A Procedure to Compensate for the Response Drift of a Large Set of Thermistors

The drift of temperature measurements by semiconductor negative temperature coefficient thermistors is awell-known problem. This study analyzes the drift characteristics of the thermistors designed and used at theRoyal Netherlands Institute for Sea Research for measuring high-frequency O(1Hz) temperature fluctuationsin the ocean. These thermistors can be calibrated to high precision and accuracy (better than 1mK) and havevery lownoise levels. The thermistors canmeasure independently for long periods of time (more than one year),and the identification and compensation of the drift are thus essential processing steps. A laboratory analysisshowing that the drift is similar, in its functional form, to the drift of commercial thermistors described in theliterature is presented. An effective procedure to estimate this drift from ocean observations is described andtested using three datasets fromthe deepAtlanticOcean. Since the functional formof the drift rate is, with goodapproximation, universal among different sensors, the procedure could easily be adapted to other datasets and,the authors argue, to measurements from thermistors by other manufacturers too