Establish correlation between auroral indices and actual currents

Determine whether a quantitative correlation exists between the auroral indices AU, AL, and AE and the actual ionospheric current systems (such as the eastward and westward electrojets) and, if such a correlation exists, characterize its functional form to enable physical interpretation and validation of index-based substorm diagnostics.

Background

The paper reviews how the auroral indices AU, AL, and AE are derived from magnetometer measurements at auroral latitudes and are used as proxies for ionospheric disturbances, with AL typically linked to the westward electrojet and AU to eastward currents. Despite widespread use, the authors note a lack of established quantitative correlation between these indices and the underlying current systems.

Clarifying whether and how the auroral indices quantitatively relate to actual currents would strengthen the physical basis for interpreting AE/AL/AU, improve model validation, and support more robust assessment of substorms and related ionospheric processes in global MHD simulations.