Are we underestimating the effect of space weather on the ionosphere?

Solar wind electric fields drive electric currents in the auroral ionosphere. Previous work shows that these currents first increase linearly and then saturate as the electric field increases. Quite naturally, these studies assume accurate electric field measurements. However, the spacecraft we use to measure these fields are about 230 Earth radii upstream from Earth at the L1 libration point. When we account for spatial and temporal inaccuracies in the measurements, we find up to a 30 to 40% increase in the average auroral electrojet currents for a given electric field. This could imply far greater currents flowing through the ionosphere than previously thought during extreme space weather events. Modeling space weather effects in the ionosphere require us to pay closer attention to measurement errors.