Identification of electron field-aligned current systems in Saturn's magnetosphere

Based on the analysis of 7 years of Cassini electron plasma spectrometer data near Saturn's equatorial plane, we computed the average directional electron current in the Northern and the Southern hemispheres separately. We determined the net current density by subtracting the downward electron current density (equator to the ionosphere) from the upward electron current density (ionosphere to the equator). From the symmetric analysis (no separation in local time), we identified: (1) layers of net upward current carried by the thermal electrons (1–10 eV) in both hemispheres inside 5–8 RS (Saturn Radius = 60,268 km) (region A) and (2) layers of net downward current carried by a population of warmer electrons (10–400 eV) inside 8–10 RS (region B). From the analysis of the currents organized by local time (dayside and nightside parsing), new features were identified such as (1) a day‐night asymmetry of the current carried by the warm and hot (400 eV–26,000 eV) electrons beyond 10 RS (region C), and (2) the possible existence of inter‐hemispheric currents directed from the Southern to the Northern hemisphere inside 4 RS (region A) and oppositely directed at about 13–15 RS (region C). Our interpretation is that the observed current system results from the superimposition of (1) a current system associated with the corotation enforcement, (2) a current system linked to the presence of the newly identified noon‐to‐midnight convection electric field and (3) a system of inter‐hemispheric currents driven by the thermosphere‐ionosphere. We finally discuss the relation of the observed currents with the newly identified Saturn's secondary auroral emissions. Key Points There are regions of net downward and upward field‐aligned currents Currents are due to corotation enforcement, local time asymmetic electric field The currents are co‐located with Saturn's secondary auroral emissions