Figure 3: The complete dataset from the ELF instruments. The data consist of the maximum axis of the polarisation ellipse, normalised by the source dipole moment and corrected for the height of the source above the seafloor. The 0.75 Hz data from Noddy cover a relatively small range of source--receiver offsets. For clarity only data with errors of less that 25 % are plotted. The data can be divided into two groups: On axis data consist of 0.35 Hz and 11 Hz signals recorded by Quail during tow 1, when both the source and receiver were on axis. Off axis data consist of 0.35 Hz signal recorded by Noddy during tow 1 and 0.75 Hz signal recorded by Quail, Noddy and Kermit during tow 2. In these cases either the source or the receiver (or both in the case of Noddy tow 2) was located away from the AVR axis. The two data groups overlap slightly at a range of 4 km.}