Data Quality Issues Cabled observatories will produce long time series of real time physical ocean data -- revealing: –Trends –Long-period fluctuations (>1 year) –Events But, without sensor drift histories and laboratory inter-calibration, trends and events will be lost in: –Sensor drift –Calibration variability

Data Quality Issues Accurate real time temperature data is easily achieved -- drift rates are typically °C/year Accurate real time conductivity and oxygen data is more difficult to achieve: –Conductivity and oxygen are subject to fouling – especially at shallow depths –Polarographic oxygen sensors drift even before deployment

Calibration Policies ARGO program: careful handling minimizes these problems in deep deployments Most accurate time series will still require: –Post deployment processing to correct drift –Comprehensive plan for sensor calibration –Conversion of data to scientific units will be performed on shore

Recommendations Establish comprehensive calibration plan: –Pre-deployment and post deployment calibrations –Inter-lab comparisons Maintain sensor calibration history as part of the data library Associate or attach this drift history to unprocessed data