400- mbar para- vs. ortho-H2 ratio. The biggest visual change was detected in the normally dark South Equatorial Belt (SEB) that 'faded' to a light color in 2010, during which both cloud thickness and NH3 abundance rose; both returned to their pre-fade levels in 2011, as the SEB regained its normal dark color. The cloud thickness in Jupiter's North Temperate Belt (NTB) increased in 2002, coincident with its visible brightening, and its NH3 abundance spiked in 2002-2003. Jupiter's Equatorial Zone (EZ), a region marked by more subtle but widespread color and albedo change, showed high cloud thickness variability between 2007 and 2009. In Jupiter's North Equatorial Belt (NEB), the cloud thickened in 2005, then slowly decreased to a minimum value in 2010-2011. No temperature variations were associated with any of these changes, but we discovered temperature oscillations of approx.2-4 K in all regions, with 4- or 8-year periods and phasing that was dissimilar in the different regions. There was also no detectable change in the para- vs. ortho-H2 ratio over time, leading to the possibility that it is driven from much deeper atmospheric levels and may be time-invariant. Our future work will continue to survey the variability of these properties through the Juno mission, which arrives at Jupiter in 2016, and to connect these observations with those made using raster-scanned images from 1980 to 1993 (Orton et al. 1996 Science 265, 625).

Orton, G. S.↗
NASA NTRS1973

Initial development of the June 1971 South Equatorial Belt disturbance on Jupiter.

Photographs taken with the Catalina 61-inch reflector from June 21 through July 10, 1971 have enabled the author to study and measure the early developments of a major South Equatorial Belt (SEB) disturbance. High-resolution photographs of the disturbance were obtained on seven nights during the 19-day interval. Our first photograph at 04:38 UT on June 21 recorded the initial outbreak at 79.5 deg longitude (System II), and -14 deg zenographic latitude. From this point, dark spots moved along the SEBs towards increasing longitude, and white spots a short distance along the SEBn towards decreasing longitude.

Minton, R. B.↗
NASA NTRS1978

Multiple frequency sounding of a Jovian cloud

A thermal asymmetry displayed in Pioneer 10 45-micron IR radiometric data between the rising and setting limbs of the Jovian South Equatorial Belt (SEB) between -5.0 and -7.0 deg latitude is examined. A high correlation is found between the longitudinal asymmetry of the SEB at 45 microns and the appearance of Jupiter in 5-micron radiation. It is shown that there was a cooler 'obscuring' cloud within the SEB latitude region which correlates highly with the location of relatively reduced intensities at 45 microns. The cloud-top temperature is estimated on the basis of simultaneous 5- and 45-micron observations

Orton, G. S.↗
NASA NTRS2012

Seasonal and Non-Seasonal Variations of Jupiter's Atmosphere from Observations of Thermal Emission, 1994-2011

We analyzed mid-infrared images of Jupiter's thermal emission, covering approx.1.5 Jovian years, acquired in discrete filters between 7.8 and 24.5 microns. The behavior of stratospheric (approx.10-mbar) and tropospheric (approx.100-400 mbar) temperatures is generally consistent with predictions of seasonal variability, with differences between 100-mbar temperatures +/-50-60deg from the equator on the order of +/-2. Removing this effect, there appear to be long-term quasi-periodic variability of tropospheric temperatures, whose amplitude, phase and period depend on latitude. The behavior of temperatures in the Equatorial Zone (EZ) suggests a approx.4-6-year period with amplitude of about +/-1-1.5 K in temperature. At mid-latitudes, the periodicity is more distinct with amplitudes around +/-1.5-2.5 K and 4-8 year periods. The 4.2-year variation of stratospheric temperatures known as the quasiquadrennial oscillation or "QQO" (Leovy et al. 1991, Nature 354, 380) continued during this period. There were no variations of zonal mean temperatures associated with any of the "global upheaval" events that have produced dramatic changes of jupiter's visible appearance and cloud cover, although there are colder discrete regions associated with updrafts, e.g. the early stages of the re-darkening ("revival") of the South Equatorial Belt (SEB) in late 2010. On the other hand increases in the visible albedos ("fades") of belts are accompanied by increases in the thickness of a 700-mbar cloud layer (most likely NH3 ice) and clouds at higher pressures, together with the mixing ratio of NH3 gas near 400 mbar (above its condensation level). These quantities decrease during re-darkening ("revival") episodes, during which we note discrete features that are exceptions to the general correlation between dark albedos and minimal cloudiness. In contrast to all these changes, the meridional distribution of the 240-mbar para-H2 fraction appears to be invariant in time.

Orton, G.↗
NASA NTRS1975

The thermal structure of Jupiter. I - Implications of Pioneer 10 infrared radiometer data

Temperature profiles for low latitude regions of Jupiter in the 1.0-0.1 bar pressure regime are recovered from Pioneer 10 infrared radiometer data. The temperature near 0.1 bar is 108-117 K, depending on the overlying thermal structure assumed. For the South Equatorial Belt (SEB), the temperature at 1.0 bar is 170 K, assuming an adiabatic lapse rate in the deep atmosphere. The South Tropical Zone temperature at this level is 155 K if pure gaseous absorption is assumed. The temperature is much closer to that in the SEB, assuming the presence of an optically opaque cloud near the 0.6 atm (145 K) level. Such a cloud presence in the STrZ may be correlated with the visible and 5 micron appearance of the planet and with NH3 saturation just below this position. The molar fraction of H2 most consistent with the data is 0.91 + or - 0.08. The effective temperatures of the SEB and STrZ are 127.6 and 124.2 K, respectively. A discrepancy with the preliminary neutral atmosphere inversion of Pioneer 10 radio occultation data remains unexplained.

Orton, G. S.↗
NASA NTRS2004

Retrievals of Jovian Tropospheric Phosphine from Cassini/CIRS

On December 30th 2000, the Cassini-Huygens spacecraft reached the perijove milestone on its continuing journey to the Saturnian system. During an extended six-month encounter, the Composite Infrared Spectrometer (CIRS) returned spectra of the Jovian atmosphere, rings and satellites from 10-1400 cm(exp -1) (1000-7 microns) at a programmable spectral resolution of 0.5 to 15 cm(exp -1). The improved spectral resolution of CIRS over previous IR instrument-missions to Jupiter, the extended spectral range, and higher signal-to-noise performance provide significant advantages over previous data sets. CIRS global observations of the mid-infrared spectrum of Jupiter at medium resolution (2.5 cm(exp -1)) have been analysed both with a radiance differencing scheme and an optimal estimation retrieval model to retrieve the spatial variation of phosphine and ammonia fractional scale height in the troposphere between 60 deg S and 60 deg N at a spatial resolution of 6 deg. The ammonia fractional scale height appears to be high over the Equatorial Zone (EZ) but low over the North Equatorial Belt (NEB) and South Equatorial Belt (SEB) indicating rapid uplift or strong vertical mixing in the EZ. The abundance of phosphine shows a similar strong latitudinal variation which generally matches that of the ammonia fractional scale height. However while the ammonia fractional scale height distribution is to a first order symmetric in latitude, the phosphine distribution shows a North/South asymmetry at mid latitudes with higher amounts detected at 40 deg N than 40 deg S. In addition the data show that while the ammonia fractional scale height at this spatial resolution appears to be low over the Great Red Spot (GRS), indicating reduced vertical mixing above the approx. 500 mb level, the abundance of phosphine at deeper levels may be enhanced at the northern edge of the GRS indicating upwelling.

Irwin, P. G. J.↗
NASA NTRS2012

Variability of Jupiter's Five-Micron Hot Spot Inventory

Global upheavals on Jupiter involve changes in the albedo of entire axisymmetric regions, lasting several years, with the last two occurring in 1989 and 2006. Against this backdrop of planetary-scale changes, discrete features such as the Great Red Spot (GRS), and other vortices exhibit changes on shorter spatial- and time-scales. We track the variability of the discrete equatorial 5-micron hot spots, semi-evenly spaced in longitude and confined to a narrow latitude band centered at 6.5degN (southern edge of the North Equatorial Belt, NEB), abundant in Voyager images. Tantalizingly similar patterns were observed in the visible (bright plumes and blue-gray regions), where reflectivity in the red is anti-correlated with 5-microns thermal radiance. Ortiz et al. (1998, GRL, 103) characterized the latitude and drift rates of the hot spots, including the descent of the Galileo probe at the southern edge of a 5-micron hot spot, as the superposition of equatorial Rossby waves, with phase speeds between 99 - 103m/s, relative to System III. We note that the high 5-micron radiances correlate well but not perfectly with high 8.57-micron radiances. Because the latter are modulated primarily by changes in the upper ammonia (NH3) ice cloud opacity, this correlation implies that changes in the ammonia ice cloud field may be responsible for the variability seen in the 5-~m maps. During the NEB fade (2011 - early 2012), however, these otherwise ubiquitous features were absent, an atmospheric state not seen in decades. The ongoing NEB revival indicates nascent 5-~m hot spots as early as April 2012, with corresponding visible dark spots. Their continuing growth through July 2012 indicates the possit.le re-establishment of Rossby waves. The South Equatorial Belt (SEB) and NEB revivals began similarly with an instability that developed into a major outbreak, and many similarities in the observed propagation of clear regions.

Yanamandra-Fisher, Padma A.↗