Preliminary results of the FRAM IV vertical array experiment

A vertical array of 960-m length was deployed in the 1982 FRAM IV experiment. The 28 hydrophones of the array measured the vertical sound field of signals and noise in the Arctic Ocean. The depth distribution of intensity, vertical directionality, and vertical spatial coherence were estimated from the data. Some preliminary results will be presented. The data clearly indicates the presence of normal mode structure in the vertical distribution of the signal. Lowest order mode amplitudes and phases were successfully derived from the shot data measurements.