An investigation of Io’s dynamical atmosphere with SMA’s broadband observations

Io, one of the most volcanically active bodies in the Solar System, possesses a dynamic atmosphere shaped by volcanic eruptions and the sublimation of surface frost. Utilizing the Submillimeter Array (SMA), we conducted high-resolution observations of Io's atmosphere to investigate its variability and thermal structure. Data collected over three nights in 2022 identified 22 rotational lines of SO₂ within the 336-364 GHz range, allowing for improved constraints on gas temperatures and column densities. Observations indicated that the SO₂ emissions on the dayside were primarily driven by frost sublimation, consistent with previous studies (e.g., Tsang et al. 2012; de Pater et al. 2020), and exhibited equatorial bands and longitudinal asymmetries. The derived gas temperatures ranged from 240 to 270 K, and SO₂ column densities were estimated to be (2-3) × 10¹⁵ cm⁻². Radiative transfer modeling, which incorporated an isothermal profile and gas turbulence —possibly associated with volcanic lava lakes on Io’s surface — provided insights into atmospheric dynamics. This study establishes a robust framework for analyzing Io's atmospheric processes and lays the groundwork for future investigations into its complex interactions with Jupiter's environment.