Daily rescued meteorological observations across Europe (1917-1990)

Digitizing was carried out by using a strict "key as you see" method, meaning that the digitizers type the values provided by data images, rather than using any coding system.

Digitizers carefully cross-checked the typed values against original sources for the 10th, 20th and 30th day of each month to make sure that no days were skipped or repeated during the digitizing process. Monthly totals and statistical summaries were computed from transcribed data and were compared with monthly totals and summaries provided by data sources to check accuracy as preliminary quality control. This dataset is considered as raw data since any consistent quality control and homogenisation testing were applied to identify potential errors and data biases.