Cloud resolving models of Jupiter ammonia storms applied to Junocam observations of small-scale convection

The high-resolution images of Jupiter obtained by the Junocam instrument on the Juno mission show a wide range of small-scale compact clouds suggestive of active convection. These features have horizontal sizes of 10-50 km and have been named in the recent literature as pop-up clouds because of their morphological characteristics [1]. The pop-up clouds appear as elevated towers projecting shadows over different meteorological systems [2, 3], and their appearance seems linked to the type of atmospheric region where they develop (in zones such as the South Tropical Zone, in anticyclones including the Great Red Spot, or in cyclones, and Folded Filamentary Regions and polar regions) [4]. Their shadows indicate cloud tops 5-20 km above their environments, although some observations have found more extreme altitudes for some specific pop-up clouds [2, 3]. Although the vertical structure and overall morphology of pop-up clouds suggest they are analogous to Altocumulus Castellanus [1], the lack of evidences of strong divergence at their cloud tops has also led to comparisons with Cumulus Humilis [4].  

Compared with strong Jovian convective disturbances [5, 6], pop-up clouds seem to represent less energetic convective storms compatible with ammonia powered moist convection [1, 3-4]. To investigate these clouds we run simulations of moist convective storms using a three-dimensional cloud resolving model at a spatial resolution of 0.5 km. We run several experiments to investigate cloud top altitudes for ammonia moist convection under a variety of ammonia abundances and environmental conditions and we also explore the energetics of these storms. We show that ascending ammonia cumulus clouds over a surrounding homogenous cloud cannot develop large vertical structures compatible with the lengths of the shadows observed. We explore under which conditions ammonia convective storms can ascend to higher levels when forced from below. We also explore the atmospheric conditions in which ammonia pop-up clouds develop isolated over a deeper homogenous NH4SH cloud [3]. 

References 

[1] Hansen et al. (2019). JunoCam Images of Castellanus Clouds on Jupiter. AGU Fall Meeting Abstracts, 2019, P44A-05. https://ui.adsabs.harvard.edu/abs/2019AGUFM.P44A..05H  

[2] Orton et al. (2022). Investigating Relative Cloud Heights in Jupiter Using Juno's JunoCam Imager. AAS/Division for Planetary Sciences Meeting Abstracts #54, 54, 306.06. https://ui.adsabs.harvard.edu/abs/2022DPS....5430606O  

[3] Guillot et al. (2024). How high are Jupiter's clouds? From high-resolution JunoCam images to a multi-wavelength analysis. EGU24. doi:10.5194/egusphere-egu24-17351       

[4] Palotai et al. (2023). Moist Convection in the Giant Planet Atmospheres. Remote Sens. 2023, 15, 219. doi:10.3390/rs15010219  

[5] Sánchez-Lavega et al. (2008). Depth of a strong jovian jet from a planetary-scale disturbance driven by storms. Nature, 451(7177), 437–440. doi:10.1038/nature06533  

[6] Sánchez-Lavega et al. (2017). A planetary-scale disturbance in the most intense Jovian atmospheric jet from JunoCam and ground-based observations, Geophysical Research Letters, 44, 4679–4686. doi:10.1002/2017GL073421.