Evidence of pure ammonia clouds in Jupiter’s Northern Temperate domain from Juno/JIRAM infrared spectral data

• DOI: 10.1093/mnras/staf381
• Publication Date: 2025-03-05T17:40:01Z
• Authors: F Biagiotti; D Grassi; G Liuzzi; G Villanueva; G Piccioni; T Guillot; L N Fletcher; S K Atreya; A Mura; F Oliva; F Tosi; E D’Aversa; C Castagnoli; A Adriani; G Sindoni; C Plainaki; R Sordini; R Noschese; A Cicchetti; G Eichstädt; S Brueshaber; C J Hansen; G Orton; S Levin; C Li; S Bolton
• Keywords: Jupiter (rocket family); Atmosphere of Jupiter

Abstract In this work, we analyze data from the JIRAM imaging spectrometer on board NASA mission Juno, to investigate presence of Spectrally Identifiable Ammonia Clouds (SIACs). Focusing first perijove passage, found that a white vortex structure near 40○N provides best candidate. Implementing atmospheric retrieval thanks Planetary Spectrum Generator (PSG), fit spectra (in 2.5–3.1 $\mu$m range) inside and outside vortex, varying gaseous ammonia profiles, clouds hazes properties composition. We is achieved using main composed tholins (approximation an unknown contaminant material). Inside when cloud decks are pure ice, or ammonia-coated tholins. therefore claim detection 38 SIACs, all detected over structure. With respect external regions, retrieved parameters distributions show: (i) higher altitude clouds, (ii) smaller haze’s effective radii, (iii) relative humidity values. Both ice physical consistent with being result moist convection storm uplifted fresh deep troposphere which in turn either condensed became possible source coating material for existing particles. This work confirms trend established by space ground-based observations, Jupiter rare connected strong convective episodes.