Journal Article

Ray Tracing of Whistler Mode Waves in Jupiter's Magnetosphere

Qin, Murong, Ma, Qianli, Kang, Ning, Li, Wen, Bortnik, Jacob

2025

Overview

Previous statistical studies have described the distributions and properties of whistler‐mode waves in Jupiter's magnetosphere, but explaining these wave distributions requires modeling wave propagation from their generation near the magnetic equator. In this letter, we conduct ray tracing of whistler‐mode waves based on realistic Jovian magnetic field and density models. The ray tracing results generally agree with the statistical wave distributions based on Juno measurements. The modeled ray paths show that high‐frequency waves generated near the equator are confined within 20° magnetic latitude due to Landau damping, low‐frequency waves can propagate to higher latitudes and lower M‐shells, with changing wave normal angles, and a portion of low‐frequency waves could propagate to high M shells at high latitudes. Our modeling results provide a theoretical interpretation of whistler‐mode wave distributions and properties, providing essential insights for future radiation belt models at Jupiter. Plain Language Summary Scientists have recently been paying more attention to “whistler‐mode waves” in Jupiter's magnetosphere, as these waves play a key role in the movement of high‐energy electrons within Jupiter's radiation belts. A recent study by Ma, Li, Zhang, Kang, et al. (2024), https://doi.org/10.1029/2024gl111882, using data from NASA's Juno spacecraft, provides detailed insights into these waves, especially at frequencies lower than the “equatorial electron gyrofrequency” in Jupiter's magnetosphere. The study uncovers new information on how these waves propagate through Jupiter's magnetic fields, especially in relation to their origin and angles of inclination relative to the background magnetic field. In the present study, we use computer models to trace how these waves propagate through Jupiter's magnetosphere, based on realistic magnetic field and density conditions. Our models reveal that the waves observed at higher latitudes and farther from Jupiter likely originate near the equator at lower frequencies and evolve as they propagate. This interpretation aligns with the findings from the Juno spacecraft and helps explain how these waves propagate within Jupiter's magnetosphere. Key Points Realistic ray tracing is conducted for Jovian whistler mode waves and results are able to reproduce statistical observations High‐frequency waves originated from equator are confined within 20° latitude and separated from high‐latitude waves originated elsewhere Low‐frequency waves maintain high wave power from the equator to high latitudes and can propagate to low M with varying wave normal angles

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Computer models / Density / Electrons / Equator / Gyrofrequency / Inclination angle / Jupiter / Jupiter magnetic field / Jupiter probes / Landau damping / Latitude / Magnetic equator / Magnetic field / Magnetic fields / Magnetic properties / Mathematical models / Modelling / Planetary magnetic fields / Planetary magnetospheres / Radiation / Radiation belts / Ray paths / Ray tracing / Shells / Spacecraft / Statistics / Wave propagation / Whistlers