Doppler acoustic velocity profiling in the arctic

During Spring 1985 two RD Instruments 150 kHz sonars were operated for 37 days in the Beaufort Sea, approximately 450 km northeast of Prudhoe Bay, Alaska. The sonars successfully profiled to a depth of approximately 350 m, with rms velocity precision of 1 cm/sec (for hourly averages). A preliminary analysis indicates that sonar accuracy levels also appear to be of order 1 cm/sec. While rather small, these levels result in significant errors in the Arctic measurementg as the naturally occurring signal levels in the Arctic are also quite small. Neverless, at low frequency ( < .2 cph), an excellent picture of the internal wavefield is obtained.