ASA 124th Meeting New Orleans 1992 October

5pUW10. Environmental forcing and water column properties as related to acoustic measurements in the Gulf of Alaska.

Jeffrey L. Hanson

Johns Hopkins Univ./Appl. Phys. Lab., Johns Hopkins Rd., Laurel, MD 20723

Larry H. White

Science Applications International Corp.

Michele E. D'Anna

Old Dominion Systems Inc. of Maryland

During the February--March 1992 Gulf of Alaska surface scatter and air--sea interaction experiment a series of detailed air--sea boundary zone measurements were closely coordinated with numerous acoustic scatter and reverberation experiments. A primary scientific objective was to evaluate the influence of various physical features of the ocean environment on subsurface bubbles and near-surface backscatter. The background meteorology, wind history, directional wave field, and mixed layer variability were carefully measured. The results allowed estimation of other air--sea boundary features including wind stress, heat flux, and surface buoyancy flux. A wide variety of surface weather conditions were experienced, including two events with winds (greater than or equal to)18 m/s and peak significant wave heights of approximately 5 m. Air temperatures mostly remained 1--3 (degrees)C cooler than the ocean surface and calculations show the average daily heat flux was negative (upwards). These unstable atmospheric conditions, coupled with a notably deep mixed layer extending to (greater than or equal to)100 m, resulted in an ideal environment for exceptionally deep penetration of subsurface bubbles.