Jupiter's ammonia distribution-derived from VLA maps at 3-37 GHz

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 417 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 8.511 degrees N latitude, near the interface between the North Equatorial Belt (NEB) and the Equatorial Zone (EZ) is prominent at all frequencies (337 GHz). Its location coincides with the southern latitudes of the NEB (717 degrees N). ii) Longitude-smeared maps reveal belts and zones at all frequencies at latitudes less than or similar to vertical bar 20 degrees vertical bar. At higher latitudes numerous fainter bands are visible at frequencies greater than or similar to 7 GHz. The lowest brightness temperature is in the EZ near a latitude of 4 degrees N, and the NEB has the highest brightness temperature near 11 degrees 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 similar to 4 x 10(-4) ) in the deep (P > 810 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 . The NH3 abundance at latitudes > vertical bar 50 vertical bar degrees is characterized by a relatively low value (similar to 1.75 x 10(-4)) between similar to 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 < 23 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 425 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 similar to 10(-5) at 0.6 bar to the deep atmosphere value (similar to 4 x 10(-4)) at 8 bar. vii) We previously showed the presence of large ammonia plumes, which together with the 5-mu m hot spots constitute the equatorially trapped Rossby wave. Observations of these plumes at 1225 GHz reveal them to be supersaturated at similar to 0.80.5 bar, which implies plumes rise similar to 10 km above the main clouddeck. Numerous small ammonia plumes are detected at other locations (e.g., at 19 degrees S and interspersed with hot spots). viii) The Great Red Spot (GRS) and Oval BA show relatively low NH3 abundances throughout the troposphere (similar to 1.51.8 x 10(-4)), and the GRS is considerably sub-saturated at higher altitudes.