Operational homogenization of daily climate series in Spain: experiences with different variables

Abstract

Calculation of the new climatological standard normals for the period 1991– 2020 was a motivation to carry out the homogenization of the required climatic variables in the Spanish Meteorological Agency (AEMET). The national observation network has undergone changes along its history that often introduce non-climatic interferences to the series. On the other hand, for the calculation of various parameters and climatic indices, it is essential to have complete daily series. With this in mind, homogenization of daily series of precipitation, maximum and minimum temperatures, sunshine hours, relative humidity, station level pressure, mean wind speed, and maximum wind gust was carried out. This paper shows how the homogenization process was performed, covering the period 1975–2020 with carefully selected daily data sets from the national climatological database. The homogenization software Climatol v.4.0 was used for this process, and derived variables such as average temperature, sea level pressure, and vapor pressure were calculated from their related homogenized series.