Observation and interpretation of the seafloor vertical electric field in the eastern North Pacific

Abstract

A 37 day long recording of the seafloor vertical electric field collected on the East Pacific Rise and south of the mouth of the Gulf of California is examined. The principal barotropic ocean tides are detected by regression analysis and display electric field values that yield typical open ocean water velocities of 1 cm/s or less. Spectral analysis and modeling indicate that internal wave‐induced electric fields consistent with the Garrett‐Munk kinematic description explain the data between the local inertial frequency of 0.033 cph and about 1 cph. At lower frequencies, a variance enhancement near 90 h period of unknown origin is also present. Low but significant coherence of the VEF with land magnetic observatory data is also demonstrated; this is probably due to motion of the electric field instrument in ambient water currents.