We observed Io with the James Webb Space Telescope (JWST) while the satellite was in eclipse, and detected thermal emission from several volcanoes. The data were taken as part of our JWST-ERS program #1373 on 15 November 2022. Kanehekili Fluctus was exceptionally bright, and Loki Patera had most likely entered a new brightening phase. Spectra were taken with NIRSpec/IFU at a resolving power R ≈ 2,700 between 1.65 and 5.3 µm. The spectra were matched by a combination of blackbody curves that showed that the highest temperature, ∼1,200 K, for Kanehekili Fluctus originated from an area ∼0.25 km² in size, and for Loki Patera this high temperature was confined to an area of ∼0.06 km². Lower temperatures, down to 300 K, cover areas of ∼2,000 km² for Kanehekili Fluctus, and ∼5,000 km² for Loki Patera. We further detected the a¹Δ ⇒ X³Σ⁻ 1.707 µm rovibronic forbidden SO emission band complex over the southern hemisphere, which peaked at the location of Kanehekili Fluctus. This is the first time this emission has been seen above an active volcano, and suggests that the origin of such emissions is ejection of SO molecules directly from the vent in an excited state, after having been equilibrated at temperatures of ∼1,500 K below the surface, as was previously hypothesized.

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We observed Jupiter four times over a full rotation (10 h) with the upgraded Karl G. Jansky Very Large Array (VLA) between December 2013 and December 2014. Preliminary results at 4–17 GHz were presented in de Pater et al. (2016); in the present paper we present the full data set at frequencies between 3 and 37 GHz. Major findings are: i) The radio-hot belt at 8.5–11° N latitude, near the interface between the North Equatorial Belt (NEB) and the Equatorial Zone (EZ) is prominent at all frequencies (3–37 GHz). Its location coincides with the southern latitudes of the NEB (7–17° N). ii) Longitude-smeared maps reveal belts and zones at all frequencies at latitudes ≲ |20°|. At higher latitudes numerous fainter bands are visible at frequencies ≳ 7 GHz. The lowest brightness temperature is in the EZ near a latitude of 4° N, and the NEB has the highest brightness temperature near 11° N. The bright part of the NEB increases in latitudinal extent (spreads towards the north) with deceasing frequency, i.e., with depth into the atmosphere. In longitude-resolved maps, several belts, in particular in the southern hemisphere, are not continuous along the latitude line, but broken into small segments as if caused by an underlying wave. iii) Model fits to longitude-smeared spectra are obtained at each latitude. These show a high NH3 abundance (volume mixing ratio ∼4×10−4) in the deep (P > 8–10 bar) atmosphere, decreasing at higher altitudes due to cloud formation (e.g., in zones), or dynamics in combination with cloud condensation (belts). In the NEB ammonia gas is depleted down to at least the 20 bar level with an abundance of 1.75×10−4. The NH3 abundance at latitudes > |50|° is characterized by a relatively low value (∼1.75×10−4) between ∼ 1 and 10 bar. iv) Using the entire VLA dataset, we confirm that the planet is extremely dynamic in the upper layers of the atmosphere, at P < 2–3 bar, i.e., at the altitudes where clouds form. At most latitudes the relative humidity within and above the NH3 cloud is considerably sub-saturated. v) The radiative transfer models that best fit the longitude-smeared VLA data at 4–25 GHz match the Juno PeriJove 1 microwave data extremely well, i.e., the NH3 abundance is high in the deep atmosphere, and either remains constant or decreases with altitude. vi) Hot spots have a very low, sub-saturated NH3 abundance at the altitudes of the NH3-ice cloud, gradually increasing from an abundance of ∼10−5 at 0.6 bar to the deep atmosphere value (∼4×10−4) at 8 bar. vii) We previously showed the presence of large ammonia plumes, which together with the 5-µm hot spots constitute the equatorially trapped Rossby wave. Observations of these plumes at 12–25 GHz reveal them to be supersaturated at ∼ 0.8–0.5 bar, which implies plumes rise ∼ 10 km above the main clouddeck. Numerous small ammonia plumes are detected at other locations (e.g., at 19° S and interspersed with hot spots). viii) The Great Red Spot (GRS) and Oval BA show relatively low NH3 abundances throughout the troposphere (∼ 1.5–1.8 × 10−4), and the GRS is considerably sub-saturated at higher altitudes.@en

We obtained the first maps of Jupiter at 1-3 mm wavelength with the Atacama Large Millimeter/Submillimeter Array (ALMA) on 2017 January 3-5, just days after an energetic eruption at 16.5S jovigraphic latitude had been reported by the amateur community, and about two to three months after the detection of similarly energetic eruptions in the northern hemisphere, at 22.2-23.0N. Our observations, probing below the ammonia cloud deck, show that the erupting plumes in the South Equatorial Belt bring up ammonia gas from the deep atmosphere. While models of plume eruptions that are triggered at the water condensation level explain data taken at uv-visible and mid-infrared wavelengths, our ALMA observations provide a crucial, hitherto missing, link in the moist convection theory by showing that ammonia gas from the deep atmosphere is indeed brought up in these plumes. Contemporaneous Hubble Space Telescope data show that the plumes reach altitudes as high as the tropopause. We suggest that the plumes at 22.2-23.0N also rise up well above the ammonia cloud deck and that descending air may dry the neighboring belts even more than in quiescent times, which would explain our observations in the north.

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Radio wavelengths can probe altitudes in Jupiter's atmosphere below its visible cloud layers. We used the Very Large Array to map this unexplored region down to ∼8 bar, ∼100 kilometers below the visible clouds. Our maps reveal a dynamically active planet at pressures less than 2 to 3 bar. A radio-hot belt exists, consisting of relatively transparent regions (a low ammonia concentration, NH₃ being the dominant source of opacity) probing depths to over ∼8 bar; these regions probably coincide with 5-micrometer hot spots. Just to the south we distinguish an equatorial wave, bringing up ammonia gas from Jupiter's deep atmosphere. This wave has been theorized to produce the 5-micrometer hot spots; we observed the predicted radio counterpart of such hot spots.

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