31 January 2018
When bottom pressure recorders are deployed, readings drift over time. It is impractical to recalibrate the instrument mid deployment, so an estimate of the drift must be removed before the data can be used.
The common approach has been to fit a short term exponential drift, combined with a longer term linear drift. However, the accuracy of this fitted drift can be improved by first removing all known annual or longer period fluctuations, such as changes due to the pole tide.
As part of a recent project, we produced code that attempts to improve dedrifting by removing these fluctuations, and today we have made it available on our website.
Please note that this technique cannot separate instrumental drift from any other secular trend, so recorders subject to this drift cannot be used to derive sea-level trends.