The aftermath of convective events near Jupiter's fastest prograde jet: Implications for clouds, dynamics and vertical wind shear

The 24 degrees N jet borders the North Tropical Belt and North Tropical Zone, and is the fastest prograde jet on Jupiter, reaching speeds above 170 m/s. In this region, observations have shown several periodic convective plumes, likely from latent heat release from water condensation, which affect the cloud and zonal wind structure of the jet. We model this region with the Explicit Planetary hybrid-Isentropic Coordinate model using its active microphysics scheme to study the phenomonology of water and ammonia clouds within the jet region. On perturbing the atmosphere, we find that an upper tropospheric wave develops that directly influences the cloud structure within the jet. This wave travels at a net (eastward) phase speed of similar to 75 m/s in our model, and leads to periodic chevron-shaped features in the ammonia cloud deck. These features travel with the wave speed, and are subsequently much slower than the zonal wind at the cloud deck. This unique morphology of the ammonia cloud, and the slower drift rate, were both observed following the convective outbreak in this region in 2016 and 2020. We find that an upper level circulation is responsible for these cloud features in the aftermath of the convective outbursts. The comparatively slower observed drift rates of these features, relative to the wind speed of the jet, provides constraints on the vertical wind shear above the cloud tops, and we suggest that wind velocities determined from cloud tracking should correspond to a different altitude compared to the 680 hPa pressure level. We also diagnose the convective potential of the atmosphere due to water condensation, and find that it is strongly coupled to the wave.

Automated summary

The 24 degrees N jet on Jupiter is the fastest, reaching speeds above 170 m/s, and is influenced by periodic convective plumes that affect the cloud and zonal wind structure. Unique morphology of ammonia clouds and slower drift rates were observed following convective outbreaks in 2016 and 2020, indicating an upper level circulation responsible for these cloud features. The convective potential of the atmosphere due to water condensation is strongly coupled to an upper tropospheric wave.