Rainfall Rescue Project – bringing archived data back to life

At the Met Office National Meteorological Archive in Exeter we deal with “national climate memory”, writes Catherine Ross, Met Office archivist.

This archive consists of the millions of weather observations produced by the Met Office since its inception in 1859 and a large collection of supporting data and information from around the world.

Catherine Ross, Archivist of the Met Office, with part of the vast Met Office archive: the national climate memory. Image: Grahame Madge, Met Office

Among this trove of weather data are ten years’ worth of rainfall books, which don’t have a very good name, and are actually binders of loose sheets of paper! They possess a vast and as yet largely untapped supply of monthly precipitation data from 1677 to 1960.

The early data comes from a variety of different published and unpublished sources. Beginning in 1860, a network of observers from throughout the British and Irish Isles sent data to the British Rainfall Organization and later to the Rainfall Branch of the Meteorological Office.

Precipitation watching turned out to be popular! When George Symons established the British Rainfall Organization in 1860, there were already several hundred rain gauges and this number increased to several thousand over the next 30 years. All of them diligently cared for and monitored by volunteer observers, some of whom have dedicated many decades of their lives to the careful collection of rainfall data.

One challenge in using the data is that each folder contains ten years of data for each season, so you have to go through each folder to find all the data in one place. Therefore, the data series was a perfect candidate for scanning into the file. One year and 66,000 sheets of paper later we had plenty of digital images uploaded to our Digital Archive and Library, but to get the most out of them, the data still needed transcription.

That’s where Ed Hawkins, the Zooniverse platform, and the RainfallRescue.org site came in. The nationwide lockdown in March 2020 also provided a sudden supply of people with free time on their hands and an incredible 16,000 volunteers transcribed the 66,000 pages (containing 5.28 million numbers) within 16 days.

In fact, each issue was transcribed four times for quality control, so the 16,000 volunteers actually transcribed 21 million observations, and with the additional collection of location information, the total number of keystrokes is estimated to be 100 million!

It was great to see the work of the 2020 volunteers reviving the records of those volunteer observers from the 18th, 19th and early 20th centuries. After a rigorous verification process by a team from Reading, the Met Office and eight dedicated volunteers from the original project, much of that data was added to the Met Office’s official national climatic precipitation series. Rainfall Rescue now accounts for 84% of the monthly observations in the HadUK-Grid for 1836 – 1960.

UK annual rainfall statistics

UK annual rainfall statistics.

From this work, we now have a record of rainfall variations and trends across the UK since 1836. To understand the risks of climate change and extreme weather events, we need to understand the past. Rainfall in the UK is notoriously variable, we are an island nation prone to both floods and droughts. Therefore, to capture past extremes we need extensive historical climate records. The figure below shows the averaged annual rainfall across the UK since 1836. An overall increase in rainfall is evident, but the driest year in the series is 1855 and the wettest 1872 with new data allowing us to map these extremes. in more detail than ever.

Driest and wettest years in the UK rainfall record.

All of this work has not only been accomplished incredibly quickly, it has also broken the definition of what constitutes a log file. In its life cycle, a document goes from being a record, in everyday use, to a file where it is kept as part of a memory, in our case, the climate memory. The 66,000 number sheets certainly count as that, but in their new transcribed form, the same numbers are “living a new life” as part of data sets available for daily use by scientists at the Met Office and around the world. . It’s a bit like a parallel universe for files! We think this is great, but we also love the fact that this data goldmine is now back in the hands of the scientists who need it.

You can read more about the project in our press release here.

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