Relating Jupiter’s Auroral Features to Magnetospheric Source Processes: New Insights from Juno

Science goals and objectives

The goal of the proposed work is to provide new insights into the links between Jupiter’s polar ionosphere and the equatorial magnetosphere. We will use Juno data to update an empirically-based mapping model between the ionosphere and the equatorial magnetosphere. We will then employ this updated model to identify the magnetospheric source region of observed auroral features, for example by mapping the location of the main auroral oval observed by Juno’s UVS instrument and comparing the predicted location of the open/closed field line boundary in Jupiter’s polar cap to features observed by Juno in Jupiter’s aurora.

Methodology

We propose to use Juno observations to update a flux equivalence mapping model that links Jupiter's equatorial magnetosphere to the ionosphere. This model uses a flux equivalence calculation that requires equal flux at the equatorial and ionospheric ends of flux tubes. The flux at the equatorial end of the flux tube is determined using a 2-D fit to magnetic field measurements there, and the flux at the ionospheric end of the flux tube is determined using a model for Jupiter’s internal magnetic field such as the Juno-era JRM09 model.

We propose to update the flux equivalence mapping to incorporate Juno data in two ways. First, we will include Juno magnetic field data to create a new 2-D equatorial field fit function that is part of the flux calculation. This will improve the fit because Juno provides additional spatial coverage in the magnetosphere. Second, we will use Juno measurements of temporal variability in the magnetic field to incorporate temporal variability in the mapping model. This will improve the model’s ability to map auroral features to Juno’s location under specific magnetospheric conditions. Finally, we also plan to update the mapping model by converting the code into Python so that it can be more freely shared with the community.

We will then use the updated model in analyzing Juno UVS images and HST images with concurrent Juno data. Specifically, we will use the model to predict the location of the open/closed field line boundary in Jupiter’s polar cap. We will survey in situ Juno particle and fields data at the predicted boundary on multiple perijoves to look for signatures of such an open/closed field line boundary.