The design of ocean turbulence measurement with a Moored instrument

Abstract

The newly designed Instrument MTMI (Moored Turbulence Measuring Instrument) developed by OUC (Ocean University of China) had been deployed in the South China Sea from October 19, 2013 to February 10, 2014 at 21° 09.900′ N 117°42.031′ E and succeed to collect time series for about 115 days in 250-m-deep water. According to the requirements of turbulence measurement, the mechanical design was developed for turbulence observation platform to achieve stability and good flow tracking. By analyzing the pitch varying with flow speed, the results suggested that the platform satisfies the requirements of stability. Then, the heading of instrument compared with the flow direction measured by RCM (Recording Current Meter), and the two groups of data matched well which showed that our platform has a good ability to track the vibration of the flow direction. Finally, the power spectrum curves of shear signals and the theoretical Nasmyth spectrum also matched well and the rate of turbulence dissipation are 10−7W kg−1 approximately. In general, instrument mechanics were rationally designed and MTMI provided a good observation platform for the long-term turbulence measurements.