Transcribing historical Canadian weather data

Abstract Historical weather journals from across Canada, spanning 1768–1884, have been transcribed from handwritten records into machine readable formats. The NORTHERN (Nineteenth-century Overseas Records Transcribed for Historical Environmental Reconstruction in the North) project transcribed nearly 2 million weather observations from 46 locations. The original documents are in archives outside Canada. The two principal archives investigated for historical Canadian weather are the United States’ National Administration and Records Archives (NARA) and the United Kingdom’s Meteorological Office (UKMO) Library and Archives. Some observations were also located in the United States’ National Centers for Environmental Information (NCEI) “Forts” dataset. Observers recorded from three to twenty weather variables, in most cases two or three times daily. Validation procedures are carried out with export files produced in both the original format and in modern units. Observations of pressure, temperature, precipitation, snow depth, cloud cover, cloud type, wind direction and wind force are transcribed along with detailed descriptions of events including fires, floods, ice formation and break up, storms and other weather phenomena. The value of these data lies in their detailed observations of sub-daily weather together with descriptive observation of disruptive or extreme weather events. These data will be used to expand knowledge of Canada’s climate variability and extreme values for three centuries and to improve global reanalysis data products.