Automating tide gauge quality control

Tide gauges provide a vital component in coastal flooding alert systems, and as a record of past events. They are used to record short duration extremes such as tsunamis, storm surges lasting a few hours, regular tides, and long term changes in relative sea-level. Globally, there is far more tide gauge data in existence than is available in the public domain for research. A significant factor obstructing the release of data is that quality control of tide-gauge records is still carried out with a great deal of manual inspection, and is therefore labour-intensive. Automated systems must carefully distinguish between spikes due to instrumental error and genuine rare extreme events; and between damaged instruments and still water. The National Oceanography Centre automatic quality control software aims to enable analysis of any high-frequency tide-gauge record around the world with minimal manual intervention or parameter selection. We demonstrate the implementation in Matlab and discuss the successes and challenges of the software.