Current meters for measurement of low-speed velocities in ice-covered lakes

Two current meters for measurement of low-speed currents in ice-covered lakes, a "drag-wire" current meter (DWCM) and an acoustic current meter (ACM), are presented. The recording range is 0.1-20 mm s(-1) for the DWCM and 0.2-70 mm s(-1) for the ACM. The accuracy, obtained from laboratory calibration, is +/-30% of the velocity reading and +/-10 degrees for direction for the DWCM and +/-40% of the velocity reading and +/-10 degrees for direction for the ACM. Comparison of the two devices in the field and between simultaneous DWCM recordings and drogue observations, performed in a wind-protected hole in the ice, showed reasonable agreement.