Isolated data showers: exploring nineteenth century weather observations by the first Ordnance Survey of Ireland.

Recent digitisation of major meteorological sources has offered valuable insights into Ireland's past climate. However, more localised historical weather data remain sparse for most of the country. A largely unexplored resource lies in the early nineteenth century Ordnance Survey (OS) statistical reports collected as a component of the first OS of Ireland. This paper sets out how researchers applied diverse techniques from text analysis and corpus linguistics, Artificial Intelligence, Geographic Information Science and sentiment analysis to explore the early OS weather records. Weather Journals from fifteen parish “memoirs” across seven northern counties were identified in the OS sources, providing qualitative weather observations and quantitative temperature and pressure data. The records were extracted, explored and visualised revealing localised weather insights from the early nineteenth century and shedding light on the experiences and practises of OS staff. The mixed methods employed illustrate the wider potential application of this suite of techniques to early weather diaries and other qualitative source materials, showcasing the possibilities of using a combination of data types and approaches in historic weather research, and contributing to a deeper understanding of Ireland's meteorological and survey history.