A tethered free-fall glider to measure ocean turbulence

A tethered free-fall microstructure glider, designed to make quasi-horizont al profiles of the ocean mixed layer, was tested at Emerald Bank on the Sco tian Shelf in June 1996. The vehicle attained a 4:1 gliding ratio with the angle of attack close to 0 degrees. The glider typically stabilized its pit ch and roll within the first 10 s of each flight. The vehicle speed started at 0.55 m s(-1) and decreased to 0.45 m s(-1) over the period of a 300-s f light due in part to the increase in drag of the tether cable. Two profiles of microstructure obtained under moderate and very light wind conditions a re presented to illustrate the performance of the glider from very near the surface to depth. These profiles demonstrate the advantages of the glider over vertical profilers in exploring the ocean mixed layer under various fo rcing conditions.