Program: GN-2022A-Q-126

We propose to measure the ongoing evolution of vertical aerosol structure in several key features of Jupiter’s atmosphere, concomitantly with Juno spacecraft measurements in its extended mission, using NIRI filtered imaging with AO stabilization. Our goal is to determine or constrain the physical and chemical processes controlling the atmosphere, extending and enhancing Juno observations by providing a global context and tracking time evolution of features of interest. The following specific questions will be addressed this semester. (1) What is the relationship between cloud color and altitude? We will test a model in which higher-altitude particles are UV-irradiated, causing changes in their colors, focusing on two regions in which such changes are taking place, (a) the central component of Jupiter’s Equatorial Zone (known as ‘EZc’) and (b) the second-largest vortex in Jupiter’s atmosphere, known as Oval BA. Each exhibits a correlation between visible color changes and changes of the near-infrared reflectivity at wavelengths sensitive to particles in the 50-250 mbar pressure range, with a darker color being associated with higher-altitude particles. Both regions are currently changing or expected to change color, and we propose to measure changes in particulate altitude associated with this change and any time lag between this altitude change and the change of visible color. (2) What structural and dynamical changes are associated with strong perturbations of the GRS? Major perturbations to the appearance of Jupiter’s Great Red Spot (GRS) in 2019 May are expected to be repeated. High-resolution NIRI observations will provide critical constraints on competing models for such interactions, specifically the vertical levels where these perturbations have been shown to be taking place. (3) What processes modulate and transport Jupiter’s prominent polar hazes? The distinct hazes defining Jupiter’s North and South Polar Regions (NPR, SPR) are the products of auroral-related chemistry. We will examine their time variability for correlation with solar wind or Juno-measured magnetospheric variability. We will correlate inhomogeneities within the SPR or NPR with the location of auroral activity and circulation patterns implied by recent spatially resolved high-resolution spectroscopy by ALMA. Our proposed observations will also provide contextual information for Juno’s Microwave Radiometer, which will sample the NPR with increasing spatial resolution in the extended mission, as well as the JunoCam and JIRAM instruments which will continue to sample the SPR. In general, the proposed observations will provide a critical component of a campaign of Earth-based support for Juno that is not available at any other facility (see https://www.missionjuno.swri.edu/planned-observations). They will also support potentially contemporaneous observations by JWST Cycle-1 Early-Release Science and Guaranteed Time programs in Cycle 1.