Jupiter's atmospheric jet streams extend thousands of kilometres deep.

The depth to which Jupiter's observed east-west jet streams extend has been a long-standing question. Resolving this puzzle has been a primary goal for the Juno spacecraft, which has been in orbit around the gas giant since July 2016. Juno's gravitational measurements have revealed that Jupiter's gravitational field is north-south asymmetric, which is a signature of the planet's atmospheric and interior flows. Here we report that the measured odd gravitational harmonics J3, J5, J7 and J9 indicate that the observed jet streams, as they appear at the cloud level, extend down to depths of thousands of kilometres beneath the cloud level, probably to the region of magnetic dissipation at a depth of about 3,000 kilometres. By inverting the measured gravity values into a wind field, we calculate the most likely vertical profile of the deep atmospheric and interior flow, and the latitudinal dependence of its depth. Furthermore, the even gravity harmonics J8 and J10 resulting from this flow profile also match the measurements, when taking into account the contribution of the interior structure. These results indicate that the mass of the dynamical atmosphere is about one per cent of Jupiter's total mass.

Clusters of cyclones encircling Jupiter's poles.

The familiar axisymmetric zones and belts that characterize Jupiter's weather system at lower latitudes give way to pervasive cyclonic activity at higher latitudes. Two-dimensional turbulence in combination with the Coriolis ß-effect (that is, the large meridionally varying Coriolis force on the giant planets of the Solar System) produces alternating zonal flows. The zonal flows weaken with rising latitude so that a transition between equatorial jets and polar turbulence on Jupiter can occur. Simulations with shallow-water models of giant planets support this transition by producing both alternating flows near the equator and circumpolar cyclones near the poles. Jovian polar regions are not visible from Earth owing to Jupiter's low axial tilt, and were poorly characterized by previous missions because the trajectories of these missions did not venture far from Jupiter's equatorial plane. Here we report that visible and infrared images obtained from above each pole by the Juno spacecraft during its first five orbits reveal persistent polygonal patterns of large cyclones. In the north, eight circumpolar cyclones are observed about a single polar cyclone; in the south, one polar cyclone is encircled by five circumpolar cyclones. Cyclonic circulation is established via time-lapse imagery obtained over intervals ranging from 20 minutes to 4 hours. Although migration of cyclones towards the pole might be expected as a consequence of the Coriolis ß-effect, by which cyclonic vortices naturally drift towards the rotational pole, the configuration of the cyclones is without precedent on other planets (including Saturn's polar hexagonal features). The manner in which the cyclones persist without merging and the process by which they evolve to their current configuration are unknown.

A giant thunderstorm on Saturn.

Lightning discharges in Saturn's atmosphere emit radio waves with intensities about 10,000 times stronger than those of their terrestrial counterparts. These radio waves are the characteristic features of lightning from thunderstorms on Saturn, which last for days to months. Convective storms about 2,000 kilometres in size have been observed in recent years at planetocentric latitude 35° south (corresponding to a planetographic latitude of 41° south). Here we report observations of a giant thunderstorm at planetocentric latitude 35° north that reached a latitudinal extension of 10,000 kilometres-comparable in size to a 'Great White Spot'-about three weeks after it started in early December 2010. The visible plume consists of high-altitude clouds that overshoot the outermost ammonia cloud layer owing to strong vertical convection, as is typical for thunderstorms. The flash rates of this storm are about an order of magnitude higher than previous ones, and peak rates larger than ten per second were recorded. This main storm developed an elongated eastward tail with additional but weaker storm cells that wrapped around the whole planet by February 2011. Unlike storms on Earth, the total power of this storm is comparable to Saturn's total emitted power. The appearance of such storms in the northern hemisphere could be related to the change of seasons, given that Saturn experienced vernal equinox in August 2009.

Raltegravir-emtricitabine-tenofovir as HIV nonoccupational post-exposure prophylaxis in men who have sex with men: safety, tolerability and adherence.

OBJECTIVES: Three-drug nonoccupational post-exposure prophylaxis (NPEP) typically includes co-formulated emtricitabine-tenofovir (FTC-TDF) and a protease inhibitor. However, protease inhibitors can cause significant toxicities, can interact with prescribed and illicit drugs, and work late in the viral cycle. Agents that act before viral integration into host DNA may have efficacy advantages. Raltegravir (RAL) is a good candidate for NPEP as it has few side effects or drug interactions and acts prior to HIV integration. The objective of this study was to investigate the use of RAL in 3-drug NPEP in terms of safety, adherence and tolerability. METHODS: We evaluated 28 days of RAL-FTC-TDF treatment in 86 men and FTC-TDF treatment in 34 men eligible for three- and two-drug NPEP, respectively. We assessed adherence (compared between groups and with nonstudy controls) and clinical and adverse events at weeks 1, 2 and 4, and efficacy at week 12. Analyses were by intention to treat, excluding from the adherence analysis subjects who ceased NPEP because their source was HIV-uninfected. RESULTS: No participant became infected with HIV. For RAL-FTC-TDF and FTC-TDF, regimen completion rates were 92% and 91% and medication adherence rates were 89% and 90%, respectively. Eight (9%) RAL recipients developed mild myalgias, with four developing transient grade 4 elevations in creatine kinase (two developed both), all of which improved to grade 2 or less by week 4 without RAL discontinuation. Eight prescribed and 37 potential illicit drug interactions with a protease inhibitor were avoided by use of RAL. CONCLUSIONS: RAL-FTC-TDF is well tolerated as NPEP, results in high levels of adherence and avoids potential drug-drug interactions. Patients and clinicians should be aware of the potential for acute muscle toxicity when RAL is used as NPEP.

Microwave observations reveal the deep extent and structure of Jupiter's atmospheric vortices.

Jupiter's atmosphere has a system of zones and belts punctuated by small and large vortices, the largest being the Great Red Spot. How these features change with depth is unknown, with theories of their structure ranging from shallow meteorological features to surface expressions of deep-seated convection. We present observations of atmospheric vortices using the Juno spacecraft's Microwave Radiometer. We found vortex roots that extend deeper than the altitude at which water is expected to condense, and we identified density inversion layers. Our results constrain the three-dimensional structure of Jupiter's vortices and their extension below the clouds.

Mars: occurrence of liquid water.

In the absence of juvenile liquid water, condensation of water vapor to ice and subsequent melting of ice are the only means of producing liquid water on the martian surface. However, the evaporation rate is so high that the available heat sources cannot melt pure ice. Liquid water is therefore limited to concentrated solutions of strongly deliquescent salts.

Jupiters great red spot: a free atmospheric vortex?

A simple hydrodynamic model yields steady-state solutions with many of the properties of the Great Red Spot and the neighboring belts and zones of Jupiter. No special forcing mechanism is necessary to maintain the circulation of the Spot. This is consistent with observations which indicate that the Great Red Spot and the zones have similar dynamic properties.

Atmospheric dynamics of the outer planets.

Despite major differences in the solar and internal energy inputs, the atmospheres of the four Jovian planets all exhibit latitudinal banding and high-speed jet streams. Neptune and Saturn are the windiest planets, Jupiter is the most active, and Uranus is a tipped-over version of the others. Large oval storm systems exhibit complicated time-dependent behavior that can be simulated in numerical models and laboratory experiments. The largest storm system, the Great Red Spot of Jupiter, has survived for more than 300 years in a chaotic shear zone where smaller structures appear and dissipate every few days. Future space missions will add to our understanding of small-scale processes, chemical composition, and vertical structure. Theoretical hypotheses about the interiors provide input for fluid dynamical models that reproduce many observed features of the winds, temperatures, and cloud patterns. In one set of models the winds are confined to the thin layer where clouds form. In other models, the winds extend deep into the planetary fluid interiors. Hypotheses will be tested further as observations and theories become more exact and detailed comparisons are made.

Triton's Plumes: The Dust Devil Hypothesis.

Triton's plumes are narrow columns 10 kilometers in height, with tails extending horizontally for distances over 100 kilometers. This structure suggests that the plumes are an atmospheric rather than a surface phenomenon. The closest terrestrial analogs may be dust devils, which are atmospheric vortices originating in the unstable layer close to the ground. Since Triton has such a low surface pressure, extremely unstable layers could develop during the day. Patches of unfrosted ground near the subsolar point could act as sites for dust devil formation because they heat up relative to the surrounding nitrogen frost. The resulting convection would warm the atmosphere to temperatures of 48 kelvin or higher, as observed by the Voyager radio science team. Assuming that velocity scales as the square root of temperature difference times the height of the mixed layer, a velocity of 20 meters per second is derived for the strongest dust devils on Triton. Winds of this speed could raise particles provided they are a factor of 103 to 104 less cohesive than those on Earth.

Annual heat balance of martian polar caps: viking observations.

The Infrared Thermal Mappers aboard the two Viking orbiters obtained solar reflectance and infrared emission measurements of the Martian north and south polar regions during an entire Mars year. The observations were used to determine annual radiation budgets, infer annual carbon dioxide frost budgets, and constrain spring season surface and atmospheric properties with the aid of a polar radiative model. The results provide further confirmation of the presence of permanent CO(2)frost deposits near the south pole and show that the stability of these deposits can be explained by their high reflectivities. In the north, the observed absence of solid CO(2) during summer was primarily the result of enhanced CO(2) sublimation rates due to lower frost reflectivities during spring. The results suggest that the present asymmetric behavior of CO(2)frost at the Martian poles is caused by preferential contamination of the north seasonal polar cap by atmospheric dust.

Simple Dynamical Models of Neptune's Great Dark Spot.

The large amplitude oscillations of the shape of Neptune's Great Dark Spot are well reproduced by simple dynamical models of an isolated vortex embedded in a background shear flow. From the time series of the aspect ratio and inclination of the vortex values are estimated for the background shear and the mean vorticity of the Great Dark Spot, and a lower bound is placed on the value of the Rossby deformation radius. These models imply the existence of a planetary-scale zone of deterministic chaotic advection in the atmosphere of Neptune.

Pioneer saturn infrared radiometer: preliminary results.

The effective temperature of Saturn, 94.4 + 3 K, implies a total emission greater than two times the absorbed sunlight. The infrared data alone give an atmospheric abundance of H(2) relative to H(2) + He of 0.85 +/- 0.15. Comparison of infrared and radio occultation data will give a more precise estimate. Temperature at the 1-bar level is 137 to 140 K, and 2.5 K differences exist between belts and zones up to the 0.06-bar level. Ring temperatures range from 60 to 70 K on the south (illuminated) side and from < 60 to 67 K in the planet's shadow. The average temperature of the north (unilluminated) side is approximately 55 K. Titan's 45-micrometer brightness temperature is 80 +/- 10 K.

Surface and airborne evidence for plumes and winds on triton.

Aeolian features on Triton that were imaged during the Voyager Mission have been grouped. The term "aeolian feature" is broadly defined as features produced by or blown by the wind, including surface and airborne materials. Observations of the latitudinal distributions of the features probably associated with current activity (known plumes, crescent streaks, fixed terminator clouds, and limb haze with overshoot) all occur from latitude -37 degrees to latitude -62 degrees . Likely indicators of previous activity (dark surface streaks) occur from latitude -5 degrees to -70 degrees , but are most abundant from -15 degrees to -45 degrees , generally north of currently active features. Those indicators which give information on wind direction and speed have been measured. Wind direction is a function of altitude. The predominant direction of the surface wind streaks is found to be between 40 degrees and 80 degrees measured clockwise from north. The average orientation of streaks in the northeast quadrant is 59 degrees . Winds at 1- to 3- kilometer altitude are eastward, while those at &8 kilometers blow west.

Galileo imaging of atmospheric emissions from Io.

The Galileo spacecraft has detected diffuse optical emissions from Io in high-resolution images acquired while the satellite was eclipsed by Jupiter. Three distinct components make up Io's visible emissions. Bright blue glows of more than 300 kilorayleighs emanate from volcanic plumes, probably due to electron impact on molecular sulfur dioxide. Weaker red emissions, possibly due to atomic oxygen, are seen along the limbs, brighter on the pole closest to the plasma torus. A faint green glow appears concentrated on the night side of Io, possibly produced by atomic sodium. Io's disk-averaged emission diminishes with time after entering eclipse, whereas the localized blue glows brighten instead.

HST imaging of atmospheric phenomena created by the impact of comet Shoemaker-Levy 9.

Hubble Space Telescope (HST) images reveal major atmospheric changes created by the collision of comet Shoemaker-Levy 9 with Jupiter. Plumes rose to 3000 kilometers with ejection velocities on the order of 10 kilometers second-1; some plumes were visible in the shadow of Jupiter before rising into sunlight. During some impacts, the incoming bolide may have been detected. Impact times were on average about 8 minutes later than predicted. Atmospheric waves were seen with a wave front speed of 454 +/- 20 meters second-1. The HST images reveal impact site evolution and record the overall change in Jupiter's appearance as a result of the bombardment.

Pioneer 11 infrared radiometer experiment: the global heat balance of jupiter.

Data obtained by the infrared radiometers on the Pioneer 10 and Pioneer 11 spacecraft, over a large range of emission angles, have indicated an effective temperature for Jupiter of 125 degrees +/- 3 degrees K. The implied ratio of planetary thermal emission to solar energy absorbed is 1.9+/-0.2, a value not significantly different from the earth-based estimate of 2.5+/-0.5.

Thermal structure of the venus atmosphere in the middle cloud layer.

Thermal structure measurements obtained by the two VEGA balloons show the Venus middle cloud layer to be generally adiabatic. Temperatures measured by the two balloons at locations roughly symmetric about the equator differed by about 6.5 kelvins at a given pressure. The VEGA-2 temperatures were about 2.5 kelvins cooler and those of VEGA-1 about 4 kelvins warmer than temperatures measured by the Pioneer Venus Large Probe at these levels. Data taken by the VEGA-2 lander as it passed through the middle cloud agreed with those of the VEGA-2 balloon. Study of individual frames of the balloon data suggests the presence of multiple discrete air masses that are internally adiabatic but lie on slightly different adiabats. These adiabats, for a given balloon, can differ in temperature by as much as 1 kelvin at a given pressure.

Implications of the VEGA Balloon Results for Venus Atmospheric Dynamics.

Both VEGA balloons encountered vertical winds with typical velocities of 1 to 2 meters per second. These values are consistent with those estimated from mixing length theory of thermal convection. However, small-scale temperature fluctuations for each balloon were sometimes larger than predicted. The approximate 6.5-kelvin difference in temperature consistently seen between VEGA-1 and VEGA-2 is probably due to synoptic or planetary-scale nonaxisymmetric disturbances that propagate westward with respect to the planet. There is also evidence from Doppler data for the existence of solar-fixed nonaxisymmetric motions that may be thermal tides. Surface topography may influence atmospheric motions experienced by the VEGA-2 balloon.

Infrared remote sounding of the middle atmosphere of venus from the pioneer orbiter.

Orbiter infrared measurements of the Venus atmosphere in the 60- to 140-kilometer region show very small diurnal temperature differences near the cloud tops, increasing somewhat at higher levels. The seasonal (that is, equator to pole) contrasts are an order of magnitude larger, and the temperatures unexpectedly increase with increasing latitude below 80 kilometers. An isothermal layer at least two scale heights in vertical extent is found near the 100-kilometer altitude, where the temperature is about 175 K. Structure is present in the cloud temperature maps on a range of spatial scales. The most striking is at high latitude, where contrasts of nearly 50 K are observed between a cold circumpolar band and the region near the pole itself.

Neptune's Wind Speeds Obtained by Tracking Clouds in Voyager Images.

Images of Neptune obtained by the narrow-angle camera of the Voyager 2 spacecraft reveal large-scale cloud features that persist for several months or longer. The features' periods of rotation about the planetary axis range from 15.8 to 18.4 hours. The atmosphere equatorward of -53 degrees rotates with periods longer than the 16.05-hour period deduced from Voyager's planetary radio astronomy experiment (presumably the planet's internal rotation period). The wind speeds computed with respect to this radio period range from 20 meters per second eastward to 325 meters per second westward. Thus, the cloud-top wind speeds are roughly the same for all the planets ranging from Venus to Neptune, even though the solar energy inputs to the atmospheres vary by a factor of 1000.