Extending Sea Level Records by Rescuing Historical Data using a Citizen Science Platform

Abstract:

Tide gauge records provide the main source of data behind the study of sea level change over the past 200 years. However, our understanding of changes in mean sea levels, tides and extremes is limited by the length of the records available. A large amount of potential data exists in libraries and archives across the world in the form of historical tidal ledgers and charts that have never been converted into digital data suitable for use in scientific studies. The Intergovernmental Oceanographic Commission’s Global Sea Level Observing System (GLOSS) has been encouraging organisations to locate, catalogue and digitise such material.

Unfortunately, the processes required to extract usable data from charts and ledgers is slow, laborious work. Promising attempts have been made to automate this using optical character recognition, but these are often hindered by changes in document formats, and hard to decipher handwriting, particularly in older records.

A possible solution is to use online citizen science platforms such as Zooniverse that bring together scientists and volunteers in projects as diverse as searching for exoplanets, investigating antibiotic resistance in tuberculosis, transcribing correspondence between anti-slavery activists, and counting penguin populations. Earlier this year, 5.25 million rainfall observations from the UK were digitised in a few weeks by about 16,000 volunteers.

Here we present our attempts to develop a citizen science project to digitise sea level data. At the time of writing the project is in active development and will initially focus on the recovery of data from about 15,000 images of ledgers recording 15-minute observations of sea level from North West England. We describe the development of the process the volunteers will undertake, the lessons learnt from early testing, and some initial results. Finally, we discuss some possible extensions of the project, including the possibility of using the platform to digitise tidal charts.