Field experiences with a new miniature vector averaging current meter

Abstract

For several years Inst. of Marine Research Bergen has been developing miniaturized modular current meters. Thanks to major improvements in electronic component technology in recent years, a physically small current meter can now be designed with processing and recording capacity which is comparable to much larger instruments. The paper describes the design and field performance of a new miniaturized vector averaging "Mini" current meter which can measure and record up to 6000 data sets. Via a built in two way optical data communication system all recorded data in the instrument can be transferred to a PC in less than 30 s. In an intercomparision experiment during May 1991 two "Mini" current meters were moored close to two Aanderaa RCM-7 current meters. The instruments were positioned 20 and 28 meters from the surface in a region where the current speed varied from 0 - 20 cm/s. Technically the new instruments functioned well and in accordance with their design specifications. The intercomparision showed that all of the RCM-7 and the "Mini" current meters when compensated for a minor directional offset in one instrument - responded almost identically to current speeds between 4- 14 cm/s. Beyond 14 cm/s the "Mini" current meters showed a slightly higher current speed.