The dayside reconnection voltage applied to Saturn's magnetosphere

The ability of magnetic reconnection between interplanetary and planetary magnetic fields to drive a planetary magnetosphere can be quantified as the resulting voltage applied to the system. We present analytical model predictions of the dayside reconnection voltage at Saturn, a planet where solar wind driving has been the subject of debate. Model-predicted voltages are in reasonable agreement with adapted terrestrial coupling function estimates, as well as voltages inferred from auroral observations. The voltage is most sensitive to the interplanetary magnetic field (IMF). Combining the model with Cassini IMF observations suggests that the voltage is rarely high enough to compete with internal driving of Saturn's outer magnetosphere. The long-term average dayside (and nightside) voltage is 40kV. We point out that the distribution of IMF strength at Saturn is not bimodal, despite the compression-rarefaction structure of the local heliosphere when the Cassini observations were made.