Vertical Microstructure Profiler - JR294
Description
A total of 139 microstructure profiles were obtained during JR294, 54 of them in conjunction with standard CTD stations and 85 as part of five tow-yos (two across the sill in the eastern trough; two along different segments of the Pine Island Glacier [PIG] front; and one along the main outflow from the PIG cavity, i.e. perpendicular to the PIG front).
The Vertical Microstructure Profiler (VMP)-2000 proved to be a very reliable instrument, and was operated successfully in sustained conditions of extreme cold (air temperatures of -8°C to -13°C and winds of 20 kn to 30 kn were common) down to depths in excess of 1500 m. Only a few stations had to be skipped due to excessive swell.
The only minor problems experienced with the instrument were related to the freezing of the CTD during transport from / to the wet lab to / from deck (this was solved by injecting warm water into the CTD tube before taking the instrument out on deck prior to deployment), and the accumulated strain on the cable due to twist that resulted from heavy usage of the instrument (this was solved by dismounting the tail end to straighten the cable a couple of times during the cruise).
The VMP-2000 broke down just before its last planned profile (station 81), the symptoms of this failure being a continuous string of bad buffer readings. The cause of this breakdown was a fault in the connector between the cable and the instrument.
References
1. Naveira Garabato, A. C., A. Forryan, P. Dutrieux, L. Brannigan, L. C. Biddle, K. J. Heywood, A. Jenkins, Y. L. Firing, and S. Kimura (2017), Vigorous lateral export of the meltwater outflow from beneath an Antarctic ice shelf, Nature, 542(7640), 219–222, doi:10.1038/nature20825. Available here
3. iSTAR - Data from research cruise analysed
4. iSTAR - Scientists unravel the process of meltwater in ocean depths
Field photo
Deploying the Vertical Microstructure Profiler (VMP) on the JR294 to detect fluctutations in water turbulence. Povl Abrahamsen, BAS