The long-term temperature record from Markree Observatory, County Sligo, from 1842 to 2011

Abstract

This study analysed long-term temperature patterns in the north-west of Ireland using a previously unexplored data-set from Markree Observatory, County Sligo. The Markree series extends back to 1842, making it one of the longest instrumental temperature records in Ireland and is renowned for holding the lowest recorded temperature for the island of Ireland, −19°C on 16 January 1881. Despite its length, this record has been largely absent from past analyses of Ireland's long-term temperature trends, rendering spatial coverage for the extended Irish climate chronology incomplete. Daily data stored in a variety of the historical archives were gathered and digitised and monthly records created. Calibrations to account for instrumentation, time of reading and exposure were applied where possible in order to standardise the record. Trends were subsequently investigated for seasonal averages of daily minimum, maximum and mean temperatures, and a comparison with previously published long Irish temperature records was carried out to situate the Markree record among the existing long-term series. Although the Markree series follows similar patterns to the other long-term temperature records, it displays more decadal variability, particularly in its minimum values which show a higher rate of late twentieth-century warming compared to the other records. Due to its geographic location and surrounding topography shielding the site from direct ocean influences and prevailing south-westerly winds, Markree displays characteristic features of a more inland station (low minimum temperatures and large diurnal ranges) even though it is located only ~7 km from the Atlantic Ocean. Such findings highlight the necessity of including the Markree data-set in future Irish climate change research.

Keywords:

• Markree
• temperature
• calibration
• Ireland
• climate change

Acknowledgements

We would like to thank Met Éireann for permission to examine the original meteorological documents and for supplying the modern automated weather data, with a special thanks to Mairead Treanor, Librarian. We are grateful to John Butler for his helpful comments and suggestions. We would like to thank the Ryan Institute, National University of Ireland Galway, for access to Ordnance Survey Ireland vector data. We would like to thank the Royal Astronomical Society for permission to reproduce Figure 2. Thanks also to Dr Stephen Galvin for providing the westerly wind data, and Carlos Chique for help in producing Figure 1. Funding for this project was provided by the National University of Ireland Galway, Arts Faculty Travel Bursary.