Figure 2: Noise levels for (a) the ELF and (b) the LEM instruments, defined as the RMS electric field in a bandwidth of 0.01-0.02 Hz (the inverse of the time series length used). The noise levels are derived from time series recorded during the break in transmission between source tows, by applying the same least squares fitting procedure as was applied to the data. The electric field values have been normalised by 10700 Am, the average source dipole moment during the experiment.}