Climate reanalysis is a systematic approach used to produce meteorological datasets for climate monitoring and research. They are created using a fixed version of a forecast model and a data assimilation system which utilises historical observations and they produce parameters that are physically consistent and often not routinely observed. Thus, climate reanalyses have the potential to extend the knowledge gained from current observation networks.

Met Éireann has carried out a 35-year very high resolution (2.5 km horizontal grid) regional climate reanalysis for Ireland using the ALADIN-HIRLAM numerical weather prediction system (www.hirlam.org). This reanalysis spans the period 1981 to 2015 and includes surface, near-surface and atmospheric parameters and is the first of its kind for Ireland.