Multipath temporal stability and horizontal arrival angle fluctuations for long‐range (800 km) deep‐water transmissions

Abstract

Pseudorandom transmissions (approximately 20 Hz bandwidth) from a WHOI deep‐moored (2000 m) source were acquired at single elements of two continental shelf mounted receivers. The receivers, at a range between 800 and 900 km, were separated by the Gulf Stream. For both receivers a total of 25 transmission samples were acquired, each 90 min in duration. These samples were distributed over a time period of one month. With appropriate averaging procedures applied to each sample, the multipath structure for the transmissions which did not pass through the Guff Stream (first receiver) is shown to be temporally stable over the full month. The multipath structure of the transmission which did pass through the Gulf Stream did not exhibit the same stability. For the first receiver, 18 twelve‐hour samples of the carrier of the PRS transmission were also acquired across the full spatial aperture of the receiver. These samples were used to study long‐term variability in horizontal arrival angle. The observed spread in horizontal arrival angle is consistent with the hypothesis that the principal spreading mechanism is the mesoscale eddy field.