An Overview of the Juno Radio Occultations at Jupiter

Radio occultation experiments provide one of the most direct probes of the shallow atmosphere of Jupiter, the only region of the gas giant accessible to in-situ measurements and a key interface between the deep interior and the observable cloud layer. By measuring the refraction of radio signals as they pass through the atmosphere, radio occultations yield high-vertical-resolution profiles of temperature, pressure, and composition, offering unique constraints on the thermal and dynamical structure of the stratosphere and upper troposphere. During its extended mission, beginning in July 2023, the Juno spacecraft has conducted the first radio occultations of Jupiter since the Voyager era, significantly expanding both the spatial coverage and scientific scope of these measurements. Using coherent two-way, multi-frequency radio links and detailed ray-tracing techniques, Juno’s occultations provide precise vertical profiles up to pressures of ~0.5 bar across a wide range of latitudes. When combined with contemporary ground-based observations, these profiles place new constraints on the variability and circulation of Jupiter’s shallow atmosphere. In this talk, I will present an overview of results from two years of Juno radio occultations, highlighting what they reveal about Jupiter’s stratospheric and upper-tropospheric structure and how they compare with earlier infrared measurements from Voyager and Cassini, as well as modern ground-based datasets. Particular attention will be given to recent occultations sampling Jupiter’s polar regions, which offer new insights into the thermal structure and dynamics of the polar stratospheric vortex. Together, these observations illustrate the renewed power of radio occultations as a tool for understanding Jupiter’s atmospheric dynamics and its coupling across vertical and latitudinal scales.