A Method for Drift Correction in Temperature and Salinity Measurements From Moored Buoys

Abstract

Abstract Temperature and salinity are essential ocean variables for understanding the oceans' physical processes. The conductivity and temperature measurements are used for deriving ocean salinity. Conductivity-temperature (CT) sensors mounted on moored buoys are widely used to collect sustained time-series observations of temperature and salinity. However, these measurements are prone to drifts that need to be corrected to ensure data quality. The present study evaluates a field validation technique to correct the drift in subsurface temperature and conductivity measurements that can potentially complement the standard calibration procedure performed by the original equipment manufacturer. The advantage of field validation is that it could be carried out soon after retrieving CT sensors, which ensures that the physical conditions and configuration of the retrieved CT sensors remain unaltered from that of the in-situ conditions. The drift in the CT sensors was analyzed by pre-deployment and post-retrieval field validation of CT sensors. A correction is applied to the raw data assuming a linear trend in drift with time. An ice test to identify and correct the errors in the timestamp of CT measurements is also discussed.