Characteristics and Changes in Ammonia Abundance Features in Jupiter’s Upper Troposphere 2022-2023

Amateur observers (Hill et al., 2024) have shown that filter-averaged measurements of the reflectance of Jupiter in molecular absorption bands of ammonia and methane can be made with modest-sized telescopes and reduced to yield spatial maps of ammonia. We now create an empirical limb correction for the ammonia abundance and effective cloud-top pressure and assemble sets of synoptic maps with partial or complete longitude coverage taken in moderately close temporal proximity (fewer than 10 Jupiter days). We then examine the maps to evaluate the characteristics and changes seen in localized ammonia enhancements and gradients in the context of effective cloud-top pressure and visual features. The ammonia depletion associated with the Great Red Spot (GRS) and the enhancements in the NEZ show significant contrast and are the focus of the study. The GRS region shows generally persistent characteristics over the period of observation, including a small southward offset of the depleted regions from the visual centroid of the GRS. The NEZ enhancements and their relationship to visual features such as plumes and North Equatorial Dark Features (NEDFs) are presented along with changes seen on timescales of days to weeks. This work demonstrates the utility of frequent observations in following the evolution of the Jovian ammonia distribution.