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The science enabled by the deep and high‐cadence survey that will be performed by the Vera Rubin Observatory has led to an increase of survey and follow‐up capabilities around the world. The infrared, has however, not match this growth due to the challenges caused by the atmospheric and the cost of large detector arrays. In this paper, we present solutions to resolve these challenges and a path toward an Antarctic observatory capable matching the volumetric speed of the Vera Rubin Observatory survey in the infrared k‐band. We will detail the current state of infrared survey telescopes, demonstrate the benefits of Antarctic high‐plateau for such observations, and show some of the development made in detector technologies to make large detector arrays a reality for such application. [ABSTRACT FROM AUTHOR]

Jupiter's atmosphere is dominated by multiple jet streams which are strongly tied to its 3D atmospheric circulation. Lacking a rigid bottom boundary, several models exist for how the meridional circulation extends into the planetary interior. Here, we show, collecting evidence from multiple instruments of the Juno mission, the existence of midlatitudinal meridional circulation cells which are driven by turbulence, similar to the Ferrel cells on Earth. Different than Earth, which contains only one such cell in each hemisphere, the larger, faster rotating Jupiter can incorporate multiple cells. The cells form regions of upwelling and downwelling, which we show are clearly evident in Juno's microwave data between latitudes 60°S $60{}^{\circ}\mathrm{S}$ and 60°N $60{}^{\circ}\mathrm{N}$. The existence of these cells is confirmed by reproducing the ammonia observations using a simplistic model. This study solves a long‐standing puzzle regarding the nature of Jupiter's subcloud dynamics and provides evidence for eight cells in each Jovian hemisphere. Plain Language Summary: The cloud layer of Jupiter is divided into dark and bright bands that are shaped by strong east‐west winds. Such winds in planetary atmospheres are thought to be tied with a meridional circulation. The Juno mission collected measurements of Jupiter's atmosphere at various wavelengths, which penetrate the cloud cover. Here, we provide evidence, using the Juno data, of eight deep Jovian circulation cells in each hemisphere encompassing the east‐west winds, gaining energy from atmospheric waves, and extending at least to a depth of hundreds of kilometers. Different than Earth, which has only one analogous cell in each hemisphere, known as a Ferrel cell, Jupiter can contain more cells due to its larger size and faster spin. To support the presented evidence, we modeled how ammonia gas would spread under the influence of such cells and compared it to the Juno measurements. The presented results shed light on the unseen flow structure beneath Jupiter's clouds. Key Points: Measurements from multiple instruments of the Juno mission are interpreted to reveal the meridional circulation beneath Jupiter's clouds16 Jet‐paired deep cells, extending from the cloud deck down to at least 240 bar, are revealed between latitudes 60°S $60{}^{\circ}\mathrm{S}$ and 60°N $60{}^{\circ}\mathrm{N}$, driven by turbulence similar to Earth's Ferrel cellsThe findings are supported by modeling the advection of tracers due to the cells, showing agreement with NH3 ${\mathrm{N}\mathrm{H}}_{3}$ data [ABSTRACT FROM AUTHOR]

The observed zonal winds at Jupiter's cloud tops have been shown to be closely linked to the asymmetric part of the planet's measured gravity field. Here, we examine to what extent, and at which latitudes, must the flows at depth resemble those at the cloud level to match the gravity signal. We show, using both the symmetric and asymmetric parts of the measured gravity field, that the observed cloud‐level wind profile between 25°S and 25°N must extend unaltered to depths of thousands of kilometers. Poleward, the midlatitude deep jets also contribute to the gravity signal, but might differ somewhat from the cloud‐level winds. We analyze the likelihood of this difference and give bounds to its strength. We also find that to match the gravity measurements, the winds must project inward in the direction parallel to Jupiter's spin axis, and decay inward in the radial direction. Plain Language Summary: Observations of Jupiter's cloud‐tops reveal very strong atmospheric winds reaching 500 km/hr. Using very accurate measurements of the planet's gravity field, provided by NASA's Juno spacecraft, the cloud‐level winds were found to extend thousands of kilometers into the interior of Jupiter, with a wind profile similar to that observed at the clouds level. However, analysis of various measurements suggested that at some latitudinal regions the flow below the clouds might be different to some extent. Here we explore the constraints posed by the Juno gravity measurements on the latitudinal profile of the zonal flow in Jupiter below the cloud level. We find that to explain the detailed latitudinal structure of the wind‐attributed gravity field, the cloud‐level winds in the 60°S–60°N range have to extend deep into the planet, approximately keeping their observed latitudinal profile. With that, we find that most of the wind‐induced gravity signal comes from the 25°S to 25°N region, where the strongest jets reside, suggesting that in the midlatitudes the observed jets at the cloud level might be somewhat different at depth. Key Points: Jupiter's cloud‐level wind profile extended to depth, matches in sign and amplitude both the measured odd and residual‐even gravity harmonicsThe majority of the signal comes from the wind profile between 25°S and 25°N, which must extend unaltered thousands of kilometers deepThe gravity signal also implies that from the cloud‐tops downward the flow must be organized in a columnar structure and also decay radially [ABSTRACT FROM AUTHOR]

Recent Juno observations have greatly extended the temporal and spatial coverage of lightning detection on Jupiter. We use these data to constrain a model of moist convection and lightning generation in Jupiter's atmosphere, and derive a roughly solar abundance of water at the base of the water cloud. Shallow lightning, observed by Juno (Becker et al., 2020, https://doi.org/10.1038/s41586‐020‐2532‐1, Nature, 584, 55–58) and defined as flashes originating at altitudes corresponding to pressure less than 2 bars, is reproduced, as is lightning at a deeper range of pressures, including those below the water cloud base. It is found that the generation of lightning requires ammonia to stabilize liquid water at altitudes corresponding to sub‐freezing temperatures. We find a range of local water abundances in which lightning is possible, including subsolar values of water—consistent with other determinations of deep oxygen abundance. Plain Language Summary: Many missions to Jupiter have detected lightning in its atmosphere, but the Juno mission now in orbit has made the most extensive observations on where, and the rate at which, lightning flashes occur. Lightning on Earth is the discharge of electricity that happens when positive and negative charges separate between raindrops and small ice particles in towering thunderheads, somewhat like how combing a cat's fur can create a static electric discharge. This same process is thought to occur in Jupiter's atmosphere, though with some important differences, and we model that process here. Comparing our model with the Juno data also supports the idea that ammonia is in Jupiter's thunderheads, dissolving some of the water ice and increasing the abundance of raindrops. Key Points: A model of the generation of lightning is applied to Jupiter, constrained by Juno data; the model reproduces well terrestrial ratesThe model allows for lightning at moderately subsolar abundances of water if ammonia is presentThe model produces lightning at shallow altitudes (heights above 2 bars) while also producing lightning at deeper levels seen by Galileo [ABSTRACT FROM AUTHOR]

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Microwave observations by the Juno spacecraft have shown that, contrary to expectations, the concentration of ammonia is still variable down to pressures of tens of bars in Jupiter. We show that during strong storms able to loft water ice into a region located at pressures between 1.1 and 1.5 bar and temperatures between 173 and 188 K, ammonia vapor can dissolve into water ice to form a low‐temperature liquid phase containing about one‐third ammonia and two‐third water. We estimate that, following the process creating hailstorms on Earth, this liquid phase enhances the growth of hail‐like particles that we call mushballs. We develop a simple model to estimate the growth of these mushballs, their fall into Jupiter's deep atmosphere, and their evaporation. We show that they evaporate deeper than the expected water cloud base level, between 5 and 27 bar depending on the assumed abundance of water ice lofted by thunderstorms and on the assumed ventilation coefficient governing heat transport between the atmosphere and the mushball. Because the ammonia is located mostly in the core of the mushballs, it tends to be delivered deeper than water, increasing the efficiency of the process. Further sinking of the condensates is expected due to cold temperature and ammonia‐ and water‐rich downdrafts formed by the evaporation of mushballs. This process can thus potentially account for the measurements of ammonia depletion in Jupiter's deep atmosphere. Plain Language Summary: The Juno mission has revealed that Jupiter's atmosphere is much more complex and intriguing than previously anticipated. Most of Jupiter's atmosphere was shown to be depleted in ammonia. While ammonia was expected to be well mixed, large scale variability of ammonia was detected at least 100 km below the cloud level where condensation occurs. We propose a mechanism to explain this depletion and variability. We show that in Jupiter, at very low temperatures (of order −90° C), water ice and ammonia vapor combine to form a liquid and we hypothesize that this subsequently triggers unexpected meteorology. During Jupiter's violent storms, hailstones form from this liquid, similar to the process in terrestrial storms where hail forms in the presence of supercooled liquid water. Growth of the hailstones creates a slush‐like substance surrounded by a layer of ice, and these "mushballs" fall, evaporate, and continue sinking further in the planet's deep atmosphere, creating both ammonia depletion and variability, potentially explaining the Juno observations. Key Points: We show that ammonia can melt water‐ice crystals in Jupiter's storms and lead to the formation of water‐ammonia hailstones (mushballs)These mushballs and subsequent downdrafts transport ammonia to very deep levelsThis can potentially explain Juno measurements that Jupiter's ammonia abundance is variable until at least 150 km below the visible clouds [ABSTRACT FROM AUTHOR]

Observations of Jupiter's deep atmosphere by the Juno spacecraft have revealed several puzzling facts: The concentration of ammonia is variable down to pressures of tens of bars and is strongly dependent on latitude. While most latitudes exhibit a low abundance, the Equatorial Zone of Jupiter has an abundance of ammonia that is high and nearly uniform with depth. In parallel, the Equatorial Zone is peculiar for its absence of lightning, which is otherwise prevalent most everywhere else on the planet. We show that a model accounting for the presence of small‐scale convection and water storms originating in Jupiter's deep atmosphere accounts for the observations. Where strong thunderstorms are observed on the planet, we estimate that the formation of ammonia‐rich hail ("mushballs") and subsequent downdrafts can deplete efficiency the upper atmosphere of its ammonia and transport it efficiently to the deeper levels. In the Equatorial Zone, the absence of thunderstorms shows that this process is not occurring, implying that small‐scale convection can maintain a near‐homogeneity of this region. A simple model satisfying mass and energy balance accounts for the main features of Juno's microwave radiometer observations and successfully reproduces the inverse correlation seen between ammonia abundance and the lightning rate as function of latitude. We predict that in regions where ammonia is depleted, water should also be depleted to great depths. The fact that condensates are not well mixed by convection until far deeper than their condensation level has consequences for our understanding of Jupiter's deep interior and of giant‐planet atmospheres in general. Plain Language Summary: Measurements by the Juno spacecraft have shown that much more ammonia is present in Jupiter's atmosphere near the equator than at higher latitudes. This was never predicted by theory. In a companion paper, we showed that ammonia can combine with water to form hail‐like particles that we call "mushballs." Here we show that mushball formation in storms can effectively dry out the atmosphere of its ammonia. Our idea is supported by lack of lightning activity at the equator compared to higher latitudes. Because lightning is generated in rainstorms, the lack of lightning at the equator suggests that the thunderstorms forming the mushballs responsible for the depletion of ammonia are not present there. In contrast, in other regions where lightning is present, we predict that not only ammonia but also water are depleted to great depths, more than a hundred kilometers below the cloud tops. The complexity of Jupiter's meteorology means we must expect similar complexity in observing the weather on other giant planets in and beyond our solar system. Key Points: Juno measurements show that ammonia gas in Jupiter has variable abundance to great depth and as a function of latitudeWe show that Jupiter's powerful storms control ammonia abundance by leading to the formation of water‐ammonia hailstones (mushballs) and evaporative downdraftsA simple atmospheric mixing model successfully links measured lightning rate to ammonia abundance and predicts variable water abundance to great depth [ABSTRACT FROM AUTHOR]