Velocity structure in the mixed layer during MILDEX.

Abstract

Discusses the Mixed Layer Dynamics Experiment (MILDEX), off the coast of California in 1983. Sensors deployed from the research platform FLIP were used to monitor the flow structure in the mixed layer. Focusses on data from fixed and movable vector measuring current meters, a real time profiler and two Doppler sonars. Describes experimental procedures and treatment of data. An LC index was developed to characterize the occurrence of Langmuir circulation. Discusses the results obtained. Both the current meter data and the sonar data indicate the sporadic occurrence of Langmuir circulation in the mixed layer. These events occur quickly after the onset of wind and during these periods brief but intense downwind currents are stronger at mid depths in the mixed layer than at 2 m depths. LC events are also associated with downward current fluctuations of roughly equal magnitude. During a period of strong Langmuir circulation, the sonar detected crosswind convergences (surface) at scales up to three times the mixed layer depth. (C.J.U.)