WIND AND TIDAL FORCING OF A BUOYANT PLUME, MOBILE-BAY, ALABAMA

AVHRR satellite imagery and in situ observations were combined to stud y the motion of a buoyant plume at the mouth of Mobile Bay, Alabama. t he plume extended up to 30 km from shore, with a thickness of about 1 m. The inner plume, which was 3-8 m thick, moved between the Bay and i nner shelf in response to tidal forcing. The tidal prism could be iden tified through the movement of plume waters between satellite images. The plume responded rapidly to alongshore wind, with sections of the p lume moving at speeds of more than 70 cm s-1, about 11% of the wind sp eed. The plume moved predominantly in the direction of the wind with a weak Ekman drift. The enhanced speed of the plume relative to normal surface drift is probably due to the strong stratification in the plum e, which limits the transfer of momentum into the underlying ambient w aters.