Focus questions for Ice Giant atmospheric studies in the next decade

Uranus and Neptune are vastly different from the other Gas Giants in the solar system, and represent an increasing population of detected exoplanets, which are smaller than Jupiter and larger than Earth in both size and mass. Their lower temperatures, rotation rate, and higher metallicity lead to a myriad of differences compared to their larger H-He-dominated relatives. However, due to their distance from Earth, they have been poorly characterized. We review our current understanding of Ice Giant atmospheric phenomena and identify key questions that can inform future studies and dedicated missions. These questions will aid in better understanding the processes that drive these atmospheres, how they differ from other Gas Giants, and help constrain solar system formation models:

What does the Ice Giants' atmospheric composition, especially the abundances of noble gases and chemical isotopes, reveal about their migration and formation history? How can those measurements inform our understanding of the origin of the solar system?

Thermal evolution and its relation to the atmospheric structure:

How have the atmospheres of Uranus and Neptune regulated their long-term thermal evolution? Why does Uranus today exhibit negligible internal heat release?

What is the role of moist convection in vertical heat transport in Ice Giant atmospheres?

How does atmospheric composition control the vertical atmospheric structure, and throttle the vertical thermal flux in the atmosphere?

Atmospheric composition and aerosol evolution: How does the atmospheric composition of the Ice Giants vary in three dimensions, and what does it tell us about the nature of large-scale atmospheric motion?

What drives the long-and short-term chemical and photochemical processes that affect the Ice Giants' atmospheric composition?

Balance of the observed state through fluid dynamical processes: How are meridional and zonal circulation patterns coupled, and how do they transport material and energy? How are these patterns of circulation maintained?

How does periodic seasonal forcing affect the state of the Ice Giant atmospheres, especially in the case of Uranus' extreme axial tilt?

How do the "dark spot" vortices form on Ice Giants, and what is their role in redistributing energy, momentum, and disequilibrium/condensable chemical species?