Simulations of Io Plasma Torus Around Jupiter: Predictions for Lenghu Observatory

Characterizing the temporal evolution of the three-dimensional structure of the Io plasma torus is essential to understand the dynamics of the Jovian magnetosphere. Optical imaging is a powerful tool to uncover the global torus structure. Currently, two ground-based optical telescopes with diameters of 0.8 and 1.8 m, respectively, are under construction at the Lenghu Observatory for Planetary Science on the Tibetan Plateau of China, to systematically observe the Io plasma torus at wavelengths between 392 and 1,100 nm. These telescopes will begin to operate in the end of 2023. In order to support the inversion and scientific interpretation of the Io plasma torus images, we perform systematic simulations of the Io plasma torus in this work. First, a three-dimensional model of electron and ion densities and electron temperature is constructed first. Then, the emissions of O+ 372.7 nm, O+ 372.9 nm, S+ 406.9 nm, S+ 671.8 nm, S+ 673.1 nm, and S++ 953.2 nm are simulated from the perspective of observing from the Earth. The simulated emission intensities and distributions are consistent with previous observations. This work provides a state-of-the-art convenient tool for ground-based telescope observation of the Io plasma torus at a specific site and time and also benefits future inversion of images to obtain physical parameters of Io plasma torus. The Io plasma torus is composed of ionized material encircling Jupiter near Io's orbital radius. Volcanic eruptions on Io, the most geologically active object in the solar system, are the main source of plasmas in the Io plasma torus. The dynamics and evolutions of the Io plasma torus is crucial to understand the mass and energy transportation in Jovian magnetosphere. The bight lines of ionized sulfur make optical imaging a useful tool for studying the global structure of the torus. Two new telescopes are being constructed at Lenghu, Qinghai, China, for this purpose. To instruct future observations and help interpret the images captured by these telescopes, we compiled a three-dimensional model of the torus with state-of-the-art plasma models from the literature and simulated the emissions at certain wavelengths of light. The simulation results match well with previous observations and will be useful for analyzing data obtained by the new telescopes. This work will provide a valuable tool for studying the Io plasma torus and obtaining physical parameters of this structure. Io plasma torus is an important structure in the Jovian magnetosphere to understand its evolutionA three-dimensional empirical model of the torus is compiled and used to simulate the images from ground stationsThe simulated images torus consistent well with ground observations and would be valuable for future observations at Lenghu station