How well does the ERA-Interim reanalysis replicate trends in extremes of surface temperature across Europe?

Trends in extremes of daily maximum and minimum temperature across Europe derived from the European Centre for Medium-Range Weather Forecasts ERA-Interim reanalysis are compared against observed data. The period 1980-2011 is considered and both station series and the gridded E-OBS data are used to determine the success of the reanalysis, with indices of the numbers of days above or respectively below the 90th and 10th percentiles of daily maximum and minimum temperature used as metrics. It is shown in this paper that the ERA-Interim reanalysis data are generally very good at replicating both the seasonally and spatially varying trends in the indices across Europe. At the station level, the reanalysis data are also able to depict the observed trends remarkably well. However, the success of the reanalysis data depends on the season and the particular index considered. The reanalysis is least successful in replicating trends in the number of days exceeding the 90th percentile of maximum temperature, particularly during the summer season. The success of the reanalysis is also somewhat dependent on the time step of the reanalysis data used. Daily maximum and minimum temperatures calculated from the 3-hourly time step reanalysis data tend to be more reliable than those derived from the 12-hourly data. Key Points Trends in extremes of temperature are replicated well by the reanalysis dataTrends are replicated best in the winter and worst in the spring and summerThe 12-hour time step reanalysis data are less consistent with observations ©2013. American Geophysical Union. All Rights Reserved.