The Juno microwave radiometer measured the thermal emission from Jupiter's atmosphere from the cloud tops at about 1 bar to as deep as a hundred bars of pressure during its first flyby over Jupiter (PJ1). The nadir brightness temperatures show that the Equatorial Zone is likely to be an ideal adiabat, which allows a determination of the deep ammonia abundance in the range 362−33+33 ppm. The combination of Markov chain Monte Carlo method and Tikhonov regularization is studied to invert Jupiter's global ammonia distribution assuming a prescribed temperature profile. The result shows (1) that ammonia is depleted globally down to 50–60 bars except within a few degrees of the equator, (2) the North Equatorial Belt is more depleted in ammonia than elsewhere, and (3) the ammonia concentration shows a slight inversion starting from about 7 bars to 2 bars. These results are robust regardless of the choice of water abundance.

Juno swoops around giant Jupiter Jupiter is the largest and most massive planet in our solar system. NASA's Juno spacecraft arrived at Jupiter on 4 July 2016 and made its first close pass on 27 August 2016. Bolton et al. present results from Juno's flight just above the cloud tops, including images of weather in the polar regions and measurements of the magnetic and gravitational fields. Juno also used microwaves to peer below the visible surface, spotting gas welling up from the deep interior. Connerney et al. measured Jupiter's aurorae and plasma environment, both as Juno approached the planet and during its first close orbit. Science , this issue p. 821 , p. 826

Oxygen is the most common element after hydrogen and helium in Jupiter's atmosphere, and may have been the primary condensable (as water ice) in the protoplanetary disk. Prior to the Juno mission, in situ measurements of Jupiter's water abundance were obtained from the Galileo Probe, which dropped into a meteorologically anomalous site. The findings of the Galileo Probe were inconclusive because the concentration of water was still increasing when the probe died. Here, we initially report on the water abundance in the equatorial region, from 0 to 4 degrees north latitude, based on 1.25 to 22 GHz data from Juno Microwave radiometer probing approximately 0.7 to 30 bars pressure. Because Juno discovered the deep atmosphere to be surprisingly variable as a function of latitude, it remains to confirm whether the equatorial abundance represents Jupiter's global water abundance. The water abundance at the equatorial region is inferred to be. !. %. × ppm, or. !. %. times the protosolar oxygen elemental ratio to H (1 uncertainties). If reflective of the global water abundance, the result suggests that the planetesimals formed Jupiter are unlikely to be water-rich clathrate hydrates. From thermodynamic calculations 1 , three types of cloud layers in the Jovian atmosphere are thought to exist: an ammonia ice cloud, an ammonium hydrosulfide ice cloud 2,3 , and a water ice and droplet cloud, formed approximately at 0.7 bars, 2.2 bars, and 5 bars, respectively, assuming solar abundances. The locations of these clouds may vary due to the local abundance, meteorology and specific model parameters. Condensation and evaporation of water contribute to weather on giant planets because water is the most abundant species apart from hydrogen and helium and the latent heat flux in convective storms is comparable to the solar and internal heat fluxes 4,5. Consequently, the thermal state of the atmosphere is affected by the amount of water vapor in the atmosphere. Prior to the Juno mission, in situ measurements of Jupiter's atmospheric composition below the clouds were obtained from the Galileo Probe 6 , which dropped into a meteorologically anomalous site (6.57° N planetocentric latitude , 4.46° W longitude) 7 , known as a 5 "hot spot" near the boundary between the visibly-bright Equatorial Zone (EZ) and the dark North Equatorial Belt (NEB) 8. The findings of the Galileo Probe were baffling, for they showed that the levels where ammonia and hydrogen sulfide become uniformly

Turbulent and radiative exchanges of heat between the ocean and atmosphere (hereafter heat fluxes), ocean surface wind stress, and state variables used to estimate them, are Essential Ocean Variables (EOVs) and Essential Climate Variables (ECVs) influencing weather and climate. This paper describes an observational strategy for producing 3-hourly, 25-km (and an aspirational goal of hourly at 10-km) heat flux and wind stress fields over the global, ice-free ocean with breakthrough 1-day random uncertainty of 15 W m −2 and a bias of less than 5 W m −2. At present this accuracy target is met only for OceanSITES reference station moorings and research vessels (RVs) that follow best practices. To meet these targets globally, in the next decade, satellite-based observations must be optimized for boundary layer measurements of air temperature, humidity, sea surface temperature, and ocean wind stress. In order to tune and validate these satellite measurements, a complementary global in situ flux array, built around an expanded OceanSITES network of time series reference station moorings, is also needed. The array would include 500-1000 measurement platforms, including autonomous surface vehicles, moored and drifting buoys, RVs, the existing OceanSITES network of 22 flux sites, and new OceanSITES expanded in 19 key regions. This array would be globally distributed, with 1-3 measurement platforms in each nominal 10 • by 10 • box. These improved moisture and temperature profiles and surface data, if assimilated into Numerical Weather Prediction (NWP) models, would lead to better representation of cloud formation processes, improving state variables and surface radiative and turbulent fluxes from these models. The in situ flux array provides globally distributed measurements and metrics for satellite algorithm development,

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Lightning has been detected on Jupiter by all visiting spacecraft through night-side optical imaging and whistler (lightning-generated radio waves) signatures. Jovian lightning is thought to be generated in the mixed-phase (liquid-ice) region of convective water clouds through a charge-separation process between condensed liquid water and water-ice particles, similar to that of terrestrial (cloud-to-cloud) lightning. Unlike terrestrial lightning, which emits broadly over the radio spectrum up to gigahertz frequencies, lightning on Jupiter has been detected only at kilohertz frequencies, despite a search for signals in the megahertz range . Strong ionospheric attenuation or a lightning discharge much slower than that on Earth have been suggested as possible explanations for this discrepancy. Here we report observations of Jovian lightning sferics (broadband electromagnetic impulses) at 600 megahertz from the Microwave Radiometer onboard the Juno spacecraft. These detections imply that Jovian lightning discharges are not distinct from terrestrial lightning, as previously thought. In the first eight orbits of Juno, we detected 377 lightning sferics from pole to pole. We found lightning to be prevalent in the polar regions, absent near the equator, and most frequent in the northern hemisphere, at latitudes higher than 40 degrees north. Because the distribution of lightning is a proxy for moist convective activity, which is thought to be an important source of outward energy transport from the interior of the planet, increased convection towards the poles could indicate an outward internal heat flux that is preferentially weighted towards the poles. The distribution of moist convection is important for understanding the composition, general circulation and energy transport on Jupiter.

The latitude‐altitude map of ammonia mixing ratio shows an ammonia‐rich zone at 0–5°N, with mixing ratios of 320–340 ppm, extending from 40–60 bars up to the ammonia cloud base at 0.7 bars. Ammonia‐poor air occupies a belt from 5–20°N. We argue that downdrafts as well as updrafts are needed in the 0–5°N zone to balance the upward ammonia flux. Outside the 0–20°N region, the belt‐zone signature is weaker. At latitudes out to ±40°, there is an ammonia‐rich layer from cloud base down to 2 bars that we argue is caused by falling precipitation. Below, there is an ammonia‐poor layer with a minimum at 6 bars. Unanswered questions include how the ammonia‐poor layer is maintained, why the belt‐zone structure is barely evident in the ammonia distribution outside 0–20°N, and how the internal heat is transported through the ammonia‐poor layer to the ammonia cloud base.

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