Depth dependence of the temporal characteristics of cw propagation in the Arctic Ocean

Abstract

Previous work by P. Mikhalevsky [J. Acoust. Soc. Am. 70, 1717–1722 (1981)] investigated the temporal characteristics of cw signals propagating in the Arctic Ocean. The previous work was limited to receivers at a depth of 91 m. In this paper, the temporal characteristics will be extended to 28 hydrophones in a vertical array with depths from 30 to 960 m. The data were taken during the FRAM IV experiment in April 1982. The signals were generated at the Tristen ice camp and received at the FRAM IV ice camp located north of Spitzbergen. The range of approximately 275 km was over the Mid-Ocean Ridge; the average water depth along the path was 3000 m. Most of the data examined are at a high signal-to-noise ratio (> 10 dB) which makes it possible to study the temporal fluctuation and the statistics of the cw signals at different depths. By employing a mode filtering technique, the temporal dependence of the amplitude and phase of the lowest order mode has been investigated. The drift rates of the ice camps were negligible during the transmission periods and hence the results apply to transmission between essentially fixed stations.