Vertically-Averaged Water Velocity from Horizontal Electric Field Observations Versus Moored Current Meter Data: Results from BEMPEX

The horizontal electric field, E sub H , at a single point in the deep ocean is theoretically proportional to a conductivity-weighted vertical integral of water velocity, plus a "noise" due to electric currents in the ionosphere. By naturally filtering out short vertical scale motions, point measurements of E sub H instruments can be deployed inexpensively in arrays across the ocean floor to obtain information on the spatial structures of low-frequency, large-scale fluctuations. These premises were the basis for the Barotropic Electromagnetic and Pressure Experiment (BEMPEX) deployed in 1986-1987 in the northeast Pacific Ocean.