Forward Modeling of 3‐D Ion Properties in Jupiter’s Magnetosphere Using Juno/JADE‐I Data

• Published in: Journal of geophysical research. Space physics 2024-04, Vol.129 (4), p.n/a
• Main Authors: Wang, Jian‐zhao, Bagenal, Fran, Wilson, Robert J., Nerney, Edward, Crary, Frank, Dols, Vincent, Ebert, Rob W., Valek, Phil W., Allegrini, Frederic, Kim, Thomas K., Szalay, Jamey R.
• Format: Article
• Language: English
• Subjects: ASTRONOMY AND ASTROPHYSICS; Datasets; Flow velocity; forward modeling; Heavy ions; Ion velocity; Ions; Jupiter; Jupiter probes; Magnetic properties; magnetosphere; Modelling; Planetary magnetospheres; plasma disk; Relative abundance; Space missions; Spacecraft; Telemetry; Velocity distribution
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1029/2023JA032218

The Jovian Auroral Distributions Experiment Ion sensor (JADE‐I) on NASA’s Juno mission provides in‐situ measurements of ions from 0.1 to 46.2 keV/q inside Jupiter’s magnetosphere. JADE‐I is used to study the plasma with two types of datasets from the same measurement: Time‐of‐flight (TOF) and SPECIES. The TOF dataset provides mass‐per‐charge measurements with a range of 1–64 amu/q but oversamples particles over 6π steradian viewing per spacecraft spin and has little directional information. On the other hand, the SPECIES dataset can provide a good measurement of the flow direction but does not provide mass‐per‐charge information due to the telemetry limit. In this study, we developed a 2‐step forward modeling method that combines the advantages and avoids the disadvantages of TOF and SPECIES data to derive the 3‐D properties of heavy ions. Assuming that the ion velocity distribution can be described with the kappa distribution, we first perform the forward model fit of the TOF data to calculate the relative abundance of heavy ion species. Then we fix the relative abundance and perform the second forward model fit on the SPECIES data. Using this method, we obtain the densities of different heavy ions, the shared temperature and kappa value, and the 3‐D flow velocity vector. Some data examples of the equatorial plasma disk before Perijove 24 are included to demonstrate the method. Plasma properties can then be mapped to explore spatial and temporal variabilities in Jupiter’s magnetosphere. Key Points Using Juno/JADE‐I SPECIES and TOF datasets we derive ion composition, density, temperature, flow velocity and direction The method provides 3‐D properties of plasma to explore spatial and temporal variabilities in Jupiter’s magnetosphere The method determines the 3‐D bulk flows vector accurately with small uncertainties