Meteorological and oceanographic data collected during the ASREX 91 field experiment

Abstract

The 1991 Acoustic Surface Reverberation Experiment (ASREX 91) took place in November and December off the coast of British Columbia. As part of this experiment, three moorings were deployed to characterize the environmental background. The moorings consisted of a meteorological/oceanographic mooring designed to measure surface meteorology, current and temperature in the upper 120 meters, and nondirectional wave parameters and two wave moorings which were instrumented with pitch-roll buoys to characterize the directional wave spectrum. This report presents results from these three moorings. The conditions seen during the experiment were extremely rough, with wind speeds at 3.4m above the water surface reaching a maximum of 22 m/s and wave heights reaching a maximum of over 10 meters. The air-sea flux of heat was strongly cooling, and the mixed layer deepened over the course of the experiment from approximately 40 to approximately 70 meters. Spectra of the temperature showed a strong semidiurnal tidal signal associated with temperature excursions of several degrees C. The velocity signal showed strong inertial oscilations with amplitudes of 30-50 cm/s. Weaker low-frequency and semidiurnal tidal signals were also seen. The waves were very strong with significant wave heights of 5-6 meters persisting for up to 2 weeks at a time. Waves were generally out of the south or the west.