Several days of continuous incoherent scatter radar observations during the November 2004 magnetic superstorm are available, as well as data from the CHAMP [CHAllenging Minisatellite Payload] satellite magnetic fiel d detector. We have found that, for zonal electric fields greater than about 1 mV/m, the linear relationship between CHAMP-deduced electric fields and Jicamarca-measured electric fields breaks down. We find that the observed magnetic field is a factor of two smaller than expected for the largest zonal electric field (3.2 mV/m) observed simultaneously in time and nearby spatially with CHAMP. The fact that similar decreases in the effective conductivity occurred during both normal and counter-electrojet conditions indicates that Farley-Buneman waves must be the source of the physical mechanism for the reduced current. In addition, we provide an explanation for a long standing (more than 35 years) discrepancy between theory and (rocket) experiments, concerning the peak height of the electrojet and the magnetic field perturbation. The correction by a factor of four of the electron-neutral collision frequency thought to explain this problem is not necessary if the field line integrated conductivities are used.
